Highly Purified versus Filtered Crude Collagenase: Comparable Human Islet Isolation Outcomes

This study was designed to retrospectively compare the impact of crude Sigma V collagenase (Sigma V, n=52) with high-purified Serva NB1 collagenase (Serva NB1, n=42) on human islet isolation outcomes. A three-step filtration was applied to the crude Sigma V to eliminate endotoxin contamination and impurities; in addition this process was used as a lot prescreening tool. Isolation outcomes were determined by digestion efficacy, islet yields, purity, viability, glucose-stimulated insulin release, and endotoxin content. The difference of the digestion efficacy between Sigma V and Serva NB1 was very small, however, statistically significant (Sigma V: 64.71% vs. Serva NB1: 69.71%, p 0.05) between groups. No significant purity differences were observed for fractions with purities greater than 75%. Viability (Sigma V: 93.3% vs. Serva NB1: 94.8%, p>0.05), and stimulation indexes (Sigma V: 3.41 vs. Serva NB1: 2.74, p>0.05) were similar between the two groups. The impact of cold ischemia and age on the isolation outcome in the Sigma V group was comparable to the Serva NB1 group. However, we were intrigued to find that the endotoxin content of the final products in the filtered Sigma V group was significantly less than that in the high-purified Serva NB1 group (0.022 EU/ml vs. 0.052 EU/ml, p