Abstract: TH-PO077

Morphometric Quantitation of Parietal Epithelial Cells in Human Kidneys

Session Information

Category: Glomerular

  • 1002 Glomerular: Basic/Experimental Pathology

Authors

  • O'Connor, Christopher Lund, University of Michigan, Ann Arbor, Michigan, United States
  • Elshayeb, Mohamed A., University of Michigan, Ann Arbor, Michigan, United States
  • Hodgin, Jeffrey B., University of Michigan, Ann Arbor, Michigan, United States
  • Wiggins, Roger C., University of Michigan Health System, Ann Arbor, Michigan, United States
  • Bitzer, Markus, University of Michigan, Ann Arbor, Michigan, United States
Background

Parietal epithelial cells (PECs) play a key role in glomerulosclerosis. We therefore developed a method for quantitation of PECs usable in routine FFPE archival histologic sections. Initial data are reported.

Methods

PECs were identified by anatomic position, lining the inner aspect of Bowman’s Capsule (BC), and positive immune-peroxidase nuclear staining for PAX8. The morphometric method used principles previously reported for podocyte quantitation in which observed PEC nuclear number per glomerular tuft profile is corrected according to nuclear size, shape and section thickness (Venkatareddy et al. JASN 2014). 600 glomerular profiles were assessed in 12 normal human kidneys obtained at nephrectomy (mean age: 64.9, range: 46-82y). Glomerular and tubule-interstitial parameters were assessed through quantitative computer-assisted image analysis on 50 glomeruli per case. Qualitative glomerular characteristics were assessed in all glomeruli (mean 198 glomeruli per sample, range 71-392). Quantitative morphometric parameters were evaluated in 50 randomly selected glomeruli per sample.

Results

PECs identified as cells lining the inner aspect of BC were >99% PAX8 positive. In contrast <5% of glomerular tufts contained PAX8-positive nuclei. In the normal human kidney sample tested the BC surface area was 159 (range 110-216) x103µm2). The number of PECs per glomerular tuft (total BC surface area) was 407 (range 70-722). The estimated average PECs per area of BC was 25.3 (range 5.2-43.6) PECS/106µm2. Average PEC cell area was 578µm2 (range 247-2103 µm2) . PEC density correlated with podocyte nuclear density (p=0.02; r=0.64), mean podocyte volume (p=0.001; r=-0.82), podocytes per glomerulus (p=0.01; r=0.69), % of normal glomeruli (p=0.01, r=0.70), fractional interstitial area (p=0.002; r=-0.78), number of globally (p=0.03; r=-0.55) and segmentally sclerotic glomeruli (p=0.004; r=-0.76), and eGFR (p=0.05; r=0.75).

Conclusion

We report a method for quantitatively evaluating PECs. PEC number per glomerulus, density and estimated cell size varies substantially between individual samples. Furthermore, these PEC parameters significantly correlate with both podocyte parameters and clinical phenotype in the small sample evaluated. Additional samples from our human kidney biobank (n>150) will be used to confirm and extend these data.