Flexible management of enzymatic digestion improves human islet isolation outcome from sub-optimal donor pancreata

Worldwide growing interest in reproducing the result of the Edmonton protocol in islet transplantation trials poses the problem of paucity of donors to supply sufficient amount of islets for clinical use. Improved outcomes include finding better ways to obtain higher yields from every donor organ processed and the possibility of extending islet isolation processing to glands of suboptimal quality. In order to optimize enzymatic digestion of marginal donor organs, we have modified the technique of tissue collection following enzymatic digestion of human pancreatic organs, allowing for reduced time of exposure of free islets to warm Liberase(TM) solution. Our results indicate that better controlled exposure to enzyme yields: (i) higher islet numbers; (ii) complete dissociation of all parts of pancreatic tissue; (iii) successful islet harvest from organs otherwise excluded. We also show that by limiting the exposure of free islets to enzyme solution, islet fragmentation and loss of insulin content are reduced. We further support evidence that enzymatic digestion may contribute to impairment of insulin secretory capacity of the islets in vitro during culture.