Promotion of beta-cell differentiation by the alkaloid conophylline in porcine pancreatic endocrine cells.

We previously found that conophylline, an alkaloid isolated from the leaves of Ervatamia microphylla, induced beta-cell differentiation in rat pancreatic acinar carcinoma cells and in cultured fetal rat pancreatic tissue and that it also decreased the blood glucose level in streptozotocin-treated fetal rats. In the present research, we looked into the effect of conophylline on the differentiation of newborn pig pancreatic endocrine cells into insulin-secreting cells. Conophylline potentiated the differentiation of monolayer cells into insulin-producing cells in the presence of nicotinamide in 3 weeks. Next we prepared islet-like cell clusters (ICC). Cononophylline together with nicotinamide also increased the number of insulin-producing cells and the insulin content in ICC in 3-6 weeks. The ICC thus prepared were sensitive to the glucose concentration for the insulin secretion. Conophylline increased the mRNA expression of PDX-1, neurogenin3, neuroD/Beta2, and insulin in ICC. Thus, the vinca alkaloid conophylline potentiated beta-cell differentiation in porcine pancreatic endocrine-rich cells in cluster cultures. Pig pancreatic cells are practical candidate for use in transplantation therapy. Conophylline may thus be useful for the large-scale preparation of porcine insulin-producing cells for the regeneration therapy of type-1 diabetes mellitus.