Effects of collagenase concentration on the purity and viability of isolated porcine pancreatic islets for use in xenotransplantation studies

Abstract: The use of lower concentrations of collagenase (0.8 mg/ml as compared to 1.25 and 1.5 mg/ml) resulted in isolation of porcine pancreatic islets retaining their original compact, wholesome appearance. In in vitro experiments, 100% of islet batches isolated with the low collagenase concentration responded to glucose stimulation, while only 63.1% of islet batches isolated with the high concentration of the enzyme did. The response to high glucose challenge of islets isolated with the low enzyme concentration was considerably higher compared to high collagenase concentration islets.
In in vivo experiments, intraperitoneal transplants of microencapsulated islets isolated using 0.8 mg/ml of collagenase reversed diabetes in diabetic BALB-c mice in a significantly larger proportion of recipients (87.5%) as compared to 33.3% of recipients grafted with 1.5 mg/ml collagenase islets.
The results of this study demonstrate that the use of a low collagenase concentration is conducive to isolation of islets of a superior morphology, purity, viability, and functioning ability.