Technical challenges in human islet isolation

Abstract: Transplantation of islets of Langerhans is an effective treatment option for patients with brittle type 1 diabetes mellitus. This treatment restores glucose control and also reduces hypoglycemia. Unfortunately, the outcome from islet isolations is variable, and many preparations do not yield sufficient islet number or islet quality.The aim of this thesis was to improve the isolation procedure, thereby making more preparations available for clinical transplantation.A well-established method for pathogen inactivation was applied to human serum used in the islet isolation process. Evaluation of isolated islets stored in medium supplemented with pathogen-inactivated serum showed that pathogen inactivation did not have negative effects. These findings will enable the use of human serum in clinical cell transplantation programs, while simultaneously increasing patient safety.Pre-incubation of islets prior to gradient separation is an established standard in the field of islet isolation. Through a reduction in the pre-incubation step, isolation time could be reduced by almost an hour without affecting the isolation outcome.A commercially available protease enzyme, clostripain, was added to the enzyme blend used in islet isolation. Addition of clostripain was found to increase the number of islets isolated as well as the purified tissue volume and fulfillment of transplant criteria. Use of clostripain should help to increase the number of successful isolations.A newly developed pancreas-specific preservation solution, I-Let protect, was evaluated. As compared to standard preservation solutions, it can be used in situations of prolonged cold ischemic time without affecting the isolation outcome or islet functionality. I-Let protect can also be used in establishing a protocol that would eliminate the need for night- time isolations.Through the work in this thesis, several key elements in human islet isolation have been optimized, and further knowledge has been gained.