So the vampires and blood cultists had a point:
https://www.nature.com/articles/s43587-024-00612-4
or the video that I saw that even let me know this was a thing: https://www.youtube.com/watch?v=lTMjmHKc2Ys
TL;DR
Younger mice small Extracellular Vesicles (sEV) contain microRNA which are different compared to older mice, which boosts PGC1alpha and shows a “return towards origin” in aged mice when young mice blood is injected into older mice (as compared to the control).
Further, young human sEVs were injected into aged mice and reproduced the effect.
I don’t believe we have a field that goes about this process in this way (neither young sEV, or PGC1alpha), but please let me know if we do. Either way, super interesting study.