Abstract 061: Cell Fate Changes During Tubular Damage and Regeneration in the Mouse Kidney

Abstract

Tubular degeneration, loss of renal tubules and interstitial fibrosis due to kidney injury lead to chronic renal disease and hypertension. Using a partial unilateral ureteral obstruction (pUUO) model in neonatal mice, we analyzed the fate cell changes that occur during obstruction and during recovery following the release of UUO. We traced the fate of cells derived from the renal stroma, cap mesenchyme and ureteric bud epithelium using Foxd1-Cre, Six2-Cre and HoxB7-Cre mice respectively, crossed with double fluorescent reporter (mT/mG) mice. pUUO was performed 24-36h after birth (n=84). In a group of pups (n=37), the obstruction was released after seven days. Sham operated animals (n=35) were used as controls. Lineage tracing revealed that Foxd1-derived interstitial pericytes acquired α-smooth muscle actin expression and underwent significant expansion due to pUUO (fibrotic area 91.06+/-6.77 %). Release of obstruction resulted in complete resolution of fibrotic areas (0.00%; p<0.005). Further, loss of Six2-derived cells at the glomerular-tubular junction in pUUO kidneys resulted in the formation of atubular glomeruli (39%). Atubular glomeruli were not observed after release. In addition, a significant loss of HoxB7-derived collecting duct tubules was observed during pUUO. Most collecting ducts recovered following release. Our study indicates that obstruction leads to significant tubular damage, expansion of interstitial pericytes, fibrosis, tubular loss and formation of atubular glomeruli. The striking recovery observed after release of ureteral obstruction suggests a reversal of cell fate changes and tubular regeneration. Elucidation of the cellular and molecular mechanisms mediating these events may be of use in the design of strategies for the prevention and/or treatment of kidney diseases and secondary hypertension.