Leverage kidney progenitor plasticity to direct the engineering of next-generation kidney organoid - PROJECT SUMMARY Kidney organoids have been developed in the past decade, offering unprecedented complex three-dimensional in vitro kidney models for kidney research. However, despite the progress, kidney organoids have not been broadly utilized in kidney research due to major limitations in lack of sufficient tissue complexity, spatial patterning, maturity and functionality. These limitations prevent the utilization of kidney organoids as reliable models for accurately modeling adult kidney physiology and pathophysiology. Here, we propose an approach to overcome these limitations and develop a spatially patterned, mature and functional human kidney organoid tool. Our approach stems from the in vivo self-assembly of mammalian kidneys from the reciprocal interactions of a few types of kidney progenitor cells. We hypothesize that, under an optimal stepwise culture condition that can mirror the stage-specific in vivo environment, kidney progenitor cells will self-organize and generate a mature and functional kidney-like tissue recapitulating normal kidney organogenesis. In the past decade, we have developed methods to expand primary mouse nephron progenitor cells (NPCs) and ureteric progenitor cells (UPCs), and human pluripotent stem cell (hPSC)-induced iNPCs and iUPCs. Consistent with our hypothesis, a spatially organized, mature and functional mouse kidney organoid is self-assembled from cultured NPCs and UPCs. Here we propose to further develop a mature and functional human kidney organoid, leveraging technological innovations based on kidney progenitor plasticity. In Aim 1, we will optimize kidney progenitor assembly and kidney culture condition to develop a protocol that can generate spatially patterned and functional human kidney organoid. In Aim 2, we will comprehensively characterize the human kidney organoid in vitro and in vivo at the molecular, cellular, and functional levels. Success of this project will have broad impact in the whole kidney research field: 1) It will offer an in vitro tool to understand human kidney maturation, a current knowledge gap; 2) It will offer an in vitro platform to more accurately model adult kidney physiology and pathophysiology; 3) It will offer an invitro mature kidney model to test drug nephrotoxicity; and 4) It will lay a strong foundation for further engineering of scaled-up functional kidney tissues for regenerative medicine.
