Science6 min read
How Cord Blood Is Cryopreserved and Stored
Cryopreservation is what makes long-term cord blood banking possible. The process is well established and surprisingly intuitive once you see the steps.
Step 1: Processing the sample
The whole-blood sample is centrifuged to separate the stem-cell-rich layer (often called the buffy coat) from red blood cells and plasma.
Step 2: Adding cryoprotectant
A cryoprotectant — usually DMSO — is mixed into the stem cell concentrate. It prevents ice crystals from forming inside cells during freezing.
Step 3: Controlled-rate freezing
The sample is cooled at a precise rate (about 1 °C per minute) to roughly −90 °C. This minimizes cell damage from rapid temperature changes.
Step 4: Long-term storage
The sample is transferred into a cryogenic tank holding vapor-phase liquid nitrogen at roughly −196 °C, where it can remain viable for decades.