Cryopreservation
Cryopreservation is the process of preserving cells, tissues, or organs at ultra-low temperatures, typically using liquid nitrogen, to maintain viability for extended periods. It is widely used in biobanking, reproductive medicine, and regenerative therapies.
What is cryopreservation?
Cryopreservation involves cooling biological materials to sub-zero temperatures—usually below −135°C—using liquid nitrogen to halt metabolic activity and prevent degradation. This process relies on cryoprotectants such as dimethyl sulfoxide (DMSO) or glycerol to minimise ice crystal formation, which can damage cellular structures. Controlled-rate freezing and rapid thawing protocols are essential to ensure high post-thaw viability.
How does cryopreservation work in practice?
In laboratory and clinical settings, cryopreservation is applied to sperm, oocytes, embryos, stem cells, and tissue samples. Samples are typically loaded into cryovials or straws, cooled at a controlled rate (e.g., −1°C per minute), and stored in liquid nitrogen vapour phase or submerged tanks. Upon thawing, the cryoprotectant is gradually removed to prevent osmotic shock. Quality control includes post-thaw viability assays, such as membrane integrity tests and functional assessments, to confirm successful preservation.
What are the key challenges and applications?
Challenges include ice crystal formation, toxicity of cryoprotectants, and variability in cell type sensitivity. Advances in vitrification—ultra-rapid cooling that avoids ice formation—have improved outcomes for sensitive samples like oocytes. Applications span fertility preservation, biobanking for drug discovery, and regenerative medicine, where cryopreserved cells are used in clinical trials and therapies. Regulatory compliance with standards such as ISO 20387 and GHS is essential for consistent quality and safety.
Related concepts
Cryoprotectants, vitrification, controlled-rate freezing, biobanking, thawing protocols, post-thaw viability, liquid nitrogen storage.