Yeah, this had me thinking. Does transplanting older organs into younger bodies force the body to rejuvenate the transplanted organ to the recipients age.

Edit: your article say so, neat.

I vaguely recall that it's the blood itself which has a big impact — to the point where blood transplants from younger blood could (temporarily) "rejuvenate" an older metabolism.

So Bryan Johnson was onto something when he was transfusing his son's blood into himself