Overview
- Researchers led by Jesse Poganik report in a bioRxiv preprint that grafted mouse hearts and 11 archived human heart biopsies showed DNA‑methylation patterns that shifted to match the recipient more than the donor.
- In mice the team transplanted hearts between young, middle‑aged and old animals and measured methylation at roughly 320,000 genomic sites to estimate epigenetic or 'biological' age.
- Clinical records analysis found some functional measures such as heart rate, posterior wall thickness and exercise capacity correlated with recipient age rather than donor age, but not all measures changed.
- The authors and outside commentators stress major limits: the paper is not peer reviewed, the human sample is small, epigenetic clocks are imperfect proxies for aging, and transplantation also causes inflammation and other pro‑aging signals that complicate interpretation.
- The study builds on prior parabiosis and rejuvenation work and raises possible policy implications for donor selection, but experts say larger clinical studies and mechanistic proof are needed before changing practice.