The importance of tryptic-like activity in purified enzyme blends for efficient islet isolation.

Journal article

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.

Authors: Brandhorst, H; Friberg, A; Andersson, H; Felldin, M; Foss, A

• Journal: Transplantation
• Volume: 87
• Issue: 3
• Pages: 370-375
• Publication date: 2009-02-01
• DOI: 10.1097/tp.0b013e31819499f0
• EISSN: 1534-6080
• ISSN: 0041-1337
• Language: English
• Keywords: Collagenases; Female; Humans; Cell Survival; Cell Separation; Islets of Langerhans; Tissue Donors; Graft Survival; Islets of Langerhans Transplantation; Transplantation, Heterologous; Insulin; Middle Aged; Mice; Male; Animals; Mice, Nude; Diabetes Mellitus, Experimental; Rats, Inbred Lew; Thermolysin; Rats; Insulin-Secreting Cells; Trypsin