.
S O U R C E : Life Extension Advocacy Foundation (LEAF)
We were at the recent Longevity Therapeutics Conference in San Francisco, and we had the opportunity to interview Irina and Michael Conboy from UC Berkeley about their pioneering work on blood factors and aging.
Irina is a member of our Scientific Advisory Board, and the Conboys’ work is well-known to rejuvenation advocates, as they are helping to develop next-generation apheresis (the removal of certain components from blood) as a way to filter out pro-aging factors in blood so that the blood returns to a youthful state, encouraging tissues and organs to repair themselves properly as they do in youth.
The Conboys have also done quite a lot of research on parabiosis (the joining of two organisms’ circulatory systems) and blood factors in the context of altered intercellular communication, a hallmark of aging that, among other things, can prevent stem cells from functioning – and which they discuss in depth in this interview.
You stated that aging is not just progression of time; it seems to be a highly regulated process with a great deal of plasticity, and by understanding that regulation, it means aging is something we might slow or reverse. Despite this evidence, why do you think the world, and even academia, have been slow to accept that aging is not a one-way process?
Irina: I think that lack of cure goes hand in hand with inability to accept that this is disease. For example, there was some resistance to accept tuberculosis as the actual disease. When there was no antibiotics or cure against it, people tended to discard it and said, oh, it’s just nerves, you need to go to a sanatorium and relax. Perhaps it’s a subjective human feeling; if we cannot cure it, let’s just say it just happens, you cannot deal with that. That is my kind of feeling about it. Instead, it goes hand in hand that as human beings, you just want to say okay, I am going to die from old age, but it’s okay, it’s just a normal process.
Do you think we can reverse it at this point; we have visibility enough to know we will be able to reverse it?
Irina: At some point. Right now, we cannot, clearly, still, but we are making great strides over the situation where we can reverse it, like for example tuberculosis, or meningitis, bacterial meningitis. It used to be that, please do not diagnose that there’s bacterial meningitis, because there is no cure. Whatever else you can come up with, do it first. Now, diagnose it as fast as possible, so we can put patients on antibiotics immediately. My prediction is that the same will happen to aging; right now, we say it’s no disease. Then, okay, just take this thing or do these things, and then you will stop deterioration; of course, we will say, yeah, it’s bad, and this is good. Why not?.
Has your attitude changed in the last few years in terms of rejuvenation and its likelihood, or has that attitude developed for some time now?
Irina: I don’t know, what do you think about my attitude?
Michael: I think it’s just as optimistic, but it’s becoming more focused on short-term practical steps towards that goal.
So incremental change, not a watershed moment, “Now we can do it.”
Irina: No, it’s not a watershed moment, “Now we can do it.” Personally, Mike and I always knew that we can do it, and we knew the general strategic approach to how to do it, but now there are more tactical steps. The strategy has already been accomplished, so now how do you go about doing the rejuvenation therapy?
Your work suggests that stem cells do not suffer the ravages of time that somatic cells do, as even older cells utilize telomerase to maintain telomeres. They don’t appear to accumulate DNA and other forms of damage as fast if at all, and activated stem cells produce young, healthy tissue, even in an aged body, so what is preventing stem cells from working properly as we age?
Michael: We and others have demonstrated that you can, from the outside, either by some signal or blood therapy, parabiosis, something like that, some intervention, jump-start the aged resident stem cells in the tissue and get them to behave as, by whatever means you’re measuring it, young or a lot closer to young than they would normally be. The intrinsic capacity of them to act that way is there.
Why is it being suppressed if they’re using telomerase?
Michael: That is getting into everybody’s personal theory of why we age. I look at aging as just development. You’re young, you’re growing, then you mature, and you differentiate. If you were a very simple organism, that’s kind of like what it would look like. If you’re human, it’s a lot more complicated, but the same thing is going on. We wear out and have all these problems with dysregulation and die because there hasn’t been enough selection to extend our healthspan longer intrinsically, although it’s my understanding that Homo Sapiens have the capacity to live a lot longer than any of our nearest ape relatives or any of our ancestral hominid species. By chance or whatever, maybe it has something to do with a delayed development to get a big brain, we differentiate over a longer period of time and have longer to live. By differentiate, I mean achieve the adult, mature form, whether that’s an organism or a tissue. I think it’s a byproduct of that that the process is, you need to differentiate cells in a tissue and differentiate the tissue into a functional organ and get all that to work together in a mature way. You don’t have the grow over the damage phenomenon, the exceptional repair that you do when you’re young and growing.
There’s been a debate for a long time now about programmed aging versus stochastic processes. Do you think aging is programmed, or is it just entropic breakdown?
Irina: Basically, to add to what Mike said, even if stem cells in our bodies and tissues have telomerase, they’re not going to activate this enzyme or divide unless they’re instructed by their environment. Because if they did, that would be horrible, we would not maintain our size and shape, we’d just become amorphous blobs of flesh. So instead, we have a regulated process, and as we grow old, the environment of differentiated niche stem cells does not provide productive instruction. It provides counterproductive instruction, which, overall, tells them just to remain quiescent and do nothing. So, they have potential to produce healthy tissue, but the potential is not realized because they simply never divide to produce the next cell that will produce the next cell. Whether it is programmed in general or is stochastic, I used to argue with Mike back and forth because I thought that it is programmed and he thought that it’s stochastic; now we came to a mutual understanding that it’s kind of neither or both. What is programmed is our limited lifespan; even though now we live longer on average than we used to live like 200 years ago, but the people who live a maximum lifespan are still around 90 or so; regardless if you were Archimedes or a millennial, still about 90. So that is programmed, and it’s programmed by multiple steps. It’s not just one gene you can reset.
Michael: It’s not a program to kill you.
Irina: Exactly. It’s not a program to kill you. It’s the lack of a program to keep you young and healthy for longer than 90 years.
You are a believer in the disposable soma theory of aging. Is that right?
Irina: Yes. Again, with all of these theories, I want to just caution people that there is no absolute.
Michael: When I think of programmed aging, I think of the salmon and the mayfly. Perfectly good fish, perfectly good bug. It just ups and dies.
We’re not salmon.
Irina: We are not salmon.
Michael: No, and we have programs and the program is programmed growth and maturity.
Irina: And what to do when you’re a damaged differentiated cell. If your program was that whenever you’re a damaged, differentiated cell, you simply trigger apoptosis and activate stem cells to make new cells, we would live much longer and healthy. The program right now is to resist being dead and replaced as much as you can for as long as you can, so cells produce too much TGF beta because it helps them to keep functioning even when they’re damaged. That too much TGF beta, ironically, inhibits resident stem cells, so they are not replacing old cells with new ones. It’s almost like, I give this metaphor so many times, like you have old bureaucrats that are running an organization and do not want to be replaced.
That’s a great metaphor. So we’re not programmed literally, we are “programmed” through negligence or poor design.
Irina: Poor design, not efficient. It was designed because what is better, to immediately replace a damaged cell or to make it function as long as possible? There are two options, and the design was to keep making it function as long as possible.
The dominance of intrinsic aging over extrinsic aging has become a popular topic recently. What studies do you think best support the dominant role of extrinsic aging?
Irina: Well, the best one is when you have, which I showed today in a talk, when you have a completely young mouse, with a young brain and young behavior, and you exchange it with old blood once, and several days later, it becomes old by numerous parameters, and there is no chronological time to impose any age-related damage. We did not start with intrinsic, we started with extrinsic, then the program of what cells are doing and how they behave.
Michael: But you could argue that there’s a certain intrinsic component, of course, too.
Irina: Of course, in all of this, right, there is an unannounced prevalence. It’s not absolute.
What are your thoughts on partial cellular reprogramming as a potential therapy?
Irina: We reviewed that in Journal Club, a paper, a couple of papers. Once again, what I want to mention is that our thoughts are probably different from most people, because we go to the data and the data show that they’re not really fully what authors wrote in the abstract or conclusion. When you look at that, my thought is that much more work needs to be done before it could be even thought to be commercialized.
Michael: Some of the things we’ve tested on mice, are we partially reprogramming?
Irina: We’re not programming them with iPS to the embryonic stage. We are resetting their epigenetics to younger cells.
Using Yamanaka factors?
Irina: Not using Yamanaka factors.
What are you using?
Irina: Anything, absolutely.
Michael: We published TGF beta inhibitor.
Irina: Oxytocin, heterochronic blood exchange.
Michael: Fibroblast growth factor, insulin-like growth factor. Stem cells, we respond to those in the tissue.
Irina: Diet and exercise. How do you think that diet and exercise work? They work through epigenetic resetting of many things in your body.
Michael: Systemic signaling.
Irina: People are saying that we need to go all the way to the chromosome by strange gene therapy, and that’s how you become younger. This is, first of all, impractical because gene therapy doesn’t work for much simpler diseases than aging. One genetic defect is not cured by gene therapy. The multiple genetic defects in aging are not going to be cured by gene therapy. More importantly, it is not needed because we can treat cells or animals with a number of growth factors, or a combination of those, to reset the epigenome to younger states.
Using Yamanaka factors to reprogram using young factors, you think that therapy is not at a point where we can say this has been effective or is an effective therapy for other interventions? It’s too soon?
Irina: Too soon.
Michael: And complicated. It’s a big spectrum, you can take Yamanaka factors, you can take some of these fibroblasts and reprogram them and make an embryonic cell, grow it up, maybe throw it in a damaged tissue. Typically, the introduced cells die, but before that, they produce some factors that rejuvenate the local tissue. Then, instead of reprogramming Yamanaka factors, you can treat that with mRNA from Yamanaka factors or even proteins like Sox, Klf4, that kind of stuff, and get some reprogramming. You can expose cells to chemical cocktails that demethylate and happen to activate certain promoters in cells just to get partial reprogramming, and then, if you go that far, then it doesn’t seem like a whole big jump from “Okay, what if you could give me some cell signaling molecules and have them reprogram their genome to a more stemmy or, if it’s a stem cell, to tell to wake up and start doing its job, even though it’s otherwise getting signals in an old environment saying to stay asleep.” We’re all differentiated, we’re all mature.
Irina: We need to remember that Yamanaka factor reprogramming is to an imperfect embryonic life state. There are numerous problems with cloning animals using Yamanaka factors. You don’t want it to cause reprogramming of any of our cells to an embryonic state, because even one cell will form a tumor and you will die very fast. So, there is a threshold, how much of the Yamanaka factors do you need to activate to become younger but not get horrible cancer? If you think about sustainable therapy, can you do it year after year after year after year? Through cumulative errors, you will start forming tumors. Absolutely. The thing is not that it will not be robust. The thing that will never be robust is hundred percent robust, and only one cell will kill you.
There’s plenty of evidence to suggest that intrinsic aging damage also plays a key role in aging. Do you believe that repair strategies will still be required for intrinsic aging even if extrinsic aging is reset, and why?
Irina: At some point, yes. I think that the first jump on longevity and health will come from an intervention on extrinsic aging. At some point, the next problem will be accumulative DNA damage, so extrinsic alone does not work. Basically, the therapies that we’re working on right now will probably buy you 30, 40, or 50 more years of productive life to figure out what to do about the next step, which is improved DNA repair.
Back in 2018, we discussed with you the idea that the rejuvenation of aged tissue was due to the dilution of pro-aging factors in old blood. Do you think that the data since then has supported the idea that this dilution is more important than adding youthful factors from young blood?
Irina: Yes, I think it supports this idea, but it is still preliminary and in progress, so we will see exactly how much support will come from it. We don’t yet have a straightforward experiment.
Michael: Next year.
Irina: What we can probably say is about mixing young and old serum.
Michael: We need to publish that.
Irina: We have published that.
Michael: The experiment we’ve done, in culture, if you have cells, they usually require some sort of serum, and they tend to grow much better in young serum from a given animal more than they do in an old serum from a given animal. If you do the experiment, “Okay, what if I mix the young and old serum together?” If there’s good stuff in the young serum that’s dominant over the pro-aging or negative stuff in the old serum, you’d think that the young serum would win. If there’s bad stuff in the old serum that’s dominant and more pro-aging than the good stuff, then the old serum would win. We’ve done that experiment; the old serum wins every time we do that.
Every time?
Irina: Every time.
Michael: Every time I did it, which was just a few times.
Irina: If you contrast that with parabiosis, which has young animal veins right next door, the young animal has a young liver and kidneys that are capable of physically removing old blood constituents, but when you don’t have that, when you simply mix them 50/50 in a culture experiment for cells, then old serum wins. These and many other things are in progress that may not just focus on this question so much, but dilutions are in progress.
Your research suggests that by using extrinsic cues, it’s possible to quickly and robustly rejuvenate aged tissues and stem cells and also that it’s possible to rapidly age young cells simply by introducing these extrinsic cues. This supports the idea that calibrating the levels of blood factors to a more youthful profile can encourage youthful regeneration of organs and tissues. You’ve already demonstrated this in mice; could you tell us a bit more about what you have achieved so far using this approach?
Irina: We have demonstrated this in mice, and we have funding for Phase 2b clinical trials as initial tests to see if the same approach will work in people. The trials should be conducted this year as soon as we have the results of the study, so nothing yet to tell beyond the work in mice, but soon, there will be; when we know things, we publish them, and we are all set to go, so in one year, everybody should know.
You mentioned apheresis today in your talk as a potential way to calibrate these various factors in aged blood to restore productive signaling in stem cells and surrounding tissues. The signaling is controlled by known networks and a combination could reset the interactions between cells to younger levels. How are you adapting apheresis to this task?
Irina: We have not adapted it yet, but we have an NIH grant to work on next-generation apheresis for small animals where we could test numerous interlocking modules and the precise administration of select factors. That is really very much in progress, I’m just working on proper support of that grant.
You’ve been using BONDCAT to identify the target blood factors. Can you explain how that works and how you have been working out what combination of factors are to be targeted?
Michael: People have been doing metabolic labeling for for hundreds of years now. You feed your favorite cell or organism some radioactive isotope for amino acid, it takes it up in the protein, you can detect it later by the radioactivity. BONDCAT works in a similar way, but instead of using radioactivity, the amino acid has a certain chemical modification to it that’s then easily and accurately detected chemically in a preparation of proteins later. How this is useful for our studies is that the gene that encodes the enzyme to help link that amino acid to the protein chain has been engineered to accept this non-natural amino acid. Because it’s a gene, you can make it transgenic, so we have mice that if you give them this, basically this amino acid substrate, it’ll put it into the product of protein and, therefore, label all the proteome of that particular mouse. You can even put this under genetic control so you can play with just the brain proteome, play with just the muscle proteome, whatever. That gives us the ability then to take that animal and say what in that animal is rejuvenative. We take the signaling or the blood or wherever your favorite theory is for what’s rejuvenative and expose another animal’s cells or tissue to that. We can see then which proteins are sticking and which proteins are being activated by that, and vice versa; we can say which is old and progeric.
So, you suggested a few years ago that you thought only a handful of primary factors and their interactions would need to be targeted for calibration. Do you still believe this is the case, and what factors are they?
Irina: We still believe it’s the case because, typically, we have only a few limited factors to build organs during embryogenesis. Through a number of our papers, we found that the same combination of the same factors work in a similar fashion to repair organs when we are adults. The same factors fail to work when we grow old. It will be limited; it will not be 70, 100, 4,000, or 50,000. Which ones, of course, we cannot tell you until the work is published.
What are your primary factors that you guys have identified right now, if any?
Michael: We and others have identified growth factors in the MAP kinase pathway.
Irina: MAP kinase pathway, TGF beta, those are the primary ones. Oxytocin in the map kinase part. Interleukin six, SASP, senescent cells’ secretory phenotype.
Michael: The hierarchy and cross talk can be signaling pathways among all the other hundreds of players. They’re nodes, and you try to go to their nodes.
Along the same lines, if it turns out that there actually are hundreds of factors to calibrate, how could apheresis be adapted to handle that kind of complexity?
Irina: So apheresis actually can be, it’s an engineering program and a problem that can be solved by engineering approaches. We don’t need 100 factors, but let’s say this 75 meters or 50 factors, they could be precisely measured and they could be calibrated precisely in a computer-operated way. It is a new combination of a few already existing engineering platforms. That is the part of the work that is partially funded by the NIH and partially by other sources that we are undertaking.
Are you using deep learning?
Irina: We’ll use deep learning and computer learning AI eventually; the first step would be to develop enough of the algorithms and patterns from which to start the computer learning.
Apheresis is already approved by the FDA, so this should make adapting the technology and getting it approved easier. What are the challenges that you’ve had so far in getting it approved?
Irina: We don’t, so far, there are really zero challenges, it’s relatively easy. It’s more like a time challenge to make administrators to work on approvals that you need, rather than any blow-up or pushback.
I think you might have already answered this, but do you believe, assuming things go well, that this therapy might be in clinical trials in the next five years?
Irina: Human clinical trials this year.
Michael: The only thing that allows it to be open to the masses is that it’s already FDA approved; any practicing physician.
Irina: Under our guidance.
That’s “our” meaning your lab?
Michael: That’s the value added part to make it work.
Irina: So that’s bringing in our collaborator, but what Mike was saying was correct, that any approved physician can potentially prescribe it, but the danger would be in the details; if you want to calibrate something that if you do not calibrate correctly, it will cause you to stop producing red blood cells, you certainly will cause more harm, and no, no improvement at all.
Given that apheresis is available, why is there a continued fixation on plasma transfusion for rejuvenation, and is it really practical or plausible?
Michael: Well, that’s already got some momentum right now to steam for the past few years. Competing theories have to ramp up and still prove themselves. We might say something, but until people believe it or somebody else reproduces some experiments, then that gets some momentum too.
Irina: I can tell you this much, some people, not many, but some people justify plasma transfusions with our original 2005 parabiosis paper, and there is no justification in that paper that taking young plasma to an old person, old mammal, will do anything. There is none. There is a scientist in charge as the first author of that paper and last senior author of a heterochronic blood exchange paper published in Nature in 2017 or 16; there is no justification in his papers. If people would like to use young plasma, they should justify that with something else, not my work.
.../...
.
