Kidney Week

Abstract: FR-OR066

NG2 Lineage Cells Migrate onto the Glomerular Tuft and Bowman’s Capsule with Expression of PEC Markers in Experimental FSGS

Session Information

• It's What's Proximal to the Efferent Arteriole that Matters
  November 03, 2017 | Location: Room 294, Morial Convention Center
  Abstract Time: 06:06 PM - 06:18 PM

Category: Glomerular

• 1002 Glomerular: Basic/Experimental Pathology

Authors

• Suzuki, Taihei, University of Washington, Seattle, Washington, United States

Taihei Suzuki, MD, PhD

• Pippin, Jeffrey W., University of Washington, Seattle, Washington, United States

Jeffrey W. Pippin,

• Eng, Diana G., University of Washington, Seattle, Washington, United States

Diana G. Eng,

• Shankland, Stuart J., University of Washington, Seattle, Washington, United States

Stuart J. Shankland,

Background

Glomerular regeneration typically relies on local stem/progenitor cells. After podocyte loss, parietal epithelial cells (PECs) and cells of renin lineage serve as adult podocyte progenitors. Although Neural/glial antigen 2 (NG2) cells are considered to have progenitor potency, their ability to participate in regeneration following podocyte loss is not fully understood. We sought to determine if NG2 lineage cells serve as adult glomerular stem/progenitors in disease.

Methods

We generated NG2CreER tdTomato reporter mice (n=11). Tamoxifen was given to 8 week-old mice to permanently label cells of NG2 lineage with the red fluorescent protein (RFP) tdTomato. After a washout period, podocytes were depleted with a cytopathic anti-podocyte antibody. Serial biopsies were taken at baseline, D14, and D28, to assess and fate map the behavior of NG2 lineage cells in individual mice.

Results

Podocyte number decreased by ~35% on D14 from baseline, and partially recovered on D28 (p<0.05 vs D14). Following podocyte loss, the percentage of glomeruli with RFP⁺ cells increased two-fold on D14 and D28 (p<0.05 vs baseline). RFP⁺ cells in glomeruli did not co-express podocyte proteins (synaptopodin, nephrin, podocin). Glomeruli with RFP⁺ cells along Bowman’s capsule increased significantly accompanied by increased PEC density, (PAX8 staining), at D14 and D28. Co-staining for PAX8 and src-suppressed C-kinase substrate to determine if the RFP+ cells along Bowman’s capsule transdifferentiated to adult PECs showed that within individual mice, the percentage of glomeruli with RFP⁺/PAX8⁺, and RFP⁺/SSeCKS⁺ on Bowman’s capsule increased significantly from baseline at both D14 and D28 following podocyte loss. Double-staining for RFP and BrdU for cell proliferation revealed that RFP⁺ cells in glomerular tuft and capsule did not co-express BrdU.

Conclusion

We showed that after an abrupt loss of podocytes in an inducible reporter mouse, NG2 lineage cells migrated onto the glomerular tuft, but did not express podocyte proteins. However, a majority of NG2 labeled cells that migrated to Bowman’s capsule co-expressed the PEC markers PAX8 and SSeCKS, which was accompanied by a higher PEC density. These results suggest that a subset of cells of NG2 lineage might serve as adult PEC stem/progenitors in glomerular disease.