A Note from James:

I’ve been obsessed with anti-aging and longevity science for a long time. I’ve had many longevity researchers on the podcast, but this episode feels different because something we’ve been discussing for years has now moved into human trials.

David Sinclair first came on the show in 2019, when his book Lifespan was published. He’s a professor of genetics at Harvard Medical School, and that first conversation changed how I lived. I started experimenting with intermittent fasting, paid much more attention to sleep, and began researching many of the supplements and lifestyle changes he discussed.

But the most important idea David talked about wasn’t a supplement. It was the possibility of reversing cellular age using Yamanaka factors—genes that can reset the instructions cells use to function. At the time, nobody knew whether this could be done safely without causing cancer or making cells lose their identities.

Now, a therapy based on three of those factors has entered its first human clinical trial. The initial target is age-related damage to the optic nerve, including open-angle glaucoma and non-arteritic anterior ischemic optic neuropathy. The trial is designed primarily to evaluate safety, but researchers will also measure visual function.

David explains how this technology worked in mice and nonhuman primates, why the eye was chosen as the first organ, and how the same approach might eventually be applied to the liver, lungs, joints, skin, and brain.

We also cover the practical questions people always ask him: NMN, NAD, metformin, berberine, testosterone, growth hormone, diet, fasting, sleep, exercise, and what David himself has started—or stopped—taking.

This is still experimental science. Nobody yet knows whether the animal results will translate into meaningful benefits for humans. But for the first time, researchers are beginning to test that question directly.

About Lifespan:

Dr. David Sinclair founded Lifespan to deliver clear, science-backed health insights that help people live longer, more vibrant lives.

He's now building the world's largest community dedicated to extending human longevity well beyond today’s limits. Join early access at lifespan.com.

New episodes of Lifespan with Dr. David Sinclair -- the #1 health and wellness podcast in its first season -- are now available on YouTube, Spotify, Apple Podcasts, and Lifespan.com.

Episode Description:

For years, longevity researchers have looked for ways to slow the biological processes associated with aging. Dr. David Sinclair and his collaborators are now testing a more ambitious possibility: whether damaged human cells can be restored to a younger, more functional state.

The experimental therapy, ER-100, uses controlled expression of three transcription factors—OCT4, SOX2, and KLF4, collectively known as OSK. These are three of the four Yamanaka factors originally used to transform adult cells into pluripotent stem cells.

Turning on all four factors can erase too much of a cell’s identity and has produced tumors and fatal outcomes in animal experiments. Sinclair’s team found that removing one factor, c-MYC, allowed cells to regain younger patterns of gene expression without completely returning to a stem-cell state.

In preclinical studies, OSK restored youthful epigenetic patterns, promoted optic-nerve regeneration, and reversed vision loss in mouse models. Life Biosciences, a company Sinclair co-founded, has now moved the technology into a first-in-human Phase 1 trial involving people with open-angle glaucoma or non-arteritic anterior ischemic optic neuropathy.

David explains how the therapy is delivered directly into the eye and activated using doxycycline, allowing clinicians to control when and for how long the genes are expressed. He also describes the development path that could follow if the treatment proves safe, including therapies targeting the liver and other organs, as well as future medicines that may reproduce similar effects without gene delivery.

The conversation then turns to interventions available today. David distinguishes between promising research and claims that have moved ahead of the evidence, discussing NMN, injected NAD, growth hormone, testosterone, taurine, nattokinase, metformin, berberine, and nootropics.

Throughout the episode, he emphasizes that no supplement has been shown to reproduce the effects researchers are attempting to achieve through partial epigenetic reprogramming—and that many of the most dramatic claims circulating online remain unsupported.

Editorial Note:

ER-100 is an investigational therapy. Authorization to begin a clinical trial does not mean the treatment has been proven safe or effective, nor has it been approved for clinical use.

The Phase 1 study is primarily evaluating safety and tolerability, with additional measurements of visual function. Results from mice and nonhuman primates do not establish that the therapy will restore vision or reverse biological aging in people.

The discussion of supplements, prescription medications, hormones, and lifestyle practices reflects the speakers’ personal views and interpretation of the research. It should not be treated as individualized medical advice. Prescription drugs, hormones, supplements, and experimental longevity treatments should be discussed with an appropriately qualified healthcare professional.

What You’ll Learn:

How partial epigenetic reprogramming differs from completely resetting a cell into a stem cell.
Why researchers selected three Yamanaka factors—OCT4, SOX2, and KLF4—instead of using all four.
What ER-100 is designed to do and why the first human trial focuses on the optic nerve.
How doxycycline acts as an external switch controlling when the therapeutic genes are expressed.
What Phase 1 researchers will measure and what would need to happen before ER-100 could become an approved treatment.
Why the eye provides a useful starting point for testing cellular rejuvenation.
What animal studies suggest about restoring vision, memory, liver function, joints, and skin.
Why delivering rejuvenation therapies throughout the body is more difficult than treating one localized organ.
The difference between oral NMN supplementation and intravenous or subcutaneous NAD.
What current research does—and does not—show about growth hormone, testosterone, taurine, metformin, and berberine.
Why muscle, exercise, sleep, diet, glucose regulation, and inflammation remain important even if rejuvenation therapies eventually succeed.
How Sinclair’s laboratory is searching for pills and small molecules that could mimic epigenetic reprogramming without gene therapy.

Timestamped Chapters:

[04:53] The First Human Trial Begins
David discusses ER-100, FDA authorization, and the treatment of open-angle glaucoma and ischemic optic neuropathy.
[06:52] What Are the Yamanaka Factors?
How reprogramming genes can reset cellular instructions—and why using all four factors can be dangerous.
[08:56] Reversing Vision Loss and Memory Problems in Animals
David describes studies involving the eyes, brain, skin, kidneys, liver, and age-related cognitive decline.
[10:09] Why Four Factors Can Cause Cancer
The difference between restoring youthful function and erasing a cell’s identity completely.
[10:54] The Three-Gene Breakthrough
How Sinclair’s student Yuancheng Lu persisted through years of failure and identified the OSK combination.
[12:03] Pulsing the Genes vs. Leaving Them Activated
Earlier four-factor experiments required intermittent activation, while OSK showed a different safety profile in animal eyes.
[13:36] The Doxycycline Safety Switch
How clinicians may use an antibiotic to activate and deactivate the therapy after it has been delivered.
[14:51] Treating the Cause Instead of the Symptoms
David argues that restoring younger tissue function could allow the body to repair damage associated with age-related disease.
[16:02] Why the Trial Starts With the Eye
Localized delivery reduces systemic exposure and makes visual changes easier to observe and measure.
[16:50] Can the Therapy Reach the Brain and the Rest of the Body?
The challenges of distributing gene-based treatments evenly across organs and through the blood-brain barrier.
[18:25] What the Phase 1 Trial Will Measure
Safety, tolerability, visual function, and the possibility of an accelerated development path.
[20:36] Expanding Beyond Glaucoma
Why each organ may require a different delivery vehicle—and how the liver could become another early target.
[21:38] How Shinya Yamanaka Found the Original Four Factors
The trial-and-error process that turned adult cells into induced pluripotent stem cells.
[22:38] How ER-100 Is Delivered
David explains the OSK genes, the AAV delivery system, doxycycline activation, and why manufacturing is expensive.
[25:21] When Could the Tre...