By Deborah Borfitz
March 23, 2022 | Leonid Peshkin, Ph.D., is an unconventional man working at an Ivy League research university in a field he believes is rightfully viewed with “great skepticism” by mainstream biologists. The war on aging he is advancing puts to the test both interventions designed to extend healthspan (the period of life where one is healthy) and our understanding how the ravages of time get undone in the germline, an approach he likens to a Russian “Koschei” fairy tale where the secret to eternal health is in the egg.
Like two of Harvard’s most prominent thinkers on the topic of longevity, George Church and David Sinclair, Peshkin holds that aging is a disease that scientists should be curing rather than its symptoms such as arthritis, Alzheimer’s, and cancer. Real progress will require radically open science less focused on making money than finding answers, he says, which is a noble if “notoriously abrasive” position in an arena inhabited by a lot of snake oil salesmen.
At present, the world of aging is being dominated by secretive companies making outrageous claims, like the ability to extend telomeres or rewrite the body’s methylation clocks, and there is no watchdog. “They’re going to say, ‘Trust us. We have encouraging results.’ And then 10 years later you realize that probably they didn’t.”
The Russian-born Peshkin, who lectures in systems biology at Harvard, wants to make clear he is “not a rotten socialist,” but he does think commercialization in the aging field is killing the science. The great temptation is to form companies that become slave to investors and start hiding the negatives and inflating the positives, he says.
Peshkin says he has been inquisitive about aging since boyhood and his motives are pure, but his methods are not without cost. It’s a passion he shared with his father, a survivor of World War II, who lived to age 97 in good health cognitively and physically.
Evidence to date points to two possible ways to extend lifespan and only one of them—the once-obscure immunosuppressive agent rapamycin (sirolimus)—is a pharmaceutical, he says. The other, seemingly more effective remedy is calorie restriction. Peshkin says two decades ago he put himself on a water-only diet for 48 hours once a month, an “easy and enjoyable” health habit even if the science remains a bit flimsy.
For his research, the animal models are primarily frogs and water fleas, specifically the species Daphnia magna, says Peshkin. It’s a tiny but complex organism with a one-month lifespan that has traditionally been used in toxicology and environmental research as well as food for aquarium fish.
Peshkin says Daphnia is ideal for testing interventions affecting measures of healthspan because many of its tissues and cell types (e.g., neurons and muscle cells) resemble their human counterparts, and it is extremely sensitive to small concentrations of drugs. Frogs, on the other hand, have giant eggs that are well suited to his work on oocyte maturation and early development and search for a process of cleansing in the germline.
Daphnia inhabits a flat, one-liter “smart tank” housed in fridge-sized incubator outfitted with a camera recording one-minute videos once per day for their short lifetime to watch behaviors characteristic of age (e.g., how they move, as with humans) and, it is hoped, identify interventions that extend active life and health, he says. A full description of the platform—including tank setup, feeding schedule, removal of offspring, and setting the light cycles and temperatures—recently appeared in Aging Cell (DOI: 10.1111/acel.13571).
The development team for the platform includes Harvard aquaculture expert Rachael Jonas-Closs and engineer Yongmin Cho, Ph.D.
The platform consists of an easy-to-assemble tank and easy-to-maintain animals because the intent is to create a standardized, scalable way to raise Daphnia and crowdsource some of the science since so many people are passionate about aging research, says Peshkin. Championing the need for another model organism hasn’t been simple, he adds, noting that the platform turned into an unfunded hobby about a year ago.
As Peshkin envisions it, the Daphnia platform could be applied in a distributed fashion much like SETI@home that uses internet-connected computers in the search for extraterrestrial intelligence. In this case, citizen scientists might be building tanks according to instructions that they then seed with Daphnia and start taking one-minute-per-day videos that get uploaded to the central server.
It’s a Wikipedia-like process that would self-correct because the “forces for good” are stronger than the potential deeds of evildoers who might post all sorts of garbage data, says Peshkin. “If you say something will increase lifespan tenfold, then many people will be interested to repeat [that experiment] and it will very rapidly get corrected.”
In an ideal world, a more sophisticated platform will eventually arise to match programmers and machine learning experts to the needs of biologists, says Peshkin, referencing the online crowdsourcing platform Kaggle that serves as a marketplace for posting and solving machine learning challenges. Until biology gets more substantially democratized, it will remain an enterprise limited to a few wealthy individuals because of the expense of animal models, cell culture, and instrumentation.
For people to start doing serious science experiments at home, or at school, will require a cookbook, says Peshkin. “This will never happen with mice, but there are Daphnia, and there are fish and worms and ants. The missing layer in biology is the infrastructure, the simple instructions… like MEL Chemistry you can order for your child.”
It is inevitable that more of the science will be done by ordinary people with fish tanks, pets, and toy microscopes, he says, noting the one-time popularity of Daphnia-like sea-monkeys as novelty aquarium pets. “I just want it to happen sooner.”
If somebody somewhere comes up with a pharmacological intervention to extend healthspan, Peshkin says, the question becomes how to rapidly verify and test the claim. It would be unethical and take too long to run experiments in humans, but none of the model organisms used up to now—be they monkeys, mice, fish, flies, ants, or worms—are suited for the job.
That’s why he’s enamored with Daphnia, which could be fed a drug for their entire relatively short life and have many characteristics of their healthspan measured, and it could be done at scale on hundreds of animals per condition. All he needs now is some funding—he is seeking grants from both the National Institutes of Health and private donors—to build out the platform to enable the citizen science to happen at scale.
The project will take a couple million dollars and a few more years, says Peshkin, whose fundraising efforts include a grant from Gitcoin, an alternative crowdfunding method that involves matching contributions from donors in the Ethereum ecosystem. But the grand tally currently sits at only a bit over $10,000.
Developing the platform comes with “increasingly defined challenges” for engineers, biologists, and aquaculture and cell culture specialists, and some of them are highly technical, he says. It would be great to have a way to cryopreserve Daphnia, for example, because colonies need to be perpetually maintained and, even then, they sometimes die out.
“The clones are precious,” explains Peshkin. “They could be very specifically selected, [or] transgenic, so being able to freeze [Daphnia] and go away and then restart cultures from frozen” would be invaluable. Many animals, tree frogs most famously, do this naturally. They freeze for a season and then thaw out and come back to life.
Machine learning algorithms are also needed to track and extract any important features, adds Peshkin, such as the age-associated way Daphnia looks and moves that are analogous to a human face and gait. Better algorithms are also needed to analyze the videos to, for example, quantify how they react to light and the length of their jumps.
The absence of funding for the platform hasn’t entirely halted progress. For example, Peshkin and his colleagues recently investigated the impact of putting Daphnia on several doses of rapamycin early in life that revealed a phenomenon similarly witnessed in mice.
The study, led by the Gladyshev lab at Harvard, currently posted in bioRxiv (DOI: 10.1101/2022.02.18.481092), demonstrate that the novel longevity intervention slows growth and causes both organisms to live about 10% longer, most notably in males, and preserve better health as measured by a frailty index, gait speed, and glucose and insulin tolerance tests. The Daphnia platform allowed for large sample sizes to confidently detect small effects, Peshkin points out.
He says he particularly likes one theory, which has yet to be adequately investigated, that rapamycin works by turning on autophagy—the body’s way of cleaning out damaged cells. It’s the same process that gets triggered by intermittent fasting.
Citizen Science Trial
Rapamycin is the only drug proven to extend lifespan across multiple organisms, Peshkin says, and “no one really knows how it works.” But the timing of its administration apparently matters. Studies in mice suggest that rapamycin can be toxic if given too early in life but can have a small but statistically significant life-extending effect if administered between the human equivalent years of 10 and 17.
The online anti-aging platform AgelessRx, which is endeavoring to make longevity mainstream, recently launched its first “citizen science” clinical trial where everyday people will be asked to take low doses of rapamycin for several months and then have some blood measurements taken to see what happens, says Peshkin.
AgelessRx CEO Anar Isman reports that the placebo-controlled Participatory Evaluation Of Aging With Rapamycin For Longevity (PEARL) trial is looking to enroll 150 people between the ages of 50 and 85 and has already recruited about 40 volunteers. “The community of people interested in rapamycin specifically and in products with potential longevity/healthspan benefits is quite engaged, although unfortunately quite small,” he says.
When the phase 2 trial was announced in 2020, it generated considerable interest in longevity circles, so no outbound recruiting initiatives have been done. The uniqueness of the trial is both that it is driven by everyday people, and it is crowd-funded. “If we execute on this trial, it will open up a potential pathway to other similar… trials.”
Tens of thousands of papers have been published on how one drug or another extended the life of a model organism, but they are all problematic for a variety of reasons, says Peshkin. DrugAge, a manually curated database of lifespan-extending drugs and compounds, gives researchers a means to see how different drugs affect the lifespans of different animals but searches often turn up inconsistent or contradictory results.
A drug might help in some species and hurt in another. Even two papers using the same species and drug dose to treat the exact same condition tend to reach different conclusions, he notes.
By way of contrast, Peshkin points to an initiative called the Intervention Testing Program (ITP), a multi-institutional program of the National Institute on Aging for evaluating agents (mostly drugs or nutraceuticals) on the aging process in mice. The program launched in 2004, spearheaded by Rich Miller at the University of Michigan, and is the only study out of the hundreds producing lifespan results that is well designed and properly run, he says.
Anyone can write a proposal for an ITP grant that funds independent investigations of the purported anti-aging agent at three labs around the U.S., one each at the University of Michigan, the Jackson Laboratory (Bar Harbor, Maine), and the University of Texas Health Science Center. Young mice are put on the agent for a year to see what happens.
“This is the only trustworthy data of this sort that I believe,” says Peshkin. One of the most interesting results to come out of the initiative is the discovery that the spike in blood glucose after consuming carbohydrates appears to be damaging, suggesting drugs that can curb the spike would be beneficial.
But even here, there’s a pesky problem with the controls. Based on an analysis Peshkin carried out with his open-access Animal Life Expectancy Comparisons Research Tool (ALEC), the medium lifespan of male control mice at one of the universities is 15% longer than at the other two universities—as much as would be termed an “amazing effect” of any anti-aging intervention.
And this was in a study by highly trained professionals under standardized conditions, Peshkin notes. The same test could be repeated for 20 years, and the lifespan differential wouldn’t budge.
When Peshkin asked for an explanation of this strong unexplained effect on the control cohort, he was told it was a mystery. “It could be the color of the pants of the technician, it could be the proximity of female to male cages, it could be many things, we have no idea,” he says.
Peshkin’s response was to write to a few peer-reviewed journals, suggesting they start requiring the submission of raw data on the lifespan of animal controls as a condition of publication. “They said, ‘Hm, that’s a good idea.’ It is 2022, hasn’t anyone thought of this?” To properly analyze results of a study, it would help to know the exact strain of mice that were used, he says. “Is it just a strain that is extremely fluid in the lifespan? This data, paradoxically, is unavailable.”
With frogs, Peshkin can tell you, the lifespan is maybe 20 years—again, no one really knows how long the animal lives or the distribution. “And this is true about many species, [including] worms and flies and mosquitoes.”
In the published literature, birth records are available for few species other than mice, including those used in the ITP studies, he continues. What is known comes from records kept on zoo animals, which contain poor statistics on very few individual animals.
Studies on mice often engineer the animals to age rapidly, adds Peshkin. But extending their life does not necessarily improve their healthspan, such as how well they eat and walk and react to stimuli, which should be the goal.
Drugs As Questions
In addition to ITP, Peshkin credits Longevica with another laudable if oddball initiative that a decade ago put mice on 1,000 different pharmacological compounds to test the effects, if any, on their lifespan. As announced by the company last year, it plans to launch supplements based on its research suggesting five substances significantly increase longevity—inulin, pentetic acid, clofibrate, Proscillaridin A, and D-Valine—by between 16% and 22%.
Longevica plans to make that dataset accessible to scientists and research institutions, and Peshkin says it is something he relies on in his work even if he has had some “good-hearted arguments” with the company about the way it carried out the bioinformatics analysis. Peshkin doesn’t believe any one drug is ever going to be a cure-all for healthy aging. Rather, he favors the approach of piecing together clues across many different drugs about the important mechanisms behind slowing the aging process.
So, when Longevica learned that Peshkin was spearheading a crowdsourcing initiative around aging research, its dataset became one of many to be embedded into the server.
Peshkin believes in using “drugs as questions,” much like the classic yes-or-no guessing game 20 questions. When trying to understand how aging works, the game is played by using a carefully chosen set of drugs to learn how the system reacts to their presence. “Those are cheap experiments… all you do is dump a drug on the system and see what happens… If it has an effect, I can use another drug as a question and [in this way] figure out what’s going on under the hood without taking expensive molecular measurements, like gene expression, proteomic mass spectrometry, or imaging.”
One seemingly “idiotic” question, Peshkin says, illustrates his approach to finding life-extending therapies: “Why are babies born young?” The egg and sperm producing new life have both been around for some time, even if both parents are 20 years old, and mixing them mysteriously undoes the damage of age in the germline.
People have been discussing this “germ-line reset” in the context of the “germ-plasm theory” of August Weismann for over 100 years, he adds, but—once again—nobody has ever properly investigated the idea. So, in addition to more rigorously testing anti-aging interventions, Peshkin wants to learn what might be happening very early in the process of oocyte separation and early development to make all the cellular garbage suddenly disappear.
To that end, a new dataset is being produced by mass spectrometry showing what happens to frog oocytes that Peshkin will analyze in search of measurable evidence of a cleansing process that is comparable to what happens during human ovulation. Specifically, he’ll be looking for protein aggregates in the eggs and, if he finds them, see if they disappear during oocyte maturation.
If so, he says, it might shed light on a pre-existing program in the genome that could be activated in adult cells to undo some of the damage of aging in various body tissues.