Viability tests of cryopreserved endocrine pancreatic cells.

Collagenase-isolated islets, which had been cultured for 1 week, were frozen at two different cooling rates. Islets frozen at 5 degrees C/min behaved from a functional point of view very similarly to that of nonfrozen, cultured control islets, except for a reduced maximal insulin secretory capacity and a reduced insulin content. Slowly frozen islets (0.5 degrees C/min), however, displayed reduced rates of both proinsulin biosynthesis and glucose oxidation. It is concluded that isolated islets can be cryopreserved with great success and that the methods of choice for viability tests are those characterizing the dynamics of insulin secretory capacity of the cryopreserved islets.