ISLETS

L. Giovannoni¹, D. Bosco², T. Berney^3
1Surgery, Cell isolation and transplantation center, Geneva/SWITZERLAND, ²Islet Isolation And Tranplantation Center, Geneva University Hospitals, Geneva/SWITZERLAND, ³Visceral And Transplantation Surgery, Geneva University Hospitals, Geneva/SWITZERLAND

Body: Introduction: Human islet preparations are characterized by various degrees of exocrine contamination. The aim of this study was to assess in vitro the effect of exocrine tissue on viability and insulin secretion of isolated islets. Methods: To this end, human islets were separated on a continuous Ficoll gradient, handpicked and subsequently mixed with increasing concentrations of autologous exocrine tissue (islet volume: exocrine volume of 1:0, 1:1 and 1:9). In 5 experiments, exocrine tissue was handpicked from the bottom layer of the Ficoll gradient (high density), and in 5 other experiments, from the lower density layers that also contain islets. After 48h of co-culture, islet viability was assessed by ELISA cytodeath assay and ATP chemoluminescence assay, and insulin secretion by a static incubation assay. Results: Results showed that compared to islets alone, glucose-induced insulin secretion of islets mixed with 1:1 and 1:9 vol:vol exocrine tissue was 26 ± 21 % and 105 ± 28 % higher (p<0.001), respectively. By contrast, high density exocrine tissue as the same islet/exocrine vol/vol ratios decreased glucose-induced insulin secretion by 26 ± 11 % and 64 ± 8 % (p<0.001), respectively. Basal insulin secretion and viability of islets were affected neither by low nor by high density exocrine tissues. Conclusion: Our results demonstrate that exocrine tissues from low and high density Ficoll layers differentially affect insulin secretion of islets in vitro. Difference in cell composition, notably presence of ductal cells, and other properties of these two sources of exocrine tissues could explain these observations. We are currently investigating these hypotheses.

Disclosure: All authors have declared no conflicts of interest.