Islet cryopreservation protocols

Low temperature banking of islets has facilitated ongoing clinical trials, allowing for the collection and long-term storage of islets during which viability and sterility assessment can be carried out. Islets from most species of animals have been cryopreserved using various freeze-thaw protocols; however, the best to date is slow cooling to -40 degrees C and rapid thawing from - 196 degrees C. If one carefully follows the three distinct steps of freezing and thawing human islets can be successfully cryopreserved, allowing for the establishment of a low temperature bank with diverse HLA (Human Leukocyte Antigen) and ABO phenotypes. Using a combination of fresh and cryopreserved islets to transplant type I diabetic patients, long-term insulin independence has been obtained.