Fig. 6

BL001 protects human islets against apoptosis and rescues insulin secretion in islets of type 2 diabetic donors. a A 24 and 72 h exposure to cytokines (CTK) or b streptozotocin (STZ) increased cell death in human islets. This effect was prevented by 10 μM BL001 (BL). n = 10 independent islet preparations, performed in either duplicates or triplicates. Double immunostaining for insulin (INS) and cleaved PARP (Cl.PARP) in sections from human isolated islets exposed to either c cytokine (CTK) or d streptozotocin (STZ) and treated or not with 10 μM BL001 (BL). Scale bars: 25 µM. Right panels of each time point are enlargements of boxed area in left panel. e After a 24-h exposure to 0 (C) −1 μM BL001, islets from normoglycemic donors (n = 5 independent donors) were similarly stimulated by glucose to release insulin. f In contrast 0.1–1 μM BL001 increased glucose-stimulated insulin secretion in islets of type 2 diabetic donors (n = 8 independent donors). Data are means + s.e.m. g Electron micrographs show apoptotic beta cells in islets of type 2 diabetic donors (T2DM), which were unfrequent when these islets were exposed to 1 μM BL001 (T2DM BL). Scale bars: 2 µM. h Quantification shows that the percentage of apoptotic beta cells decreased after exposure to 1 μM BL001, in three independent donors. i Western blot of cleaved caspase-3 (Cl.C3) and actin in protein extracts isolated from control (T2DM) and BL001 treated T2DM islets (T2DM BL) along with j densitometric analysis. n = 3 independent donors. k 10-week-old C57BL/6 male mice were transplanted with 150–200 human islets under the kidney capsule. Two days after transplantation, mice were treated daily with BL001 or vehicle for seven days. Kidneys were harvested and processed for immunofluorescence. Two independent representative image sets of kidney sections immunostained with sera against insulin (red) and glucagon (green). DAPI nuclear counterstaining is used. Scale bar: 25 µM. Right panels correspond to the white squares indicated in the left panels. Rc Renal cortex. l Quantification of insulin-positive cells in islets transplanted under the kidney capsule. n = 5 independent transplantations. *p < 0.05, **p < 0.01, ***p < 0.001, and ****p < 0.0001, two-way ANOVA (a, b) and Student’s t test (e, f, h, j, l)