228.2: Vascularized endocrine pancreas for type 1 diabetes

Vanguard Consortium. Background: This study aimed to engineer a functional, vascularized endocrine pancreas by utilizing decellularized human placental cotyledons (hPLCs), human blood outgrowth endothelial cells (BOECs), and pancreatic islets. BOECs, which can be obtained from recipients, were used for revascularizing the construct. Methods: hPLCs were decellularized using 1% SDS and 0.1% Triton. Acellular hPLCs were repopulated with BOECs and then seeded with 1500 human islet equivalents (IEQ). Recellularization was confirmed through histological and immunohistochemical methods, while endocrine function was assessed by glucose-stimulated insulin secretion tests. Vascularized endocrine constructs were transplanted into the subcutaneous (SC) space of STZ diabetic NSG mice (PLCs+Islets+BOECs). Control mice were transplanted with non-endothelialized scaffolds (PLCs+Islets) containing the same number of islets and free islets in prevascularized subcutaneous spaces (SC) and under the kidney capsule (KC). Results: Engineered vascularized endocrine constructs exhibited a continuous CD31+ endothelial cell network within the hPLC, with islets embedded in the vascular bed. These constructs also demonstrated physiological insulin release in response to glucose stimulation. In the first week following transplantation, 80% of mice in the PLCs+Islets+BOECs group achieved normalized blood glucose levels, compared to 60% in the PLCs+Islets group. Mice transplanted with islets in the prevascularized subcutaneous space did not return to a normoglycemic state. Graft-bearing construct removal led to hyperglycemia recurrence in all mice within 24 hours. Immunohistochemical staining revealed a larger β-cell mass, as assessed by insulin-positive area per field, in the PLCs+Islets+BOECs group compared to the PLCs+Islets group 90 days post-transplant. CD31-stained explanted grafts indicated significantly higher vessel density in the PLCs+Islets+BOECs samples compared to the PLCs+Islet samples. Conclusions: The engineered vascularized endocrine pancreas provides a fully biocompatible construct that closely mimics the native islets’ matrix environment and offers mechanical protection, enabling transplanted islets to engraft and function long-term. This work was supported by grants from the European Commission (Horizon 2020 Framework Program; VANGUARD grant 874700), the Juvenile Diabetes Research Foundation (JDRF; grant 3-SRA-2020-926-S-B), the Shota Rustaveli National Science Foundation (grant FR-19-19760) and the Swiss National Science Foundation (grant 310030_173138 and grant CRSII5_209417).