The influence of collagenase solvent on the isolation of islets from 5 week old pigs: a comparison of TCM-199 and UW.

Abstract

Islet transplantation is a potential treatment for diabetes, but the techniques for islet isolation are inefficient and the recovery rates for isolated islets are often low. As the solutions employed during the isolation process may affect islet yield, we have investigated the effect of collagenase solvent, and compared the effect of dissolving collagenase in TCM-199 (TCM) or University of Wisconsin (UW) solution on yield and viability of islets isolated from 5 week old pigs. Pancreata were transported to the laboratory in UW solution, and the islets isolated using a manual method of collagenase digestion. The optimum concentration of collagenase which would liberate the maximum number of islets was determined for each solvent, and then the yield and viability of islets isolated using collagenase in TCM and UW were compared. It was found that, when UW was used as collagenase solvent, a higher concentration of collagenase was required to liberate the maximum number of islets. Comparative experiments revealed that although the total number of isolated islets was greater using UW as the solvent, the number of islet equivalents was similar in both preparations. More than 90% of the cells in both preparations excluded trypan blue, although according to a scoring system, preparations isolated using UW showed greater viability. The stimulation indices in response to glucose and theophylline were similar for both preparations, but islets isolated using UW generally responded with a lower but more sustained insulin release. In conclusion, there was no difference between the total amount of islet tissue isolated using TCM or UW as solvent for collagenase. The preparations isolated using UW were more fragmented, but exhibited superior viability.