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Abstract: FR-PO376

Effects of Re-Expression of Renal Progenitor Genes in Mature Human Kidney Cells

Session Information

Category: Development‚ Stem Cells‚ and Regenerative Medicine

  • 500 Development‚ Stem Cells‚ and Regenerative Medicine

Authors

  • Pode Shakked, Naomi, Shena Medical Center, Pediatric Stem Cell Research Institute and Sackler Faculty of Medicine Tel Aviv University, Tel Hashomer, Tel Aviv, Israel
  • Dekel, Benjamin, Sheba Medical Center, Safra Children's Hospital, Division of Pediatric Nephrology, Pediatric Stem Cell Research Institute, Tel Hashomer, Tel Aviv, Israel
  • Pleniceanu, Oren, Sheba Medical Center, Pediatric Stem Cell Research Institute, Tel Hashomer, Tel Aviv, Israel
Background

During human nephrogenesis, fetal renal progenitors give rise to approximately 106 nephrons. It is currently believed that this progenitor pool is abolished postnatally due to the silencing of renal progenitor genes, depriving the mature kidney of the ability to generate new nephrons. At the same time, the incidence of end-stage renal disease is constantly growing, underscoring the need for new kidney regeneration strategies.

Methods

Here, we used lentiviral vectors to evaluate the effects of ectopic induction of two major renal progenitor genes (OSR1 and SIX2) in primary adult kidney (AK) cells.

Results

OSR1 over-expression resulted in a transient change in cellular morphology into a cuboidal, mesenchymal-like phenotype, accompanied by upregulation of renal developmental transcription factors PAX2, SIX2, CITED1 and GDNF, while maintaining the expression of the GDNF protein, the major factor secreted from kidney stem cells and thus a marker of their functionality. However, no change in clonal efficiency or proliferation rate was noted in OSR1-expressing AK cells. In contrast, SIX2 over-expression led to significantly higher clonal efficiency and enhanced proliferation compared to control cells, consistent with its role as a regulator of self-renewal in renal stem cells. Surprisingly, although SIX2 induction resulted in elevated OSR1 levels, other renal progenitor genes (PAX2, SALL1 and GDNF) showed significantly lower expression levels. When injected subcutaneously into immunodeficient mice, SIX2-expressing cells demonstrated robust tubulogenic potential, giving rise mostly to CD13+EMA- proximal tubule cells, but were unable to integrate into developing renal tubules when co-cultured with embryonic mouse kidney cells. Importantly, cells over-expressing both OSR1 and SIX2 were both tubulogenic and showed distinct capacity of integrating into developing fetal renal structures.

Conclusion

Taken together, our results demonstrate that OSR1 induction in AK cells activates several other renal progenitor genes while SIX2 induction endows the cells with enhanced proliferation and colony formation potential, which could serve as a basis for generating an expandable in-vitro population of renal progenitor cells.