Figure 4. Parietal epithelial cell (PEC) density in aged kidneys is increased by SS-31.

(A) Pax8 and hematoxylin staining to identify PECs. Representative images for Pax8 immunohistochemistry used to identify PECs (darkest brown nuclear staining along Bowman’s capsule, red arrows show examples) in glomeruli from the outer cortex and juxta-medulla in 26m-old mice given either 8w of saline or SS-31. Hematoxylin identifies all nuclei.

(B) Average number of Pax8 stained cells along Bowman’s capsule per glomerulus. The average total number of PECs was not statistically different in outer cortical glomeruli between 24m-old baseline (triangles), 26m-old saline vehicle treated (open circles) and 26m-old SS-31 treated (closed circles) mice. PEC number in juxta-medullary glomeruli was higher in SS-31 treated animals compared to aged baseline mice, and to age matched saline treated mice.

(C) Average Bowman’s capsule length per glomerulus. In outer cortical glomeruli, the average capsule length was lower in 26m-old mice as compared to 24m-old aged baseline mice, regardless of treatment. Average capsule length did not differ in juxta-medullary glomeruli.

(D) PEC density. PEC density was measured as the average PEC number per 100μm of Bowman’s capsule length. PEC density in outer cortex and juxta-medulla glomeruli did not differ between 24m aged baseline and 26m saline treated mice. In contrast, in 26m-old mice given 8w of SS-31, PEC density was significantly higher compared to baseline and saline treated mice, in both glomerular compartments. These results show that when mice aged 24m are given 8w of SS-31, PEC density is increased.