Expression of Stem Cell Markers in the Human Fetal Kidney

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.

Inhibiting Angiotensin-Converting Enzyme Promotes Renal Repair by Limiting Progenitor Cell Proliferation and Restoring the Glomerular Architecture

“…CD133 proteins do not identify progenitor cells due to interspecies differences, which prompted us to search for another stemness marker. One of us had previously discovered neural cell adhesion molecule (NCAM), normally expressed in rodent and human metanephric mesenchyme, 27,21 in the Bowman's capsule of the mature kidney. 20 At that time, the possibility that stem cells existed along the Bowman's capsule was not conceived.…”

Renal Hypodysplasia Associates with a Wnt4 Variant that Causes Aberrant Canonical Wnt Signaling

“…The tissues were handled within 1 hour after the procedure. 31,32 All studies were approved by the local ethics committee and informed consent was provided by the patients involved in this research according to the Declaration of Helsinki. Both HFK and HAK tissues were washed with cold Hanks' balanced salt solution (Invitrogen, Carlsbad, CA) and minced into approximately 1-mm cubes using sterile surgical scalpels.…”

Targeted therapy aimed at cancer stem cells: Wilms’ tumor as an example

“…Moreover, although NCAM is a renal developmental marker [87][88][89][90], human nephrogenesis completely ceases at 34 weeks of human gestation, excluding the potential for aberrant development caused by anti-NCAM treatment. Therefore, from a clinical standpoint, a combined regimen involving the specific eradication of the WT CICs via targeting of the NCAM molecule, might prove useful in reducing chemotherapy toxicity in all WT patients and particularly in those that do not respond to conventional treatment or those with recurrent disease.…”