Hypoimmune Human Primary Pancreatic Islets Survive and Function in Humanized Diabetic Mice

Treatment of type 1 diabetes mellitus (T1DM) via allogeneic donor transplant has limited success due to morbidities from immunosuppression (IS) and a gradual loss of engrafted pancreatic islet function. We set out to engineer human primary pancreatic islets (PI) using our hypoimmune strategy that could engraft and evade host immune detection in the absence of IS. Human cadaveric PIs were engineered to knock-out function of HLA class I and II and overexpress CD47 (HIP PI) . Unedited PIs were cultured identically (Wt PI) as controls. NSG-SGM3 mice were reconstituted with human CD34+ cells and had >45% engraftment of human CD45+ cells. Mice were rendered diabetic (streptozotocin) . A total of 300 HIP PI or Wt PI were transplanted IM. After 6 days, splenocytes and serum were obtained for immune analyses. HIP PI showed no T cell recognition (ELISpot) , no graft-specific antibodies (Abs) , and were protected from NK cell and macrophage killing. Wt PI had a strong adaptive immune response with high ELISpot frequencies and an increase in graft-directed Abs. Serial BLI showed survival of all HIP PI grafts but rapid rejection of Wt PI, confirmed by histopathology at 4 weeks. Glucose levels gradually decreased after HIP PI transplantation and remained stable around 200 mg/dl after 14 days. These data suggest that hypoimmune engineering may generate HIP PI capable of persisting and functioning in diabetic patients without IS. Disclosure X.Hu: None. C.Gattis: None. C.Young: Employee; Sana Biotechnology Inc. A.G.Olroyd: None. E.Y.L.Chu: None. K.White: None. A.Friera: None. S.Schrepfer: Other Relationship; Sana Biotechnology Inc.