Increased islet viability by addition of beraprost sodium to collagenase solution

The digestion of pancreatic tissue with collagenase is an essential part of the islet isolation procedure. However, the process exposes islets to vari ous types of harmful factors, including collagenase contaminants, enzymes r eleased from the acinar cells, warm ischemia, and mechanical agitation. Nit rogen oxide production and cytokine release may also contribute to islet ce ll damage. Protection of islets from such damage would improve the islet yi eld, survival, and function. Beraprost sodium (BPS) is a prostaglandin I, a nalogue, is stable in aqueous solution. and has a cytoprotective effect on various types of cells. BPS has been shown to improve the yield and functio n of cryopreserved and/or cultured islets. These findings prompted us to ex amine its cytoprotective effect on islets during the islet isolation proces s. Canine islets were isolated by means of a two-step digestion method and purified on Euro-Ficoll density gradient solutions (the procedure used for human islets). BPS at a concentration of 100 nM was added to the collagenas e solution. After purification, the islet yield was 434,561 +/- 35,691 isle t number expressed as 150 mum equivalent size (IEQ)/pancreas or 8,799 +/- 3 45 IEQ/g of pancreas in the BPS group and 349,987 +/- 52,887 IEQ/pancreas o r 7,998 +/- 1610 IEQ/g of pancreas in the control group (n = 8, each), The percent viability was 88.5 +/- 0.7% in the BPS group and 82.0 +/- 0.9% in t he control group (P < 0.01), Therefore, the recovery of viable islets (calc ulated by islet number x % viability) was 384,586 +/- 46,804 IEQ/pancreas ( 7,743 IEQ/g) in the BPS group and 186,989 +/- 43,367 IEQ/pancreas (6,558 IE Q/g) in the control group (P < 0.02). After culture, significantly higher n umbers of islets were also recovered in the BPS group than in the control g roup. The islet insulin content was significantly higher in the BPS group t han controls (237.8 +/- 38.5 versus 92.3 +/- 25.6 muU/IEQ P < 0.02), althou gh islets of bath groups responded with high stimulation indices (>6). Thes e results indicate that the addition of BPS to the collagenase solution inc reases the recovery of viable islets, and improves beta cell function.