Scalable Bioreactor-based Suspension Approach to Generate Stem Cell–derived Islets From Healthy Donor-derived iPSCs

Background. Induced pluripotent stem cells (iPSCs) offer the potential to generate autologous iPSC-derived islets (iPSC islets), however, remain limited by scalability and product safety. Methods. Herein, we report stagewise characterization of cells generated following a bioreactor-based differentiation protocol. Cell characteristics were assessed using flow cytometry, quantitative reverse transcription polymerase chain reaction, patch clamping, functional assessment, and in vivo functional and immunohistochemistry evaluation. Protocol yield and costs are assessed to determine scalability. Results. Differentiation was capable of generating 90.4% PDX1 + /NKX6.1 + pancreatic progenitors and 100% C-peptide + /NKX6.1 + iPSC islet cells. However, 82.1%, 49.6%, and 0.9% of the cells expressed SOX9 (duct), SLC18A1 (enterochromaffin cells), and CDX2 (gut cells), respectively. Explanted grafts contained mature monohormonal islet-like cells, however, CK19 + ductal tissues persist. Using this protocol, semi-planar differentiation using 150 mm plates achieved 5.72 × 10 4 cells/cm 2 (total 8.3 × 10 6 cells), whereas complete suspension differentiation within 100 mL Vertical-Wheel bioreactors significantly increased cell yield to 1.1 × 10 6 cells/mL (total 105.0 × 10 6 cells), reducing costs by 88.8%. Conclusions. This study offers a scalable suspension-based approach for iPSC islet differentiation within Vertical-Wheel bioreactors with thorough characterization of the ensuing product to enable future protocol comparison and evaluation of approaches for off-target cell elimination. Results suggest that bioreactor-based suspension differentiation protocols may facilitate scalability and clinical implementation of iPSC islet therapies.