Engineering a new β-cell: a critical venture requiring special attention to constantly changing physiological needs

Hedgehog signals in pancreatic differentiation from embryonic stem cells: revisiting the neglected

Recent demonstrations of insulin expression by progenies of mouse and human embryonic stem (ES) cells have attracted interest in setting up these cells as alternative sources of beta-cells needed in diabetes cell therapy. It is widely acknowledged that information gathered in the field of developmental biology as applied to the pancreas is of relevance for designing in vitro differentiation strategies. However, looking back at the protocols used so far, it appears that the natural route toward the pancreas, which goes via the definitive endoderm, was usually bypassed. As a consequence Hedgehog signaling, the earliest inhibitor of pancreas initiation from the endoderm, was generally not considered. A recall of the status of this pathway during ES cell differentiation appears necessary, especially in the light of findings that Activin A treatment of mouse and human ES cells coax them into definitive endoderm, a lineage showing wide Hedgehog ligands expression with the potential to hinder pancreatic programming.

Cellular sources of new pancreatic beta cells and therapeutic implications for regenerative medicine

Replacing missing insulin-producing beta cells to treat diabetes is a major challenge for regenerative medicine. A better understanding of beta-cell embryogenesis and regeneration in adult life is needed to devise means to derive these specialized cells in sufficiently large numbers from stem or precursor cells. It is also critical to ensure that any surrogate or regenerated beta cells have perfectly regulated insulin production, which is essential for physiological glucose homeostasis.