Extracellular vesicles (EVs)

Extracellular vesicles (EVs) are membrane-bound particles released by virtually all cell types and conventionally classified into exosomes (30–150 nm, endosomal origin via multivesicular bodies), microvesicles (100–1000 nm, direct plasma membrane budding), and apoptotic bodies (>1000 nm); they carry bioactive cargo including proteins, lipids, mRNA, microRNA, and DNA that can reprogram recipient cells upon uptake. EVs serve as key mediators of intercellular communication and are upregulated by senescent cells as part of the SASP, with aged plasma showing a distinct EV proteome and miRNA content that can accelerate senescence and inflammation when transferred to younger organisms in parabiosis-inspired experiments. Concurrently, EVs derived from young or stem cell sources are investigated as candidate therapeutic agents in regenerative medicine, with studies reporting improvements in muscle, cardiac, and cognitive function in aged rodent models, though mechanisms of selectivity and in vivo dosing remain areas of active investigation.