CRYOGENIC PRESERVATION OF ISOLATED RAT ISLETS OF LANGERHANS - EFFECT OF COOLING AND WARMING RATES

Isolated rat islets of Langerhans were frozen to and stored at -196.degree.. After thawing, these islets were capable of secreting near normal levels of insulin in response to graded glucose challenge. Maximal retention of functional viability as measured by the ability of the islets to secrete insulin in response to a glucose challenge was obtained after freezing islets at a cooling rate of approximately 75.degree./min in the presence of 1.0 M dimethyl sulfoxol followed by warming at rates of > 3.5.degree./min. The critical feezing parameters include the time and temperature of exposure to dimethyl sulfoxide, the rate of cooling, the temperature of the post-thaw dilution from the freezing medium and the presence of serum in the dilution medium.