TRANSPLANTATION OF PURIFIED ISLET CELLS IN DIABETIC RATS .1. STANDARDIZATION OF ISLET CELL GRAFTS

A standardized procedure was developed for the preparation of rat islet cell grafts with selected cell number and composition. After collagenase digestion of pancreases and elutriation of tissue fragments, islets were isolated and dissociated, and cells were purified by autofluorescence-activated cell sorting. Approximately 30% of the initial-beta-cell mass was lost during digestion and elimination of small mostly exocrine particles. Fifty percent was recovered in isolated islet preparations and 30% in the purified-beta-cell suspensions of > 95% purity and viability. Sorting according to cellular flavin adenine dinucleotide content discriminated islet-beta-cells from islet endocrine non-beta-cells, fibroblasts, leukocytes, and exocrine cells. Purified endocrine islet cell grafts were prepared by aggregating 10(6) pure-beta-cells with or without 8 x 10(5) pure endocrine non-beta-cells. In contrast to intact islets, the purified aggregates were devoid of nonendocrine and damaged cells. Intraportal implantation of a pure-beta-cell graft rapidly and permanently normalized the diabetic state of streptozocin-administered animals. The standardized preparation of purified-beta-cell grafts allows us to address several metabolic and immunological questions concerning islet cell transplantation in diabetes.