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 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. Furthermore, vascularization accelerated diabetes reversal post-engraftment of a subtherapeutic SC-islet dose. We show that vasculature leads to formation of an islet-like basement membrane that contributes to functional improvement of SC-β-cells. Furthermore, 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. In this analysis, we used single-cell RNA-seq (scRNA-seq) to profile 9197 cells from control and 5 ng/ml BMP4-treated stem cell-derived islets (SC-islets) derived from the H1 human embryonic stem cell line. To characterize gene expression changes in stem-cell β-cells (SC-β-cells), we identified different cell populations by clustering and performed pair-wise comparison of gene expression between control and BMP-4 treated SC-β-cells.