87-OR: Engineered Vasculature Induces Functional Maturation of Pluripotent Stem Cell–Derived Islet Organoids

Blood vessels play a critical role in islet health and function. Native islets are richly vascularized and their interaction with blood vessels is important for β-cell function. Therefore, vasculature ought to be an integral component of a model for studying human islet physiology and diabetes pathobiology. Here, we develop a vascularized islet organoid model by integrating hPSC-derived islets (SC-islets) with human endothelial cells (ECs) and fibroblasts (FBs). To analyze β-cell function, we generated an hPSC line carrying GCaMP6f, a Ca²⁺ reporter, as Ca²⁺ oscillation can be used as a proxy for insulin secretion. Comparing β-cell Ca²⁺ responses of non-vascularized and vascularized SC-islets revealed more frequent and stronger Ca²⁺ influx in response to high glucose and the GLP-1 analogue in vascularized SC-islets. To identify vasculature-derived signals beneficial to β-cell function, we performed cell-cell interaction network analyses based on single-cell transcriptomic data from SC-islets, ECs, and FBs. Among the top candidates were integrin receptors that interact with extracellular matrix proteins. Consistent with these predictions, a higher number of β-cells were in contact with EC-derived basement membrane proteins (e.g., laminin α1, collagen IV) and exhibited activation of integrin β1. The analysis also revealed BMP4-BMPR2 as a potential crosstalk between ECs and β-cells. Indeed, BMP4 addition augmented Ca²⁺ response and insulin secretion of β-cells under glucose stimulation. Finally, to develop a system mimicking in vivo physiology, we integrated SC-islets into a microfluidic platform where the organoids are supported by a network of perfused microvessels. Our newly-established model of vascularized SC-islet organoids will enable further studies of crosstalk between β-cells and vasculature under conditions mimicking the native islet microenvironment. The model will serve as a platform to study disease mechanisms of diabetes and test therapeutics.