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

Islet transplantation is a potential treatment for diabetes, but the techni ques for islet isolation are inefficient and the recovery rates for isolate d islets are often low. As the solutions employed during the isolation proc ess 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 collagena se 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 wer e compared. It was found that, when UW was used as collagenase solvent, a h igher concentration of collagenase was required to liberate the maximum num ber of islets. Comparative experiments revealed that although the total num ber of isolated islets was greater using UW as the solvent, the number of i slet equivalents was similar in both preparations. More than 90% of the cel ls in both preparations excluded trypan blue, although according to a scori ng system, preparations isolated using UW showed greater viability. The sti mulation indices in response to glucose and theophylline were similar for b oth preparations, but islets isolated using UW generally responded with a l ower but more sustained insulin release. In conclusion, there was no differ ence between the total amount of islet tissue isolated using TCM or UW as s olvent for collagenase. The preparations isolated using UW were more fragme nted, but exhibited superior viability.