Juan Carlos Izpisua Belmonte, Altos Labs | All-In Summit 2024

Juan Carlos Belmonte’s central result is that short pulses of Yamanaka factors rejuvenated accelerated-aging mice without correcting the mutation causing their disease. The intervention changed the epigenome instead, producing healthier animals that lived longer despite retaining the underlying genetic defect.

The effect was not confined to one disease model. In leptin-mutant mice, treatment reduced liver fat and restored youthful glucose responses despite continued overeating, while Belmonte reported similar results in laboratory models of kidney, skin, liver and muscle disease.

The crucial safety distinction is partial reprogramming: prolonged Yamanaka-factor exposure can erase a cell’s identity, impair organ function and permit cancer, while brief pulses preserve identity. Belmonte described the pulse as a temporary chromatin “shock” after which cells retain their type but function better.

Belmonte’s team says it can restrict reprogramming to unhealthy cells instead of exposing healthy tissue. Using markers associated with dysfunctional cells, the researchers targeted Yamanaka factors selectively and reported longer lifespan, prevention of gray hair and dramatically improved wound healing in very old mice.

Rejuvenating organs outside the body may be the safest first bridge to human medicine. Belmonte described treating old donor kidneys with a short ex-vivo pulse before transplantation, which improved recipient survival and could eventually make some currently discarded organs usable.

Human rejuvenation has not yet been demonstrated in whole people; Belmonte said the work has reached isolated human cells, with animal-to-human translation still requiring caution and replication. He identified severe acute diseases and organ transplantation as plausible early targets because the risk-benefit case is clearer than treating ordinary aging.

Belmonte said exercise produces surprisingly similar gene-expression changes to short Yamanaka-factor pulses, linking ordinary lifestyle interventions to the same cellular-resilience pathways under study. He nevertheless offered no precise exercise prescription, saying much of this biology remains unresolved and human translation is only beginning.

Altos Labs is pursuing this as both fundamental science and drug development, backed by billions of dollars and searching beyond the original Yamanaka proteins. The longer-term goal is to find proteins, peptides or small molecules capable of producing comparable epigenetic effects safely enough to become an ordinary medicine, potentially even a pill.