Young Plasma Factors

Parabiosis research groundbreaking. Alkahest and others developing therapies. Simple plasma dilution (TPE) may offer similar benefits. Key factors like GDF11, TIMP2 identified. UPDATE (August 23, 2026): PEER-REVIEWED, PRECLINICAL. Nature Communications 2026 (Hemmer, Philippi, Ferreira et al.) provides the most detailed mechanistic case yet for TIMP2, one of the named factors above, and shifts its proposed site of action from neurons to brain innate immunity. TIMP2 is elevated in very young human and mouse plasma and declines steeply into adulthood and old age. Genetic deletion in mice exacerbated aging-associated microglial phenotypes — activation-associated transcriptomic changes, altered lysosomal markers and phagocytosis, and elevated stress and inflammatory proteins in brain extracellular space measured by in vivo microdialysis — and deleting specific cellular pools of TIMP2 increased microglial CD68 and altered myelin phagocytosis. Administering TIMP2 to aged mice reversed several of these: decreased microglial activation, a reduced proportion of proinflammatory microglia, and enhanced phagocytosis of physiological substrates. The significance for this category is that it moves "young plasma" from a diffuse systemic claim toward a single identified protein with a defined cellular target and a reversal experiment. The limits are equally clear: this is mouse-only, endpoints are cellular and biochemical rather than cognitive or survival, recombinant TIMP2 does not exist as a human therapeutic, and TIMP2 is a matrix metalloproteinase inhibitor whose effects on tumour invasion and matrix remodelling would need characterisation before any human protocol.

Evidence Scale