Chris Mason and Afshin Beheshti: Is Life in Space Possible?

Transcript

Daniel Levine: I’m Daniel Levine and welcome to MitoCast. As researchers have taken a multiomics dive into the effects of travel and space on the bodies of astronauts, they’ve discovered that through the increased exposure to radiation and the effects of microgravity, it has damaging effects on mitochondria. In fact, the damage is similar to what happens to mitochondria as we age. As plans are being made for new trips to the moon and there are discussions of a lunar space station and even trips to Mars, our ambitions for a future space age may rest on our success at figuring out ways to protect and rejuvenate mitochondria. And the development of such approaches, in turn, can have profound effects on our ability to treat mitochondrial diseases and address the effects of aging. We spoke to NASA principal investigators, Chris Mason and Afshin Beheshti about what’s been learned about the effects of space travel on mitochondria, why it represents a critical barrier for the future of space travel, and why solving the problem may give us ways of extending healthy years of life on Earth. Afshin, Chris, thanks for joining us.

Chris Mason: Thanks for having us.

Afshin Beheshti: Yeah, it’s a pleasure to be here. Thanks.

Daniel Levine: You’re both principal investigators with NASA. There are many authors on your papers and others are publishing on the biological data being collected and generated by NASA. Can you perhaps start by giving us a sense of the scope of the research being done, the range of researchers involved, and what your roles in the research are? What makes your work unique?

Chris Mason: Sure. I’ll kick it off, but Afshin and I have both worked on many, many projects over the years and with Dr. Beheshti’s work, and many collaborators. I really stand here on behalf of hundreds of researchers across the world for some of these projects. But in a nutshell, the main goal is to better understand what happens to the human body and other organisms’ bodies when they go into space. This includes microbes, plants, animals, particularly focusing in my laboratories a lot on human space flight, but we take a really broad multi-kingdom view of the biology. So whether it’s human and microbial interactions or how things changes in your gut, for example, or genetics and epigenetics. So, we take a broad view to look at the cellular, molecular, and full physiological changes that happen to the body to help us prepare for longer missions that are coming; and eventually to also start to look even at countermeasures and precision medicine, which I think Afshin would talk about as well.

Afshin Beheshti: Yeah, sure. As Chris said, we worked with many, many people. We embrace the whole open science and open collaborative global network because the space biomedicine world or space biology world can’t be researched by one person. Obviously that has to be done as a global effort since it’s so expensive and so many things are involved with doing it—so yeah, with my work specifically, embracing that whole open science area. we’ve worked with Chris, Dr. Mason, we’ve done many different projects together, not just covering, let’s say mitochondria, which we’ll talk about later, but many aspects of systemic impact of the body since space is an accelerated model for aging and lots of diseases. Specifically, I work on mitochondria and one aspect of the unique things that I’m trying to figure out is the magic pill that you see in sci-fi movies they want to take so they’re like, oh, cured from all damage done in space. So, maybe we’ll make a cocktail. We’ll try and work with Chris closely with much of this stuff obviously, and as we’ll get into, we’ll give some hints that potentially it’s a mitochondrial magic cure that we could take—a magic pill to do that. It could be other things too, but that’s kind of the ultimate goal that I would push forward to say while we understand the science of space on your body, the space environment to your body, really we need to figure out how to make it safer for average people like me with a gut to go in space, rather than the 0.001 percent of fit people that are currently going right now, which is good that they’re going now and I’m not going.

Daniel Levine: Well, Chris, you and I have spoken about your book, The Next 500 Years Engineering Life to Reach New Worlds. Before we talk about what’s been learned from studying mitochondria in space, it might be worth taking a step back and having you begin with the greater vision for the intensive study of the effects of space on astronauts and really why the survival of men may depend on our ability to go beyond earth.

Chris Mason: Yeah, and thanks again for the book plug and it is out now wherever books are sold. So it’s basically a collection of goals, dreams, and aspirations of what I think humanity can do and also should do in the sense that we’re the only species as far as we know in the whole universe that’s aware of extinction and the frailty of life, particularly stark in the vacuum of space and the stressors on the body and the radiation. I think about this almost every day that eventually earth will be engulfed by the sun. And so, if we’re still here, even if we have perfect global harmony and world peace and there’s no war and everyone has enough to eat—we will all still be burned by the sun. So, I always look through the lens of a billion years and all ethical problems become quite clear. And I always think about this in terms of how do we start to look at the first forays into space, thinking about going to the moon or Mars, not just because we are curious, but because actually eventually we literally have to go that way too if we want to survive in the long term. But in the short term, a lot of it is actually a forcing function for precision medicine here on earth. So if you have to use very limited power, limited size and ease of use, that’s portable medicine, that’s precision medicine in austere environments, for example. So the book is about the why and the how. So, eventually we go to the outer planets. Eventually we go towards a new solar system and plan to live there. And also, the ways you could even modify gene expression or genetics to enable organisms to live there potentially someday, even humans. We have to wait and see. Maybe humans can survive just fine, but if we need help, we’ll take any help we can get from any technology we can safely use.

Daniel Levine: Let’s talk about mitochondria. We all know of mitochondria as the powerhouses of the cells and other critical functions, but to what extent are mitochondria limiting factors both in terms of lifespans on earth and then to your work for the potential for human life beyond the planet?

Afshin Beheshti: Yeah, maybe I’ll take this one first. So, from our work that Chris and I have done we’ve shown that this is back up for the aging process. As everyone ages, your mitochondria declines. That’s one of the hallmarks of aging. Through the past few years, some scientists have defined 12 hallmarks of aging and one of them is mitochondria. There’s 11 more related with telomere shortening and so on. But I’m biased and I think mitochondria is actually the hub of everything else downstream, but that’s not what common view is, other than the fact if you become a mitochondriac, which hopefully will convert everyone in the world to become mitochondriacs, meaning that mitochondria is the most important thing ever. But again, that’s a biased view I have. So, with aging it obviously declines. There’s a lot of diseases that are attributed to mitochondrial dysfunction. For example, with cancer, there’s the Warhol war break effect where cancer hijacks and suppresses your mitochondrial energy production and replaces the glucose glycolytic activity, which is bad for your body, but great for cancer to thrive and grow.

Chris Mason: And even theft. The recent papers have shown that mitochondria can be stolen by cancer cells to get more mitochondria, which is just kind of fascinating to think about.

Afshin Beheshti: Exactly. So, there’s many diseases and you can keep going down the list. Basically, a lot of the brain or CNS related issues, brain neural degeneration issues are related with mitochondrial dysfunction—meaning 20 percent of your mitochondrial is found in your brain and your brain’s only 2 percent of your body mass. So, imagine all that mitochondria packed in there from Parkinson’s, Alzheimer’s. You just go down the list. A lot of schizophrenia, even autism, has been shown to potentially be mitochondrial dysfunction related. So that’s the clinical side. And now what we found with space, from our paper of almost four and a half years ago that we published in Cell, we saw that indeed mitochondrial is the central hub of this regulation in space due to the whole environment in space of the radiation microgravity combined. And then when you look at the parallels of what happens with diseases and aging—and we’re going to have a follow-up paper that hopefully will end up in Cell again—the idea, now that we’ve done a deep dive looking at all the detailed mitochondrial pathways related with energy production to all the downstream metabolic factors and metabolism changes to how it impacts your immune system, that indeed you get that advanced aging phenotype due to the mitochondrial dysfunction and all the diseases and health risks associated with them is probably stemming from mitochondrial. Again, I could be very biased with my viewpoint here, but the data for me is pointing that way. And probably Chris might agree with me here.

Chris Mason: Yeah, a lot of signs, like “all roads lead to Rome” in the old days, is sort of like “all stressors lead to mitochondria” in many diseases. And I think in space flight, one thing that we saw that was shocking was that mitochondrial DNA and mitochondrial RNA were both elevated when Scott Kelly spent a year in space, which was just really surprising. It was just a really unexpected result. And we thought, well, maybe it’s sporadic. It could just be this person. But now this Japanese space agency published a paper last year that showed a replication of this result, and we’ve seen it now for other crews. So, this ejection is probably an interferogenic response we think, or priming the interferon pathways, like the immune pathways of the body to prepare it almost for what it thinks is an infection or a stress. So, it’s really interesting to see that this mitochondria is really the sensor as well as a mediator of the stress on the body. And we keep seeing it pop up—quite literally—popping up in odd cells and into the bloodstream.

Afshin Beheshti: Even for the shorter missions, like all these commercial missions, we see the same thing happens. It doesn’t matter if it’s Scott Kelly for a year or Japanese agencies’ data that was there for 120 days on ISS, even for the three day short mission of inspiration that Chris was heading or in charge of, a lot of the data showed the exact same thing. So, it like doesn’t matter—it’s space, the mitochondrial has that same kind of stressor as Chris pointed out.

Daniel Levine: If the effects of space on mitochondria are similar to the effects of aging, what are we learning about mitochondrial stress on astronauts that have a potential to broaden our understanding of aging in ways of extending healthy life on earth?

Chris Mason: Well, I think for a lot of it, we can use it as a model for testing new drugs, new interventions, new therapeutics, because it is an accelerated aging model. We see a lot of the same stress markers show up. Epigenetic age—we’ve looked at this a little bit—that doesn’t seem to accelerate it too much fortunately. But a lot of the other physiological phenotypes, for example, bone loss, muscle loss, cachexia, various phenotypes that look like aging or sarcopenia, we’ve seen frailty markers. We’ve also published kidney stones being more likely, or at least in the rat models. So, there’s a lot of interesting phenotypes of things that you just get as you get older, and we can see them coming up at a higher risk for the crews as well as the animals that fly.

Daniel Levine: So, in terms of the effects of space on human biology, are the effects that we see on mitochondria the most significant, or are they just one aspect of our biology that’s affected among many?

Afshin Beheshti: I think it’s probably the most significant, but I think it’s probably maybe the first line of impact to your body that causes, again I’m biased to say this, but we’ve shown, and Chris has shown, and other people have shown that all the immune function and inflammation is highly impacted. You see all this dysregulation, for example, of your innate immune functions being suppressed, and then inflammation goes up and cytokines get released, similar to what happened in COVID, in SARS infections. But we’re making the argument that mitochondrial is causing this downstream impact of these greater signals that you see later on. But the mitochondria has a great suppression of energetics happening across tissues long-term too.

Daniel Levine: Some viewers may be familiar with the 44 article package of studies on space summits that was published in Nature. Can the two of you give a sense of the totality of what’s been done to study the effects of space on our bodies and the bodies of other organisms, and how many subjects have been studied, what’s been the duration, how granular or longitudinal look have researchers taken of the biology of astronauts in space?

Chris Mason: Sure. Guess I’ll jump in first. There are just about 700 people who’ve been to space, including some of the suborbital launches, which just get past that Karman line of a hundred kilometers. But for orbital flight, it’s just below 700 of people who’ve been in space in orbit of the planet for a while. And the mission with the Kelly twins, the NASA twin study, he was up there for 340 days, but there has been a Russian cosmonaut out that was up past 500 days in space. And so we know that there’s been some longer missions, but not that many. Our knowledge of people in space for more than a few weeks is not that many. We have many three to six month missions, and by many, I mean maybe a couple hundred at this point. And that’s about it. So, it’s really a few hundred examples of people that have been in space for months on end, six months, let’s say. We’ve published some of the papers with Dr. Beheshti that look at about 60 of those astronauts from some measures, say protein measures or cytokines, working with Dr. Scott Smith at NASA and other collaborators. We’ve tried to collect all of the data we could that’s ever been publicly available or that we publish a lot with the Inspiration4 crew, and get that into one atlas, the space omics and Medical Atlas package of papers, mostly because this is something that’s actually very common in cancer research and genetic research where you have a question and you see a mutation or you see a change. If you see any kind of molecular change, you want to know, well, is this common, Is this rare, does this happen for… is this only in breast cancer? Is this something you see just as a function of age? Is this just stress? So generally, you need to have a large context and large number of samples before you can better understand your data. So, we’re trying to bring some of the tools of precision medicine and molecular biology to space medicine and also to general astrobiology—the microbes in space. And we basically took every single data we could get that people had consented for and was possible to release into one atlas, and any mouse that had ever flown and rat. So you type in a human gene, you see all the changes that have ever been seen. You can also then look at the orthologs gene or the matching gene that’s present in a mouse or a rat and have that plot up as well. So we want to get every bit of data we possibly could into one spot. And this was made possible with Gene Lab and the OSDR, the NASA databases, which really made it possible. So we wanted to make it so you can have a hypothesis and quickly look at it and access that data. And it was really also the crew, the Inspiration4 crew was very generous and said, “We want to generate these data and get this out for people to use it.” So a lot of the bravery from the crew and the generosity of the crew made this possible.

Afshin Beheshti: One thing to point out with these paper packages is the good thing is when you get the community to do that, a lot of the papers that come out, if you put them individually by themselves, you read them and be like, oh, this is a great paper. Six months later you might read another paper, but you’ve forgotten half the things that are in another paper. Because these days, the attention span of people is shorter. But when you put the whole package together, we have the table that Nature put nicely about the systemic impact from the whole organism to the tissue, to the cell, to the molecular level. And then you see the pieces of the puzzle now as a whole together as opposed to the bits and pieces, pieces of the puzzle you might read every two or three months, which then you forget how these things are connected. And when you see the connection happen, now you’re like, oh, now you see, let’s say the kidney. For example, in this paper package from our collaborator, Keith Siew of University College London. He did this massive paper about kidney, a hundred authors on there, the most comprehensive analysis that anyone’s ever done on how space impacts your kidney. You read that, but then you say, how’s that connected to, let’s say, your cardiovascular system and brain? But you have the papers together, you’re like, oh, the whole mechanisms actually connected and the circling factors might be involved this way. And I think that was the key with everything Chris mentioned, how the data’s there now and then how all the papers come together. That’s really neat to see because now you see the systemic impact, and I think it really accelerates how people think about how all these papers impact potential countermeasure development or understanding the basic science.

Daniel Levine: This is not like doing your typical clinical study. What are the particular challenges you face in studying mitochondrial health and astronauts? And do you do this in real time? Do you rely on bios, samples and data being sent back to earth?

Chris Mason: Whenever we can, we do it in real time assays, in situ or in place assays right at that moment. And we’ve validated a sequencing protocol with what’s called a nanopore sequencer that could be done in flight. And there’s other assays we try to do in real time that we’ve just been validating and flown a couple of times, but we would like to make it so you could do it in the space station or in the spacecraft, but often just getting blood draws, we get them either freshly drawn or you have to spin them down and freeze them. And so it is a challenge. I mean, there are logistical challenges that samples have to be aliquoted, prepared, frozen, preserved, and then brought back and re-aloquoted for investigators. So, you have to run controls and then additional controls and ideally even more controls, you really have to make sure that you’re not just seeing a consequence of noise or some other technical artifacts.

Afshin Beheshti: Yeah, and one of the things we rely on now is a lot of mouse data because obviously the astronauts are not going to give us a biopsy of their liver or kidney. Maybe in the future Chris can vent. He’s pretty convincing. So maybe Chris can do this in the future, but right now we don’t have that. That’s the one limitation as opposed to let’s say the clinic, if someone’s getting a surgery for something, yeah, a patient might consent, oh yeah, if I’m having a surgery in this organ, and it’s safe, take a biopsy and give it to the scientific research. So, a lot of the basic research is relied on mice in space. And then now we could actually look at all the different organs, which this is what we’ve been doing in our last paper, in the most recent paper, you can find the pre-print available. So, then you translate everything Chris said to the human data. And you could do that and you could piece it together nicely. But that is one of the limitations. That’s one of the bigger limitations now for real-time monitoring. But we hope, let’s say based on what we see in the mice, we see it translate to humans. Then we could find the marker circulating due to mitochondrial dysfunction, circulating like the mitochondrial DNA, for example, a low hanging fruit, or other factors related to what we see in the mice. And in these papers we’re showing, okay, this is what actually could be circling to humans. And then Chris could monitor your key mitochondrial factors for what’s going to be predicting your advanced aging or frailty that might occur due to the suppression that happens in your bioenergetics.

Daniel Levine: Are there things you think can be done to better understand the intricacies of mitochondria and zero gravity or under increased radiation?

Afshin Beheshti: Right now, we do simulated experiments on earth. So, we go to, for example, NASA has set up a NASA space radiation laboratory at Brookhaven National Labs. So Brookhaven National Lab is a high energy physics collider where the physicists take particles, smash them together, and of course you get the fundamentals of life and mass and what’s there. And so there they actually produce the radiation types and ions you get exposed to in space. So that’s where these heavy high energy—you could produce the ion particles, the protons, and anything in between—the ions that are in deep space that you’re exposed to. So, then they set up a whole facility there where they took part of that beam and you could put the mice, cells, anything you want, plants, electronics and then you got that same kind of dosage that you might get in space. Well, in space you get accumulated fractionated dose over time, a constant low radiation dose. You can’t really do that on earth, but we give the total absorbed dose. You might get, let’s say for 30 days in space, or let’s say a year round trip to Mars, how much dose that be. So we say, okay, well zap the cells or the mice with that and then study them that way. So we do a lot of studies like that on earth in those kind of environments. And then there’s, of course, there’s “micro grav,” simulators where, for example, things called clinstats, basically random position machines that rotate and you put the cell in there and it displaces the gravity to be microgravity in a sense. And then there’s things we do with mice experiments called high end limb loading. You hang the mouse by the tail, which is silly, but for a period of time what it does is basically unload the weight of the back leg. And this causes muscle degeneration, the fluid shifts, which you might see in the mice and which happens in humans, so there’s some similarities. You could never truly simulate what’s microgravity on earth, but as humans, we got to get close. So that’s as close as we can get. And then we go to, okay, we know what happens, we potentially have maybe potential drugs or countermeasures, which we can get into later, that could potentially mitigate the mitochondrial damage. And then now we say, can we test it in astronauts? And then that’s where Chris does his magic and gets us access to all the commercial missions to maybe test the potential counter measures.

Chris Mason: And that’s what we’re trying for in future missions to basically use the accelerated aging environment of space flight and the stress of space flight, but use it as a rapid iteration platform for testing new therapeutics and countermeasures, including help for mitochondrial function. Kaempferol  is one of the molecules we’ve been looking at, but looking at any number of possible drugs and small molecule screens that could help survive in space.

Daniel Levine: Well, we appear to be on the cusp of a new age of space travel. There are new missions planned for the moon. There are discussions of a lunar space station and there are visions for future missions to Mars. The notion of extra planetary settlement, once the fodder for science fiction, appears now to be within reach. Gordon Friedman, the founder of MitoWorld, said to me the other day that no one’s going to Mars until we figure out mitochondria. Is he right?

Afshin Beheshti: Yeah, absolutely. I would agree. So again, I’m biased, but that’s what we were showing right now. We could predict based on our data we have, if an astronaut goes to Mars without any kind of countermeasure or precautions to take, their mitochondrial be so heavily suppressed and the biologic damage that I don’t know how they’ll function. Think of COVID and what happens with long COVID patients, which we are defining as a mitochondrial disease. Think of that multiplied by 10 or 20 or a hundred by the time they get to Mars. I mean, the cognitive issues alone will be hard for them to focus based on the mitochondrial decline you get there. I would predict that. But there might be hope because we are testing, as Chris pointed out, countermeasures to boost your mitochondrial signal, which has some very promising results that some of it’s been in a pre-print, but this’ll be a whole slew of papers coming out in the next year to show the promising results of that.

Daniel Levine: Let’s talk about what is in space that has such an ill effect on our bodies. There are two primary concerns. The first is the effect of radiation and the other is microgravity or prolonged effects of weightlessness. Let’s go through each of those. Broadly speaking, how significant is the exposure to radiation in space and what effects does that have on our body over time?

Chris Mason: I mean, the radiation, of course, you don’t want too much radiation. Some of it is unavoidable by just living in the universe. The Inspiration4 crew got only about four milli-Sieverts of radiation, and that was just over a few days. But when Scott Kelly was in space it was 146 milli-Sieverts and that’s the equivalent of getting a few chest x-rays every day, which again, it doesn’t kill you, but that number 146—to put that in context, once you get to about six to 700. That’s about the expected lifetime exposure that you should get. So within just one year he went to almost a quarter of what he should get for his whole life. So, it is an accelerated risk, but in low earth orbit, it’s not too bad in the sense that we’re still protected by the Van Allen belts. The earth is still a really big shield for a lot of radiation that’s coming from space. And so that is a helpful feature, but we’re worried about the radiation, the fluid shifts, the isolation. You’re also far from any help on earth, the microbiome changes because you’re in a really sealed environment. So that also changes how your immune system responds. We see a lot of immune perturbation in almost every mission we’ve looked at. So, these are all factors we’re considering that we know are going to need to solve or at least mitigate for the longer missions.

Afshin Beheshti: Yeah, also the exposure to the heavy ions in space. So something that Chris mentioned, the doses you’ll get. So, in space you got something called, well, in radiation biology we got things called LET, which is a linear energy transfer. So the amount of energy the ion will transfer to your cells or tissue. So on earth, everything that does your chest x-ray is a gamma or x-rays you got exposed to. And those are fast moving particles that travel through your cells and tissue and as they travel, what transfer the energy scattered throughout the cells. But in space you got highly LET radiation, meaning you got these heavy ions from protons all the way up to iron particles of silicon, just go through the periodic table. And then what happens is they’re slower moving, but as let’s say an iron particle is like a bowling ball, it’s moving slower, but then the energy just goes right into your cell, deposits all of the energy into your cells as opposed to passing through. So now let’s say an equivalent dose of a chest x-ray of highly LET radiation, meaning the space irradiation, and I’m just making up a number, say two grays. The dose you might get for cancer therapy is a gamma radiation. If you got two grays of the high LET radiation, they have iron particles in the mixed beam up there that’s equivalent to 10 gray or more of gamma. So, it’s almost lethal getting that high dose. So the biology changes a lot. That equivalent dose that Chris mentioned is really important to understand that these heavy ion particles have a whole different biological interaction with your body than what people are used to getting that chest x-ray. So, getting those a hundred or what do you say about 10 chest x-rays is actually a lot more damaging than you actually get into 10 x-rays on earth, chest x-rays, on earth compared to their radiation equivalent in space. So that’s the part where we’re thinking that alone, with what impact of the mitochondrial, causes even a greater damage to the mitochondrial is exposed to the gamma that you might get exposed to on earth—that equivalent dose you get.

Daniel Levine: How about microgravity? What would the long-term effects of a trip to Mars be?

Chris Mason: Well, this is a big debate. I mean, we know it’s not going to be pleasant on the body, but actually I would even say the biggest challenge is not so much living in space, but when you have to land again, it’s much harder on the body. We see a lot of the most significant spikes and changes the day of return to gravity. A lot of it is just the muscles and body realizing the shock of suddenly having to use and build and rebuild a lot of the muscles and bone. So it is tough on the body. But one good thing about that is Mars is 38% gravity, so maybe it’ll be 38% as hard as it is landing back on earth, we hope, but it has other perchlorates in the soil and a different atmosphere and you can’t go outside and there’s things that might kill you there very easily in terms of the environment. So, it is harder in other ways, but I think we want to plan ahead these long missions with all that in mind.

Daniel Levine: So mitochondrial dysfunction underlies a lot of the ill effects that you’ve seen on the body. What exactly happens to the mitochondria in space?

Afshin Beheshti: So, it’s a whole cascade of events. So, in our most recent paper, we’ve kind of really dissected that out with the help of one of the lead authors on there, Joe Garineri who’s this mitochondrial expert, young guy who’s helping us out on that. But what we see is a cascading event where the first impact of the mitochondrial is your whole oxidative phosphorylation activity. So, this is like your ATP energy production, whereas the different complexes, complex one through five is basically involved with all your energy production. So that’s where we show the longer in space was kind of intuitive. The more suppression of this happens and then when let’s say mice or even astronauts come back in the circling factors, we see long-term suppression happen. Even from this Inspiration4 data that Chris has provided, we see even up to 120 days from the latest point we had, it’s the suppression of mitochondrial OXPHOS (oxidative phosphorylation) activity, so your energy production and then mice tissue, we see the same. But then what happens cascade from this is that it helps produce reactive oxygen species. So, the key is reactive oxygen species can be produced from suppression of OXPHOS activity, but also radiation we know produces reactive oxygen species. So it’s double impact. So that in turn creates hypoxia. So then hypoxic events in your body is bad, you don’t want that to happen because that’s going to create a whole slew of aspects to increase cancer arrest to cardiovascular arrest. And you just go down the list and then the cascade event after that, which is going to impact your immune system where you get the inflammation that happens. And then also reduction or suppression of innate adaptive immune activity that makes you more prone to infections now. So, for example, we see viral reactivation herpes viruses happening in space and other potential viruses. Maybe people don’t understand why these viruses might become reactivated. Maybe it’s because of the mitochondrial dysfunction suppressing your immune system, causing you to be more prone to infection or reactivation of viruses. That has to be proven still, but that’s a hypothesis. And then eventually from down there, from that it will cause cell death, apoptosis of cells, and then basically some mutations might evolve from mitochondrial DNA to happen there. So, this is in the current paper that’s under review that we’re showing this whole cascade of events that happen downstream, which is very parallel to most things that happen in aging alone, but in an accelerated manner, obviously with aging over 90 to a 100 depending on the people living to a 100 now. But now, over a short 30 day period in mice we see this happen in the space as opposed to over your lifespan.

Daniel Levine: One of the other things the data has shown is that mitochondrial DNA is more susceptible to damage than our genome. Why is that?

Chris Mason: Well, it’s a lack of DNA repair mechanisms that don’t exist as natively in mitochondria. So, in our cells we all get mutations every day, but almost all of them get repaired by enzymes and homologous recombination and other methods that basically look at the ends or broken ends of DNA and fix it and repair it. That’s actually one great thing about DNA is because it has two strands, you always have a backup copy if you look right across the pond of DNA. And so there’s my other confirmation of my backup copy. So, there’s a really great feature in animal DNA and eukaryotic DNA, but we don’t see that in mitochondria. And so they’re subject more to the mutations. They have some protective mechanisms, but they can accumulate mutations faster. They also have something called heteroplasty where there’s many copies of mitochondria per cell and some more than others, but they have a whole dynamic range. We have half our DNA from our mom and half from our dad for the human DNA. But the mitochondria, DNA is all from our mother. And also, it shifts depending on different cells, and the brain has more mitochondria. So it really depends on where you’re on the body and what they’re doing. There’s different amounts of mutations and different numbers of mitochondria. So it’s kind of like a hybrid ecosystem of DNA and genomes inside of our bodies. Much like plants have their host DNA and chloroplast very similar where they have a little ecosystem inside them.

Daniel Levine: One area where mitochondria are rich are eyes, which it turns out are particularly vulnerable to the effects of space. Can you explain neuro ocular syndrome and what’s understood about its causes?

Afshin Beheshti: Yeah, space associated neuro ocular syndrome stands for SANS we call it. Originally it was thought to be because of the whole microgravity environment, you get the flattening of edema, the fluid shifts that might happen. So they’re like, oh, that’s going to cause where the issue that happens. The whole issue is some astronauts get declined in vision over time, some don’t and then some recover and some are wearing glasses or get a thicker prescription when they come back and some recover fully. So, what makes some astronauts more prone to not having anything happen in that time in their eyes versus some that do get the decline and some that have long lasting effects and some recover? Now as you pointed out, there’s a lot of mitochondria, not a lot, but there’s some mitochondrial diseases that are associated with vision loss. Even macular degeneration has been linked to mitochondrial dysfunction and suppression. So this is where we are showing in this paper also in mice, not in humans. We look at the eyes of the mice and we see definitely that same whole mitochondrial cascading events happen in the eyes. So in long-term effects that happens in the mice we looked at. What’s interesting is that now we’re working on other factors related to clinical associated diseases, very similar to things like bone disease and the mitochondrial disease that relates to vision loss, that whole cascade events that happen. Now what really causes SANS, we’re still trying to figure out, but I wouldn’t be surprised in a year or two. We say Eureka! it’s mitochondria.

Chris Mason: And it’s different. The women seem to be less affected than men, which we don’t quite know why yet. There’s all sorts of interesting mysteries still about SANS, but more missions and more crew members sharing their data will help us figure that out.

Afshin Beheshti: For sure. And I think truly if we maybe characterize the people before they go to space, their mitochondria, that might explain maybe the woman had more resilience due to some mitochondrial trait that men don’t have. But I think even the astronauts who might not be prone to the vision loss, I bet it’s due to some mitochondrial resilience they have versus the ones who get the decline in the vision.

Daniel Levine: So, at the top, when Chris was rattling off the different ill effects that was seen in astronauts from time and space, he mentioned sarcopenia, which is the loss of muscle mass. I’m wondering if you can talk a little about the role that mitochondria play in this kind of space induced frailty.

Afshin Beheshti: Yeah, one paper we’re working on, and the paper we published last year was actually looking at frailty in the frailty index. So, in a clinic as you grow older, they find you are your physical age, but not all people in their internal clock might be 80 years old. Their body might be like a 70-year-old versus an 80-year-old, or you might be a 90-year-old. So that’s their little frailty index in the clinic that a clinician might define that your true age is actually what might be defined something differently than your actual age due to the physical changes in your body. So, with sarcopenia, we looked in the literature, we know what happens in sarcopenia is that something, one of the factors is OXPHOS suppression in the muscle that happens with sarcopenia decline and more and more happens, you see that by energetics in the muscle getting further damaged. We see that same exact parallel happen in space, granted we haven’t dissected out whether that’s going to be microgravity or radiation having the greater impact, through the similar experiments you’re doing on earth. We’re looking at that now. I’m biased and I think the radiation probably has a greater impact causing the sarcopenia mitochondrial dysfunction versus microgravity just in the mitochondrial part of it. But again, that part still has to be really worked out, which component of space causes the greater mitochondrial decline. But basically that’s what we’re seeing. And probably Chris has something to add too.

Chris Mason: And over what timeframe. So I think we’ve seen there’s a dose effective space play where the longer you’re in flight, the more pronounced some of these changes and markers seem to be in terms of their responsiveness. So we’ve seen the same idea of the right drug for the right patient at the right dose. It’s kind of like in space flight. You want to be the right protections for the right astronaut at the right dose. And some people might need more, some people might need less. But we’re looking at all these markers now for the different crew members.

Daniel Levine: And how lasting are the effects of space on mitochondria? And does the recovery suggest anything about the ability to restore health to mitochondria from other sources of stress?

Afshin Beheshti: Yeah, I mean right now the longest time point we have from the humans is from Chris’s data in Inspiration4. We see 120 days later circulating factors related mitochondrial suppression still. Now, luckily it seems like we looked at complexes one through five, the whole OXPHOS related energy production cycle of mitochondria, and depending what Chris had done in single cell RNA seq on this, we know that different immune cells that some of the immune cells like the T cells and B cells might, after 120 days, they start coming back to normal levels. That’s good. But then the monocytes were the ones that were really impacted with the mitochondrial suppression that they still weren’t recovering from the mitochondrial suppression we saw, which could be prone to infectious diseases and beginning to be more prone to infections. So that’s the key. And then the promising thing is from our countermeasure experiments that we’re doing that Chris mentioned, kaempferol, which is one of the things we’re looking at that’s from funding from Otsuka, which is trying to launch it as a nutritional supplement. Kaempferol is a flavonoid found in a lot of things. You probably had a lot of kaempferol this morning if you had blueberries or you had spinach, kale, but they have a more purified version and they modified it so it could be easier to get in your system. So, we’re starting from the experiments we’re doing with Chris and other folks, and our other collaborators where we did the simulated mouse experiments at Brookhaven. And then we also did it on these 3D organoids, basically tissues on a chip, through kaempferol. And we saw that indeed we’re actually mitigating the damage caused by the space radiation impact (simulated) and the microgravity. And it was really neat to see that indeed, so far the data is showing is actually restoring a lot of the OXPHOS related activity that’s being suppressed. It’s bringing it back down to normal levels. And for example, like our collaborator, Rob Schwartz at Weill Cornell Medicine, he has these organoid models, human tissues in the dish. So, you could create a heart, for example, that’s derived from human cells that are similar, but it’s in a dish that can simulate. So, the heart actually beats like how your heart would beat in your chest. So radiation, what it does is reduces the beats significantly. You give this kaempferol and it reduced it back to normal. And then from all the data we’re analyzing now we’re saying, oh, we’re actually restoring a lot of these OXPHOS activity and the metabolic factors. So it’s really neat that it’s probably not just one mitochondrial supplement, it’s probably going to be a cocktail of things we have to get. We probably have to have a mitochondrial cocktail and then give that to the astronauts and figure about that. I’m sure.

Chris Mason: Yes, and I think it’s also organ weight. We can see the damage to organs is less pronounced or is lessened overall, the stress markers are better off. So, I think there’s definitely room for this countermeasure or others to help make sure we can protect mitochondrial function.

Daniel Levine: Have you had to find ways to monitor mitochondria health and has this given us any way to monitor the health of mitochondria on earth?

Chris Mason: Yeah, I mean one of the ways we do it is there’s something called the cell-free nucleic acid where you sequence all the DNA and RNA that’s in plasma when you look at your blood. And that gives us a really broad view of the number of changes that we see for many human genes, but also mitochondrial RNA. So that’s one thing we’ve been looking at. But we do want to embed these metrics into a full health profile and full disease profile as well.

Daniel Levine: You talked about countermeasures and kaempferol, but some of the other stuff you were looking at were B vitamins, is that right?

Afshin Beheshti: Yeah, I mean we weren’t looking at that, but that was people from Brian Cru, from JC and Scott Smith. They’ve done a lot of studies where on the astronauts right now, the only standard supplement they take is vitamin D, which is a mitochondrial booster, but it doesn’t fully mitigate any damage, but it’s good they take it still. But there’s a study done by Brian K. Scott Smith where they did vitamin B think it was, I forget which version.

Daniel Levine: B3 I think.

Afshin Beheshti: Yeah, B3, correct. And then they were showing, for example, they were looking at SANS specifically and it was able to restore some of the physiological changes that happened with SANS by vitamin Be. Didn’t fully recover or anything, but it was really promising. That’s good.

Daniel Levine: Other things that seem particularly promising to you?

Chris Mason: For molecules or just for future missions?

Daniel Levine: Anything that would be a countermeasure?

Afshin Beheshti: I’m actually ponding this. I have an interesting one too where my collaborator Cliff Calloway and Kate Re from University of Pittsburgh, from the sci-fi movies where you see the person in cyber suit and they wake up after a hundred day minutes traveling in that space. There’s something to that because from some of their research and some of the stuff that we’ve been starting to do with other kinds of organisms that go in hibernation and even this extremophile that our collaborator Jason Podrabsky from Portland State University, it’s called killifish. Killifish, for example, is found in Amazon river beds and African river beds where nine months out of the year the river beds are dry. It’s basically mud piles. When the fish lay their eggs, to have their progeny survive, those embryos become extremophiles because they have three diapause stages. In the second diapause stage, what happens really simulates hibernation where all these other people are studying it. What he’s been showing is that in the diapause two stage, the mitochondrial and metabolism basically shut down to zero. The eggs are basically hibernated. So, what we’ve done and what he’s shown from the normal low LET, gamma radiation, he could give him 50 gray, 100 gray, which would kill us if you get that, but they’re fine. Nothing happened to them. So that was like, wow. He had one day accidentally spilled 4% hydrogen per peroxide. And I came back the next day and he is like, they’re still alive and they could survive in this anoxic environment. So, they’re very, in a high state, they’re very resistant to a lot of damage due even to radiation. We’ve actually now done some simulated experiments at Brookhaven at a very high dose, which is more than any human will get after 10 years in space. They seemed fine. They were sent to space, they seemed fine. And the key is now why I think my hypothesis is that we’re in the hibernation state where this metabolism set down to zero, basically reactive oxygen species and not being produced anymore. And I think one of the key things we’re showing from mitochondria is that reactive oxygen species and that suppression of OXPHOS causes this whole downstream events of things. Sure, you’re still going to get DNA damage in the cells, but there’s nothing to interfere now with the DNA repair mechanisms. So maybe in that hibernating state, why they can take 50 gray or we went up to five galactic cosmic gray, which is pretty detrimental to humans. Maybe that’s why they could survive it. Now the mitochondria is like, well, we’re fine. We just don’t work at this point because we’re hibernating. I don’t know, Chris, you have ideas there, but I find that fascinating. I think this’s really neat.

Chris Mason: And changing the function, changing when they go to sleep or hibernate, they’re all the levers we’re trying to look at for mitochondrial function.

Daniel Levine: Well, you say it’d be an interesting counter measure. Would that have implications on earth?

Chris Mason: Yeah, radiation workers, if you think a cancer patient is doing radiotherapy in one spot, but you want to protect the other adjacent regions and keep them safe. So there’s definitely some applications where we’re using radiation or other risky procedures, but want to protect the cells nearby or in general, if you’re in a high risk environment.

Daniel Levine: And do you think across the data, were there any surprising findings about the effects of space on mitochondria that have you thinking at all differently about mitochondria?

Afshin Beheshti: I think overall, the neat thing we did recently was does this only impact mice or humans or is it other species? So, on the NASA gene lab or the open science data repository that has all these omics data from all the multiple missions and species, we didn’t only look at mice and humans, we looked at C elegans worms, fruit flies. We even looked at plants. Plants have a whole different mitochondrial impact, but they still have mitochondria. And the same thing is we were showing that it’s agnostic, whether you’re a plant, a worm, or a human, it has the mitochondria and space doesn’t care how it damages the mitochondria. So we’re not too different from a plant or a worm in space when it comes to mitochondrial damage. That’s basically what I found. I was like, oh, okay, neat.

Chris Mason: Yeah, my biggest surprise was just the fact that it was ejected from cells—that it’s being found in plasma. Because other cases where that’s been observed is, for example, people who attempt to commit suicide and they don’t succeed, but then they go to the hospital and blood is drawn, their levels of mitochondrial DNA would spike up really high, which is interesting. Like I said, the stress marker has normally been seen in really severe stressors like an attempted life. But then when you look in the blood, you see the spikes. So seeing this really, really stark sign of bodily stress, it was interesting to see where else we see that.

Daniel Levine: So, we see the White House and NASA accelerating planning for manned missions. Is this going to happen without giant strides of mitochondrial improvements? And is this on anyone’s radar other than mitochondrial biologists like you?

Afshin Beheshti: Yeah, I think we need to really target that. And if you don’t address the mitochondrial cocktail for the potential or the hibernation or a combination of hibernation mitochondrial, or something related to mitochondrial research—yet I don’t think it’s going to, because I think a lot of times, a lot of people might try to come up with a countermeasure that remedies what’s below the actual source. So, if you, let’s say, come up with something that might help your immune system, you’re still at the risk of the mitochondria. So that’s just a Band-Aid of what’s truly happening to the actual source of damage that constantly is going to cause that immune dysfunction, for example.

Daniel Levine: So if NASA called on the two of you and said you needed to solve this problem in the next five years, what would you recommend?

Chris Mason: Easy. We just need like $10 billion and a few missions and well, actually I mean I joke, but not totally because actually the things we’d really want to do is do large scale screens of many molecules to look at the effects of radiation and microgravity on mitochondrial function. We want to fly missions that have sets of two or four people, dozens of people up there, and there’s many space stations being built right now that might help us get larger sample sizes and do these clinical trials and track people long term as they start going into space. And you could do that if you had billions of dollars, you could run these big studies on earth and in space and then do large counter measures, do more screens, more synthesis testing and chemistry of other mitochondrial modifiers. And if you do all that, maybe by 2035, we get a head out tomorrow.

Afshin Beheshti: And the key is though, I mean, some people would be like, well, are you spending $10 billion to try to cure something that happens for four or eight people—fraction thing? The thing is, as I said earlier, this is an accelerator model for a lot of mitochondrial diseases. So any countermeasure we come to solve that problem can easily be applied back to what’s happening with all the clinical mitochondrial diseases. The SANS issue can be applied back to all the vision loss issues that happen in space in the clinic. So, I just go down the list, all the cognitive issues that happen, the cardiovascular. So that’s where, let’s say the $10 billion investment that Chris said could actually really excite all the mitochondrial diseases on earth, and that’s the key to happen.

Daniel Levine: Would you include aging as a mitochondrial disease in that regard?

Afshin Beheshti: Of course, yes, of course. We don’t want to call aging a disease, but it sort of a chronic disease, right?

Chris Mason: It’s certainly unwanted, let’s say. Yeah, for most people, yeah, it looks like Tourette syndrome. If you have a weird tick, you can just have a weird tick. But if it bothers you, then it becomes a disease. So I think most people are bothered by getting too old, too fast.

Daniel Levine: Chris Mason, professor of physiology and biophysics at Weill Cornell Medicine and Afshin Beheshti, director for the Center for Space Biomedicine at the University of Pittsburgh. Both are principal investigators with NASA. Chris, Afshin, thanks so much for your time today.

Chris Mason: Thanks a lot.

Afshin Beheshti: Thank you, a pleasure.

Daniel Levine: To stay up on the latest news and research from the world of mitochondria. Be sure to check in with MitoWorld regularly. For MitoCast, I’m Daniel Levine. Thanks for watching.