Expression of Stem Cell Markers in the Human Fetal Kidney

Sally Metsuyanim,Orit Harari-Steinberg,Benjamin Dekel,Reuvit Halperin,Herzl Ben-Hur,Ella Buzhor,Naomi Pode-Shakked,Dorit Omer,David Schneider,Annarosa Leri

doi:10.1371/journal.pone.0006709

Sally Metsuyanim, Orit Harari-Steinberg + Show 8 more

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https://doi.org/10.1371/journal.pone.0006709

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Abstract

In the human fetal kidney (HFK) self-renewing stem cells residing in the metanephric mesenchyme (MM)/blastema are induced to form all cell types of the nephron till 34th week of gestation. Definition of useful markers is crucial for the identification of HFK stem cells. Because wilms' tumor, a pediatric renal cancer, initiates from retention of renal stem cells, we hypothesized that surface antigens previously up-regulated in microarrays of both HFK and blastema-enriched stem-like wilms' tumor xenografts (NCAM, ACVRIIB, DLK1/PREF, GPR39, FZD7, FZD2, NTRK2) are likely to be relevant markers. Comprehensive profiling of these putative and of additional stem cell markers (CD34, CD133, c-Kit, CD90, CD105, CD24) in mid-gestation HFK was performed using immunostaining and FACS in conjunction with EpCAM, an epithelial surface marker that is absent from the MM and increases along nephron differentiation and hence can be separated into negative, dim or bright fractions. No marker was specifically localized to the MM. Nevertheless, FZD7 and NTRK2 were preferentially localized to the MM and emerging tubules (<10% of HFK cells) and were mostly present within the EpCAMneg and EpCAMdim fractions, indicating putative stem/progenitor markers. In contrast, single markers such as CD24 and CD133 as well as double-positive CD24+CD133+ cells comprise >50% of HFK cells and predominantly co-express EpCAMbright, indicating they are mostly markers of differentiation. Furthermore, localization of NCAM exclusively in the MM and in its nephron progenitor derivatives but also in stroma and the expression pattern of significantly elevated renal stem/progenitor genes Six2, Wt1, Cited1, and Sall1 in NCAM+EpCAM- and to a lesser extent in NCAM+EpCAM+ fractions confirmed regional identity of cells and assisted us in pinpointing the presence of subpopulations that are putative MM-derived progenitor cells (NCAM+EpCAM+FZD7+), MM stem cells (NCAM+EpCAM-FZD7+) or both (NCAM+FZD7+). These results and concepts provide a framework for developing cell selection strategies for human renal cell-based therapies.

Highlights

Identification of multipotential progenitor populations in mammalian tissues is important both for therapeutic potential and an understanding of developmental processes and tissue homeostasis
Trzpis et al(Trzpis et al 2007) have recently shown that in mid-gestation human fetal kidney (HFK), hEpCAM was expressed by the ureteric bud (UB) and comma-shaped (C) and S-shaped (S) bodies, whereas the MM did not express hEpCAM
We have analyzed for the expression of putative stem cell markers in the in the human fetal kidney

Summary

Introduction

Identification of multipotential progenitor populations in mammalian tissues is important both for therapeutic potential and an understanding of developmental processes and tissue homeostasis. Progenitor populations are ideal targets for gene therapy, cell transplantation, and tissue engineering of bioartificial organs(Weissman 2000; Xu et al 2000). A demand for kidney progenitors is increasing because of a severe shortage of donor organs for orthotopic kidney transplantation. The early development of the mammalian metanephros, the direct precursor tissue of the adult kidney, is a complex process that involves highly regulated interactions between two derivatives of the intermediate mesoderm, the wolffian duct and the metanephric/nephrogenic mesenchyme. The condensed mesenchyme is thought to form a precursor cell population, which both maintains itself at the tips of the UB (via proliferation and/or addition from the surrounding non-condensed mesenchyme) and gives off cells that differentiate into nephrons, the functional filtration unit of the kidney(Rosenblum 2008). Recent experiments have established that the progenitor cell in the MM fulfils the criteria of a true committed stem cell in that is capable of self-renewing and of differentiating towards different types of nephron epithelia(Self et al 2006; Boyle et al 2008; Kobayashi et al 2008)

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