Engineered enteroendocrine cells secrete insulin in response to glucose and reverse hyperglycemia in diabetic mice

Type 1 diabetes is a metabolic disorder caused by loss of insulin-producing pancreatic β-cells. Expression of insulin in non-β-cells to create β-cell surrogates has been tried to treat type 1 diabetes. Enteroendocrine K cells have characteristics similar to pancreatic β-cells, such as a glucose-sensing system and insulin-processing proteases. In this study, we genetically engineered an enteroendocrine cell line (STC-1) to express insulin under the control of the glucose-dependent insulinotropic polypeptide promoter. We screened clones and chose one, Gi-INS-7, based on its high production of insulin. Gi-INS-7 cells expressed glucose transporter 2 (GLUT2) and glucokinase (GK) and secreted insulin in response to elevated glucose levels in vitro. To determine whether Gi-INS-7 cells can control blood glucose levels in diabetic mice, we transplanted these cells under the kidney capsule of streptozotocin (STZ)-induced diabetic mice and found that blood glucose levels became normal within 2 weeks of transplantation. In addition, glucose tolerance tests in mice that became normoglycemic after transplantation with Gi-INS-7 cells showed that exogenous glucose was cleared appropriately. These results suggest that engineered K cells may be promising surrogate β-cells for possible therapeutic use for the treatment of type 1 diabetes.