Ex Vivo Generation of Functional Kidney Tissues for Transplantation

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PROJECT SUMMARY In the U.S. alone, up to 26 million people have chronic kidney disease, over 460,000 people are on dialysis, and 100,000 people await kidney transplants with 3,000 new patients added monthly. Given the growing lack of transplantable organs, patients typically require renal replacement therapies that themselves lead to substantial morbidity and mortality. We posit that biomanufactured kidney tissues, and ultimately, organs may offer an important solution to this growing problem. Indeed, recent protocols in developmental biology are unlocking the potential for stem cells to undergo differentiation and self-assembly to form “mini-organs”, known as organoids. Kidney organoids exhibit remarkable tissue microarchitectures with high cellular density and heterogeneity akin to their in vivo counterparts. To bridge the gap from these kidney organoid building blocks (OBBs) to therapeutic organs, integrative approaches that combine bottom-up organoid assembly with top-down bioprinting are needed. While it is difficult, if not impossible, to imagine how either organoids or bioprinting alone would fully replicate the complex multiscale features required for kidney function – their combination could provide an enabling foundation for de novo organ manufacturing. To generate 3D functional kidney tissues ex vivo for potential transplantation, our highly collaborative research team will undertake two primary aims. In Specific Aim 1, we will create kidney organoids enhanced by multilineage induction that display functional differentiation of nephrons. We will produce iPSC-derived kidney organoids and subject them to fluid flow during their differentiation and maturation on an adherent extracellular matrix (ECM). Through multilineage induction, we will also induce collecting duct cells that self-assemble and structurally bridge other tubular nephron segments. We will evaluate the effects of mimicking kidney organogenesis on kidney organoid structure and function using microperfusion and micropuncture methods. In Specific Aim 2, we will create 3D functional kidney tissues composed of these optimized kidney OBBs with embedded macrochannels produced by bioprinting that serve as both vascular and urinary output conduits. We will first produce a densely cellular, tissue matrix composed of kidney OBBs that facilitates bioprinting of embedded macrochannels. We will then establish connections between the printed macrochannels embedded in this OBB-laden matrix and the self-assembled microvascular and collecting duct networks within individual OBBs. Finally, we will assess the glomerular filtration, tubular maturation, and primitive urinary production of these 3D kidney tissues. If successful, our proposed project will provide a foundational advance in kidney organ engineering for potential renal therapeutic applications.