Heterochronic parabiosis / Young plasma
DEHeterochrone Parabiose / Junges Plasma
Heterochronic parabiosis (HCP) is an experiment where a young and an old animal are surgically joined so they share one blood supply. Each is continuously exposed to the other's blood. Clive McCay did classic versions in the 1950s, and the field was revived in the 2000s and 2010s by Irina and Michael Conboy (2005, Nature), Amy Wagers, Saul Villeda, and others. The finding: old mice joined to young partners show better muscle regeneration, more new neurons, healthier heart growth, and improved liver function, while the young partners partly deteriorate. Two competing explanations emerged. The 'young factors' model says rejuvenating substances in young blood do the work; the protein GDF11 was first championed for this, then disputed. The 'dilution' model, from Irina Conboy and colleagues, argues the real driver is diluting the pro-aging factors (like TGF-β and β2-microglobulin) that build up in old blood. That view is backed by experiments swapping in young saline-albumin instead of actual young blood. Human efforts include Alkahest (a 2014 spin-out from Tony Wyss-Coray's Stanford lab, with Saul Villeda advising), which split plasma into defined protein fractions (GRF6019) for Alzheimer's and Parkinson's trials. Small commercial young-plasma infusion services also popped up, the kind you may have seen marketed, and in 2019 the FDA issued a safety alert against these unproven infusions. No plasma-based aging therapy is approved by the FDA or EMA today.
Last reviewed:
This definition is educational and is not medical advice, a diagnosis, or treatment. Talk to a doctor about any health decisions. Read our full medical disclaimer