Engineered vasculature induces functional maturation of pluripotent stem cell-derived islet organoids

Blood vessels play a critical role in pancreatic islet function, yet current methods for deriving islet organoids from human pluripotent stem cells (SC-islets) lack vasculature. We engineered three-dimensional (3D) vascularized SC-islet organoids by assembling SC-islet cells, human primary endothelial cells (ECs), and fibroblasts in a non-perfused model and a microfluidic device with perfused vessels. Vasculature improved stimulus-dependent Ca²⁺ influx into SC-β cells, a hallmark of β cell function that is blunted in non-vascularized SC-islets. Moreover, vascularization accelerated diabetes reversal post engraftment of a subtherapeutic SC-islet dose into mice. We show that vasculature leads to the formation of an islet-like basement membrane that contributes to the functional improvement of SC-β cells. Furthermore, single-cell RNA sequencing (scRNA-seq) data predicted BMP2/4-BMPR2 signaling from ECs to SC-β cells, and correspondingly, BMP4 enhanced the SC-β cell Ca²⁺ response and insulin secretion. Vascularized SC-islets will enable further studies of crosstalk between β cells and ECs and will serve as an in vitro platform for disease modeling and therapeutic testing.