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Glomerular podocytes express proteins, such as nephrin, that constitute the slit diaphragm, thereby contributing to the filtration process in the kidney. Glomerular development has been analyzed mainly in mice, whereas analysis of human kidney development has been minimal because of limited access to embryonic kidneys. We previously reported the induction of three-dimensional primordial glomeruli from human induced pluripotent 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 (Figure A). These induced human podocytes exhibited apicobasal polarity, with nephrin proteins accumulated close to the basal domain, and possessed primary processes that were connected with immature slit diaphragm–like structures. Microarray analysis of sorted iPS cell–derived podocytes identified well-conserved marker gene expression previously shown in mouse and human podocytes 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 (Figure B, C), and iPS cell–derived podocytes with numerous cell processes and the slit-diaphragm-like structures accumulated around the fenestrated endothelial cells (Figure D). Therefore, the podocytes generated from iPS cells retain the podocyte-specific molecular and structural features, which will be useful for dissecting human glomerular development and diseases.

Figure
The kidney tissues derived from human iPS cells
A.The kidney tissue generated in vitro, which shows green fluorescence in each glomerulus.
B.Vascularized glomerulus formed upon transplantation into the mouse. Many red blood cells (arrowhead) are observed, and the substance exists in the lumen (*), suggesting the possible filtration.
C.Mouse vascular endothelial cells (green) are incorporated into the glomerulus that consists of podocytes (magenta).
D.The slit diaphragm (arrow) formed between the cellular processes of the podocytes.