An inhibitor of fibroblast growth factor receptor-1 (FGFR1) promotes late-stage terminal differentiation from NGN3+pancreatic endocrine progenitors

Human induced pluripotent stem cells (hiPSCs) provide a potential resource for regenerative medicine. To identify the signalling pathway(s) contributing to the development of functional beta cells, we established a tracing model consisting of dual knock-in hiPSCs (INS-Venus/NGN3-mCherry) (hIveNry) expressing the fluorescent proteins Venus and mCherry under the control of intrinsic insulin (INS) and neurogenin 3 (NGN3) promoters, respectively. hIveNry iPSCs differentiated into NGN3- and mCherry-positive endocrine progenitors and then into Venus-positive beta cells expressing INS, PDX1, NKX6.1, and glucokinase (GCK). Using these cells, we conducted high-throughput screening of chemicals and identified a specific kinase inhibitor of fibroblast growth factor receptor 1 (FGFR1) that acted in a stage-dependent manner to promote the terminal differentiation of pancreatic endocrine cells, including beta cells, from the intermediate stage of pancreatic endocrine progenitors while blocking the early development of pancreatic progenitors. This FGFR1 inhibitor augmented the expression of functional beta cell markers (SLC30A8 and ABCC8) and improved glucose-stimulated INS secretion. Our findings indicate that the hIveNry model could provide further insights into the mechanisms of hiPS-derived beta cell differentiation controlled by FGFR1-mediated regulatory pathways in a temporal-dependent fashion.