Human induced pluripotent stem cell-derived podocytes mature into vascularized glomeruli upon experimental transplantation

Abstract

Glomerular podocytes express proteins, such as nephrin, that constitute the slit diaphragm, thereby contributing to thefiltration process in the kidney.Glomerular development hasbeenanalyzedmainly in mice,whereas analysis of human kidney development has been minimal because of limited access to embryonic kidneys.We previously reported the inductionof three-dimensional primordial glomeruli from human inducedpluripotent stem(iPS) cells. Here, using transcription activator-like effector nuclease-mediated homologous recombination, we generated human iPS cell lines that express green fluorescent protein (GFP) in the NPHS1 locus, which encodes nephrin, and we show that GFP expression facilitated accurate visualization of nephrin-positive podocyte formation in vitro. These induced human podocytes exhibited apicobasal polarity, with nephrin proteins accumulated close to the basal domain, and possessed primary processes that were connected with slit diaphragm-like structures.Microarray analysis of sorted iPS cell-derived podocytes identified well conserved marker gene expression previously shown inmouseandhumanpodocytes in vivo. Furthermore,we developed a novel transplantation method using spacers that release the tension of host kidney capsules, thereby allowing the effective formation of glomeruli from human iPS cell-derived nephron progenitors. The human glomeruli were vascularized with the host mouse endothelial cells, and iPS cell-derived podocytes with numerous cell processes accumulated around the fenestrated endothelial cells. Therefore, the podocytes generated from iPS cells retain the podocyte-specificmolecular and structural features, which will be useful for dissecting human glomerular development and diseases.