Cell freezing and the biology of inexorability: on cryoprotectants and chemical time.

What can't freezing hold still? This article surveys the history of substances used to protect cells and organisms from freezing damage, known as cryoprotectants. Dimethyl sulfoxide (DMSO) has since 1959 been the most widely used of these agents in cryopreservation. Here, its evolution from pulp and paper waste byproduct to wonder drug to all-but-invisible routine element of freezing protocols is used to trace the direct arc from protection to toxicity in theories of how and why cryoprotectants work, from the 1960s to today. The power of these agents to simultaneously protect and degrade is shown to reside in manipulation of chemical time via hydrogen bonding and electron exchange, thereby reframing freezing as a highly active and transformational process. Countering long-held assumptions about cryopreservation as an operation of stasis after which the thawed entity is the same as it was before, this article details recent demonstrations of effects of cryoprotectant exposure that are nonlethal but nonetheless profoundly impactful within scientific and therapeutic practices that depend on freezing infrastructures. Understanding the operationalization of chemical time in the case of cryoprotectants is broadly relevant to other modern technologies dedicated to shifting how material things exist and persist in human historical time.