Islet isolation from the pancreas of large mammals and humans: 10 years of experience

Despite experience, that has been obtained in the field of islet isolation in large mammals for about the past 20 years, allo- and autotransplantation of both human and porcine islets are still not routine procedures. The reasons for islet isolation and purification associated problems, which prevent a continuous isolation success and regular islet transplantation, can be categorized to variables related to 1) pancreas donor; 2) pancreas procurement; 3) isolation-techniques and 4) purification techniques. The development of porcine and human islet isolation was carried out by the authors since 1986. During this period several techniques for the isolation and purification of human and porcine islets were compared with regard to their influence on islet isolation outcome, integrity of islet morphology, islet in-vitro and in-vivo function: sequential vs continuous digestion-filtration, counterflow elutriation vs neutral density separation, conventional density gradient centrifugation vs Cobe cell separation and discontinuous vs continuous gradient purification. Furthermore, we analysed the influence of donor factors and variables related to organ procurement on islet isolation success. From this experience we concluded that successful porcine islet isolation is possible if islets of adult donors are isolated utilizing the continuous digestion-filtration following distension with UW-solution prior to a neutral density gradient purification on a Cobe. Human islets can be successfully isolated by digestion-filtration and purified utilizing a continuous Ficoll-sodium-diatrizoate gradient on a Cobe when intact pancreata are harvested after a secondary pancreatic warm ischemia time <20 min from adult donors >30 years.