Characterization of collagenase blend enzymes for human islet transplantation

Background. Efficient islet isolation represents a necessary requirement for successful islet transplantation as a treatment for type I diabetes. The choice of collagenase for pancreas digestion is critical for the isolation outcome, and Liberase(TM) is the most widely used enzyme, although large intra-batched variability in activity and efficiency has been observed. Methods. The aim of this study was to characterize Liberase(TM) components and their relative role in pancreas digestion. Liberase batches were characterized by micro electrophoresis. Results. By means of microelectrophoresis, we identified three main proteins each with different prevalences between batches. Two proteins were found to correspond to class I (CI) and one to class II (CII) collagenase. In a series of 163 islet isolations, we observed that the CII correlated with islet yield (P < 0.001) and digestion time (P < 0.001); additionally, CI directly correlated with purity (P=0.028). Finally, when CII and one of the CI isoforms were > 50 percentile, 15 of 36 preparations were transplanted, with 27 of 127 transplanted in the other cases (P=0.013). Conclusion. These results represent an important step toward the characterization of enzymes, with the final aim of identifying key components for a standardized product.