Pancreatic stellate cells can form new beta-like cells.

Regenerative medicine, including cell-replacement strategies, may have an important role in the treatment of Type 1 and Type 2 diabetes, both of which are associated with decreased islet cell mass. To date, significant progress has been made in deriving insulin-secreting beta-like cells from human ES (embryonic stem) cells. However, the cells are not fully differentiated, and there is a long way to go before they could be used as a replenishable supply of insulin-secreting beta-cells for transplantation. For this reason, adult pancreatic stem cells are seen as an alternative source that could be expanded and differentiated ex vivo, or induced to form new islets in situ. In this issue of the Biochemical Journal, Mato et al. used drug selection to purify a population of stellate cells from explant cultures of pancreas from lactating rats. The selected cells express some stem-cell markers and can be grown for over 2 years as a fibroblast-like monolayer. When plated on extracellular matrix, along with a cocktail of growth factors that included insulin, transferrin, selenium and the GLP-1 (glucagon-like peptide-1) analogue exendin-4, the cells differentiated into cells that expressed many of the phenotypic markers characteristic of a beta-cell, and exhibited an insulin-secretory response, albeit weak, to glucose. The ability to purify this cell population opens up the possibility of unravelling the mechanisms that control self-renewal and differentiation of pancreatic cells that share some of the properties of stem cells.