Promotion of monolayer formation in cultured whole pancreatic islets by 3-isobutyl-1-methylxanthine.

Normal adult rat islets usually remained intact and encapsulated, even after many days in culture. In contrast, islets cultured in the presence of the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (0.1 mM) attached more readily to the surface of plastic culture dishes and almost uniformly formed monolayers of endocrine cells. The mechanism of this effect is not known but presumably involves increases in cellular cyclic AMP content. Fibroblast growth did not appear to be stimulated by the inhibitor. These adult pancreatic endocrine monolayer cultures can be produced readily and provide useful preparations for further morphological and biochemical studies of factors affecting the differentiation, growth, and regenerative capacity of islet cells.