Generation of Kidney Organoids Model of Nephronophthisis from Human Induced Pluripotent Stem Cells (iPSCs)

Background: Nephronophthisis (NPH) is an inherited kidney disease characterized by progressive tubulointerstitial fibrosis. NPH is clinically important as the most common cause of end-stage kidney disease in the juvenile period; however, no reliable animal model faithfully mimicking the pathology of human NPH is available. Consequently, the molecular mechanism of NPH caused by NPHP1 deficiency, the most common form of NPH, has not yet been elucidated. Therefore, new models to recapitulate the pathology of NPH are required. In this study, we used human induced pluripotent stem cells (iPSCs) to generate a 3D kidney organoid model of fibrosis that provides insight into the pathogenesis of NPH. Methods: Wild-type iPSCs and NPHP1-/- iPSCs derived from the same cell line were induced to differentiate into 3D kidney organoids, and the phenotypes associated with NPHP1 deficiency were analyzed. First, we compared the morphology of both wild-type and NPHP1-/- organoids by immunofluorescence. Next, we induced fibrosis by treatment of IL-1β and evaluated the difference in the severity of fibrosis between the two groups. Results: We successfully generated kidney organoids from both wild-type and NPHP1-/- iPSCs. In the absence of any stimulation, no difference in morphology, including nephron-like structure or fibrotic status, was observed between the two groups. This is consistent with the clinical course of human NPH caused by NPHP1 deficiency, in which renal dysfunction does not appear during the postnatal period. On the other hand, fibrosis was induced at a significantly lower dose of IL-1β in NPHP1-/- organoids compared to wild-type organoids. This suggests that the NPHP1-deficient kidney is more sensitive to fibrotic stimuli than the wild-type kidney, which may explain why NPHP1-deficient NPH patients reach end-stage kidney disease earlier. Conclusion: We generated NPHP1-deficient 3D kidney organoids; the first system capable of reproducing NPH pathology using human cells. This is an important pathological model for investigating the pathogenesis of NPH and developing therapeutic strategies. Funding: Government Support – Non-U.S.