Measuring aging – epigenetic clocks, piRNAs, blood tests, imaging.
Single experiment (n=1) in brain‑deceased recipient – Type A kidney treated with enzymes to remove A‑antigens, transplanted into mismatched type O recipient. Kidney functioned for 2 days without hyperacute rejection. By day 3, antigens regenerated and mild rejection began. Caveats: Antigen regeneration remains unsolved. Clinical trials years away.