Out With the Old Blood

There is great promise in 2020 that we might be able to make our bodies young without having to explicitly repair molecular damage, but just by changing the signaling environment.

Do we need to add signals that say “young” or remove signals that say “old”?

Does infusion of biochemical signals from young blood plasma rejuvenate tissues of an old animal? Or are there dissolved signal proteins in old animals that must be removed?

For a decade, Irena and Mike Conboy have been telling us removal of bad actors is more important. But just last month, Harold Katcher reported spectacular success by infusing a plasma fraction while taking away nothing. Then, last week, the Conboys came back with a demonstration of the rejuvenating power of simple dilution. [Link to their new paper]

Dilution procedure

They simply replaced half of the blood plasma in 2-year-old mice with a saline solution containing 5% albumin. What is albumin? Blood plasma is chock full of dissolved proteins, about 10% by weight. About half of these are termed albumin. Albumin is the generic portion. It doesn’t change through the lifetime. It doesn’t carry information by itself. But albumin transports nutrients and minerals through the body.

The Conboys took care to show that albumin has no rejuvenation power on its own, and had nothing to do with their experimental results. Rather, they had to replenish albumin in diluting blood, because the animals would be sickened if half their albumin were removed. Replacing the albumin in a transfusion is akin to replacing the volume of water or maintaining the salinity.

In preparation for this experiment, the Conboys have invested years in miniaturizing the technology for blood transfusions, so that mice can be subjected to the same procedures that are commonplace in human hospitals.


The Conboy lab replaced 50% of mouse blood plasma. They got spectacular results with a single treatment, based on a lucky guess. They have not yet experimented with 30% or 70%. They don’t know yet how long the treatment will last and how often it needs to be repeated.

Evidence of rejuvenation

As with previous papers from the Conboy lab, the group focused on repair and stem cell activity as evidence of a more youthful state. Three separate tissue samples were taken from liver, muscle, and brain.

“Muscle repair was improved, fibrosis was attenuated, and inhibition of myogenic proliferation was switched to enhancement; liver adiposity and fibrosis were reduced; and hippocampal neurogenesis was increased.”

  • They measured nerve growth factors in the brain, and detected a more robust response, typical of young mice
  • They lacerated muscles and showed repair rates typical of much younger animals
  • They examined microscope slides of liver tissue, and showed that it is less fatty and striated than is typical of older mice

Figure 2. Rejuvenation of adult myogenesis, and albumin-independent effects of TPE. One day after the NBE, muscle was injured at two sites per TA by cardiotoxin; 5 days later muscle was isolated and cryosectioned at 10 µm. (A) Representative H&E and eMyHC IF images of the injury site. Scale bar = 50 µm. (B) Regenerative index: the number of centrally nucleated myofibers per total nuclei. OO vs.ONBE p = 0.000001, YY vs ONBE non-significant p = 0.4014; Fibrotic index: white devoid of myofibers areas. OO vs ONBE p = 0.000048, YY vs YNBE non-significant p = 0.1712. Minimal Feret diameter of eMyHC+ myofibers is normalized to the mean of YY [9]. OO vs. ONBE p=3.04346E-05, YY vs. YNBE p=0.009. Data-points are TA injury sites of 4-5 YNBE and 5 ONBE animals. Young and Old levels (detailed in Supplementary Figure 1) are dashed lines. Representative images for YY versus YNBE cohorts are shown in Supplementary Figure 6. (C) Automated microscopy quantification of HSA dose response, as fold difference in BrdU+ cells from OPTI-MEM alone (0 HSA). There was no enhancement of myogenic proliferation at 1-16% HSA. N=6. (D) Meta-Express quantification of BrdU+ cells by automated high throughput microscopy for myoblasts cultured with 4% PreTPE versus PostTPE serum and (E) for these cells cultured with 4% of each: PreTPE serum + HSA or PostTPE serum + HSA. Significant increase in BrdU positive cells is detected in every subject 1, 2, 3, and 4 for TPE-treated serum (p=0.011, <0.0001, <0.0001, 0.0039, respectively), as well as for TPE-treated serum when 4%HSA is present (p<0.0001, <0.0001, <0.0001, =0.009 respectively). N=6. (F) Scatter plot with Means and SEM of all Pre-TPE, Post-TPE, +/- HSA cohorts shows significant improvement in proliferation in Pre TPE as compared to and Post TPE cohorts (p*=0.033), as well as Pre+HSA and Post+HSA cohorts (p*=0.0116). In contrast, no significant change was observed when comparing Pre with Pre+HSA (p=0.744) or Post with Post+HSA (p=0.9733). N=4 subjects X 6 independent assays for each, at each condition. (G) Representative BrdU IF and Hoechst staining in sub-regions of one of the 9 sites that were captured by the automated microscopy. Blood serum from old individuals diminished myogenic cell proliferation with very few BrdU+ cells being visible (illustrated by one positive cell in Pre-TPE and arrowhead pointing to the corresponding nucleus); TPE abrogated this inhibition but HSA did not have a discernable effect.

What’s missing? They did not test any measures of physical or cognitive performance at the level of the organism.

  • Evidence of behavioral changes (learning and memory, endurance, strength)
  • Inflammatory markers
  • Blood lipids
  • Methylation clock (Horvath, UCLA) or proteomic clock (Lehallier, Stanford)

Some of this is planned for future research. Mike and Irina plan to submit tissue samples for analysis by the Horvath mouse methylation clock.


I am a committed enthusiast for the methylation and proteomic clocks that are the best surrogates we have for aging. These technologies can tell us whether anti-aging interventions have been effective without having to wait for animals (or humans) to die before reporting results. But the Conboys still regard these technologies as unproven, and they bristle at the word “clock”.  The closest they come is to catalog the entire proteome of treated mice, comparing it to untreated young and old mice.

Multi-dimensional t-SNE analyses and Heatmapping of these data revealed that the ONBE proteome became significantly different from OO and regained some similarities to the YY proteome. Supplementary Figure 4 confirms the statistical significance of this comparative proteomics through Power Analysis, and shows the YY vs. OO Heatmap, where the age-specific differences are less pronounced than those between OO vs. ONBE, again emphasizing the robust effect of NBE on the molecular composition of the systemic milieu.

Translation: As controls, they had mice that underwent plasma exchange with mice of similar age. YY were young, positive controls, and OO were old, negative controls. Treated mice were ONBE=”Old—Neutral Blood Exchange”. Rather than relying on “clock” algorithms that compute an age from the proteome, they compared the entire proteomes of test animals with those of old and young animals, and foud that they resembled the young animals more closely.

Aging and epigenetics

I was an early advocate of the theory that aging is driven primarily by changes in epigenetics. Other proponents include JohnsonRando, and Horvath. This theory is now mainstream, though its acceptance is far from universal. (The main reason people have difficulty with the idea is the question, “why would the body evolve to destroy itself?” I present a comprehensive answer in my popular book and my academic book.)

On the face of it, the new Conboy result is powerful evidence for the epigenetic theory. They have shown that there are proteins in the blood that actively retard growth and healing. Remove half theses proteins and the animals are able to grow youthful tissues and to heal better. The obvious conclusion is that, with age, there are signaling changes in the blood that weaken the animal and inhibit repair.

There are, however, other ways to interpret the changes. Aubrey de Grey has said (personal communication)

“When everything in the blood except the cells and the albumin is replaced by water, the body will definitely respond by synthesising and secreting everything that it detects a shortage of, whereas the bad stuff will not be so rapidly replaced, since by and large it was only there in the first place as a result of impaired excretion/degradation.”

The Conboys don’t embrace the programmed aging perspective, but neither is their understanding of what they see the same as Aubrey’s. The way Irina explained it to me is that the age of the biological of the body is simply a measure of how much damage has accumulated, but that cycles of epigenetics and catalysis are self-reinforcing.

“Epigenetic, mRNA, and protein are steps of one process, regulation of gene expression. And none of these steps are permanent they all actively and constantly respond to cell environment &mdash; tissue and systemic milieu…With aging there is a drift which is re-calibrated by a number of rejuvenation approaches…When an auto-inductive age-elevated ligand is diluted, it cannot activate its own receptor and induce its own mRNA, so ligand levels diminish to their younger states for prolonged time.”

The Conboys theorize that these harmful proteins are part of a positive feedback loop, in other words, a cycle that is self-sustaining

epigenetic state ⇒ gene expression ⇒ translation to circulating proteins ⇒ feedback that alters the epigenetic state

With age, the body has slipped into a dysfunctional, self-sustaining cycle, and with the shock of disruption, they are able to nudge it back into a more robust and youthful cycle, also self-sustaining.

Figure 6. Model of the dilution effect in resetting of circulatory proteome. System: A induces itself (A, red), and C (blue); A represses B (green), C represses A. A dilution of an age-elevated protein (A, at D1: initial dilution event), breaks the autoinduction and diminishes the levels of A (event 1, red arrow); the secondary target of A (B, at event 2 green arrow), then becomes de-repressed and elevated (B induces B is postulated); the attenuator of A (C, at event 3 blue arrow), has a time-delay (TD) of being diminished, as it is intracellular and was not immediately diluted, and some protein levels persist even after the lower induction of C by A. C decreases (no longer induced by A), and a re-boot of A results in the re-induction of C by A (event 4 blue arrow) leading to the secondary decrease of A signaling intensity/autoinduction, and a secondary upward wave of B (events 5 red arrow and 6 green arrow, respectively). alpha = 0.01, kc = 0.01, beta = 0.05, epsilon = 0.1, ka = 0.1. Protein removal rates from system: removalA = 0.01, removalB = 0.1, removalC = 0.01, Initial values: initialA = 1000, initialB = 400, initialC. = 700

For me, the surprising thing in Irina’s account is that there is no hysteresis in this system. The reprogramming responds to changes in the blood levels of signals within minutes. It is difficult for such a system to be homeostatic. I wonder how that can be. Life is all about homeostasis, and intuitively, we all imagine that negative feedback loops are more common than positive feedback loops. (Negative feedback loops lead to homeostasis; positive feedback loops lead to runaway, exponential change.)

Is there a clock somewhere? Is the brain special?

In the Conboy view, signals in the blood are emitted from all over the body, and not especially from the hypothalamus. If brain tissue responds in a seemingly exceptional way to proteins in the blood, it is because of selective passage of those proteins by the blood-brain barrier.

The authors remind us that in past parabiosis experiments (where blood is exchanged between old and young mice), the brain tissue of the young mice grew older but brains of the old mice didn’t get younger. This was an indication that brain aging is caused by affirmative action of “bad actors” in the plasma, and that these are able to penetrate the blood-brain barrier. This observation was part of the inspiration for the current experiments.

The corresponding procedure in humans is already FDA approved

Therapeutic Plasma Exchange (TPE) is a well-established medical procedure, and has already been performed on an experimental basis by co-author Dobri Kiprov. There is anecotal history of suggestive results, which I will write about in my next post.

Comparison with Katcher’s Elixir

This week’s announcement from the Conboys and last month’s preprint from Katcher/Horvath come from the same school of thought: that aging is coordinated through the body by signal molecules in the blood. Both demonstrated dramatic rejuvenation in rodents based on a short-term intervention, and both have plans for commercialization and human trials to begin ASAP.

So it is curious that in other ways, the programs of Katcher and Conboy are so different.

  • While both approaches are rooted in differing compositions of blood plasma between young and old, the Conboys focus exclusively on removing species that are inhibiting youthful regeneration, while Katcher’s approach is to add back the proteins that formerly kept the animal young.
  • The Conboys have fully disclosed all aspects of their experimental protocol, whereas the content of Katcher’s elixir remains a trade secret.
  • Katcher is on the fringe of academic research, and the Conboys’ lab is at one of the premier academic institutions in the world.
  • Katcher is a year further along, having experimented with different dosages and timings. Neither Katcher nor the Conboy lab has yet demonstrated life extension.
  • The Conboys demonstrate rejuvenation with wound healing, tissue structure, and renewal of nerve growth. Katcher’s claim is based on physiology (especially inflammation), cognitive performance, and methylation clock algorithms.
  • In fact, Katcher regards restoration of youthful methylation patterns as the best evidence he could offer for rejuvenation (I agree), while the Conboys are reserving judgment about the importance of methylation, and bristle at the language of a methylation “clock”.
  • Katcher understands the effects of plasma transfusions in terms of a broad theory (which I support). Aging is an epigenetic program, governed and enforced by a “clock” that operates via a feedback loop between circulating proteins that govern gene expression and gene expression that generate those proteins. The Conboys recognize they are working this feedback loop (their Fig 6) but they resist the theory that it is the essential cause of aging.

My guess is that a combination of their two approaches will be necessary for full remediation of aging, and that a combination of their resources, credibility, theoretical foundations, and contacts would be a transformative event for medical science, for biotech industry, and for biological theory. It is my fervent hope that Katcher and the Conboys might work together.

218 thoughts on “Out With the Old Blood

  1. I side with the Conboys in bristling at use of the word “clock.” A “clock” is a kind of oscillator. Where’s the oscillator of the Horvath “clock”?

    • An hourglass is also a clock, and afaics doesn’t oscillate, merely progresses in its time course measuring time. Anything that can show progression, such as a sun dial or even the rotting time of a particular food in a particular environment can be used as a clock.

    • What is the point of politics and semantics in research?

      Why not simply all work together on this important research, no matter what it is called, and agree to disagree about the labels.

      • An ‘hour glass’ would be more appropriate – because a clock doesn’t run out (especially these days). But an ‘aging hour glass’ isn’t exactly catching terminology, so ‘aging clock’ it is. Anyone with two neurons to rub together will get the general idea.

        Why? Because I said so 😉

  2. One of the moderators of the lifespan IO discussion said that the Conboy’s agreed to try and replicate Harolds results. Is that true?

  3. Hi Josh, a bit more than 10 years ago, I wrote to Aubrey de Grey telling him that I believed I could reverse aging. My ‘technique’ (published in 2013) I called (and was the first to do so and to publish on it) was called ‘Heterochronic Plasma Exchange, HPE, and I thought that by replacing all old plasma (99%) with ‘young’ plasma (a standard medical procedure, I would get rid of all the aging factors in the old plasma (just as the Conboys claim) plus, return the youth-promoting factors to the old body, under the assumption that there were age-promoting (like eotaxin, Villeda’s work) agents and there were ‘youth-promoting’ agents. It seems that I was correct about both. At this point, I’d probably like to try a combination of albumin (the NORMAL exchange fluid for a plasma exchange) solution with a shot of Elixir – but, probably not as Elixir can do much better by itself and doing a plasma exchange would offer unnecessary risk and cost more.

  4. Oh sorry, I’ll check before I hit ‘reply’ but I just wanted to say, I offered this to anyone, and expressed my willingness to cooperate – and now, unless somehow off-the-shelf albumin is better than young plasma, we KNOW that my HPE technique WOULD HAVE WORKED! So Aubrey missed that opportunity (and I offered it – and it was also suggested HPE to the Conboys AT THAT TIME (and I have the correspondences) and they sort of laughed it off and made some statement about platelet-rich plasma having healing effects, as I recall (for me it was exciting – the thrill is gone). So, nothing that I haven’t thought of and done much better a long time ago.

  5. Josh always likes to leave out the first paper that I wrote in 1998 which was kind of a mess but was the first to predict and go into detail as to how DNA methylation was invloved in controlling aging. The term epigentics had barely been used at that point so that is why you will see Josh’s and Rando’s papers as being the “early ” ones to promote epigenetic control of aging in 2012 and 2013….if you search epigentics and aging…the word “epigentics” was not widely used back in 1998 when my paper came out-I had not head of it… I asked Pub Med to add the word epigentics to the keywords of my paper but they refused.
    I had put out this idea way back in 1998 in “The Evolution of Aging – A new Approach to an Old Problem of Biology…kind of a mess but it made many predictions which came true including Luteinizing hormne would be found implicated in causing Alzheimers disease whch was confirmed by the NIH in 2006 (see below).
    Everyone told me that idea was crazy! Lots of laughter!!!

    And before me, concerning epigentics, there was a guy named Alexander Mazin who years before my paper had noticed the correlation between DNA methylation and the Hayflcik limit. (That was my big clue) He beat Rando and Josh by years when he published>>>
    “Suicidal function of DNA methylation in age-related genome disintegration and presents a very dark view of DNA methylation as possibly being at the heart of the aging process.” in May of 2009.

    And I correspomded wit Josh back in `1998 just when he was cutting his teeth in aging research, I had been at it full bore for about 10 years by then, and he actually said he did read my paper back then but I don’t think he understood it . In one paper of his he referred to it as of uneven quality (that was being generous I admit) but full of gems of evolutioanry wisdom…finally in 2013 he rediscovered the DNA metylation idea that he had read about in 1998..isn’t that true Josh? So when he calls himself an early advocate….I kind of have to laugh…What took so long!!??? Why such a later advocate is my querstion..

    So a little credit where credit is due….

    And I had a paper published in 2000 that predicted that chromtin condensation and its associated proteins woudl also be found to be involved in controllnig aging…via gene silincing

    Anyway since Josh didn’t add this thuoght I would let’s see if josh let’s this go through….
    .2006 Apr;29(2):257-69. doi: 10.1385/ENDO:29:2:257.
    The Role of Gonadotropins in Alzheimer’s Disease: Potential Neurodegenerative Mechanisms
    Anna M Barron 1, Giuseppe Verdile, Ralph N Martins
    Affiliations expand
    PMID: 16785601 DOI: 10.1385/ENDO:29:2:257
    In addition to the classical role of gonadotropins as a modulator of sex hormone production, it is now becoming apparent that the gonadotropins may have actions within the central nervous system. Evidence is also mounting that age-related increases in levels of the gonadotropin, luteinizing hormone (LH), may exert neurodegenerative effects such as those seen in Alzheimer’s disease (AD).

  6. And I also wonder why they didn’t use rats instead of mice?? Much bigger veins to work with and they dont stink like mice!!

  7. well thank you josh….for allowing my post…

    do you have any comments on it?

    did I miss anything? do you disagree with anything in it??

  8. Happy to see another systemic approach succeed. For very long aging was being approached like cancer therapies. Aimed at individual aspects of a very complex problem. Thats why we did not succeed in cancer. Ditto with aging.
    While we like the Conboys – had a great lunch together recently – it would be difficult to collaborate as there are fundamental differences in our understanding of aging which would sooner or later affect the research decisions. Its the classic case of the blind men and the elephant. Each one is so wedded to their view of aging. Secondly we are on our way to file with FDA for a commercial product so its like asking Alkahest to collaborate with the Conboys. There will be and there should be multiple therapies that systemically reverse aging – all originating from the parabiosis done by Conboys – but the one that will succeed as a product in the marketplace will need to have FDA approval, have scalability to meet demand and be reasonably priced. Anyway its all good news for the longevity enthusiasts hopefully soon there will be option available to become young again at a price of our annual cable TV, data and streaming subscriptions.

  9. Non-scientific layman’s perspective here: This is all very fascinating but I don’t expect a pertinent commercially available treatment anytime soon. I’ve seen too many promising scientific white papers subside into oblivion in my time and I’m no spring chicken. At least Harold Katcher and Akshay Sanghavi are actively working on actually commercializing a treatment/product we all may benefit from.

    To lend from the play book of the U.S. Federal Reserve over the past decade of quantitative easing: Until a cure for aging can be found the name of the game for life extension science is to kick the can of mortality down the road. After all – the PERFECT FDA approved treatment won’t do me any good if I’m resting six feet under.

    • Well said Michael and agree completely. The analogy with The Fed kicking the can down the road is an apt one. Hopefully the Elixir and gel patch being developed by Harold & team is the real deal.

  10. So I’m looking at this from outside the field of Biology (I’m a physics teacher), and I observe that some experts seem to be thrilled by the lab results. I wonder if it’s too early. No mice or rats have been shown to live longer (yet). No human results. I know you can cure almost anything in animals, but the results seldom translate to humans. Could this happen here? Also, a scenario where almost everything in the body is rejuvenated, but where a crucial component is not, leading to death at the usual age, might that be a possibility?

    • I agree with you on most points except your concern of death still occurring at the ‘usual age’. To be honest if I could pop a pill that gets me to 90 years of age looking and feeling 35 I’d be elated. Consider for a moment that we spend almost 50% of our lives being considered ‘old’ or ‘over the hill’. If nothing else this has always been my main motivator for interest in life extension. Plus it’s much easier to fix or maintain a small handful of life threatening conditions than dozens or hundreds. Entropy is a cruel mistress and in the end she gets us all.

      Finally, per my ‘kicking the can down the road’ comment: It doesn’t matter if any currently available treatment fails to extent life indefinitely. The goal for the next 10 to 20 years should be to arrest aging as much as possible until the science has matured sufficiently to offer us a real cure.

      • Yes you are right of course. I haven’t yet been hit by an old body (I’m 45), so that wasn’t on my mind.What I am trying to say is, as mentioned elsewhere, it sounds (way) too good to be true. I have been sure that it would be like this: Gradually you could slow aging to a crawl, hopefully before you get too old. And then new therapies would reverse aging and make you younger. Nothing like this should be here already.

      • “I agree with you on most points except your concern of death still occurring at the ‘usual age’. To be honest if I could pop a pill that gets me to 90 years of age looking and feeling 35 I’d be elated. Consider for a moment that we spend almost 50% of our lives being considered ‘old’ or ‘over the hill’.”

        Even if a magic pill got you to 90 years of age looking and feeling 35, your actions and the reactions of those around you (with the exclusion of the passer-by who isn’t aware of your chronological age) aka your life wouldn’t be all that different.

        Think about it: an actual 35 year old isn’t keen on marrying someone who will kick the bucket in a couple of years, so feeling young without added life expectancy is only a notch up from cosmetic surgery.
        And it goes on, because no bank would give an 87 year old – no matter how good and strong he looks – a mortgage; and who would hire someone with just a couple of career years left? Not to mention that the octogenarian in question is unlikely to invest in time consuming and almost certainly dead-end (given how little he has left) ventures such as, say, acquiring a PhD.
        Until we can add extra decades to our current lifespan we will be considered “over the hill” even if we look like a million bucks.

        Finally, in my opinion an 87 year old who feels invincible but knows that his days are numbered is in for a much bigger psychological trauma than an 87 year old whose brain has started winding down and whose body doesn’t crave the stimuli of youth. It’s about what you have to lose, and there’s a good reason why a thirty year old finds it much harder to welcome the Grim Reaper than his grandfather does.

        • Hi, Barabara:
          Like Michael Mehrle, I also would be extremely happy if such a pill existed. Of course, this is a highly hypothetical situation. But it is still useful to think about such a situation.

          You have some concerns such as:
          Would a 35-year-old marry a 90-year-old? Maybe not. But this 90-year-old would be quite satisfied marrying a 90-year old that looked and acted as 35 years old. Or maybe no need to marry. Just have a good time with the person. I could even think of possibilities that a 35-year-old would be eager to marry a 90-year old that looked and acted 35, and in a couple of years would leave a good inheritance.

          Would a bank approve a mortgage to a 90-year-old person, if he / she is expected to die in a few years? Possibly not. But also there would be no need to buy a house. This person could rent for a few years.

          Would a 90yr old try to get a PHD? Most likely not for a career. Because there is no need for it. But if this person has strong interest in the subject, maybe yes.

          I am sure society will adjust to any new situation.

          I personally believe this outcome is very unlikely. If a pill gives us 10-20 years of healthy life, science will find another pill, that will give us even more. In other words, I expect that at some point we will reach Longivity Escape Velocity. I just am not sure if I will be arround when that is reached.

          • Zisos replying to your last line of your reply:
            You will surely be around when this happens. Its round the corner.

          • We are all rooting for you Akshay – please keep up the good work.

          • Hi Akshay:
            I am not a pessimist. Quite the contrary. I had hope that your elixir will be available early enough for me to reach LEV. With this statement of yours, I don’t just have hope. I am convinced. And that is a great feeling. It means that I can dream about the future the same way as when I was 30 years old, instead of dreading the problems of old age that were sure to come if no such intervention was possible. In the meantime, I am trying my best to remain healthy (including your suggestion of resveratrol / pterostilbene / andrographis a few times per week). Thank you.

          • All these are excellent philosophical questions which we are unfortunately unable to answer at this point. It’s a waste of time to think about problems/issues we would like to have but aren’t even close to having yet. Plus consider that we as human beings have a tendency to think mostly linear which makes it very difficult to project forward.

            That said if such a treatment existed (hint hint) then it’s not just that our physiological appearance and our well being would change. Society would rapidly change along with it. Whether or not a 90 year old would want to marry a 25 year old or the other way around is hard to predict. I can imagine pluses and minuses in such a relationship. I am very happily married for 20 years now and most definitely can imagine spending another half century with my lovely wife. Maybe she’ll be sick of me by then, who knows – only one way to find out 😉

            Of course the way we are wired and the way our biology has been wired was originally based on us shuffling off this mortal coil around 35. Now most of us live to 80+ and then some. Society as a whole has rapidly adjusted – not always for the better but we are a very adaptable species and I am confident that we will continue to adapt.

          • In 2019 I wrote about the economic benefits to society directly stemming form anti-aging advancements. ( https://medium.com/@touche/affordable-global-universal-healthcare-f7caab0a0114 ) Younger individuals have dramatically lower healthcare cost and that benefit would extend to old individuals who undergo regenerative treatments. Lower healthcare cost will benefit the entire spectrum of healthcare providers and payees including you. Sociological, psychological and economic issues aside, not being sick or even just fatigued would be an amazing improvement to the quality of life of anyone over 50. If I can’t get a bank loan at least I will have the stamina to continue being a productive participant in life, or just rob that dam bank ;√).

        • Barbara – if a 90 year old would look and feel like a 35 year old I can easily imagine a bank granting him/her credit. But I gotta tell you – if a 90 year old actually NEEDS to apply for credit without being able to offer collateral then he or she has really not done very well for himself/herself. Compound interest is a mathematical reality that is able to turn almost anyone into a millionaire within a 50 year timeframe. The problem we all face today is that many of us don’t expect to live long enough to enjoy the fruits of compound interest and long term investments.

          It’s easy to focus on the negative when there are many positives to long life and that’s not even counting experience, contacts, personal relationship. Not to brag but I have learned so much in the past 20 years that I sometimes look back and wonder what a damn idiot I was back as a young buck. I can only imagine all the things I would learn, know, and be capable of doing should I be so lucky to count another 50 active years with my mental and physical capacities intact.

    • Martin,
      I would agree with you that many therapies that work in mice do not translate as well in humans but almost all of them are synthetic or a biosimilar derivative of a natural. We are using Nature’s own technology to keep us healthy when we are young. Regarding your 2nd question until a intervention is successful and can get specific at transcriptional level aging program is going to continue if treatment is not administered regularly. With regards one part being left out: our system is pretty interconnected: even a single successful intervention like CR has ripple effects. So upon treatment there is no reason why a youthful health can not be achieved from what we know so far. Of the top 10 causes of death in world 9 are aging related. One can still die of infection or bad lifestyle.

    • Although I’m just another amateur in biology (I’m an IT guy), following this stuff pretty closely puts me in the “thrilled” camp because: (1) senolytics have extended rodent lifespan, (2) Harold’s Elixir caused a remarkable decrease in senescent cells (which probably rivals the importance of the Horvath clock changes), and (3) this was confirmed by precipitous drops in IL-6 and TNF-alpha (etc) within 8 days which are reliable SASP markers. So the Conboy’s results are interesting but not entirely surprising, and considering the short trial length (6 days for some measures) it’s primarily interesting in terms of mechanism, less interesting in terms of therapy.

  11. When I am reading all this I am scratching my head: It sounds too good to be true to “reverse aging”. As a “normal” GP MD, I can’t fathom how the bofy could “rejuvenate” virtually thousands of parts in the body which get degraded and dysfunctional over the course of normal aging.
    Heart valves, cartilade, restricted blood vessels, accumulated debris virtually everywhere inside the body, cholesterol depositions, lesions, you name it. We still do not have a clue on how to reverse atherosclerosis, especially in older folks.

    I hope I am wrong or just plain ignorant but I simply can’t see how any of these problems can be solved in the foreseeable future.

    • The more upstream is the treatment the more global will be the changes. For example debris: there tools like autophagy mitophagy which recycle and clean up the debris. Their efficiency goes down as we age but if one can bring back their efficiency they will again clean and recycle everything.

    • In the brain, it is known there are superagers with little to no degeneration and youthful cognitive function. It is likely similar exists regards the other organs of the body.

      For those who have had degradation of tissues, the damage may be repairable by rejuvenation, up to an unknown degree.

      For heart valves, one of the issues, calcification might be reversible through vitamin k2, it might even be delayed or preventable by adequate k2 supplementation.

      Regards atherosclerosis. It is still preliminary, and perhaps a bit controversial, but if I’m not mistaken both pomegranate as well as nattokinase appear able to significantly reverse it

  12. Josh,

    Good to see you back on the anti-aging track. 🙂

    This may be somewhat of a dumb question, but anyway…

    Blood plasma certainly is highly influenced by what is going on in the gut microbiome. There is a Quanta Magazine article out there that discusses some studies showing the sleep deprivation kills not by its effect on the brain but its effect on the gut. There is also evidence of changes in gut microbiome are associated with aging. Almost all of the foods we associate with anti-aging (fresh fruits,vegetables, whole grains, etc) also seem have positive effects on the guit microbiome. Fasting alters the gut microbiome.

    Is there a way of potentially altering blood plasma by altering the gut microbiome?

    • To add briefly to my reasoning above.

      Does the signal go from the brain to the gut to the plasma? And most of the current interventions – caloric restrictions, fasting, even metformin (recently shown to have effects on microbiome of gut) etc. are primarily working by slowing or modifying the signal through modifying the microbiome of the gut?

    • James:

      I just thought I would note that in the sleep deprivation study, where animals died from sleep deprivation, the animals that were given antioxidants did not die.

      Here is a link to the Harvard.edu article


      Portion from the link:
      “When fruit flies were given antioxidant compounds that neutralize and clear ROS from the gut, sleep-deprived flies remained active and had normal lifespans. Additional experiments in mice confirmed that ROS accumulate in the gut when sleep is insufficient”

      and more…

      “Even more surprising, we found that premature death could be prevented. Each morning, we would all gather around to look at the flies, with disbelief to be honest. What we saw is that every time we could neutralize ROS in the gut, we could rescue the flies,” Rogulja said.

      • Heather
        It’s very fascinating. Why does sleep deprivation cause such an amazing amount of ROS in the gut ? Is it from microbial mitochondria ? And how is it killing them with All tissues appearing totally normal on biopsy ? Can they now survive with absolutely no sleep just by continuously neutralizing ROS ? Maybe Blagosklonny is right that we’d all die from ROS except that mTOR gets us first.

        • Paul Rivas:

          I agree: Maybe Blagosklonny is right that we’d all die from ROS except that mTOR gets us first.

          It is also interesting that Modafinil/Provigil a drug that keeps people awake iss an inducer of the CYP34A enzyme.

          Cytochrome P450 3A4 (abbreviated CYP3A4) is an important enzyme in the body, mainly found in the liver and in the intestine. It oxidizes small foreign organic molecules (xenobiotics), such as toxins or drugs, so that they can be removed from the body.

          James Cross:

          All good thoughts: Hippocrates is famously quoted as saying “All disease begins in the gut.”

      • Heather,

        I’m thinking that possibly gradual dysfunction in the intestinal lining, perhaps in epithelial stem cells, leads to a whole body inflammation reaction and the cascade of other changes in aging. The sleep deprived flies have essentially the same problem but antioxidants can mitigate the effects because there is still sufficient reserve capacity in the cells. Caloric restriction, fasting, and alteration of the microbiome also provide a temporary mitigation that allow the cells and tissue to degrade more slowly.

        Anyway, just thinking.

  13. For those who bristle at the phrase “epigenetic clock”, how about just changing it to “epigenetic state”?

  14. Would the biologists among us please explain to me why tha following is wrong:

    1. All proteins in the cytoplasm will eventually break down or be consumed or whatever.

    2. Therefore, if a signaling mechanism is introduced Into a cell that reduces the production of certain proteins, then there would be no need to separately remove them.

      • Hi PD! You may remember me as Proud Daddy! I was going to reference your iron theories here, but you beat me to it.

        I used the word protein because Dr Katcher uses the term plasma protein fraction. I assume you are referring to things like RNAs, maybe lipofuscin and other waste products. I would note that RNAs are downstream of their transcription factors which are proteins. Also, I have no idea how much of the non-protein in a cell “leaks” into the plasma.

        Good to see your participation here!

  15. It is funny to see how some people are rushing to publish or present their results since Harold Katcher and Akshay Sanghavi’s paper prepublication. Seems like they are suddenly realizing that the finish line is getting closer and they are lagging behind.
    Regarding the fact that a rejuvenation effect can be obtained without removing the detrimental proteins from the blood, I don’t think it is something really strange. At least we could explain it in some cases. For example, if the decrease of beneficial proteins leads to the production of detrimental ones, then by injecting of enough beneficial proteins we can stop the production of the detrimental ones, those already present in the blood being quickly eliminated naturally. Certainly, the reality is not that simple, but anyway an explanation can be found.

  16. It’s been recognized for some time that frequent blood donors are healthier than non-frequent donors (somewhat obviating healthy user bias), and randomized trials of therapeutic phlebotomy have shown better vascular health, better insulin sensitivity, decrease in gout attacks, and less cancer incidence. Usually the effects have been attributed to lowering of body iron stores, and that may well be true, at least in part. But this new research leads me to think some of the effects of phlebotomy/donation may be due to an overall rejuvenating effect. On the other hand, perhaps some of what the Conboys are seeing is due to lowering of free iron in the blood. Free iron would be in the plasma fraction, and it’s highly reactive.

  17. Hello Josh,
    Great paper. Great presentation. Huge breakthrough in potential treatment anti-aging medicine.
    Senescent cells and the burden of SASP is newest big thing in anti-aging medicine. Current approaches have been senolytics to remove senescent cells.
    Plasma Exchange to remove the entire proteome burden of senescent cells is an extraordinary idea. Currently plasma exchange used for long list of diseases. (cost @ $100,000). The big question is how long will the effect of removal of total SASP in plasma be effective if leave behind the senescent cells. Funny that Conboy never mentioned senescent cells or SASP in entire paper.

  18. Like there are molecules that the aging mouse kidney and liver cannot remove efficiently.
    I wonder why this method isnt used instead of dialysis in end stage kidney disease. Could this potentieally be used in ESRD?

  19. I wonder what medical practitioners, who routinely prescribe TPE for patients, have to say about this research. If the method really works they must have had noticed beneficial changes after TPE, for instance increased insulin sensitivity. There must be a lot diabetic patients among TPE receivers.

      • I wonder if TPE replaces anywhere near 50% of plasma in a single procedure?

        I have looked but can’t find an answer.

          • Where does “purified commercial albumin” come from?

            “Specifically, we performed a “neutral” blood exchange (NBE) by replacing the platelet-rich-plasma (PRP), fraction with physiological saline, supplemented with 5% purified commercial (fraction V) albumin (e.g. replenishing the depletion of blood albumin). “

          • Thats a lot! Human blood volume is 4-5 liters, but plasma is only 55% of blood volume.
            However plasma can mix to a degree with interstitial fluids. Albumin cannot mix, but small molecules can. Interstitial fluids are 11 liters.
            I cannot help but speculate that this kind of dilution might clear some of the debris off the extracellular matrix. Aged extracellular matrix in itself has a deleterious effect on stem cells thus tissue renewal.

            “Age‐related ECM alterations directly disrupt MuSC responses, and MuSCs seeded ex vivo onto decellularized ECM constructs derived from aged muscle display increased expression of fibrogenic markers and decreased myogenicity, compared to MuSCs seeded onto young ECM. ”


          • So donating plasma rather than whole blood might possibly provide more life extension?
            Especially since 60 liters of plasma vs 4 liters whole can be donated per annum.

  20. Follow-up prior note,

    Plasmapheresis only a few thousand dollars and widely used for many diseases. Maybe a treatment for SASP proteome.

  21. Rather than focusing on specific aging or youthening factors that need to be added or removed, it might simply be a plasma turnover issue. If the contents of the plasma is the output of cells then it stands to reason that over time a fraction of un-eliminated waste (a small fraction of harmful or damaged proteins for example) will increase and further impair the healthy turnover of the plasma. Simple replacement of the whole lot would allow the turnover process to be reset. Even partial replacement may allow the turnover process to catch-up. It remains to be seen how ‘sticky’ such a reset is; Harold’s results suggest the rejuvenation lasts a fair while, though re-aging is faster than it was naturally (albeit with cumulative benefits from further treatments). So potentially not all of aging is in the blood, or rejuvenating cells need multiple plasma replacements. I note that previous Conboy work did show a significant reduction in p16 senescent cell load.

    The fact Harold and Akshay added something but didn’t take away is a mystery – but probably indicates that the added factor/s up-regulated turnover of the plasma.

    • As I said before, and Wayne Johnson also, it is not a mystery. Bad molecules don’t last forever in the blood, and if the body can be rejuvenated by adding good ones, it won’t produce them anymore (or at least less).

      • Right on! Meanwhile, it might be good to note that the bigger point is what now seems to be accepted fact: changes in plasma composition can produce rejuvenation. Tell that to researchers 10 years ago, and you would have been ridiculed!

    • I am guessing that the trick with Harold and Ashkay method is the dose effect. Conboys do volumetric replacement of whole plasma all the time while the Elixir might contain higher concentration of specific molecules than in normal young plasma.

      I like this changing the used engine oil approach though. I wonder how risky is to take such intervention. I guess the tricky part is that you need to retain the cellular fraction. Maybe giving blood four times a year, then re-infusing the cellular part with albumin, electrolytes and sugar could help. Alternatively this might give an impulse to artificial erythrocyte production. Infusing artificial erythrocytes + albumin + electrolytes. Probably losing half your circulating leucocytes is something you can survive when not infected.

    • Mark – You imagine the essence of aging to be accumulation of taxic waste. That’s not my understanding, nor is it the way Harold or Mike or Irina thinks. Let go of that idea and there are fewer mysteries.

      Old and young are different states of the signaling environment, with different metabolic consequences. Let go of the idea that young is stronger, fitter, better. Let go of the idea that surely the body would prefer to be in a younger state, and something beyond the body’s control must be preventing that.

      • Hi Josh,

        What you say here and write in your book makes a great deal of sense, particularly from an evolutionary point of view. The issue for me is the lack of a smoking gun to cause the body to decide not to maintain itself. Whereas it is easy to see how a stochastic process would work to cause aging. I agree it is highly suspicious that the most important genes for self-repair seem to be the ones to be down regulated at certain life stages. But I’d like to see more. Can we pin this aging signal down to something extracellular? Is it possible the intracellular aging mechanisms we have spent so long understanding are irrelevant? Could it be that Hayflick has set us on the wrong track and we should have been considering cells to be immortal (in the right serum conditions) after all?

        In either case aging as we experience it seems to be mainly epigenetic and hence it is reversible. I suggest we proceed with all speed on that basis.

  22. I wonder whether what we are seeing in the Conboy experiment is truly aging reversal, or simply hormetic “aging delay” of the type you might see with fasting or taking a drug like rapamycin. Based on the Horvath “clock” results, the Elixir appears to truly reverse biological age. The Conboy approach needs to be similarly validated. Of course, the real test for both approaches will be to see actual healthy life extension. We need to see a healthy and young 5-year old mouse! LOL

  23. It seems that Harold and the Conboy”s are reversing two different aspects of programmed aging, a build up of toxic substances in the blood, and the loss of youthful signalling factors in the blood. This is exactly as I predicted long ago in my first paper on aging in 1998 where I firmly predicted that aging is caused by a large increase in some reproduction related hormones in BOTH MEN AND WOMEN after age 50 (up to 1,000%!) (FSH, LH and hCG) and dramatic declines in other reproduction related hormones (most drop by 90% or so!! , estrogen, progesterone (up to -100%!), testosterone, melatonin (-95%!) DHEA, pregneolone. For some reason Harold has never been a believer in the diea of hormones controlling aging as he has mentioned in the past that the hormonal theory of aging was discredited in the 1950’s. I think these two teams are just cleaning out the negative downstream effects of dramatically elevated LH FSH and hCG, as well as repllacing the loss of the downstream positive effects of pregenolone, progesterone, dhea, melatonn , estrogen and testosterone.(the reproduiction related steroids)-except for melatonin….Sure makes things a lot simpler and dovetails nicely with what we see in nature where
    hormone changes
    cause the flowering and death of bamboo plants after about 50 years, all at once…actually legnth of time varies between species but usually has something to do with prime numbers to make it harder for predators to time their life cycle to match the bamboo’s cycle. It also dovetails with the fact that Pacidic salmon are killed off rapidly while/after spawning by reproducuiotn related hormonal changes in a 3 day period at the age of 3 but can live 7 years of so if castrrated. Same with the female ocotpus who dies while brooding her young but lives on if you remove the optic gland. Explains wy marsupial male mice die after periods of rampant reproductiion. I ams eeing a pattern here- some reproduction related hormones will KILL YOU>.
    So basically the Conboys are just removing the damaging substances that were triggered by the mopuse equivalent of FSH LH and hCG increases, as well as the excess FSH LH and hCG, (I think mice use prolactin as an aging hormone) and Harold is basically adding back the good factors had been were generated from pregnenolone, progesteone, dhea, melatonin, estrogen and testosterone… (altough I am cautious about adding testosteone to the anti-aging category as supposedily Korean temple guards who had been castrated lived about 15 years longer than intact males). Just a thought!!

    So simple! Amazing it took so long to get to this point!

    Bamboos seldom and unpredictably flower and the frequency of flowering varies greatly from species to species. Once flowering takes place, a plant declines and often dies entirely. In fact, many species only flower at intervals as long as 65 or 120 years. These taxa exhibit mass flowering(or gregarious flowering), with all plants in a particular ‘cohort’ flowering over a several-year period. Any plant derived through clonal propagation from this cohort will also flower regardless of whether it has been planted in a different loc…

    Extended flowering intervals of bamboos evolved by …
    https://www.ncbi.nlm.nih.gov › pubmed › 25963600
    A prediction of the hypothesis is that mast intervals observed today should factorise into small prime numbers. Using a historical data set of bamboo flowering observations, we find strong evidence in favour of this prediction. Our hypothesis provides the first theoretical explanation for the mechanism underlying this remarkable phenomenon.

    Cited by: 12
    Publish Year: 2015
    Author: Carl Veller, Martin A. Nowak, Charles C. Davis

      • Hi there…hormone changes are as programmed as menopause right? that sure seems to be a program…From a mechanical point of view for some reason the pineal gland stops producing as much melatonin…some say it is from gradual calcification…I believe it is a tightly controleld program , at least in women, as almost all women go through mernopause like bamboo plants around the age of 50. The drop in melatonin is what starts the process of menopause where the sex tissues are attacked, the breasts turn from muscle to fat (the hollow breast syndrome), the vagina dries up
        etc e tc…. Melatonin suppresses LH FSh and hCG, as the melatonin decliines the menopause begins and FSH LH and hCG skyrocket in women…the same thing happens in men wtih more age variance….and at the same time the sex steroids plunge it turns out if you give melatonin to women recently begining meopauise it reverses it.. Also when an animal is starving (caloric restriction) it causes its nightime peak of melatnin to shoot way above normal!! It also causes men’s testosterone to drop 50% and the DHEA to incresae 100% (after 5 days iof complete fasting) amongst other things…Oh and the melatonin increase during CR suppresses the LH and hCG by large amounts and I think TSH…also need to check that one it is in my 1998 paper….a classic!

        • Interesting information. My wife and I have been taking melatonin every night since we were in our early 30s, so about 20 years now. She recently turned menopause and is starting to use bio identical progesterone and estradiol which has reversed it somewhat – specifically she’s not having constant hot flashes anymore. I wonder if she would have hit menopause in her mid 40s instead of her early 50s had she not taken melatonin regularly. She does still look very young however – for her age – but I guess with the means currently available to us time has finally caught up with her.

          I wonder if increasing the amount of melatonin at night may help. What is your take?

          • Hi there, how much melatonin has she been taking??? for anti aging purposes she can take as much as 70 mg a night which is the amount they uised in European studies for birh control.Worked great..So I beleive if you take enough to prevent reproduction you are also getting a maximal anti aging effect ..Why? Beause during Caloric restriction female fertility is impaired if severe enough. Evoluiton detects a famine, wants the mother to not reproduce shuts down her reproduction, AND slows/reverses her aging process so that she will be young enough to reproduce when the famine is over. Starving raises meatonin levels dramatically..So basically with high dose melatonin you should get the similar health effects to CR. Most women actually start showing impaired fertility in their 40’s and it is very difficult to have kids after age 45 for most….As far as hot flashes go, that I hear from tjose on thje know is causwed by unopposed estrogen. Unopposed by progesterone and the good doctors are prescribing 300 mg/day of progesterone a day to prevent menopause symptoms like weight gain and hot flashes. Brand name prometrium usualy given to pregant women. I think you can get a synthetic progesterone over the counter wqith no preoscription..the morning after pill…But it is best to use bioidentical progesterone. I lookdded into buying prometrium once it was ridiculsou!! like $600!!! for a small supply ahuge rip off!

          • Hi Jeff – thanks for you insights. She’s only been taking 1mg/night as a lot of health professionals are warning people about taking too much melatonin. I would also be worried about taking such massive amounts and knocking myself out completely. Plus wouldn’t the body stop producing natural melatonin altogether when supplementing such high dosages?

            Suffice it to say that finding anything over 5mg will be difficult/expensive especially over here in Europe.

          • Hi there…dont worry your body will stop producning melatoin naturally all on its own…go to google or bing search mealtonin aging levels then click on images and you will see what is oging on..

            Yes it knocks you out for about 3 to 4 months needing to sleep like 12 hours a day and then extra naps being able to sleep like a kid again sitting up in a moving car…but eventually your body adjusts It also makes your hair grow back like crazy for males….but it also lowes your sex driove temporarily and semen volume dries up to almost nothing seems like evolution does not want you to reproduice during a famine!! ..but after 4 months the sleep and sex sie seffects
            go away even on the hgh doses all in my book….the guy who did the birth control studies I think also had people take 400 to 500 mg a night for several months with no bad side effects..I personally have taken 500 mg a night for a few years in a row!! you can read all about high dose melatonin experiments in my book on melatonin at amazon…lots of neat stuff Melatonin in the nighttime drinking water of mice also made them live 20% longer…I can get a a kilogram of melatonn powder for about $333 in the US see taked3.com he might be able to ship to the UK….Peter@vitaspce.com you might also check UK’s ebay for powder melatonin it is only 33 cents a gram (1,000 mg) here.

    • Hi Jeff, Your hormonal theory is elegant and fits with a lot of evidence, but can you reverse aging using just the hormones you mention? The evidence would seem to say no, as correcting hormone imbalances has not led to healthy 200 year olds.

      It’s not entirely clear what is driving what, but I would say is this: If Harold’s Elixir performs as promised, I would expect it to reverse the damaging hormonal changes that come with aging.

      • HI there

        I don’t knwo what you mean by adjustng hormonal imbalnces…After age 50 your FSH LH and hCG goes up from 500% to 1000% so how do you adjust that hormnal imbalance? You cold take lupron for the rest of your life which they use to sauppress precoious puberty but I dobnt think it has ever been tried as an anti aging therapy.ANd it has lots of side effecs…What are you rreferring to?? Adjusting hormnal imbalances??

    • I know nothing about Biology. So I am not sure I fully understand your thinking. If I understand correctly, you say that sex hormones are “upstream” of any antiaging effect. I would then conclude that you cannot improve sex hormones (i.e. increase testosterone) substantially by any interventions that do not directly effect these hormones.
      My experience (N=1) shows the opposite. Ten years ago my testosterone was about 120. Now I am 69 years old, and my testosterone is more than 600. I have been using supplements such as NMN, NAC, coQ10, Sylimarin, Berbernine, Resveretrol, Apigenin and Melatonin 1mg (every now and then). I have also taken fisetin in large dose twice a year for senolytic effect. These have resulted in a substantially lower “Biological Age” as calculated in “aging.ai”.
      To my understanding, these interventions do not effect the levels of testosterone directly. So testosterone should not improve substantially, if sex hormones are upstream of any antiaging effect. Yet, I have experienced substantially higher testosterone, even ten years later. If anything, it should drop. So the “antiaging” interventions appear to increase testosterone, and not the other way around.
      Therefore, my conclusion is that your claim that hormones are “upstream” of any antiaging effect is not valid, at least for one sex hormone (testosterone).
      Of course, it is possible that I misunderstood your claims. In which case, I will be happy to see your explanation

      • HI there thanks for writing, yes you are right testosterone is a tricky one, I think what is happening is that testosterone itself has an anti-aging effect and is an anti-aging hormone, but when it is cconverted to its evil twin DHT, that the DHT actually is a pro-aging hromone that causes heart disease and high blood pressure (nnot to mention acne and hair loss) etc…the diseases seen at higher rates in men.( believe DHT and FSH
        are the “male”-ish aging hormones….as FSH increases by a higher percentage level in men than women after age 50…..So what seems to be going on with the Korean Eunchs living 15 years longer (if this is true) is that the removal of the Testosterone is having a life extending effect by getting rid of its downstrem evil twin. So if your T levels are high and you are taking something that blocks the conversion of T to DHT like melatonin then in that case I beileve T is an anti aging hormone…Melatonin will block the conversion by increasing your progesterone levels progesterone is natures 5 alpaa reductase inhibitor and it was plagarized by Big Phrma to make proscar (finesteride) an Avodart (duta steride) which blocks DHT production from T. Just look at the 3 chemical structures of progesterone and the 2 drugs and you will see what Big Pharma did… it appears that both T ad DHT declione in 80-89 year olds, but also that hCG which increases with aage, causes a large increase in DHT,,at least with an intial injection of it..>>>
        Serum 5 alpha-dihydrotestosterone (DHT) and testosterone (T) were measured in 78 normal men aged between 12 and 89 years, separating DHT and T by celite micro-column and using reliable radioimmunoassay. In four age groups of young (20-39 years), middle aged (40-59 years) and old (60-79 years and 80-89 years) men, the mean +/- SEM for serum DHT were 98 + 12, 91 +/- 9, 82 +/- 7 and 54 +/- 15 (ng/100 ml), respectively. The corresponding values for T were 696 +/- 27, 698 +/- 18, 624 +/- 20 and 457 +/- 21 (ng/100 ml). DHT and T showed significant correlation in each age group: r = 0.625, p less than 0.05 (young men), r = 0.727, p less than 0.02 (middle aged men), r = 0.673, p less than 0.05 and r = 0.734, p less than 0.02 (old men), respectively. There was a significant decline in DHT and T levels of 80- to 89-year-age group compared those of 30- to 39-year-age group (p less than 0.05 and p less than 0.005 respectively). But there was no significant changes in DHT and T levels between other age groups. After 3 daily in injections of 4,000 IU human chorionic gonadotropin (hCG) the levels of serum DHT of the young group (20-32 years) and old group (72-78 years) increased 2.6 times and 1.9 times more, respectively. T increased 2.7 times and 1.4 times more, respectively.

      • Would you mind sharing more details about your fisetin regiment? I am taking a few scoops of quercetin 2x month to reduce SASPs. Wouldn’t mind adding fisetin if you think it’s worth doing on top of quercetin? I’m too much of a chicken for Metformin.

        • I just noticed that the link I provided is relatively new. I had started before this was started, on basis of another clinical trial by Mayo Clinic. Not sure which. It might be this one:
          Again, 20mg/Kg, which is about 1500mg/day for me.

          It looks like this regimen is used in more than one clinical trials by Mayo Clinic

        • kaempferol (yet another flavonoid derived from rutin and derivative of quercetin – although many plants creates it from naringin not quercetin) seems to lower SASP more than quercetin does.

  24. Oh and once you accept the idea that aging is programmed and driven by changes in reproduciton related hormones it reveals that the theory of evolution is incomplete. We only know half of it. the selfish gene half…there is another undiscovered half….undiscovered untill Januray 1 2018 (actually in my paper form 2000- Sex kings an Serial Killers….when I published the answer to this question>>>>>>ta daaa- The Unselfish Genome-
    How Darwin & Dawkins Missed The 2nd Half Of The Theory Of Evolution:
    New Research Identifies The Hormone Changes That Control Human Aging
    updated versions inclide
    What Darwin Couldn’t See,
    2034 A.D> Evolution 101 The textbook of the Future, and the most recent version>>>
    On the Origin of Sex and Aging which has a few more neat facts added that suport the argument. The frist book is tehe funniest ,,had to add some humor!! Took much of it out in later versions…
    All ignored by the mainstream squirrel hunters looking up the wrong tree..Teh squirrel is in this tree!!! over here!!!

    • DHEA was part of the Greg Fahy’s “cocktail” in his Thymus Regeneration study last year. It was the first intervention that conclusively showed a reduction in epigenetic age.

      There was a bit of debate at the time on whether DHEA was actively causing any rejuvenation or diminishing it.

      If I remember right Steve Horvath also mentioned in some of his talks that Hormone Replacement Therapy in women had some effect in reducing the DNAm age of tissue.

      Female breast tissue also shows an increased eAge in comparison with the rest of the body. Is this due to increased sensitivity to sex hormones that also drive its deferentially increase growth? (as compared to men).

      • HI

        Probably the more cell divsions a cell goes through the more methlation is lost

        In fact Alex Mazin showed that the Hayflick limit could be predicted perfectly well by measuring the methylation contend 5mC of the DNa of a cell

  25. This is just evidence in favor of a method known from biblical times for treating almost all diseases by bloodletting. You can find Ancient Greek painting on a vase, showing a physician (iatros) bleeding a patient.
    For bloodletting, just go to the blood transfusion station and become a blood donor. You do not have to pay for the procedure; moreover, you will be paid extra for it. Do not forget to take with you a bottle with a solution of Rehydron and Actovegin tablets to enhance the regeneration processes. Drink before bloodletting a solution of Rehydron with two tablets of Actovegin (to replenish the balance of minerals), and the body itself will take what is need. Do not recommend this procedure to those over 75 years old. Its frequent repetition weakens the body and does not prolong life. https://en.wikipedia.org/wiki/Actovegin https://en.wikipedia.org/wiki/Bloodletting

  26. I’m wondering whether albumin is truly neutral.

    “In studies of many populations, comprising healthy subjects and patients with acute or chronic illness, serum albumin concentration is inversely related to mortality risk in a graded manner over its entire range; the estimated increase in the odds of death ranges from 24% to 56% for each 2.5 g/l decrement in serum albumin concentration.”


    • Albumin is a significant component of the PhenoAge clock. But it shouldn’t make any difference if the before/after concentrations were the same?

      • I wonder if the age of the donor albumin matters? It sounds like the Conboy’s got just whatever random aged albumin the supplier sent.

        Human albumin fraction V can be purchased.

        General description
        Highly purified plasma protein that is useful as a stabilizing agent and as a carrier protein.
        Highly purified preparation.
        1, 5 g in Plastic ampoule
        Toxicity: Standard Handling (A)
        Preparation Note
        Prepared from serum that has been shown by certified tests to be negative for HBsAg and for antibodies to HIV and HCV.
        Alternatively, this product may be stored in the refrigerator (4°C) prior to reconstitution. Following reconstitution, aliquot and freeze (-20°C). Stock solutions are stable for up to 6 months at -20°C.”

        • If you read the paper, the albumin has nothing to do with it. They are simply replacing what they took away so that the mice could have the ability to transport nutrients.

          Good thing is that there is an extremely easy way to “simulate” their experiment. Give whole blood often. In theory, the effect would be the same with a substantially lower risk profile.

          Also, if I am to believe this research works, they there should be historical precedent simply because it is so easy to do. Bloodletting does have a rich history with many references to increase in health, but you cant find even one reference (at least from what I can find) of someone living to a very old age and saying that bloodletting was the cause of their longevity. Meaning, new form of “bloodletting” research probably is pointing in the right direction, but common deductive logic would point that the effect is probably not too significant.

          • Giving blood is a sensible plan but there are many blood donors out there that give frequently and you don’t hear that they appear rejuvenated.

            It seems to me that the blood needs to be diluted a large amount all at one time to get the signalling effects.

          • Plasma is replaced in the blood within 24 hours. RBCs take around 4 to 6 weeks to replace depending on diet and health status.

            Another “advantage” of donating plasma only is that plasma companies typically pay pretty good money. Meaning, if your donating for health reasons anyway, why not share in the profit they are making on your plasma.

          • Ok. But does donating plasma confer a greater lifespan benefit over whole blood donation. You can donate 80% of your whole blood per year. How much plasma is actually donated vs “cleaned”of factors and returned?

          • No where in the research doc does it suggest that the technique will increase lifespan. The hope is to increase tissue regeneration and slow healthspan declines. The question(s) not answered is how long does this “brute force” removal technique hold down inflammation signaling, and what are the expected side effects to doing this? These questions were not answered, but its unlikely that you can remove 50% of someone’s plasma and not have at least one side effect to doing it.

          • I called and a plasma donation company near me pays $30 for your plasma.

            Get paid to (potentially) extend your life while doing good at the same time?

          • Temporarily eliminating plasma signaling helps healing tissue doesn’t seem to be earth shattering knowledge. Technically this was already known which is why the term “inflammaging” exists.

            Aspirin, exercise, statins, mTor inhibitors, etc… They all appear to be trying to do the same thing, which is to disrupt the various inflammatory positive feedback loops. Eliminating the physical signaling proteins that exist in plasma now seems like another way of doing this, but logic would suggest the effect is temporary at best.

          • I somehow doubt plasma donation companies would add back anything to your blood.
            This would make the process more expensive and also more risky.
            I guess they just skim off a little plasma, maybe a fraction of the passing through blood. So the effect is probably like a mild volumetric depletion.

  27. It sounds to me like this Covid plasma trial is doing what the Conboy’s have done but actually replacing more than 50% of plasma.

    Maybe Steve Horvath can check before and after methylation on the trial participants.

    “The intervention group will receive TPE, plus empiric treatment for COVID-19. TPE is administered using the Spectra Optia TM Apheresis System equipped with the Depuro D2000 Adsorption Cartridge (Terumo BCT Inc., USA). The first dose is 1.5 plasma volumes, followed by one plasma volume on alternate days or daily for five to seven total treatments. Spectra Optia TM Apheresis System operates with acid-citrate dextrose anticoagulant (ACDA) as per Kidney Disease Improving Global Outcomes (KDIGO) 2019 guidelines. Plasma is replaced with albumin 5% or fresh frozen plasma ”

    • 1.5 plasma volumes means plasma fraction of whole blood in circulation times 1.5?
      thats a lot. I wonder what the effective dilution rate is as the replaced plasma and the old plasma is constantly being mixed in the blood vessels.

  28. Consider this study

    Fruit flies are sleep deprived to such a degree that their lifespans are reduced by 50%. All tissues looked normal except for very significant ROS accumulation in the gut. Giving supplements like NAD and melatonin completely reversed the effects and allowed for a totally normal lifespan.

    So in this example , the bad guys are present and have had a significant impact on longevity. So they gave the good guys and this totally neutralized the bad guys. If you were only to look at the sleep deprived flies prior to intervention, and again after intervention, you would say that melatonin doubled their lifespan, but it only actually restored it to.normal. Very interestingly, giving the intervention to flies that were not damaged did absolutely nothing for their lifespan.

    So perhaps, Harold’s formula is neutralizing the bad guys present in old age and would allowi us to reach our “ normal” of maybe 120 years., but not say some dramatic extension to maybe 200 years. This is not to trivialize their achievement, but maybe more work needs to be done .

    • My takeaway on that discovery is slightly different. It is that there may be some major factor in the gut-brain axis affecting life expectancy. No real idea what. It is interesting that the microbiome changes with aging. I think there is even a mcirobiome aging clock that has been developed. Apparently changes in the microbiome with aging is across species even in Drosophila and longevity can be extended with probiotics.

      • It’s pretty clear that the driving factor was ROS accumulation in the gut. Adding in melatonin, lipoid acid , or NAD completely reversed the effect. I’m not sure why ROS accumulates in the gut with sleep deprivation, or why it had such a profound impact on lifespan. All other tissues were completely normal. I’m just wondering if Harold , by adding in the good components in a human experiment, will give us a similar result in that we’ll make it past 85 to our “ actual normal” of say 120, if he neutralizes the bad guys in the blood. That’s a great achievement but it falls short of actually curing aging.

          • You may well be on to something. I now recall that study and remember why I take that disgusting triphala. It’s very possible that sleep deprivation leads to a disruption of the gut microbiology which in turn is causing the accumulation ofROS’s. .https://www.sciencedaily.com/releases/2019/10/191028164311.htm

            The fatal part of that equation may be a deleterious effect on the brain via the axis. So I’m thinking that this can be reversed by physically removing the bad actors, or just adding neutralizing good actors. In either case, it’s actually the presence of the bad actors, and not the absence of the good ones, that’s causing aging

          • “It’s very possible that sleep deprivation leads to a disruption of the gut microbiology which in turn is causing the accumulation ofROS’s.”

            That’s exactly my thinking too.

          • I don’t guess they actually checked the microbiome to see if sleep deprivation changed it.

            However, I can think of a good reason why there could be a connection between brain and gut.

            Here’s some complete speculation.

            The brain needs nutrients. When the brain rests, it uses less fuel. It may also tell the gut to take it easy too. If the brain is not resting, it must continually fire up the gut for fuel. The continual fired up state of the gut leads to inflammation which also alters the microbiome and causes the accumulation of ROS’s. Aging is similar breakdown leading to chronic inflammation and eventually the same end, death.

          • I am not sure there is much we can learn from sleep deprived fruit flies, given they were cured of an unnatural condition, not normal aging. It may instructive of what can shorten life, but not extend it.

            But what you are really saying here Paul and James, is that you don’t really believe Harold and Akshay have reversed aging. It may be semantics what ‘aging’ is, but that is what you are saying.

            I am certain Harold, or Josh for that matter, would not agree. At the end of the day, many biomarkers of things that change for the worse with aging were reversed, as well as the methylation clock, which many regard as the best measure of aging that we have. It’s not as good as looking in the mirror and seeing a 21yo again, but its not nothing. Let’s hope the lifespan studies come back with the goods. I find it reassuring however, that the IL-6 levels of Harold’s rats after 2 treatments seemed to be better than the (normal aging) controls.

          • Mark
            To be more clear, I think that A and H have done some remarkable work but I’m hung up on the concept of “ curing or reversing “ aging. If that’s been done then we could live forever if we avoid things like accidents. I’m skeptical on that front.

            I think that humans are very capable of considerable life extension if you remove or nullify the bad actors to a certain degree. Maybe we make it to 120 or so. A significant achievement. But I’m far from convinced based on a clock that we’ve achieved immortality. I’ll need to see that in a more definitive manner.

          • Mark,

            The study I linked to extended life of fruit flies with a combination of probiotics and triphala. That is a different study from the sleep deprived flies. The sleep deprived flies are another suggestion of gut brain connection.

            My comments have been slightly OT and not really addressing what or if aging has been reversed by any particular method. They really came from my thought that whatever aging factors that are in plasma might come the gut or at least be able to be influenced through a gut connection, which would be easier treatment than a plasma exchange.

    • Intriguing results. I think the sleep/awake cycle is one of the major candidates for a body-wide aging clock. I believe Josh touched on this in the past.

      Sinclair’s finding that Double Strand Breaks drive epigenetic age is also very suggestive, and it could provide a clock at the cellular level. My question would be how predictable this DSB rate can be per unit of time, and more importantly during a life time spanning decades.

      As Jeff mentioned above, women enter menopause at a predictable age. Moreover, you can usually tell a person’s age with certain accuracy just by looking at the them.

      So how can the body keep *chronological* time so well? I am not sure an intracellular metabolic clock is the full explanation. Although this was Steve Horvath’s best guess until recently. I wonder if he has changed his mind a bit after seeing Greg Fahy’s and Harold’s results.

  29. This therapy could be done right now with existing technology and zero donor albumin.

    1. A month prior to your therapy you go donate plasma on several occasions.
    2. After the therapy provider has enough of your plasma, they extract your albumin from your plasma and store it until your therapy date. They throw away the remaining plasma unless it has some other things that can be extracted.
    3. On your therapy date they remove 50% of your plasma which they can then sell, and they put back in your own albumin in saline solution as described in the experiment.

    Done. Now you don’t have to get donor microbiome in some random commercial albumin and it is a self sustaining process.

  30. probably these are SASP components… how these effects (Elixir and/or plasma dilution) compare to SASP (>90%) removal and senescent cells (>90% body wide) removal?

  31. Modern medicine has a natural reflex action of blocking or knocking out targets to achieve temporary mitigation of symptoms. Its in the business interest not to do a permanent cure. Every molecule is there because of its utility in highly complex engineering designed by Nature and optimized over hundreds of millions of years. A bad actor means we have not discovered its other uses yet. If a molecule is upregulated as we age and seems responsible for harm, it is deliberately upregulated by Nature for a orchestrated lifecycle. Nature is continuing to finetune it to ensure and optimize survival at species level and recycling at individual level. We do not notice it because of it is done over much longer timespan. As Dr. Charles Serhan says, “One of things that we are trying to teach people from what we are learning is that we don’t want to knock anything out,” he says. “We want to fine-tune it.” Our approach has been to fine tune something that has gone deliberately and predictably askew using the tools Nature used in our homeostatic peak without knocking out or blocking anything. This approach may reward us by easily passing all the safety tests.

    • An argument can be made that this study and mTorc1 targeting are doing the exact same thing, but just using different techniques. Argument being that “inflammaging” is the ultimate cause, and that positive feedback loops intensify the older a person gets. (Inflammaging = chronic inflammatory response causing chronic mTorc1 growth stimulation which then causes even more chronic inflammation).

      From this perspective, it would explain why removing 50% of the plasma “worked”. They simply removed the inflammatory signaling molecules as one way of dampening the inflammatory positive feedback loop(s). Another technique that potentially would work equally well is by picking a growth target like mTorc1 and intermittently inhibiting it. The end result could be the same, however, which is to dampen systematic inflammation which would then allows the growth signaling to work properly again.

      • Inflammation is critical for us. When we are young it works fine. Only problem is when it remains unresolved and chronic. But why does chronic inflammation occur? That root cause wont change by dampening it. The transcriptomic and proteomic changes that cause dysfunctions that lead to chronic inflammation will continue. One may only see a temporary respite to a small extent. Ideal is a systemic treatment that resolves the root cause.

      • I absolutely agree, Akshay. Senolytics CANNOT be a monotherapy; if senescent cells are to be removed they must have adequate replacements otherwise the predictable result is fibrosis. My feeling is that we do not understand senescent cells very well at present and they are being blamed for many issues, much like we blame bacteria for dental decay, when the real issue is sugar consumption.

        • When I take a senolytic treatment, the next day I have snaps and pops in my neck and friction in my lower back. After a week, I’m back to normal. I attribute these effects to senescent cartilage cell removal and replacement. I’m 81.

          • Cartilage is made of collagen, so glycine, lysine and proline might help. Replacing chrondrocytes might be more tricky, but I’d suggest a stem cell stimulant prior or after to the senolytic. There are plenty on the market.

  32. I have been trying to figure out if we should see rejuvenation in plasma donors.

    Blood is about 55% plasma.
    An average person has ~5 liters of blood
    An average person has ~2.5 liters of plasma
    A person can donate about 2/3 liter of plasma at a time up to twice weekly (in the US)
    That means when donating plasma a person loses ~ 25% of their plasma.

    To me this means we should be seeing health benefits in plasma donors. I am not aware that this is actually being seen.

    To me this means that this new therapy in this Conboy paper might not transfer to humans, or 25% plasma loss is not enough to trigger the signalling changes, or there is some magic in the albumin replacement the Conboy’s add which standard plasma donation does not provide.

    • Yes that’s interesting. A lot of people must have done a 25% plasma donation. I wonder how long the procedure of only removing blood plasma have been going on? Also, they are returning the blood without the plasma, is that significant? Any studies been done of the health of long time plasma donors?

      • I’ve done plasma donation at the Red Cross. I used to be called regularly until I took a trip to a malaria area and they didn’t want me. Bottom line is I doubt there are a lot of people who have donated plasma for more than a few years. It takes a long time sitting still and involves needles in both arms. People who do it for money are likely to have risk factors that would affect the study. Age is a reason you will not be desirable. So the people you would most likely want to test any effect with are most likely not to be doing it.

        • I see. So even if you are extremely healthy, you get dropped at a certain age. Wow, maybe some people’s health deteriorated quickly because of this, who knows.

          • I’m 81 and I donate regularly. They checked with “OneBlood” Florida and the maximum donation age is 103.

          • “Commercial plasma donation and individual health in impoverished rural China”

            “Donating plasma is associated with a .83 standard deviation (SD) decline in self-rated health, a .54 SD lower self-rated health relative to peers in their age group, a .74 SD higher chance of being infected with hepatitis, lacking of strength to conduct farm work, and experiencing appetite loss, fatigue, nausea, and vomiting.”


        • This new Conboy’s paper saw results from a single 50% dilution procedure, not years.

          I would think a plasma donor should see something from a single donation. Any additional plasma donations couldn’t achieve a greater than 25% dilution. To me, the Conboy’s showed that diluting all at once is what triggered the rejuvenation.

          • My first thought when I read Josh’s posting was this might be the body’s interpretation of receiving what it interprets as a strong signal that a large blood loss had occurred. Large blood losses normally occurred after some sever trauma requiring repair, clearing and restoration protocols by the systemic system. Given the improvement to various tissues and compartments that appears to be occurring at some threshold of removing > than X percent of the plasma.

          • One Problem is we are not mice. We really need a controlled human study and from what I’ve read they are going to start one.

        • Tom,

          Was that plasma or blood? To clarify, actually I was donating platelets which includes some plasma.

          This commercial center has a 65 cut off.


          The Red Cross is more flexible apparently but has some things that might disqualify older people, especially medications.


          There is usually some screening which would stop older people.

    • This “experiment“ has been done by many people trying to make money by donating plasma > 2 times a week, which is relatively easy to do if you live near state lines. No one has ever reported better health by doing this. The decline in immune health occurs typically after 3 to 4 weeks.

      • Another question would be whether or not receiving plasma from an older donor might have negative health consequences for the recipient. Of course, in an emergency, it might be the only option and possibly the negatives might be outweighed by the positives, but longer term there could a downside for the recipient. Should older people be deferred from donating plasma?

        • I looked this up yesterday. The plasma collection companies are big business and they pool up to 1500 donors plasma for processing. I think you would get plasma the average of the age of all donors.

          Also, the Conboy experiment did not involve receiving of plasma, only removal although the mice did receive albumin which is a pooled product.

        • I personally think the true insight in their research is not their technique (ie. If it worked, then why does the historical literature on “bloodletting“ not notice it? You see many references to 50% bloodletting. If there is significant rejuvenation effect why didn’t they notice this?). The unique insight in this research is the realization that positive feedback loops (likely immune related) are long lasting and potentially are a significant issue in tissue recovery during aging. This could potentially be a great starting framework to explain why Rapamycin is still able to extend life even when used transiently in older animals.

          • Maybe the magic in this mouse study was them adding albumin? There are many papers on the therapeutic action of albumin n humans.

            I have read 50% blood loss was fatal, no?

          • I think more likely the “rejuvenation” is statistically significant, but not significant enough to be life changing significant. Bloodletting existed for about 3000 years, so you can assume it must have some benefit(s) to last that long. Keep in mind you see statistical exaggerations all the time in research, which is why you should always remind yourself that the researchers have biases too.

            Every generation has wanted the same thing, which is to live as long as possible. Basic deductive logic would suggest that if something as simple as removing 50% of a person’s plasma rejuvenated to the same as youth (even with adding albumin), you can sure as hell bet this fact would have been known earlier.

            As far is if you can remove 50% of the blood. A simple google search will show instances of early practitioners doing exactly this historically. I would assume many died (death was a normal part of life), but clearly some lived. The simple fact that history doesn’t show any of these people living significantly longer than anyone else at least suggests it’s not a fountain of youth.

          • If you are not looking for something, you are never going to see it.

          • Paul,

            That’s a fascinating study and one of quite a few other showing beneficial effects associated with changes in the biome. The more I look the more I find.

            Since I started looking at this, I’ve started taking a probiotic with prebiotics, triphala, and butyrate. I’m also looking to dietary changes with more fermented foods.

          • I like that concoction. I haven’t tried butyrate yet. I’m not certain if gut microbiology is related to longevity but it’s clearly related to health. It’s incredible when you consider that each of us are composed of more microorganisms than human cells. There’s much that we still don’t know about it , but its been ignored for far too long. Feed those buggers.

          • Hello tehee long ago when i was researching what happens to hormones during caloric restriction in humans I found a study where 5 navy men consuemd no calories at all for 5 days and they measured a lot of the hormone and other blood changes.. One thing I noticed was that beta hodroxy butyrate..went up by 1,000%! At the time I didn’t think much about it like it was just a way the body was breaking down fats for energy….but then i remember later seeing studies that it increased life span here and there in different experiments like this one>>>
            Aging (Albany NY)
            . 2014 Aug;6(8):621-44. doi: 10.18632/aging.100683.
            D-beta-hydroxybutyrate Extends Lifespan in C. Elegans

          • And this study was also referenced https://pubmed.ncbi.nlm.nih.gov/28371201/
            It seems that it mimics CR, but not via mTOR inhibition, but rather by suppressing insulin signaling and up regulating the longevity gene, FOXO 3. This could be an interesting synergistic add on to rapamycin. Astaxanthin also influences FOXO 3.

  33. I think that the following study shows how women’s longevity is affected by normal regular blood loss vs Oral Contraceptives.

    Oral Contraceptives and Life Expectancy
    – The model assumes women who use oral contraceptives continuously for 5 years and then stop, and
    compares this with a base population of US women aged 15-49 who are not using oral contraceptives.
    – Results drawn from these data are that oral contraceptives taken for 5 years have
    no effect on life expectancy of women under 30;
    – 5 years of use during the 30’s reduces average life expectancy by 7-22 days; and
    – among older women (over 40) life expectancy decreases up to 88 days.

    Heavy periods: Overview
    – heavy periods if she regularly loses more than 80 milliliters of blood during one menstrual period.
    – the total amount of blood lost during one period is usually about 60 milliliters (around 2.7 ounces).

  34. I think that the following study shows how women’s longevity is affected by the date she enters menopause.
    BTW. Average female blood loss appears to be about 2 pints per year

    Age at Menopause, Cause-Specific Mortality and Total Life Expectancy
    – Age-adjusted mortality is reduced 2% with each increasing year of age at menopause.
    – In particular, ischemic heart disease mortality is 2% lower.
    – Although the risk of death from uterine or ovarian cancer is increased by 5%, the net effect of a later menopause is an increased lifespan.

        • Now try to explain this one from an evolutonary point of view>>>

          left handed women enter menoppause 5 years earlier than rigth handed women I have already figured this one out but never written about it>>>any ideas josh? HAHAHA you actaually need a unified theory of human pesonality and mental illness (associated with handedness) and it extends past humans into the animal world as well….there is a lot of evolutonary secrets wrapped up into handedness… we actually have two brains…the left and the right and so do animals and they each have a unique function for survival is kind of a general way of looking at it…check out David Horrobins book the disease that made us human is a good starting point

      • Hello there

        Robin Holliday wrote a paper once that I can no longer find anywhere, but he examined the age of mearche (puberty) (becoming fertile) etc. and age of menopause or declining fertitliiy in multiparous (?) (more than one offspring per litter usually) and maximum lifespan between species and fund that they all were linked >> When one factor shifted to an older age they all shifted together…. I think it might hold true in human females as well on an indivdual basis..

        Another inteeresting fact>>>>
        Compared to women with one child, women who had three or more children had a 12% lower risk of dementia. And that effect was still seen after accounting for the other factors collected by researchers. In addition, with each additional pregnancy miscarriage a woman reported, her average risk of dementia rose by 8%.
        How pregnancy and childbirth may protect some women from …

        http://www.latimes.com/science/sciencenow/la-sci-sn-pregnancy-childbirth-dementia-…Compared to women with one child, women who had three or more children had a 12% lower risk of dementia. And that effect was still seen after accounting for the other factors collected by researchers. In addition, with each additional pregnancy miscarriage a woman reported, her average risk of dementia rose by 8%.

        When a women is pregnant and breast feeding her LH is suppressed, and progesterone elevated so this might be what is protecting her from dementia via multiple pregnancies. (See my prior post here about how skyrocketing LH after the age of menopause in both men and women has been shown to be involved with promoting neurodegeneration.

  35. Unless I missed a post or two, it seems that only Patricio and I are asserting that there is likely no need to filter or dilute our plasma to remove the Conboys’ deleterious substances. We would surmise that all that is required is to add a substance or substances that inhibit their production.

    (Patricio, please feel free to correct my understanding of your position.)

    • Thanks. That interview was well done and they make a strong argument that the deal is to remove, or in this case just dilute out the age promoting factors. This leads to rejuvenation of multiple tissues. On the other hand , diluting out the blood of young animals does not make them old as one would suspect if it’s all about having more youth promoting factors. This is an interesting debate and we’ll have to wait to see how it all pans out in humans.

      • The Conboy’s views seem to be a direct contradiction of Harold’s work. Can they both be right? I’m sorry the interviewer did not ask their opinion on the Elixer.

        • Needing to remove aging factors from plasma to effect rejuvenation is not necessarily Inconsistent with adding factors which reduce their production.

        • The Conboy’s base much of their argument on their prediction that if youth promoting factors are the main drivers, then diluting the blood of very young mice would lessen the amount of the youth promoters to such a degree that they should grow old. But they don’t.
          They may have such an enormous amount of youth promoters at that age that even a 50% dilution isn’t enough to age them. Their basic assumption in that regard may be flawed.
          It may be possible to reconcile the two theories if the main function of the youth promoters is to neutralize the action of the age promoters. So reducing the age promoters will work since then the youth promoters aren’t really needed ( Conboy), or just jack up the youth promoters which will,effectively neutralize the age promoters ( Harold).

          • Is that really the Conboy’s argument? It seems rather basic. Why not something more nuanced, like a ratio of young/old molecules? If old molecules build up slowly and reduce the turnover of young molecules, then removing both young and old factors in equal measure would effect rejuvenation, as would adding young factors. I’m not saying that is right – but the theory took me about 20 seconds to come up with and is plausible. It’s also consistent with the (admittedly incomplete) data we have at present; for example showing how autophagy upregulation improves health and disabling autophagy (even in the young) causes rapid deterioration. This can’t be that complicated.

      • In the US, one can already donate blood plasma up to 2x per week and the removed plasma is replaced with saline.
        Isn’t this nearly the exact same procedure used in the study? Shouldn’t regular plasma donors be reporting rejuvenation or increased health?
        Why are we not seeing regular plasma donors experience rejuvenation?
        In fact, there is some evidence that regular plasma donation can be detrimental to health: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4502079/

  36. The interview with the Conboys (see 1 below) pushed me to follow up on my earlier posts.

    Could women’s normal regular blood loss be a contributor to the longevity differance between men and women?

    Women’s blood loss is about 2 pints per year due to their monthly cycle.
    If a woman using oral contraceptives were to donate 2 pints per year after the age of 40 would she reverse the negative longevity effects of using oral contraceptives?
    Would a man see an increase in longevity by similiar donations of blood?

    One of the interesting things from the below study (2) “Oral Contraceptives and Life Expectancy” is that the effect on longevity accelerates as women age.
    The study only included women 15-49 yrs,
    so I can’t tell if the curve continues to accelerate after age 50 yrs.

    That is why I followed up with the 2nd study (3)
    “Age at Menopause, Cause-Specific Mortality and Total Life Expectancy”
    which shows a continued positive effect on longevity the later in life that menopause occurs, ie: continued blood loss

    BTW: I agree with earlier comments about the rate of aging affecting when menopause occurs.

    In the interview post the 16th:
    Diluting Blood Plasma Rejuvenates Old Mice
    Irena said:
    With respect to the monthly blood loss, this is an amazing idea;
    I have never thought of it. Never really came to mind, but I have known that,
    for example, women are healthier than men for some time with respect to cardiovascular disease.
    I wonder how much of that comes from this effect of dilution of blood? I don’t know.

    Oral Contraceptives and Life Expectancy
    – The model assumes women who use oral contraceptives continuously for 5 years and then stop, and
    compares this with a base population of US women aged 15-49 who are not using oral contraceptives.
    – Results drawn from these data are that oral contraceptives taken for 5 years have
    no effect on life expectancy of women under 30;
    – 5 years of use during the 30’s reduces average life expectancy by 7-22 days; and
    – among older women (over 40) life expectancy decreases up to 88 days.

    Age at Menopause, Cause-Specific Mortality and Total Life Expectancy
    – Age-adjusted mortality is reduced 2% with each increasing year of age at menopause.
    – In particular, ischemic heart disease mortality is 2% lower.
    – Although the risk of death from uterine or ovarian cancer is increased by 5%, the net effect of a later menopause is an increased lifespan.

  37. Possible Heterochronic exchange example: I am 75 years old. Last year I suffered a bleed likely due to diverticulitis. My hemoglobin count decreased to 5.4 from a normal range of 13 to 14. In the hospital I received 5 to 6 bags of blood to raise my count to approximately eight. About a 1/3 exchange. Last year I noticed a dramatic surge in my energy, At the time feeling like I was 15 or 20 years younger. I attributed it to taking glutathione and NAC from Josh’s recommendation. Now I think it may have been the “exchange”. Opinions?

    • Only pure speculation is possible. With your age of 75 the donor blood age is almost certainly younger.

      Has the feeling of being younger persisted?

      • It persisted from April to December. However at that time I had a surgical procedure which had a side effect for several months of my being up frequently at night. This sleep interruption sapped my energy significantly. I am largely recovered but may still be feeling the effects.

        • Maybe you could enter your before and after bloodwork data into the Levine phenotypic age calculator that is floating around online to see if you got younger.

          • Speaking of the Levine PhenoAge clock, one of its parameters is serum albumin. The Conboy paper in one place states that albumin does not change with age and in another place states that it declines slightly.

            I leave it to others to determine whether the Conboy albumin replacement was truly neutral. However, it should be noted that only a slight difference in the albumin content of the replacement medium would significantly affect Levine PhenoAge.

            Unless I’ve got it backwards, those in this comments group looking to improve their longevity by simple plasma dilution would be increasing their PhenoAge significantly.

          • @Wayne
            Not yet interested in this therapy but I would guess albumin bounces back quickly considering you can donate plasma twice weekly.

            I don’t think the albumin replacement was neutral. I now think it was a necessary part or else you would see some rejuvenation in plasma donors.

          • After retrieving my blood test results before, during and after my experience I tried the link to the test available through a web search. Unfortunately it was broken. Great idea though!

          • I did at last find the spreadsheet. However my physician does not normally measure C-Reactive Protein. So I left that at “1.0” for all three samples. In the past when I requested it he said that it was “low” and did not indicate high levels of inflammation. I have no CRP data. I had data for the other variables. The results are puzzling:
            Test 1 (12/4/18): Ptypic Age: 70.98, Est DNAm Age: 69.07
            Test 2(5/23/19-Right after bleed): 77.61, 75.0
            Test 3 (6/10/20): 67.64, 66.01

            As I said, I am puzzled.

          • @Ed
            After your bleed you measured older until your body stabilized after which you got 3 years younger. So maybe you were not imagining feeling younger. This phenoage measurement moves around a lot with dietary and lifestyle interventions so it is not remarkable to see yours change.

            In my opinion this test does not so much measure age but instead frailty or risk of death. That yours moved backward is a good sign. You may want to use one of the online lab services to order your own bloodwork and get yourself a CRP test to complete your data. Then you will better know where you are at. You can also look at Michael Lustgarten’s site and learn how you can make dietary changes to improve your numbers. Daily carrots and red peppers will help.

          • @Ed
            I didn’t read your data well enough.
            In 2018 you calculated at 69 years old and in 2020 you calculated at 66 years old.
            You got 4 1/2 years younger not 3 from your bleed or other things you did.

          • Yes, that’s interesting. So all you have to do to get a “free” Heterochronic blood exchange is:
            1). Get old
            2). Develop diverticulitis
            3). Then have a life threatening bleed.
            As a result receive a blood transfusion with blood likely younger than yours.

  38. It seems the TPE with albumin replacement been trialed for at least past 8 years for Alzheimer’s per first link below. Also TPE used +100,000 times in Europe per second link below. Mentioned TPE can cause clotting problems. Also wonder about any damage to red and white blood cells when run thru the TPE machines. If red blood cells are damaged then free iron released along with other break down debris into general blood stream. Conboy team reviewing all this work and their trials to fine tune for those too with just normal age related decline – so could be several years before really available for use by people without major issues?



  39. Josh,

    I’ve been wanting to ask if “Restoration of Senescent Human Diploid Fibroblasts by Modulation of the Extracellular Matrix”(1) has been brought up in your blog before?

    In the Study (1) senescent cells taken from an old donor were placed into ECM taken from a young donor.

    After a bit of signaling between the senescent cells and the ECM, the cells apparently de-aged to roughly the age of the young donor.

    I thought this could be an amazing “test bed” to determine which ECM signals are needed to de-age cells.

    I’ve been watching to see if researchers followed up on this study.

    The direction of investigation seemed to be a switch to interest in the ECM.

    There has been a lot of money spent on scafolding (ie ECM) to generate new organs and valves etc.. or repair existing scafolding in the body.

    I think in that research we may find another path to de-aging via ECM signals.

    I am hoping for your thoughts on this.

    Restoration of Senescent Human Diploid Fibroblasts by Modulation of the Extracellular Matrix
    – Herein, we report that interaction with extracellular matrix (ECM) from
    young cells is sufficient to restore aged, senescent cells to an
    apparently youthful state.
    – In addition to cell morphology, phenotypic restoration was assessed
    by resumption of proliferative potential, growth factor
    responsiveness, reduction of intracellular reactive oxygen species
    levels, recovery of mitochondrial membrane potential, and
    increased telomere length.

    • There’s been lots of work done on ‘conditional reprogramming’, whereby you can take pretty much any cell somatic type and with the right culture media, get them to turn back into a type of progenitor cells that proliferate indefinitely. On resumption of normal culture media they revert to the type of cell they were before, no karyotype abnormality, no cancer, no immortalisation.

      In other work cells have been shown to behave quite differently in 2D (normal) or 3D (more realistic) culture, as it affects the shape of the cells via their adhesion. The cells’ shape, via mysosin and actin (kind of like intracellular muscle and skeleton), basically determines what type of cell it becomes, with stem cells much simpler and smaller than more differentiated cells.

      Put these pieces of work together and I am not at all suprised at the effect of the ECM on cells. It all adds up to external signalling being the driver of cell behaviour, even including ‘age’.

      Let me know if you want any references.

      • Hi Mark,

        So far, from a few studies on the ECM signals, I’ve compiled a small/medium list of Growth factors that are involved in the ECM signalling. I think I also found some info in the wiki pages and an online book.

        I’m wondering if anyone has come across a public website that has a masterlist of ECM signals. I’m looking to validate/update/correct my current list of ECM signals.

        Then I want to look for studies that deal in things like regeneration, telomere lengthing, etc… that would be involved in de-aging that reference the ECM signals.

        What I am hoping to find is that some of these ECM signals are involved in a positive de-aging way in the diseases of aging.

        Since these signals come from outside the cell, a topical/cosmetic approach to applying them might be possible to validate there effectiveness.

  40. Thanks, Gerald! I didn’t know about this and in fact, I am pretty fuzzy about what an extra-cellular matrix is. It certainly looks like it deserves follow-up by someone with a lot more background in cellular biology than I have.

    The article was published in 2013, and PubMed lists 23 articles in the intervening years that cite this work. Of these, perhaps the most interesting is this one:

  41. Josh,

    What got me interested in the ECM was the following TED talk.

    Mina Bissell gave a TED talk about ECM and cancer that I have found to be very helpful in understanding the ECM’s importance. It’s about 16min long.

    From the Ted Talk page:
    “For decades, researcher Mina Bissell pursued a revolutionary idea — that a cancer cell doesn’t automatically become a tumor, but rather, depends on surrounding cells (its microenvironment) for cues on how to develop. She shares the two key experiments that proved the prevailing wisdom about cancer growth was wrong.”


    • As a follow-up to the Bissel Ted talk on ECM and cancer.

      Of interest is that hyaluronic acid is a major component of the ECM.

      The following review (1) points out that the naked mole rat’s cancer resistance appears to come from it’s hyaluronic acid.

      I believe in one of the studies that they shut down it’s hyaluronic acid production and the mole rat filled full of cancer. From what I understand, living underground in contact with heavy metals does an enormous amount of damage to their DNA.

      Cancer resistance, high molecular weight hyaluronic acid, and longevity
      – Longevity varies greatly among mammals.
      The naked mole rat is among the longest-lived rodents, having an average lifespan of 32 years,
      compared to the similarly-sized house mouse with lifespan of 4 years.
      The rate of cancer also varies widely among mammals and interestingly,
      the naked mole rat is essentially cancer-free (Gorbunova et al., Nat Rev Genet 15(531):540, 2014).
      A series of elegant studies (Tian et al. Nature 499:346–349, 2013) has revealed that this cancer resistance derives
      from the abundant production of high molecular weight hyaluronic acid.
      Remarkably, high molecular weight hyaluronic acid, which accumulates within the extracellular matrix,
      stimulates an intracellular pathway that induces expression of p16ink4a and suppresses oncogenic transformation.

  42. Do you happen to know anything about the telomere length of the mice & rats used?

    If lab mice tend to have significantly longer telomeres than humans, do you think that could be an issue with translation of the result? Is this also an issue with rats?

    It would be interesting to try this in mice with artificially short telomeres, or with other mammals where telomeres play a larger role in aging.

    • Hi Oliver,

      I don’t know the telomere length of the mice in the study, it wasn’t mentioned.

      An odd fact about naked mole-rats is their telomeres lengthen throughout their lives.

      I agree, short telomeres lead to damaged DNA and possible cancer cells.

      Have you watched the TED talk by Mina Bissell yet? It completely changed my view of cancer.

      In her talk she showed that cancer cells can be made to behave as normal healthy cells by placing them in contact with good healthy extra-cellular matrix.

      The high-molecular-mass Hyaluronic acids that naked mole-rats have are like wifi-extenders for the cell’s communications. This allows the damaged naked mole-rats cells that would behave like cancer to continue behaving normally.

      Without the high-molecular-mass Hyaluronic acids the cells fell back into the cancer pattern of uncontrolled growth.

      How this translates to us is that if we can repair our damaged ECM to a healthy ECM and keep all the cells with DNA damage in contact with healthy ECM, cancer could be as rare in us as it is in the naked mole-rat.

      Also it you noticed my first post on “Restoration of Senescent Human Diploid Fibroblasts by Modulation of the Extracellular Matrix”, the study took senescent cells from a senior donor and placed them in ECM from a young donor.
      The senescent cells de-aged to roughly the age of the young donor.
      The study showed that communication between the senescent cells and the young ECM caused the cells to de-age to close to the young donor’s age.

      What I am interested in, is looking into what the ECM signals were that triggered the age reversal in the old cells.

      How might this be used to reduce the effects of aging?

        • Hi Akshay,

          Thank you for the update on your therapy.

          Have you been able to resume your product development?

          Everyone I know is tired of this virus and ready to resume their lives.

          Best wishes to your team.

          Again thanks for the update.

          • Gerald all your recent posts and links were awesome. You are absolutely on the right track. We are frustrated due to the enforced delay. Hoping to catch up by launching multiple trials simultaneously.

        • Hi, Akshay
          I have a question for you.
          You mention that your therapy “creates a young ECM”

          In wikipedia for ECM, there is this statement:
          “In human fetuses, for example, the extracellular matrix works with stem cells to grow and regrow all parts of the human body, and fetuses can regrow anything that gets damaged in the womb. Scientists have long believed that the matrix stops functioning after full development.”

          So, my question is this:
          Using your methodology, would it be possible to make the ECM very young, to the point that it is similar to fetus’s ECM? If that were the case, then this method could possibly be used to re-grow parts of the body?
          Or am I extrapolating too much?

          • Zisos it is something we have to find out. The ECM results are a validation of what Harold has been saying from a while and seen from our results that aging is systemic and not cellular and environment is the key.

      • To my understanding Gerald, the ECM is oftentimes the culprit in preventing rejuvenation. Hence inhibiting several signalling pathways that hold cells in rigid place such as Rho-kinase, tgf-B seem to have the power to set cells free to regenerate the tissue. Perhaps the ECM is a scaffold that becomes overly restrictive on cells with age. This might be related to the fact it is turned over less often with age. I realise this is not in agreement with your naked mole rat research, but HA is only one of several important ECM components like collagen and elastin, and in the mole rat case you can see how a strong ECM could restrict the migration of cancer cells (via contact inhibition controlling of cell size and shape), just as I have argued it also restricts rejuvenation. This is related to how 2D culture is overly rigid and restrictive compared to 3D models, which are closer to how things are in the body.

        Just some ideas.

        • One other note

          Translation is much better from rats to humans than from mice to humans; dogs would be better than both.

      • Yes–this demonstrates that cancer is a systemic disease. It’s not caused by mutations in the cell nucleus, but by a metabolic environment.

        There’s an even better-known series of experiments that I associate with Jerry Shay. They swapped out DNA from a cancer cell and put it in a normal cell, and vice versa. The result was that putting the mutated DNA into a normal cell didn’t turn the cell cancerous, but putting normal DNA into a cancer cell didn’t rescue the cell from being cancerous.

        • Thanks to both you and Mark, you have some good points.

          That the ECM has a way of controlling regeneration/cancer doesn’t surpise me.

          That 2d and 3d environments differ was a big part of what the Bissel talk was about. So I think I understand where you’re coming from.

          I can see how putting damaged DNA in a normal cell might not cause cancer.

          But putting normal DNA in cancer cells and not seeing an improvement
          is new to me. I’ll have to keep that in mind.

          Your comment:
          “this demonstrates that cancer is a systemic disease. It’s not caused by mutations in the cell nucleus, but by a metabolic environment.”

          I’d like to know more about how this process works.

          Do you have a blog on the metabolic environment perhaps? Or can you point me to a specific study or website?

          Thanks again to both of you for the info!

  43. Josh,

    Has anyone proposed an ECM clock?

    The Study “Restoration of Senescent Human Diploid Fibroblasts by Modulation of the Extracellular Matrix” had two results that seemed odd to me.

    1) Old cells placed in young ECM were de-aged.

    2) Young cells placed in old ECM retained their youthfulness.

    This seems to point to at least 2 clocks, one in the cell and a second in the ECM.

    These clocks seem to be syncing to the younger age, which is interesting.

    • You’ve convinced me, Gerald, that there is a difference in the ECM between young and old. I also think this can effect aging, even regeneration, of adjacent cells.

      Given that, my limited understanding is that the ECM itself is not metabolically active and its components are produced by the cells it supports. Thus the root cause would go back to the cells themselves as the creators of the younger substances. I would guess that whole body transplantation of ECMs is not feasible, so the value in your research would be identification of the substances/composition of young vs. old ECM and then looking at their production by young vs. old cells.

      I’m way out of my depth here, as I don’t even know if there is a difference in old vs. young collagen, etc. Your continued enlightenment would be much appreciated.

        • Hi Lee,

          Great post, we have a close friend that is battling this very thing.

          From your posts it seems that it more common than I thought.

      • Hi Wayne,

        Good to hear from you,

        As I understand it, the ECM becomes damaged as we age, and
        pits and cracks form, leading to holes.
        If cancer cells get into these holes, they lose contact with the ECM
        and it starts to grow all packed together. Then we have a problem.
        Young ECM doesn’t have these holes so the cancer is in contact
        with healthy ECM and behaves like a normal cell.
        So you are right in that we need to find a way to regenerate/repair the ECM to a
        younger healthier state.

        Good news for us is that a huge amount of research is being done
        in the area of ECM to that end.

        But an even better option may be:

        “Akshay Atomic Bliss on June 26, 2020 at 2:19 am said:
        Our therapy creates a young ECM”

        I am excited to see the results from their upcoming trials.

        • My admittedly limited research has been unable to find even a hint as to the signaling mechanism used by young ECM. Perhaps you could enlighten me.

          Are substances of ECM origin (not its surrounding plasma) passed through the cell membrane? I doubt this because they all appear to be very large molecules, but…

          You (Gerald) say you have compiled a partial list of ECM signals. Would you give me an example?

          Perhaps the ECM Is acting on certain surface receptors of the cell? If so, which ones?

          Mina Bissell seems to indicate that the mechanism is physical, not chemical. If I remember correctly, she uses the word “form”. In the study reversing senescent cells, could molding the larger and flatter senescent cells into a more supportive smaller sphere change the inner workings of the cell?

          As you may note, my analysis assumes that the ECM does not, and cannot, create any of its own substances.


          • Wayne,

            Thanks for asking.

            “Growth factors” are used in the ECM signalling.
            The “Growth factors” wiki page contains a list of growth factors (see 1 below)

            The “FGF2” Growth factor looks of interest to me. (see studies 2-10 below)
            “FGF2” appear to be involved in tissue regeneration.
            BTW: FGF2 comes in several different sized molecules.
            The smallest seems the best for our purposes.

            From my reading the growth factors can be released from and reloaded into the ECM.

            Protein folding/unfolding seems to be involved in the release and reloading process.

            Again thanks for your question.

            Growth factor(wiki page)

            Studies follow:

            The role of FGF2 in spinal cord trauma and regeneration research

            Effect of FGF-2 on Collagen Tissue Regeneration by Human Vertebral Bone Marrow Stem Cells

            Periodontal Regeneration by FGF-2 (bFGF) in Primate Models

            Regeneration of Bone Using Nanoplex Delivery of FGF-2 and BMP-2 Genes in Diaphyseal Long Bone Radial Defects in a Diabetic Rabbit Model

            FGF2 Triggers Iris-Derived Lens Regeneration in Newt Eye

            Recombinant human fibroblast growth factor-2 promotes nerve regeneration and functional recovery after mental nerve crush injury

            The role of FGF-2 in smoke-induced emphysema and the therapeutic potential of recombinant FGF-2 in patients with COPD

            Age-Related Changes in FGF-2, Fibroblast Growth Factor Receptors and ß-Catenin Expression in Human Mesenchyme-Derived Progenitor Cells

            Fibroblast Growth Factors: A Controlling Mechanism of Skin Aging

          • >My admittedly limited research has been unable to find even a hint as to the >signaling mechanism used by young ECM. Perhaps you could enlighten me.

            Growth Factors are stored and released in the ECM.
            Protein folding and unfolding are involved .
            The unfolding/folding of the protein in the ECM is the mechanical part used to
            release/reload the growth factors.

            >Are substances of ECM origin (not its surrounding plasma) passed through the >cell membrane? I doubt this because they all appear to be very large molecules, >but…

            From my reading the receptors are on the surface of the cell.

            >You (Gerald) say you have compiled a partial list of ECM signals.
            >Would you give me an example?

            Sure, the Growth factor wiki page contains a list of the growth factors used in ECM signalling. I have not validated the Wiki list is correct or complete in regard to the ECM.

            >Perhaps the ECM Is acting on certain surface receptors of the cell?
            >If so, which ones?

            From what I’ve read they do use the surface receptors.
            I don’t recall which ones.
            If what I read was specific.

            >Mina Bissell seems to indicate that the mechanism is physical, not chemical.
            >If I remember correctly, she uses the word “form”.
            >In the study reversing senescent cells, could molding the larger
            >and flatter senescent cells into a more supportive smaller
            >sphere change the inner workings of the cell?

            Form and function.
            This is the matrix part of ECM.
            The matrix is like the 2×4 structure that builders place on the foundation.
            You can look at it and see thats its going to be a house.
            Even without the walls, flooring or roof.
            Each matrix is matched to a function or each function has its own matrix.
            Looking at the matrix you know what it’s function will be.
            The location and angle of where the cells attach to the matrix is fixed.
            So if a matrix has say 6 attachment point for cells, you need all 6 in place
            for it to function properly. Each of the 6 cells may have a specific part to play.
            That’s why you can look at an arm and know it’s an arm, or a eye is an eye.

            Not sure about the cell shape.

            > As you may note, my analysis assumes that the ECM does not,
            > and cannot, create any of its own substances.

          • Thank you, Gerald, for being so helpful to, and patient with, me. I certainly have learned a lot about the ECM from you and the sources you have pointed me to. But I am still having problems seeing how the ECM could reverse aging. Akshay said, “Our therapy creates a young ECM.” He did not say a young ECM creates our therapy. As I understand growth factors, they are great for wound healing but have a lot of dark sides. Most are definitely pro-aging if you define aging as increasing mortality, not skin appearance. (Yes, I find the theory of antagonistic pleiotropy somewhat compelling.)

            To sum up: if I needed to regenerate an arm, I’d be studying the ECM like crazy, but if I wanted to live to see my son graduate from college, I’d study epigenetics. (I’m 79, he’s 7.)

        • Except blood plasma is composed of entirely different substances and is not, to my knowledge, a matrix. It seems to me that blood cells could only be rejuvenated by substances different than regular ECM or by a different mechanism. As i understand it, OKSM reprogramming works on blood cells, not just cells surrounded by elastin, etc., which would indicate to me that ECM is not essential. However, this does not mean that ECM doesn’t offer some clues as to what a cell undergoing rejuvenation might be experiencing.

          • Great points.

            I agree OKSM reprogramming turns back the clock.

            Akshay’s therapy should also work, and Harold said it should only need to be repeated every 2 years.

            But your age set-point, for lack of a better word, pulls the cell forward again to your current age.

            The goal would be to find a way to change the age set-point to a younger age and let our normal age control mechanisms do the work for us.

            What I’m beginning to wonder is if there are several different kinds of clocks all syncing to each other, with at least one clock in the cell and at least one in the ECM.

            We might need to set all the clocks at once to correct the age set-point.

  44. Wayne,

    Your point was that the blood plasma does appear to be a matrix, and thus calling it ECM, makes no sense. I was just going from the wiki page on the response.

    The ECM is thought of as a scaffolding on which the cells hang. Free flowing cells in the blood move around freely and have no need of a scaffolding. Your point is well taken.

    Unlike other cells in the body the blood cells are not self-replicating. I am told they come from stem cell pools. The place to fix the blood is probably at their creation point by fixing the the stem pools.

  45. The aging set-point idea may need at least 3 clocks, all syncing to each other.

    An example:
    The space shuttle used 3 different software programs to control it’s flight.
    All three were used to calculate each flight decision, a 2 out of 3 method was used to decide what it did. If a conflict occured between two, the third broke the tie.

    I would guess the methylation aging clock is the one used in the cells realtime.

    It is compaired to the ECM clock, and at least another clock source to allow for tie breaking.

    A redundant clock system would explain why it has been so hard to reset the aging set-point to a younger age.

  46. Yes ECM seems to be a low hanging fruit in rejuvenation therapy. Most evidence points to the chromatin being the driver of aging but chromatin is very hard to influence pharmacologically. Chromatin is double enveloped by the cell membrane and the nucleus. However the ECM is a much easier target. Drugs just have to cross the endothelial membrane and have their effect on the ECM directly.
    Differential expression of collagen with age for instance is a well defined phenomenon. Also ECM related changes might be thought of the continuation of the development program thus a prime candidate for programmed aging.

  47. Hi Gabor,

    “Differential expression of collagen with age for instance is a well defined phenomenon. Also ECM related changes might be thought of the continuation of the development program thus a prime candidate for programmed aging.”

    Perhaps Fibroblast Growth Factors might be used to increase Collagen? (see 1,2)

    I believe Hyaluronic acid levels may also change with age.

    Fibroblast Growth Factors: A Controlling Mechanism of Skin Aging
    – In addition, the FGF has a relevant role in anti-aging therapy
    because it is related to collagen and elastin synthesis activation
    responsible for skin resistance and elasticity, characteristics
    that are diminished with skin aging. Thus, the present article
    aims to review several scientific studies that demonstrated the
    cell signaling involved with the action of FGF on skin aging.

    Effect of FGF-2 on Collagen Tissue Regeneration by Human Vertebral Bone Marrow Stem Cells

  48. Would repeated plasma donations be as effective as a single 50% plasma dilution ?
    The plasma donations would be about 3 weeks apart and I think I would need 5 or 6 to be effective.

  49. Ron Davis at Stanford has found the blood plasma in ME/CFS patients to likely be causative. I wonder if the same replacement strategy would work for people with Chronic Fatigue Syndrome.
    As I am 72, rejuvenation is near critical, I developed ME/CFS in 1993 and from that point on I have been unable to work and can barely take care of myself. That is 27 years of waiting to start my life over again. Coming down with this disease was like going to bed with the Flu and waking up 90 years old.

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