High-Yield Generation of Glucose-Responsive Pseudoislets From Murine Insulinoma Cells for In Vitro Studies and Longitudinal Monitoring of Graft Survival In Vivo.

Compared to primary pancreatic islets, insulinoma cell-derived 3D pseudoislets offer a more accessible, consistent, renewable, and widely applicable model system for optimization and mechanistic studies in type 1 diabetes (T1D). Here, we report a simple and efficient method for generating 3D pseudoislets from MIN6 and NIT-1 murine insulinoma cells. These pseudoislets are homogeneous in size and morphology (~150 µm), exhibit functional glucose-stimulated insulin secretion (GSIS) up to 18 days (NIT-1) enabling long-term studies, are produced in high yield [>35,000 Islet Equivalence from 30 ml culture], and are suitable for both in vitro and in vivo studies, including for encapsulation studies. To enable non-invasive longitudinal monitoring of graft survival in vivo, we transduced NIT-1 cells with green fluorescent protein-luciferase and confirmed comparable morphology, viability, and GSIS to untransduced cells in vitro. After subcutaneous implantation, we show capability to monitor graft survival in immunodeficient mice, recurrence of autoimmunity in non-obese diabetic mice, and allorejection in C57BL/6 mice. Overall, this platform provides an accessible protocol for generating high yields of 3D pseudoislets and non-invasive longitudinal monitoring of graft survival in different models offer advantages over primary islets for optimization and mechanistic studies of β cell biology, drug discovery, T1D pathogenesis and prevention, and β cell transplantation.