Improved islet yield and function by use of a chloride channel blocker during collagenase digestion

Protection of pancreatic islets during isolation procedures is mandatory for successful islet transplantation. Chloride channel inhibition has been reported to prevent cell death induced by various stimuli. We examined the effects of the chloride channel blocker, 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid disodium salt (DIDS) and extracellular Cl(-)-free conditions on islet isolation outcomes.

Experimental groups were created based on the collagenase solutions used for Wistar rat islet isolation: control group, Hanks' balanced salt solution; DIDS group, 200 μM DIDS; and Cl(-)-free group, sodium gluconate substituted for sodium chloride. We determined whether collagenase digestion induced the death of islet cells through Cl(-) influx into the cells. We then assessed islet yield and the viability of isolated islets.

We observed an increase in intracellular Cl(-) concentration under collagenase digestion conditions using a Cl(-)-sensitive fluorescent dye and subsequent rupture of islet cells. Consequently, islet yields were significantly higher in the DIDS and Cl(-)-free groups than in the control group, and islet morphology of the former groups was preserved. Of streptozotocin-induced diabetic severe combined immunodeficiency mice transplanted with a marginal dose of islets, all seven mice in the DIDS group and six of the seven mice in the Cl(-)-free group became normoglycemic, compared with two of seven mice in the control group (control vs. DIDS, P=0.010; control vs. Cl(-) free, P=0.051).

Our results indicate that DIDS inhibition of Cl(-) influx into islets protects islets during digestion procedures, offering a new strategy for the improvement of islet isolation outcomes.