Cryo-preservation is a process where cells, tissues, or any other biological constructs susceptible to damage caused by unregulated chemical kinetics are preserved by cooling to very low temperatures, typically in liquid nitrogen at -196 degrees Celsius.

The Human Mammary Epithelial Cells (HMEC) are a type of cell often used in breast cancer research and can be cryo-preserved for future use. Before cryopreservation, cells are usually mixed with a cryoprotective agent (CPA) such as DMSO (Dimethyl Sulfoxide) to protect them from the formation of ice crystals which could cause mechanical damage to the cells.

Upon thawing, the cells are typically placed in a suitable growth medium in a culture dish to allow them to recover, multiply, and be used for experiments.

Cryo-preservation allows researchers to maintain a stock of cells that are genetically identical, which improves the consistency of experimental results. It also allows cells to be shipped and shared between different research laboratories.

However, the process of freezing and thawing cells can cause stress and potentially alter cell behavior, and not all cells survive the process. Therefore, careful quality control is needed to ensure that cryo-preserved cells maintain their expected characteristics and behavior after thawing.