Transplanted hearts adopt biological age of recipient, study finds

September 28, 2026 at 12:31 PM1 min

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Hearts from young donors age rapidly in older recipients, while older hearts are rejuvenated in younger ones, according to a preprint study from Harvard University. The findings, based on mouse experiments and human biopsy samples, suggest donor age limits could be expanded.

Key Facts

In the United States, 4,636 heart transplants were performed in 2024, an 81.5% increase from 2013.
The study was posted on the preprint server bioRxiv and has not yet been peer reviewed.
Researchers measured DNA methylation in about 320,000 genetic regions to assess biological age.
Current guidelines generally recommend heart donors younger than 45 years old.

Mouse Experiments

Jesse Poganik and colleagues at Harvard University grafted hearts from young, middle-aged, and old mice into recipients of all three age groups. Four to six months after surgery, the team measured DNA methylation levels in about 320,000 genetic regions of the grafted hearts. The biological ages of donated hearts shifted to more closely match those of the recipients. Young hearts grafted into older mice showed accelerated ageing, while old hearts in younger recipients were rejuvenated. These results align with earlier parabiosis studies showing that young blood extends the lifespan of older mice.

Human Biopsy Analysis

The researchers examined historical heart transplant biopsies from Brigham and Women's Hospital in Boston. They selected cases where biopsy samples were available for DNA methylation testing. The analysis aimed to determine whether the biological age changes observed in mice also occur in human transplant recipients.