Collaborative Research: Engineer a functional 3D vascularized islet organoid from pluripotent stem cells

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PIs: Banerjee, Ipsita / Rege, Kaushal / Hoying, JamesProposal Numbers: 1706674 / 1706268 / 1706742Pancreatic islets are micro-organs that produce and release multiple hormones, primarily insulin, into the blood stream. Deterioration of islet health and function results in diabetes, which has become an epidemic healthcare problem worldwide. A promising treatment of diabetes lies in islet transplantation--where isolated islets from donors are transplanted into the patient. In the absence of sufficient islet donors, the current focus is on generating islets in the laboratory from human pluripotent stem cells (hPSC). Pancreatic islets primarily consist of hormone producing cells interlaced with a dense network of capillaries for efficient transport of released hormones. In addition to nutrient delivery, the islet vasculature plays a critical role in islet development and function. Hence, when deriving islet-organoids from hPSCs, there will be multiple benefits in engineering the intra-islet vasculature, which is the objective of this project. This objective will be achieved by integration of multiple novel techniques, including the aggregation of pancreatic cells into spheroids and the inclusion of microvessel fragments (MFs) obtained from adipose (fat) tissue to enhance vascularization. The most significant impact of the regenerative organoids will be in cell therapy for diabetes. An even more achievable goal is the use of functional islet organoids as an in-vitro model for testing the efficacy and toxicity of drug compounds for diabetes. The interdisciplinary faculty team, representing the University of Pittsburgh, Arizona State University and the University of Louisville, will leverage the multidisciplinary approach of this project to train students at the graduate and undergraduate levels and to broaden outreach programs to increase opportunities for a diverse population of students. The team will develop a joint summer internship program, where minority students from each institution will intern in the other two Universities, thereby enhancing collaborative opportunities as well as student training.The goal of this collaborative project is to engineer in-vitro vascularized pancreatic islet organoids from human pluripotent stem cells (hPSCs). Self-organization of hPSCs will be engineered into heterogeneous three-dimensional (3D) constructs with a physiological islet vascular network and endocrine function. The team has developed a novel hydrogel system that closely mimics the 3D islet physiology through self-organization of hPSC derived pancreatic progenitor cells. The hydrogel platform enables precise control over the 3D culture configuration as well as allowing multicellular aggregation. This is a substantive departure from status quo, where hPSCs are randomly aggregated in a stirred suspension resulting in uncontrolled aggregates of varying size and phenotype. In-vitro vascularization will be engineered by incorporating isolated adipose-derived microvessel fragments within the engineered 3D cellular construct. These microfragments retain the endothelial, vessel matrix components, and supporting cells necessary for angiogenesis. This pre-embedment and development of a vascular network is a substantive departure from status quo, where in-vivo implantation and host vasculature integration is relied upon for microvascular network formation. The project perhaps represents the first attempt to generate in-vitro vascularized pancreatic islet organoids from hPSCs. The Research Plan is organized around three aims: 1) to determine culture conditions inducing aggregation of hPSC derived cells; 2) to induce islet-specific microvascular network within the islet organoids; and 3) to induce and characterize mature islet functionality (endocrine phenotype and glucose responsive insulin production) in the vascularized organoids in vitro and in vivo in an immunocompromised mouse model. It is hypothesized that adequate reproduction of islet microenvironment within the organoid will induce islet-specific vascular characteristics and phenotype in the adipose-derived microvessels. Such regenerative islet organoids will be directly relevant for pancreatic tissue and organ engineering, and methods developed have the potential to transform the field of tissue engineering in general.