CD81 marks immature and dedifferentiated pancreatic β-cells

Objective: Islets of Langerhans contain heterogeneous populations of insulin-producing beta-cells. Surface markers and respective antibodies for isolation, tracking, and analysis are urgently needed to study beta-cell heterogeneity and explore the mechanisms to harness the regenerative potential of immature beta-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-beta H1 beta-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 beta-cells during postnatal maturation. Single-cell gene expression profiling and high-resolution imaging revealed an immature signature of beta-cells expressing high levels of CD81 (CD81(high)) compared to a more mature population expressing no or low levels of this protein (CD81(low/-)). Analysis of beta-cells from different diabetic mouse models and in vitro beta-cell stress assays indicated an upregulation of CD81 expression levels in stressed and dedifferentiated beta-cells. Similarly, CD81 was upregulated and marked stressed human beta-cells in vitro. Conclusions: We identified CD81 as a novel surface marker that labels immature, stressed, and dedifferentiated beta-cells in the adult mouse and human islets. This novel surface marker will allow us to better study beta-cell heterogeneity in healthy subjects and diabetes progression. (C) 2021 The Author(s). Published by Elsevier GmbH.