IMPROVED HUMAN ISLET ISOLATION USING A NEW ENZYME BLEND, LIBERASE

Enzymatic digestion of donor pancreases is a vital step in human and l arge mammalian islet isolation. The variable enzymatic activities of d ifferent batches of commercially available collagenase is a major obst acle in achieving reproducibility in islet isolation procedures. In th e present work, the effectiveness of Liberase, a standardized mixture of highly purified enzymes recently developed for the separation of hu man islets, was compared with that of a traditional collagenase prepar ation (type P). The results of 50 islet isolations using Liberase enzy me were compared with those of 36 isolations with collagenase, type P. No significant differences in donor age, cold ischemia time, digestio n time, or weight of the pancreases were observed between the two grou ps. Islet yield was significantly higher in the group where the Libera se enzyme was used. All parameters examined (islet number, islet numbe r per gram of tissue, islet equivalent number, and islet equivalent nu mber per gram of tissue) were significantly improved when Liberase enz yme was used. Different lots of Liberase enzyme were tested, and no di fference was observed. Islets isolated with Liberase enzyme were also of larger size and mere much less fragmented, suggesting a gentler enz ymatic action and better preservation of anatomical integrity. Islets isolated with Liberase enzyme, assessed both in vitro and in vivo, rev ealed a functional profile similar to that of islets separated with co llagenase. Liberase enzyme appears, therefore, to represent a new powe rful tool for improving the quality of human islet isolation.