In vitro differentiation of human induced pluripotent stem cells (iPSCs) into functional islets holds immense potential to create an unlimited source of islets for diabetes research and treatment. A continuous challenge in this field is to generate glucose-responsive mature islets. We herein report a previously undiscovered angiopoietin signal for in vitro islet development. We revealed, for the first time, that angiopoietins, including angiopoietin-1 (Ang1) and angiopoietin-2 (Ang2) permit the generation of islets from iPSCs with elevated glucose responsiveness, a hallmark of mature islets. Angiopoietin-stimulated islets exhibited glucose synchronized calcium ion influx in repetitive glucose challenges. Moreover, Ang2 augmented the expression of all islet hormones, including insulin, glucagon, somatostatin, and pancreatic polypeptide; and β cell transcription factors, including NKX6.1, MAFA, UCN3, and PDX1. Furthermore, we showed that the Ang2 stimulated islets were able to regulate insulin exocytosis through actin-filament polymerization and depolymerization upon glucose challenge, presumably through the CDC42-RAC1-gelsolin mediated insulin secretion signaling pathway. We also discovered the formation of endothelium within the islets under Ang2 stimulation. These results strongly suggest that angiopoietin acts as a signaling molecule to endorse in vitro islet development from iPSCs.
This content will become publicly available on January 20, 2025
Biomedical devices such as islet‐encapsulating systems are used for treatment of type 1 diabetes (T1D). Despite recent strides in preventing biomaterial fibrosis, challenges remain for biomaterial scaffolds due to limitations on cells contained within. The study demonstrates that proliferation and function of insulinoma (INS‐1) cells as well as pancreatic rat islets may be improved in alginate hydrogels with optimized gel%, crosslinking, and stiffness. Quantitative polymerase chain reaction (qPCR)‐based graft phenotyping of encapsulated INS‐1 cells and pancreatic islets identified a hydrogel stiffness range between 600 and 1000 Pa that improved insulin Ins and Pdx1 gene expression as well as glucose‐sensitive insulin‐secretion. Barium chloride (BaCl2) crosslinking time is also optimized due to toxicity of extended exposure. Despite possible benefits to cell viability, calcium chloride (CaCl2)‐crosslinked hydrogels exhibited a sharp storage modulus loss in vitro. Despite improved stability, BaCl2‐crosslinked hydrogels also exhibited stiffness losses over the same timeframe. It is believed that this is due to ion exchange with other species in culture media, as hydrogels incubated in dIH2O exhibited significantly improved stability. To maintain cell viability and function while increasing 3D matrix stability, a range of useful media:dIH2O dilution ratios for use are identified. Such findings have importance to carry out characterization and optimization of cell microphysiological systems with high fidelity in vitro.
more » « less- NSF-PAR ID:
- 10486784
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Biology
- ISSN:
- 2701-0198
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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