Localization of PDGF alpha-receptor in the developing and mature human kidney.

Using in situ hybridization and immunocytochemistry we describe the renal localization of the PDGF alpha-receptor. PDGF alpha-receptor mRNA was uniformly present in human metanephric kidney in interstitial cells and vascular arcades that course through the blastema. PDGF alpha-receptor mRNA was present in some mesangial structures in early glomeruli, but was largely lost as glomeruli matured. It was present in adventitial fibroblasts, but usually not in vascular smooth muscle cells or endothelial cells of the fetal vasculature. This pattern persisted in adult kidneys, with extensive expression of mRNA by interstitial cells and only occasional expression by mesangial cells. All in situ hybridization findings were corroborated by immunocytochemistry. Double immunolabeling confirmed the rare expression of the PDGF alpha-receptor protein by vascular smooth muscle cells and the absence of its expression by endothelial cells. Given that both PDGF A- and B-chain can promote smooth muscle cell and fibroblast migration and proliferation and that both signal through the PDGF alpha-receptor, these data suggest that PDGF alpha-receptor may play important roles in the early vasculogenesis of the fetal kidney as well as in the pathogenesis of renal interstitial fibrosis.