A new clinical trial is set to explore the potential of partial cellular reprogramming in humans, a technique that could enable ageing cells to function like younger ones. This method builds on the work of Shinya Yamanaka, who discovered how to reprogram adult cells into a stem-cell-like state using specific proteins known as Yamanaka factors. The upcoming trial will specifically target patients with glaucoma, a condition that damages the optic nerve and can lead to vision loss. Researchers will deliver three Yamanaka factors into the eye using a modified virus, activated only with a specific drug to minimize risks. While animal studies have shown promising results, including improved tissue repair and restored vision, experts caution that the complexity of human biology may pose significant risks, including the potential for cells to become unstable or cancerous. Safety will be the top priority as the trial progresses over several years.