Slow and steady is the key to β-cell replication

Diabetes is a chronic disease of failed glucose homeostasis Structure and function of the adult pancreas Diabetes is an attractive target for cellular replacement therapy In vitro differentiation of beta-cells from embryonic stem cells beta-cell maintenance and expansion Strong evidence that new beta-cells come from old beta-cells All beta-cells contribute equally to islet growth and maintenance Putative pancreatic stem cells Reported evidence for bone marrow stem cells giving rise to beta-cells Reported evidence for spleen stem cells giving rise to beta-cells Reported evidence for ductal stem cells giving rise to beta-cells Reported evidence for acini stem cells giving rise to beta-cells Reported evidence for islet and/or pancreatic stem cells giving rise to beta-cells beta-cell turnover beta-cell mass is dynamic beta-cell replication changes with age beta-cell replication increases during pregnancy beta-cell replication increases in cases of increased blood glucose and/or insulin resistance beta-cell replication is regulated by cell cycle genes The elusive circulating beta-cell growth factor Increasing beta-cell replication in vivo In vitro culture of beta-cells Summary The beta-cells of the pancreas are responsible for insulin production and their destruction results in type I diabetes. beta-cell maintenance, growth and regenerative repair is thought to occur predominately, if not exclusively, through the replication of existing beta-cells, not via an adult stem cell. It was recently found that all beta-cells contribute equally to islet growth and maintenance. The fact that all beta-cells replicate homogeneously makes it possible to set up straightforward screens for factors that increase beta-cell replication either In vitro or in vivo. It is possible that a circulating factor may be capable of increasing beta-cell replication or that intrinsic cell cycle regulators may affect beta-cell growth. An improved understanding of the in vivo maintenance and growth of beta-cells will facilitate efforts to expand beta-cells In vitro and may lead to new treatments for diabetes.