Reprogramming Cells with Vittorio Sebastiano of Turn.bio

Turn focuses on using the Yamanaka factors to promote cellular rejuvenation.


Vittorio SebastianoVittorio Sebastiano

Vittorio Sebastiano is an Associate Professor (Research) of Obstetrics and Gynecology at Stanford University and one of the most prominent scientists in the emerging field of cellular reprogramming. He is also co-founder and Scientific Advisory Board Chairman of Turn Biotechnologies, a cellular rejuvenation company based on the research done in Sebastiano’s Stanford lab.

Turn recently closed a fundraising round that attracted support from two international pharmaceutical organizations, Daewoong Pharmaceutical and HanAll Biopharma, along with Astellas Venture Management, a venture capital group. We talked with Sebastiano about the status of cellular rejuvenation research and the intriguing path that his company is taking towards this goal.

Last time you gave an interview to Lifespan.io was three years ago almost to the day. What has happened to the reprogramming field since then, what advances have been made? 

We have seen very significant progress during the last two, three years. Back in 2019, many people still thought that this idea of transient cellular reprogramming, or partial reprogramming, was more science fiction than science. Today, mainstream science, researchers, companies around the world are trying to find the best way to rejuvenate cells.

Many labs have started working on these ideas since we published our work. I strongly believe that our proprietary approach, which we call ERA (Epigenetic Reprogramming of Aging), holds the greatest promise in regenerative medicine, because it’s a finely tuned and controlled way to reset the epigenetic landscape of cells to a more youthful, functional phenotype without impacting their identity, which is obviously a risk factor that’s associated with reprogramming.

Just to recap, in 2020, we were the first to demonstrate the applicability of this to human cells that were derived from elderly individuals. As important as animal studies are, in the end, you need to show that it works in human cells derived from aged tissues, and that’s exactly what we did. We were the first to demonstrate that in human cells, and we are also very hopeful to be the first to demonstrate that it works in patients. That’s our goal.


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That begs the question, when will we see human trials?

Very soon, hopefully. We’re progressing very rapidly on a couple of indications in dermatology and immunotherapy. Soon, we’re going to move into at least Phase I clinical trials.

I always like to emphasize the fact that Turn as a company is not just about ERA. This is the foundational technology of Turn, but at the same time, since it relies on the delivery of mRNAs that are used to perform that resetting of the epigenetic landscape, we are also working heavily on the cargo (that is, the mRNAs), and on the delivery system. These three are the three pillars of Turn that are going to enable rapid clinical implementation of this technology for a variety of indications.

There has been great progress in terms of research on all three of those, but most importantly, there has been major progress recently in partnering up with big players in the pharma field that are mission oriented.

I’d like to highlight this because that’s what we really care about: the mission. Also, they know how to develop a drug, a product. I’m referring to Daewoong Pharmaceuticals, Hanall Biopharma, and Astellas Venture Management. These are really big players in the pharma field that in a way are putting a stamp of approval on us, showing that they really believe in this technology and they’re going to help us develop the products. This is very exciting for us, a big step. These organizations know their business, so it’s a very important signal that really speaks for the value and the potential of Turn.

The first important component is the mRNA technology that we are using. This is the technology that the most successful COVID vaccines are based on, and it has been a game changer for several reasons. First, because it’s a very safe approach. You’re not using viral vectors, nor DNA molecules. From a safety standpoint, this is extremely important. Viral vectors are immunogenic for obvious reasons, even though some of them can be used.


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Second, it’s very hard to control the duration of the expression of the factors. Typically, you have to control them through molecules such as antibiotics – for example, doxycycline. Antibiotics are found in some foods, so that’s a potential issue when you need to keep the factors silenced and not randomly activated in the cells.

As to DNA, any DNA molecule can integrate into the genome, so, there is always a potential side effect. You cannot control the integration. You don’t know where it’s going to end up, you may mess up some important genes. This may lead to cell death and even to carcinogenesis, if it integrates in the wrong part of the genome.

So, mRNA and RNA in general do not have those issues. By their nature, they only stay in the cytoplasm, they code for the proteins they are supposed to be coding for, and never get into the nucleus, never integrate into the genome. This is why they are much safer to work with.

Then there are several secondary reasons why it’s so important. Again, let’s look at COVID. The industry is developing fast methods to generate large amounts of RNAs. This will make any RNA-based technology very affordable in the long run. This is important to me and to Turn because we want to change the rules of the game, to democratize this technology, making it affordable for everyone, not just for a few wealthy people.

But, RNAs come with a downside, which is delivery. That’s why Turn is also working on developing new delivery systems that are non-cytotoxic, very specific, and very efficacious in targeting specific cell types that we want to rejuvenate. Potentially, this could become a business model on its own because many companies are trying to achieve good targeting, and liquid nanoparticles are going to be an important part of our products.


Liquid nanoparticles themselves are an established technology, so I would guess the problems are mostly with targeting?

Not only. There are some very practical problems, like patenting. The current technology is owned by only a couple of players, and we are developing our own proprietary technology, because there are going to be new opportunities in the market for delivery. Also, some of the current solutions elicit a bit of cytotoxicity and immunogenicity. Some of the adverse effects that we see from vaccines, for example, are due to an immune response to liquid nanoparticles. We are working to make them less immunogenic and more tolerable to the body.

Then, of course, the delivery. With vaccines, and I’m simplifying here, it doesn’t really matter what cells you target, as long as those cells express the epitope of the protein that needs to be recognized by the immune system. In our case, it’s a big deal: we need to make sure that we target specific cell types, because those are the ones that we want to rejuvenate.

RNA also degrades rapidly, which, I guess, could be both good and bad for partial reprogramming, right?

Yes, mRNAs in general have a relatively short half-life. That means, if you bring them into the cells, they’re going to exist there for a few hours, 24, maybe 48 hours, and then they’re gone. So, if you need multiple deliveries into the cells, how do you do it?

This lies at the intersection of the RNA program and the delivery program at Turn. You can think about it in many ways. For example, you can develop a delivery system with slow release in the tissue: the cargo is always the same, but it’s delivered in impulses or slowly released across the period needed to achieve efficacy. The second way is to change the structure of the RNA, so that after it’s delivered, it can last longer in the cells. It can also have regulatory sequences that, if it lasts too long, can shut it down safely and efficiently.

All this is very important in vivo, because you are putting something in the body, and you have to dictate the duration. If you think about ex vivo, you isolate the cells and you have them in culture, and then even if your RNA has a short half-life, you can still hit the cells many times with “pulses of reprogramming”. You can make sure that the cells haven’t lost their identity, that they have a very robust juvenile phenotype. At that point, you reintroduce them back into the body.

Both strategies are still open. For in vivo, you need to make sure that you are really in control of the cargo, the delivery, the duration. Ex vivo, most of these problems are irrelevant. That’s why immunotherapy is probably going to be a very fast program for us, because it’s an ex vivo program.

You have your artificial niche technology to help you with ex vivo. Explain that a bit. 

The artificial niche was developed by Marco Quarta, one of the co-founders, when he was working at Stanford. It is a method to isolate stem cells from muscles and keep them quiescent – basically, to keep their stemness, which is crucial. This is how you maintain their ability to differentiate into all the cells of the muscle tissue. It’s a technology that is exclusively licensed to Turn and that we’re going to utilize for the rejuvenation of the muscle stem cells after they are biopsied out and isolated from the tissue. It can be extended potentially to other contexts.

Every stem cell is different. Stem cells that reside in the intestine are different from those in the muscle. So, every micro-niche needs to be defined in a different way, but for now, we have the one that works very well for muscle cells. That’s going to be utilized in combination with ERA for ex vivo treatments of muscle stem cells that are isolated from the patient.

So, the idea here is to rejuvenate stem cells so that they regain their youthful function, right?

Correct. That’s because most of the cells in the tissue are not stem cells. Probably 99.9% of the cells in any tissue are fully differentiated, and they make up the organ. There is obviously a possibility to intervene on those cells, but probably a smarter idea is to target the cells that are responsible for the regeneration of the whole organ. You can target those in vivo, if you know how to do it, or ex vivo, if you know how to culture, which is where the artificial niche comes in handy.

If you make a stem cell younger, you are making the whole organ younger, because that cell now is going to regenerate the entire tissue. We were able to restore strength of a whole muscle to the level of a young untreated muscle. This is very significant.

This sounds like a really “lean” strategy that could be implemented quickly. That brings me to the question of competition. The reprogramming field has become crowded with well-funded ventures like Altos Labs but also many smaller companies.

On one hand, it’s actually reassuring in some sense. First and foremost, I’m a scientist, so I’m a big believer in reproducibility of data. As long as this is reproducible, I’m the happiest man in the world, because that means that what I did is working (not that I have reasons to doubt it). If somebody else sees the same thing in a different context, tissue, environment, in a different humidity or whatever that is, it’s very reassuring. So, I’m pleased that the field is booming.

When it comes to competition between companies, as I said, we were the first to show that this works in humans. We have the technology that is by far the safest and probably the one that’s going to develop to clinical fruition most rapidly.

It’s good that the field is so big: there are so many things that we can do. At the end of the day, there’s going to be room for everybody. What I care about is to show that what we have done works in humans. We want to be the first ones to start working with humans, and I think we’re close.

There are also a lot of conditions that you can work on.

Yes. Actually, I see Turn as a platform company. We have these ideas and this technology, including delivery, that can be, in principle, applied in various contexts to many different conditions and indications. We want to tackle many of them one by one, but currently we are being very down-to-earth and strategic about how we achieve that. We want to start with something that is going to make a difference for people quickly.

Despite the field being crowded, we haven’t seen a lot of successes. The elephant in the room is Calico, which apparently has little to show. Does this worry you a bit?

No, I am very optimistic based on what I see happening at Turn. To be fair, though Calico have been around for a while, they haven’t been working on reprogramming until recently. They’re dealing with longevity in a different way, focusing on neurobiology, I think. Turn, on the other hand, was one of the first companies to really work on reprogramming, and now, of course, there are the Altos Labs.

I’m not too concerned about that, no. Again, I can speak about Turn. We’re making tremendous progress, and our data is strong. Am I worried about the fact that big money is being put into other entities or corporations? No, because in the end, having a lot of money doesn’t guarantee success. The execution, the strategy, the foundational science are all very important, and we check all those boxes.

Let’s talk again about reprogramming as a whole. Here’s something I just read on Twitter, from a prominent researcher. He wrote that the Yamanaka factors are simply “oncogenes”. It’s a rather widespread concern, so could you maybe briefly explain the relationship between cellular reprogramming and cancer?

Sure. I don’t know who said that, but it’s an overly simplified statement. It’s like saying that the only thing fire does is destroying forests. It’s definitely not the whole truth.

It boils down to the control of the reprogramming window. If you know how to control the duration of the reprogramming, you can achieve partial reprogramming, reverting only some aspects of the epigenetic landscape to a more juvenile and functional state, without impacting the cellular identity.

Some of the factors are definitely potentially carcinogenic in the long run. C-Myc, for example, is a proto-oncogene, but there are a few thousand or a few hundred thousand cells in the body that express high levels of it. They know how to regulate it, how to utilize it, and in the short run, c-Myc does very good things.

For example, it impacts the mitochondrial activity, it represses retroviral elements. If you express it at super-abundant levels for a long time, there is a possibility that c-Myc may become carcinogenic, but the technology we are using is short-term, tuneable, and regulatable. This lets you take the advantage of c-Myc expression without the disadvantages. And the same is true for all the other factors.

Now, does that mean that this is going to be the cocktail that we’re going to use for every cell, every tissue for the rest of our lives? Probably not. We’re starting there because we know it’s the most powerful cocktail that gives the highest degree of rejuvenation in the shortest amount of time, so, first, we are studying this process.

We’re also learning that as a consequence of the expression of those factors, other factors are getting engaged, and potentially we may complement the cocktail with one or more of those, substitute some of them, or maybe replace the cocktail with something entirely different. The good thing about this cocktail that we’re using is that it works across many different cell types equally.

I think you’ve added two more factors to the original four. Why? 

If you use those six factors, you get the fastest reprogramming to iPSCs, that is, full reprogramming. It takes two to three weeks for the cells in culture to go all the way to an embryonic-like state.

Our original thinking was, let’s use this cocktail, which is the most powerful and effective, and let’s see when during this process we can stop the reprogramming but still see rejuvenation in the cell. Then, maybe we can change the cocktail, take some factors out, and expand the timing of that process, because it is true that if you remove three or four of these factors –  if you use just OSK, for example – it takes you probably twice as long to make iPSCs (induced pluripotent stem cells). That means that there is a much safer window of opportunity.

Right now, we are using the most powerful cocktail, but we’re treating the cells for a very short time. At some point, we may come up with an abridged version of the cocktail that could have less potential side effects, even for a longer period of time.

The third option would be to replace the cocktail entirely with something that still does the rejuvenation but without this potential downside of carcinogenesis, which, again, is a problem only if you lose control of those factors, but we don’t.

You probably need to do it quickly because you want to keep the stem cells quiescent?

Yes, but it’s also about the cost – the shorter the treatment, the cheaper it’s going to be, and that’s very important. And we are seeing that in stem cells, two days of treatment are enough to get the muscle younger by years.

What are the limits of reprogramming? How big is the part of aging that reprogramming can fix? Because there are things like damage accumulation in the extracellular matrix, accumulation of somatic mutations, et cetera.

It’s an excellent question, but not an easy one, so let’s unfold it. Strictly speaking, when it comes to genetic mutations, there is nothing we can do with this technology. If there is a mutation, you cannot reverse a cell with that particular mutation to a state before the mutation occurred.

This is not a major issue in my view because most of the mutations that happen in cells are harmless. Only a small fraction of cells accumulate very dangerous mutations, and those are the senescent cells. They constitute a small fraction of all the cells in the body, probably between 1% to 5%. Senescent cells accumulate large mutations, chromosomal rearrangement, shortening of telomeres. They are massively genetically affected.

We don’t want to reprogram those cells; we want to eliminate them. You can do that in two ways. One way is to specifically target them with senolytics, getting them out of the equation, but you still have an aged body left behind. You have aged cells, and there’s nothing you can do about it, unless you reprogram them, and that’s what Turn wants to do.

The second thing is that, if you know how, to target in vivo the non-senescent cells. In fact, the senescent cells are non-proliferative, they’re stuck there, just secreting pro-inflammatory cytokines. If you target the cells that are non-senescent but still aged, and you revert them to a more juvenile phenotype, these cells start proliferating. They start producing new cells, diminishing the relative ratio of the senescent cells in that specific issue, and that creates a positive feedback loop.

The third point, again, we mentioned that if you can target the stem cells, then you are working at the root of the tissue, on the cells that generate all the cells in the body. That means you can regenerate the entire tissue just by targeting the cells that are responsible for the regeneration of the tissue. We have seen this: we have targeted the stem cells, and we have seen the rejuvenation of the entire tissue.

What about the damage to the extracellular matrix? That’s something that neither reprogramming nor senolytics seem to be able to tackle, right?

That’s not necessarily true. For instance, reprogramming of fibroblasts, which we have done, leads them to a state where they’re secreting more collagen, more elastin. They not just become younger, they also start secreting juvenile factors and produce less pro-inflammatory cytokines and more anti-inflammatory cytokines, which affects the environment around them. They also produce more metalloproteinases, which are the enzymes that degrade that the extracellular matrix.

In short, they really start behaving like young fibroblasts, restructuring the environment around them. In my opinion, this is a domino effect. You target one cell type, and it starts not just looking young but behaving young, rebuilding the whole tissue.

To really tackle aging, we probably do need combinations of senolytics, reprogramming, and other things. So, what are you currently excited about in the longevity field as a whole, in terms of technologies and advances? 

I am excited about senolytics. I still have to see tangible repercussions of this, but I think they’re going to come in the near future. And I am particularly excited about the combination of senolytics and reprogramming, also because I have a hunch that removing senescent cells might help a lot. Senescent cells have been shown to promote reprogramming in vivo to an embryonic-like state. So, if you remove them first, then subsequent rejuvenation can potentially be much more effective any even safer.

There are a lot of research avenues that are very exciting. For example, the work that has been done on metformin, on diet supplementation and caloric restriction. Each one of those, with the exception of senolytics, is targeted towards a very narrow aspect of aging. Reprogramming, on the other hand, treats aging at the very root. It is broadly applicable as a concept, and it has a number of repercussions, as we have shown. If you target the nucleus, the chromatin, the epigenetic landscape, you are also targeting all kinds of downstream effects – that is, aging in its entirety, you might say. We have shown that the cells are behaving in a more youthful way on the physiological level, the transcriptomic level, the methylation level, the epigenetic level, and the functional level. So, it is a much deeper and more effective way of treating aging at its roots.

I am a bit worried about what I see as the tendency to shy away from the idea of lifespan extension. For instance, Altos Labs has said repeatedly that it’s not a longevity company, as did your CEO in a recent interview. What is the reason for that?

I think that the field, unfortunately, is cursed in a way by this idea that by doing what we are doing, we are thinking about extending longevity, about immortality, et cetera. I think it’s very important to clarify that it’s not our mission.

It’s not that I’m shying away from the idea of living longer, and I don’t think there’s anything wrong with that idea. We do this on a daily basis when we think about our diets, when we exercise. But I want to stress that, first of all, we just want to impact people’s healthspan. Obviously, every time you do a medical intervention that saves life, you’re impacting longevity. That’s the purpose, right? You want to prevent people from dying, and so they live longer.

That’s not what we are aiming at. I want to make sure, for example, that a person who is crippled by osteoarthritis can walk. I want to make sure that people who are frail because their muscles have lost strength, can perform their daily duties without pain. I want to make sure that people who lost their sight because of glaucoma or macular degeneration can start seeing again.

What we want to achieve is a healthier life that will inevitably be longer as well.

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About the author
Arkadi Mazin

Arkadi Mazin

Arkadi is a seasoned journalist and op-ed author with a passion for learning and exploration. His interests span from politics to science and philosophy. Having studied economics and international relations, he is particularly interested in the social aspects of longevity and life extension. He strongly believes that life extension is an achievable and noble goal that has yet to take its rightful place on the very top of our civilization’s agenda – a situation he is eager to change.