BACKGROUND: The isolation of islets from the human pancreas critically depends on an efficient enzyme blend. Previous studies have solely focused on the presence of collagenase and neutral protease/thermolysin. Despite improved characterization of these components, the lot-related variability in efficacy still persists suggesting that additional so far disregarded enzymes are required for efficient islet cleavage. METHODS: Varying activities of a tryptic-like enzyme were identified within collagenase NB1 lots, which were selected according to a matched ratio between tryptic-like and collagenase activity (TLA-ratio). Rat and human pancreata were processed with current standard procedures. RESULTS: Increasing the TLA-ratio from 1.3% to 10% reduced pancreas dissociation time in rats by 50% without affecting islet yield, viability, or posttransplant function in diabetic nude mice. Enhancing the TLA-ratio from 1.3% to 12.6% for human pancreas processing resulted in a significant reduction of recirculation time and increased incrementally human islet yield without affecting purity, in vitro function or recovery after culture. Optimized pancreas digestion correlated with a higher percentage of islet preparations fulfilling quality criteria for clinical transplantation. CONCLUSIONS: We conclude that TLA is an effective component that should be included in moderate amounts in enzyme blends for human islet isolation to optimize the efficiency and minimize the lot-related variability.
BACKGROUND: The isolation of islets from the humanpancreas critically depends on an efficient enzyme blend. Previous studies have solely focused on the presence of collagenase and neutral protease/thermolysin. Despite improved characterization of these components, the lot-related variability in efficacy still persists suggesting that additional so far disregarded enzymes are required for efficient islet cleavage. METHODS: Varying activities of a tryptic-like enzyme were identified within collagenase NB1 lots, which were selected according to a matched ratio between tryptic-like and collagenase activity (TLA-ratio). Rat and human pancreata were processed with current standard procedures. RESULTS: Increasing the TLA-ratio from 1.3% to 10% reduced pancreas dissociation time in rats by 50% without affecting islet yield, viability, or posttransplant function in diabeticnude mice. Enhancing the TLA-ratio from 1.3% to 12.6% for human pancreas processing resulted in a significant reduction of recirculation time and increased incrementally human islet yield without affecting purity, in vitro function or recovery after culture. Optimized pancreas digestion correlated with a higher percentage of islet preparations fulfilling quality criteria for clinical transplantation. CONCLUSIONS: We conclude that TLA is an effective component that should be included in moderate amounts in enzyme blends for human islet isolation to optimize the efficiency and minimize the lot-related variability.
Authors: Meirigeng Qi; Luis Valiente; Brian McFadden; Keiko Omori; Shiela Bilbao; Jemily Juan; Jeffrey Rawson; Stephen Scott; Kevin Ferreri; Yoko Mullen; Mohamed El-Shahawy; Donald Dafoe; Fouad Kandeel; Ismail H Al-Abdullah Journal: Transplant Direct Date: 2015-05
Authors: A M Posselt; M D Bellin; M Tavakol; G L Szot; L A Frassetto; U Masharani; R K Kerlan; L Fong; F G Vincenti; B J Hering; J A Bluestone; P G Stock Journal: Am J Transplant Date: 2010-08 Impact factor: 8.086
Authors: Gregory L Szot; Michael R Lee; Mohammad M Tavakol; Jiena Lang; Florinna Dekovic; Robert K Kerlan; Peter G Stock; Andrew M Posselt Journal: Transplantation Date: 2009-09-27 Impact factor: 4.939