Isokinetic gradient centrifugation prolongs survival of pig islets xenografted into mice

Highly purified porcine islets were prepared by isokinetic gradients perfor med subsequently to isopycnic gradients. This additional purification step separates ductal, vascular, and lymphoid tissue effectively from endocrine tissue. Although ductal, vascular, and lymphoid tissue comprises only a min or contamination of the islet suspensions, a significant prolongation of th e survival of porcine islets xenografted into streptozotocin diabetic C57BL /6 mice can be achieved by the elimination of the non-endocrine tissue. Rej ection after islet transplantation is delayed from 2.2+/-0.4 days (n=27) to 13.1+/-2.1 days (n=36), respectiveley, when conventionally purified and hi ghly purified islets are compared. Irrespective of the purification state, pretreatment of islets by low temperature culture had no effect on xenograf t survival.