Cellular reprogramming rests on a discovery that won Shinya Yamanaka the 2012 Nobel Prize: four specific transcription factors, now called Yamanaka factors, can take a mature, specialized adult cell and reset it back to an embryonic-stem-cell-like state. Full reprogramming erases the cell's identity entirely. Partial reprogramming, the version most longevity research is built around, aims to roll back epigenetic age markers while stopping short of that full reset, so a skin cell stays a skin cell, just a younger-behaving one.
The evidence base is genuinely strong in animal models: partial reprogramming has extended lifespan and reversed markers of aging in mice, and even partially restored vision in aged and injured mouse eyes in Belmonte-lab work. What it has not yet done is clear the much higher bar of demonstrated human safety and efficacy. The central unresolved risk is that reprogramming factors, powerful enough to reset cell identity, are also associated with uncontrolled cell growth in some contexts, meaning the dose, timing, and delivery method all matter enormously and are still being worked out.
This is the most heavily capitalized area of longevity biotech for a reason: companies including Altos Labs and Retro Biosciences are building their core research programs around this mechanism. For the full treatment of the science, evidence, and open questions, see the companion article on cellular reprogramming.