Generation of Functioning Nephrons by Implanting Human Pluripotent Stem Cell-Derived Kidney Progenitors

Abstract

SummaryHuman pluripotent stem cells (hPSCs) hold great promise for understanding kidney development and disease. We reproducibly differentiated three genetically distinct wild-type hPSC lines to kidney precursors that underwent rudimentary morphogenesis in vitro. They expressed nephron and collecting duct lineage marker genes, several of which are mutated in human kidney disease. Lentiviral-transduced hPSCs expressing reporter genes differentiated similarly to controls in vitro. Kidney progenitors were subcutaneously implanted into immunodeficient mice. By 12 weeks, they formed organ-like masses detectable by bioluminescence imaging. Implants included perfused glomeruli containing human capillaries, podocytes with regions of mature basement membrane, and mesangial cells. After intravenous injection of fluorescent low-molecular-weight dextran, signal was detected in tubules, demonstrating uptake from glomerular filtrate. Thus, we have developed methods to trace hPSC-derived kidney precursors that formed functioning nephrons in vivo. These advances beyond in vitro culture are critical steps toward using hPSCs to model and treat kidney diseases.

From organoids to transplantable artificial kidneys

“…A similar mechanism may operate in glomerular vascularization in mammals. Interestingly, most endothelial cells in the glomeruli in the transplantation experiments were derived from the host animals rather than from the transplanted iPSCs . In contrast, another group detected some integration of hiPSC‐derived endothelial cells upon transplantation.…”

Kidney organoids: accurate models or fortunate accidents

“…The implications of this become the most stark when one considers the prospects for renal replacement. A number of groups have shown evidence that a transplanted organoid can draw in a host vasculature with evidence of substantive glomerular and tubular maturation (Sharmin et al 2016;Bantounas et al 2018;Tanigawa et al 2018;van den Berg et al 2018). However, if there is no prospect of ongoing nephrogenesis, all current approaches fall short with respect to tissue mass and will not generate new nephrons after transplantation.…”

“…In addition, protocols for the generation of specific renal cell subtypes, such as podocyte or collecting duct epithelium, are being reported (Musah et al 2017;Taguchi and Nishinakamura 2017;Hale et al 2018;Yoshimura et al 2019). Finally, a variety of approaches have now been proposed to improve vascularization in vitro (Homan et al 2019) or provide vascular flow in vivo (Sharmin et al 2016;Bantounas et al 2018;van den Berg et al 2018;Garreta et al 2019;Gupta et al 2019). In most instances, these involve modifications of prior differentiation protocols (Table 2; Taguchi et al 2014;Freedman et al 2015;Morizane et al 2015;.…”

“…What is evident is that the provision of an ex vivo blood supply does improve tubular ultrastructure. This has been achieved via transplantation either under the renal capsule or subcutaneously in immunocompromised mice or culture of organoids on the chick chorioallantoic membrane (Bantounas et al 2018;van den Berg et al 2018;Garreta et al 2019). In both examples, a nascent host-derived vasculature grows into the grafted organoid with TEM evidence for the presence of glomerular capillaries.…”

Progress in the Development and Challenges for the Use of Artificial Kidneys and Wearable Dialysis Devices

“…The basic strategy of bioengineered kidney constructs is to exploit the structure of the native kidney through seeding cultured cells into a 3D scaffold system and subsequently implant the cell-seeded scaffold in vivo to restore kidney functions. Various scaffolding systems, including natural (e.g., collagen) and synthetic biomaterials, have been used, and recent advances have been made in the generation of kidney organoids in vitro that engraft in vivo [25, 26]. Although promising, these technologies are still far from clinical application due to difficulties in the fabrication of large-sized functional renal constructs with complex renal structures that could readily integrate into host kidney tissue for clinical translation [27].…”