3D quantification of changes in pancreatic islets in mouse models of diabetes type I and II

Abstract

Diabetes is characterized by rising levels in blood glucose and is often associated with a progressive loss of insulin producing beta cells. Recent studies have demonstrated that it is possible to regenerate new beta cells through proliferation of existing beta cells or trans-differentiation of other cell types into beta cells, raising hope that diabetes can be cured through restoration of functional beta cell mass. Efficient quantification of beta cell mass and islet characteristics is needed to enhance drug discovery for diabetes. Here we report a 3D quantitative imaging platform for unbiased evaluation of changes in islets in mouse models of type I and II diabetes. To determine if the method can detect pharmacologically induced changes in beta cell volume, mice were dosed for 14 days with either vehicle or the insulin receptor antagonist S961 (2.4 nmol/day) using osmotic minipumps. Mice dosed with S961 displayed increased blood glucose and insulin levels. Light sheet imaging of insulin and Ki67-immunostained pancreata revealed a 43% increase in beta cell volume and 21% increase in islet number. S961 treatment resulted in an increase of islets positive for cell proliferation marker Ki-67, suggesting that proliferation of existing beta cells underlies the expansion of total beta cell volume. Using light sheet imaging of non-obese diabetic (NOD) mouse model of type I diabetes we also characterized the infiltration of CD45-labelled leukocytes in islets. At 14 weeks 40% of small islet volume, but more than 80% of large islet show leukocyte infiltration. These results demonstrate how quantitative light sheet imaging can capture changes in individual islets to help pharmacological research in diabetes.