Once an organ is removed from a donor, it starts to degrade. Surgeons usually flush it with a preservative, bag it, and put it on ice, leaving only hours to transplant. Alternatively, some hospitals use machines to pump nutrients and remove waste for six to 12 hours, mimicking the body. Recent studies suggest this perfusion helps organs perform better after transplant.

Now, scientists found that perfused organs get younger at a molecular level. The research, shared with MIT Technology Review, offers clues why younger donor organs succeed more and why perfused organs fail less. Researchers hope to develop new tests and repair tools for discarded organs. "If [we] can improve the utilization of organs beyond what the current systems can do, then that’s a win in my book," says Jesse Poganik, who studies aging at Brigham and Women’s Hospital in Boston and coauthored the study.

Poganik, along with Heidi Yeh and Alban Longchamp, transplant surgeons at Mass General Brigham, used aging clocks on donated livers. In 37 samples from 19 livers, machine-perfused livers had lower biological age than non-perfused, chronologically younger ones. Analyzing 208 samples from 103 livers, they confirmed perfused livers were biologically younger. "Pumping them at 34 degrees with oxygen and nutrients actually reversed the biological age," says Longchamp. The effect was about 30% after adjusting for chronological age. Biological ages increased after transplant but remained younger in perfused organs. Nathanael Raschzok, a transplant surgeon at Charité Universitätsmedizin Berlin not involved, notes the findings are promising.