Development of Novel Cell Therapeutic Strategies for AKI and CKD Using Human Induced Pluripotent Stem Cell (iPSC)-Derived Nephron Progenitor Cells

Background: The therapeutic effect of human iPS cell-derived nephron progenitor cells (hiPSC-NPCs) on acute kidney injury (AKI) has been reported in mice but has not been clinically confirmed. No reported studies have examined the therapeutic potential of hiPSC-NPCs on chronic kidney disease (CKD). On the other hand, it was recently reported that the properties of hiPSC-NPCs differ depending on differences in iPSC lines and batches among experiments. Therefore, a large number of uniform hiPSC-NPCs are required to realize cell therapies for AKI and CKD, but effective expansion cultures remain to be developed. Methods: We screened culture conditions that maintained the function of hiPSC-NPCs by multiple combinations of the low-molecular-weight compounds and growth factors. Furthermore, we transplanted expanded hiPSC-NPCs into the renal subcapsule of cisplatin-induced AKI model (cis-AKI) mice and aristolochic acid-induced CKD model (AA-CKD) mice and evaluated renal function and histological changes. We also administered conditioned medium (CM) produced by expanded hiPSC-NPCs to cis-AKI mice to examine the therapeutic effects, and performed mass spectrometry of CM and RNA-sequencing of hiPSC-NPCs. Results: We established a novel expansion culture condition (CFY medium) that enables more than 1,000-fold proliferation of hiPSC-NPCs in three passages while maintaining NPC marker expression. We demonstrated that hiPSC-NPCs expanded by CFY medium attenuate kidney injury and improve survival rate in cis-AKI mice. Furthermore, we found that hiPSC-NPCs prevent kidney functional decline, interstitial fibrosis, and senescence in AA-CKD mice. In addition, the contralateral kidneys transplanted with hiPSC-NPCs in AKI and CKD mice were also treated, suggesting that the therapeutic effects of hiPSC-NPCs were due to reno-protective factors. Therefore, we administered CM produced by expanded hiPSC-NPCs to cis-AKI mice, which prevented kidney functional decline and improved survival rate. Furthermore, we identified some reno-protective factors contained in CM and demonstrated that angiogenesis in the injured kidney is involved as part of the mechanisms by which hiPSC-NPCs exert therapeutic effects. Conclusion: The expanded hiPSC-NPCs are useful for cell therapies for AKI and CKD and will open new avenues in the treatment of kidney diseases. Funding: Commercial Support - Rege Nephro Co., Ltd, Government Support – Non-U.S.