Promoting metabolic maturity of islet organoids pre- and post-transplantation

University Of Michigan At Ann Arbor, Ann Arbor MI

Investigators

Abstract

Type I diabetes (T1D) affects an estimated 1.25 million Americans, and although insulin therapy has been successful, hypoglycemic events and vascular complications persist. Intraportal allogeneic islet transplantation has recently become an approved therapy yet is limited in part by a shortage of donor islets. These limitations have led to the investigation of culturing human pluripotent stem cells (hPSC) to islet organoids as an unlimited source of functional β-cells. Multiple investigators, including our team, have demonstrated the feasibility of generating islet organoids in vitro, and transplantation allows a reduction of exogenous insulin. Nevertheless, analysis of the islet organoids from our laboratory and that of all others indicates that the current culture platforms do not produce β-cells with mitochondria comparable to that of native pancreatic islets. Mitochondrial reactions within the metabolic networks of pancreatic ꞵ-cells are responsible for regulating insulin secretion through KATP channel stimulation, downstream membrane depolarization and insulin granule release. These reactions make ꞵ-cells obligate mitochondrial respirators, meaning they cannot perform their basic functions by anaerobic respiration, and highlight the importance of metabolic networks. The metabolic immaturity can lead to dysfunction and limit survival following transplantation. Herein, we propose to investigate approaches to enhance metabolic maturity of islet organoids during in vitro culture and post-transplantation into a clinically translatable site, the omentum. Aim 1 will investigate metabolic and functional maturation of in vitro differentiated islet organoids using pharmacologic agents and 3D culture to enhance metabolic development and will develop a dynamic genome wide metabolic model to analyze the impact of these interventions and to predict additional targets to close the gap between islet organoids and islets. Preliminary data with Exendin-4, which has been used extensively with islets yet not with organoids, and PPAR agonists that address lipid metabolism demonstrates an enhanced metabolic pathways and organoid function. 3D culture will be performed on microporous scaffolds to improve cell interactions and metabolic development in our studies and other engineered tissues. Aim 2 will investigate metabolic function of organoids post transplantation and will target the delivery of factor to enhance metabolic maturity and to reduce the impact of factors, such as the inflammatory mediators TNFα and IFNγ, that contribute to the dysregulation, de-differentiation, or induction of -cell death. Transplantation will be performed using microporous scaffolds, which have been employed for islet transplantation to support host integration and restores normoglycemia. As with the first aim, we will analyze the metabolic function both experimentally and computationally to identify the mechanisms for the interventions and identify additional targets. We anticipate that directly enhancing metabolic function either prior to or post-transplantation, or limiting metabolic decline, will limit stress on transplanted cells, and will enhance survival and function of the islet organoids.