Cryopreservation of insulin‐producing tissue in rats and dogs

Transplantation of frozen‐thawed islets of Langerhans normalized urine volume, urine glucose, plasma glucose, and weight gain in diabetic rats. However, these animals had abnormal intravenous glucose tolerance tests (ivGTT) at 3 mo post‐transplant. Modified cryopreservation protocols were extended to canine islet‐containing tissue: a higher temperature was used during equilibration in the 2 M dimethyl sulfoxide. Recipients of frozen‐thawed isografts had prolonged normoglycemia with plasma glucose <105 mg/100 ml for up to 18 mo. During ivGTT at 6 mo post‐transplant, K values (decline in glucose concentration, %/min) were similar in dogs autotransplanted with fresh (K=1.22±0.37) or cryopreserved tissue (K=1.8±0.4). Because of the similar compactness of the pancreas in humans and dogs, this canine model should be useful for formulating an optimal cryopreservation technique for human islets.