Partial Reprogramming Helps Heart Cells Divide After Heart Attack in Mice

Heart disease remains a leading cause of death worldwide, and one reason recovery from heart attacks is so poor is that adult heart muscle cells — cardiomyocytes — cannot meaningfully regenerate. When they die, the heart patches the damage with scar tissue, which progressively weakens cardiac function and can lead to heart failure. Finding a way to restore regenerative capacity in these cells is a major goal of longevity and cardiovascular medicine.

Researchers publishing in the Journal of Molecular and Cellular Cardiology tested whether partial cellular reprogramming could unlock this capacity. They used three of the four classic Yamanaka factors — OCT4, SOX2, and KLF4 (OSK) — to partially reverse the maturity of cardiomyocytes. The key finding was that OSK did not make more cells attempt division, but dramatically increased the proportion of cells that successfully completed division, resolving a long-standing bottleneck where cells replicate DNA but fail to physically split into two daughter cells.

Critically, the fourth Yamanaka factor, c-Myc, was deliberately excluded. When included, c-Myc drove uncontrolled proliferation and loss of cardiac cell identity — a pattern resembling pre-cancerous behavior. OSK alone produced controlled dedifferentiation, shifting gene expression toward an embryonic profile while preserving cellular identity, a much safer outcome.

In living newborn mice, OSK delivered via a heart-targeted virus reproduced these effects and reduced cardiac damage following simulated heart attacks. The treated hearts showed disassembled sarcomeres, more single-nucleus cells consistent with successful division, and less scarring.

Important caveats apply. This research was conducted in neonatal and adult mice, not humans, and the long-term safety and efficacy of in vivo OSK delivery remain untested. Translation to human cardiac therapy is likely years away, but the mechanistic insight — that partial reprogramming can unblock cytokinesis without triggering cancer risk — is a meaningful step forward.