Silicon Valley billionaires are obsessed with 'reprogramming' their bodies for longevity. The first human trial suggests they may be onto something.

Jeff Bezos Mustafa Yalcin/Anadolu via Getty Images Tech billionaires are obsessed with "reprogramming" their bodies for longevity.

Jeff Bezos, Peter Thiel, Yuri Milner, and Sam Altman have all invested in the rejuvenation strategy.

The very first human attempt at cellular reprogramming is underway, and it looks like it's working.

Getting old can be painful.

Stick around long enough, and you're bound to weather some kind of age-related decline, like creaky joints, clogged arteries, or vision loss.

Silicon Valley billionaires, including Jeff Bezos, Peter Thiel, Yuri Milner, and Sam Altman , who want to skip all that mess and reprogram their cells back to a more youthful state, have invested in startups working on the hottest trend in longevity science: cellular reprogramming .

The technique has rejuvenated lots of mice and monkeys, but it had never been tried in humans — until this year.

The first human trial of cellular reprogramming is underway at Life Biosciences, where patients are being dosed with a first-of-its-kind rejuvenation therapy for glaucoma, an eye disease that can cause vision loss.

On Thursday, Life Biosciences released its first safety data.

So far, three patients received the experimental therapy: an eye injection, coupled with eight weeks of daily antibiotics that turn on the rejuvenation factors inside their cells.

The company said none of the patients reported major side effects and that it was "well-tolerated." The goal of the treatment is to essentially turn back time at the cellular level, making old eyes young again by delivering genetic programming instructions, similar to those that rejuvenate stem cells and embryos.

The first cellular reprogramming therapy aims to rejuvenate people's eyeballs, restoring sight.

Edward Berthelot/Getty Images Cellular reprogramming as a 'master key' for age-related health issues There are some early signals that the technique might be working.

Two of the three patients showed significant vision improvements on a standard eye exam, suggesting that the new drug might be restoring sight, or at least improving it.