CD81 marks immature and dedifferentiated pancreatic β-cells.

Abstract Objective The islets of Langerhans contain heterogeneous populations of insulin-producing β-cells. Surface markers and respective antibodies for isolation, tracking and analysis are urgently needed to study β-cell heterogeneity and to explore the mechanisms to harness the regenerative potential of immature β-cells. Methods We performed single-cell mRNA profiling of early postnatal mouse islets and re-analyzed several single-cell mRNA sequencing datasets from mouse and human pancreas and islets. We used mouse primary islets, iPSC-derived endocrine cells, Min6 insulinoma and human EndoC-βH1 β-cell lines and performed FAC sorting, western blotting and imaging to support and complement the findings from the data analyses. Results We found that all endocrine cell types expressed the cluster of differentiation 81 (CD81) during pancreas development, but the expression levels of this protein were gradually reduced in β-cells during postnatal β-cell maturation. Single cell gene expression profiling and high-resolution imaging revealed an immature signature of β-cells expressing high levels of CD81 (CD81high) compared to a more mature population expressing no or low levels of this protein (CD81low/-). Analysis of β-cells from different diabetic mouse models and in vitro β-cell stress assays indicated an upregulation of CD81 expression levels in stressed and dedifferentiated β-cells. Similarly, CD81 is upregulated and marks stressed human β-cells in vitro. Conclusions Here, we identified CD81 as a novel surface marker that labels immature, stressed and dedifferentiated β-cells in the adult mouse and human islets. This novel surface marker will allow to better study β-cell heterogeneity in healthy and diabetes progression.