Cryoprotectant

A cryoprotectant, or cryoprotective agent (CPA) is a substance used to protect biological tissue from freezing damage (i.e. that due to ice formation). In cryonics, M22 and CI-VM-1 are commonly used cryoprotectants in cryopreservation of people. Cryopreservation without a cryoprotectant is called straight freeze.