LOCALIZATION OF PDGF ALPHA-RECEPTOR IN THE DEVELOPING AND MATURE HUMAN KIDNEY

Using in situ hybridization and immunocytochemistry we describe the re nal localization of the PDGF alpha-receptor. PDGF alpha-receptor mRNA was uniformly present in human metanephric kidney in interstitial cell s and vascular arcades that course through the blastema. PDGF alpha-re ceptor mRNA was present in some mesangial structures in early glomerul i, but was largely lost as glomeruli matured. It was present in advent itial 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 hybrid ization findings were corroborated by immunocytochemistry. Double immu nolabeling confirmed the rare expression of the PDGF beta-receptor pro tein 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 tha t both signal through the PDGF alpha-receptor, these data suggest that PDGF alpha-receptor may play important roles in the early vasculogene sis of the fetal kidney as well as in the pathogenesis of renal inters titial fibrosis.