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For eight weeks, three people with glaucoma swallowed a daily dose of doxycycline, an antibiotic usually prescribed for acne or Lyme disease. None of them had an infection. The pill was a switch. As long as the drug stayed in their blood, three genes were switched on in the retina of one eye: three of the four that Japanese biologist Shinya Yamanaka used in 2006 to turn adult mouse cells into something close to embryonic ones.
Yamanaka’s factors have been known for twenty years. Partial reprogramming is a younger idea: switch the genes on briefly, so a cell grows younger without forgetting its job. Until now it had been tested in living animals only in mice; the key paper came out in 2020. Now it is being tried in humans for the first time. On October 8, 2026, Boston-based Life Biosciences reported its first results. Over 56 days nobody had a serious side effect, and two of the three saw their visual field improve. Eye drops and surgery for glaucoma only slow the loss of retinal cells. The company’s therapy, ER-100, is the first attempt in people to make ailing cells work like young ones. So far, the evidence amounts to three people, eight weeks and no control group.
A pill for a switch
The therapy targets retinal ganglion cells. Their long fibers bundle together into the optic nerve and carry the picture to the brain. In glaucoma these cells slowly die, most often because of high pressure inside the eye, and vision closes in from the edges toward the center.
ER-100 is a gene therapy. A single injection into the eye delivers a virus that is harmless to people and serves as an envelope. Inside the envelope are three of Yamanaka’s genes, OSK for short. They encode proteins that turn hundreds of other genes on and off. Think of them as master switches for a cell’s programs.
Genes delivered this way stay in retinal cells more or less permanently. So the construct has a built-in safety catch: the genes run only while doxycycline is in the body. Stop the pills, and the switch flips back off.
Yamanaka’s fourth factor, c-MYC, was left out. Of the four, it is the one most closely tied to cancer risk.
A backup copy of youth
Those four factors won Yamanaka the 2012 Nobel Prize, which he shared with Britain’s John Gurdon. Leave the full set switched on, and a cell slides back to a state from which any tissue can grow. That is handy in a culture dish and dangerous in a living body. The cell forgets its specialty; in mice, this ended in teratomas, tumors made of jumbled tissue types.
Hence the idea of switching the factors on only briefly, so the cell gets younger but stays itself. ER-100 rests on a paper in Nature that the Harvard lab of geneticist David Sinclair published on December 2, 2020. The team switched on OSK in the ganglion cells of mice. The cells regained a youthful pattern of DNA methylation, the chemical tagging that scientists use to estimate a cell’s age. Nerve fibers regrew after injury. Vision came back in mice with a glaucoma-like condition and in mice that were simply old.
Sinclair blames aging on epigenetic noise. The DNA itself barely changes, but the tags that tell a cell which genes to read drift out of place over time. Picture a book whose text is intact but whose bookmarks have been shuffled. From the mouse work, Sinclair concluded that cells keep a record of where the bookmarks sat in youth, and that the record can be recovered.
Sinclair co-founded Life Biosciences. In the 2020 paper he disclosed an equity stake in the company’s subsidiary that develops this kind of therapy. He called the trial “the first opportunity to test whether restoring that information can ameliorate human disease.”
What three patients showed
This is a phase 1 trial, so its main job is to check safety. It plans to enroll 18 people.
The first three got the lowest dose. They did have adverse events, but the company puts all of them down to the injection itself, to conditions the patients already had, or to prednisolone, a steroid given to damp inflammation. Nothing turned up that would stop the dose from going up. An independent safety board cleared a threefold higher dose.
The doctors measured vision with a Humphrey visual field test. You stare at the center of a bowl and press a button whenever you notice a flash somewhere off to the side. The flashes keep getting dimmer, and for each point the machine finds the threshold below which the eye sees nothing. Here decibels track how dim a flash the eye can still detect, so a gain of 4 dB means the eye now catches a light about 2.5 times fainter than before.
// The first three
The company says nothing about the third participant. Sharon Rosenzweig-Lipson, its chief scientific officer, called the results encouraging and, in the same breath, reminded everyone that the study was designed to test safety. Fair enough. The trial is open-label: patients and doctors both know who got the treatment. With no comparison group, there is no way yet to tell the effect of the genes from random swings. Longevity.Technology, a site that covers life extension and is hardly hostile to the field, called reading human cell rejuvenation into data like this “a rather athletic leap.”
Doses and timelines
The trial is registered as NCT07290244 and started on March 2, 2026. People with open-angle glaucoma go first, on rising doses. At each dose level one person goes ahead alone, and the rest follow only after a safety committee reviews that person’s results.
The viral envelope is AAV2, an adeno-associated virus, and the three genes inside it are OCT4, SOX2 and KLF4. The first dose is 2×10¹¹ vector genomes, given as a single injection into the vitreous, the clear gel that fills the eyeball. A higher dose level is 6×10¹¹. Participants take doxycycline daily for 56 days, alongside a tapering course of prednisolone, a steroid that damps the inflammation the immune system mounts against the virus shell. The trial’s primary measures are the rate of adverse events and dose-limiting toxicities, plus blood tests through day 112.
Why start with the eye
For a first attempt, the eye is a convenient place to start. An injection puts the drug into a small, closed space exactly where it is needed, and the result comes from a machine, not from how someone feels.
The trial’s second group will be people who suddenly lose vision because the optic nerve stops getting enough blood, a kind of stroke in the nerve. Doctors call it NAION, which is easier to say than non-arteritic anterior ischemic optic neuropathy. There is no approved treatment, and the trial takes only people who lost their sight no more than 14 days before the injection. They will be treated once the glaucoma group has settled on a dose. The name may ring a bell: in 2025 the European Medicines Agency listed NAION as a very rare side effect of Ozempic and Wegovy.
Could he join the trial? A reader asked exactly that under a post about the results on the Fight Aging blog. He described himself as a retired physician in New Zealand with NAION in both eyes. For people with a disease that has no treatment, even three patients and eight weeks look like hope.
What the skeptics fear
Paul Knoepfler, a biologist who has written a stem cell blog for years, laid out ER-100’s weak spots back in February. The biggest fear is a tumor in the eye. In his piece, stem cell researcher Jeanne Loring pointed out that switchable systems leak, so the genes can run a little even without the pill, and that Yamanaka factors are very potent. Since the genes stay in the cells, participants’ eyes will need watching for years.
Knoepfler raises a simpler doubt as well. ER-100 does nothing about pressure in the eye, so if cells do grow younger, they will face the same damage as before, and any benefit may fade. Data from monkeys, he notes, have been presented at meetings but not published in a journal.
Sixty years in fifty days
While the three patients were working through their 56 days, a lab in Bonn showed vividly that epigenetic clocks can be wound back by decades. Its method is a close cousin. Oliver Brüstle’s group at University Hospital Bonn took red blood cell precursors from an 80-year-old donor and converted them directly into neural stem cells, skipping the embryonic-like stage. The cells changed careers, which is exactly what partial reprogramming tries to avoid. The work appeared in the journal Aging Cell. After 50 days, epigenetic clocks, which read age from the tags on DNA, put the cells at under 20. The rejuvenation came gradually, and the team tracked it for more than 100 days.
Brüstle is confident that cells rejuvenated this way also behave like young ones. Still, the clocks count tags, not health. A younger cell in a dish says nothing about the person it came from. The authors themselves describe the work as a lab model, useful for studying conditions such as Alzheimer’s disease.
The two studies are mirror images. Bonn measured the age of the cells but not how they work in a body. Life Biosciences measured vision in its three patients but reports no numbers on how old their cells are.
They took the pill for 56 days, yet the genes will stay in their retinas for life. By March 2032, when the trial is due to end, it has to show two things: whether patients see more, and what the switch does long after the last pill. The first numbers fit into eight weeks; the central question of rejuvenation will take years to answer.
