Extracellular vesicles (EVs)

Extracellular vesicles (EVs) are tiny membrane bubbles that nearly every cell releases. They come in rough size classes: exosomes (30 to 150 nm, born inside the cell), microvesicles (100 to 1000 nm, pinched off the surface), and apoptotic bodies (over 1000 nm, from dying cells). Because the categories overlap, the official MISEV2018 and 2023 guidelines suggest labeling them by physical size (like 'small EVs') unless you can prove where they came from. EVs carry a cargo of proteins, lipids, mRNA, microRNA, and DNA that can reprogram whatever cell takes them up. That makes them key messengers between cells. Senescent cells pump out more of them as part of the SASP, and old blood carries a distinct EV cargo that can speed up senescence and inflammation when transferred into young animals. The flip side is promising: EVs from young or stem-cell sources are being tested as therapies, with reports of better muscle, heart, and brain function in aged mice. How they pick their targets, and how to dose them in the body, are still open questions.

Last reviewed: June 22, 2026

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