Current status of regeneration of pancreatic β-cells

Newly generated insulin-secreting cells for use in cell therapy for insulin-deficient diabetes mellitus require properties similar to those of native pancreatic β-cells. Pancreatic β-cells are highly specialized cells that produce a large amount of insulin, and secrete insulin in a regulated manner in response to glucose and other stimuli. It is not yet explained how the β-cells acquire this complex function during normal differentiation. So far, in vitro generation of insulin-secreting cells from embryonic stem cells, induced-pluripotent stem cells and adult stem/progenitor-like cells has been reported. However, most of these cells are functionally immature and show poor glucose-responsive insulin secretion compared to that of native pancreatic β-cells (or islets). Strategies to generate functional β-cells or a whole organ in vivo have also recently been proposed. Establishing a protocol to generate fully functional insulin-secreting cells that closely resemble native β-cells is a critical matter in regenerative medicine for diabetes. Understanding the physiological processes of differentiation, proliferation and regeneration of pancreatic β-cells might open the path to cell therapy to cure patients with absolute insulin deficiency.