Cryo-preservation is a process where cells, tissues, or any other biological constructs are preserved by cooling to very low temperatures, typically in liquid nitrogen at -196 degrees Celsius. This technique is used to maintain the viability of cells for long periods.
Human Mammary Epithelial Cells (HMEC) are often used in research, including breast cancer studies. These cells can be cryo-preserved for future use. Here’s a general outline of the process:
- Cell Culture: HMECs are cultured in a suitable growth medium until they reach the desired density.
- Harvesting: The cells are detached from the culture flask using an enzyme like trypsin.
- Centrifugation: The detached cells are then centrifuged to create a cell pellet.
- Resuspension: The cell pellet is resuspended in a cryoprotective agent (CPA). This substance helps protect the cells from damage caused by ice crystal formation during freezing. Commonly used CPAs include DMSO (Dimethyl Sulfoxide) and glycerol.
- Freezing: The cells are then slowly cooled to a very low temperature, typically by placing them in a controlled-rate freezer or a -80°C freezer before transferring them to a liquid nitrogen tank for long-term storage.
- Storage: The frozen cells are stored in liquid nitrogen at -196°C.
- Thawing: When the cells are needed, they are quickly thawed in a warm water bath, usually at 37°C. The cells are then washed to remove the CPA and placed in fresh growth medium to recover.
It’s important to note that not all cells survive the cryo-preservation process, and those that do may not retain their full functionality. Therefore, quality control measures are usually in place to check the viability and functionality of the cells after thawing.