Overview
- Researchers reported in a late September 2026 preprint that in controlled mouse grafts a donor heart’s DNA-methylation‑based epigenetic clock shifted within months to match the recipient’s biological age.
- The team analyzed archived biopsies from 11 human heart transplants at Brigham and Women’s Hospital and found the same pattern of epigenetic age change in the grafted tissue.
- Some clinical measures one year after transplant — including heart rate, posterior wall thickness, and exercise capacity — correlated with the recipient’s age rather than the donor’s age.
- Authors observed changes in mitochondrial-related gene activity and suspect circulating factors in the recipient’s blood or immune environment drive the effect, but they stress mechanisms are unresolved.
- The study is a bioRxiv preprint not yet peer reviewed, and experts say larger, controlled human studies and functional tests are needed before changing donor‑selection rules or clinical practice.