The quest for factors regulating the development of chick embryonic insulin cells in vitro.

A mesenchymal factor(s) is believed to modulate the development of the embryonic pancreas. However, the identity of this factor(s) remains elusive. Its importance in the development of the endocrine cells of the pancreas, particularly insulin cells, is considered. Our studies seek to identify factors that may influence insulin cell proliferation and differentiation, and hence may have positive implications for patients suffering from diabetes. Our experiments are based on the in vitro model which utilised the 5-day dorsal pancreatic bud of the chick embryo. These buds, devoid of most of their mesenchyme, are cultured on Matrigel in a serum-free medium for 7 days. We have investigated the effects of retinoic acid, retinoic acid in combination with IGF-1, nicotinamide and activin in this system. While most of these factors increased the proportion of insulin cells over that of their respective controls, as yet none have matched or exceeded the proportion of insulin cells demonstrated in vivo.