Experience with pancreas islets separation, immunoisolation and cryopreservation.

Experience of Warsaw Pancreas Laboratory is presented. Some improvement in the methods of rat, human and pig pancreases digestion, and in identification of Langerhans islets by means of intravenous injection of I-DTZ was achieved. For immunoisolation of islets, 2 methods were elaborated: capsules containing alginate/polyethyleneimine/protamine/heparin membrane prepared by modified Sun method, and microcapsules based on Zekorn method. Biocompability of hollow fibers, prepared with polypropylene (PP), surface modified PP (PPS) and polysulphone (PS) was assessed in vitro. Only PS fibers were fully compatible. It was shown, that the mixture of exocrine tissue did not influence in vitro insulin secretion, providing that alginate in which islets are embedded remain gelled. The efficacy of 3 methods of islets cryopreservation was compared: freezing in "semicontrolable" conditions, in programmable Kriomedpol machine, and vitrification. The highest percentage of frozen/thawed living cells, and the most reliable results were obtained with Kriomedpol method.