Betacellulin and nicotinamide sustain PDX1 expression and induce pancreatic beta-cell differentiation in human embryonic stem cells.

The major obstacle in cell therapy of diabetes mellitus is the limited source of insulin-producing beta cells. Very recently, it was shown that a five-stage protocol recapitulating in vivo pancreatic organogenesis induced pancreatic beta cells in vitro; however, this protocol is specific to certain cell lines and shows much line-to-line variation in differentiation efficacy. Here, we modified the five-stage protocol for the human embryonic stem cell line SNUhES3 by the addition of betacellulin and nicotinamide. We reproduced in vivo pancreatic islet differentiation by directing the cells through stages that resembled in vivo pancreatic organogenesis. The addition of betacellulin and nicotinamide sustained PDX1 expression and induced beta-cell differentiation. C-peptide-a genuine marker of de novo insulin production-was identified in the differentiated cells, although the insulin mRNA content was very low. Further studies are necessary to develop more efficient and universal protocols for beta-cell differentiation.