How Stem Cells Are Cryopreserved

Freezing a living cell without destroying it is a controlled chemical and physical process, not just a temperature drop.

Why Cryopreservation Is Hard on Cells

Water expands when it freezes. Inside or around a cell, uncontrolled ice formation can physically rupture membranes and organelles. Slow, controlled cooling encourages water to move out of the cell before it freezes, reducing intracellular ice — but that process creates its own stress, as the cell becomes exposed to a highly concentrated, dehydrating environment as the surrounding water freezes out.

Cryopreservation protocols are designed to balance these two competing sources of damage.

The Basic Process

1. Cryoprotectant addition — cells are suspended in a cryopreservation medium designed to limit ice damage. See DMSO vs. DMSO-Free Cryopreservation.
2. Controlled-rate cooling — the sample is cooled at a defined rate, often using a rate-controlled freezer, to encourage gradual, more predictable ice formation rather than rapid, damaging crystallization.
3. Transfer to long-term storage — once frozen, product is moved to ultra-low temperature storage, typically in vapor-phase liquid nitrogen, where biological activity is effectively suspended.
4. Cold-chain shipment — product is shipped to the point of use under temperature-controlled conditions, since a temperature excursion during transport can reduce post-thaw viability.
5. Thaw — at the point of use, product is thawed following a defined protocol; thaw technique and time-to-administration both affect final viable cell count.

Why the Process Matters Clinically

This page is educational reference material for licensed healthcare providers and does not constitute medical, legal, or regulatory advice. HCT/P products are not FDA-approved.