PLATELET-DERIVED GROWTH-FACTOR A-CHAIN EXPRESSION IN DEVELOPING AND MATURE HUMAN KIDNEYS AND IN WILMS-TUMOR

Regulated expression of PDGF A-chain may be important in kidney develo pment. We employed two polyclonal antisera to detect expression of PDG F A-chain in fetal and normal adult kidneys by immunohistochemistry. S pecificity of the antisera was demonstrated by Western blots of fetal and adult kidneys, demonstrating monospecific bands at 10 to 15 kD, an d by absorption studies with PDGF-A peptide. PDGF A-chain is uniformly expressed by visceral glomerular epithelial cells and the epithelial cells of the distal nephron, including collecting ducts and contiguous urothelium lining the renal pelvis, in both fetal and adult kidneys. Fetal kidneys also demonstrate expression of PDGF A-chain at the earli est stages of Vesicle formation from the metanephric blastema; this ex pression is then only intermittently detectable in developing glomerul i until differentiation of visceral epithelial cells occurs. Fetal and mature arterial smooth muscle cells, and some neointimal smooth muscl e cells in sclerotic arteries in adult kidneys also express PDGF A-cha in. In situ hybridization with a riboprobe made from PDGF A-chain cDNA showed close correlation of mRNA expression with protein immunohistoc hemistry. PDGF A-chain expression was also identified in epithelial el ements of 5/6 Wilms' tumors studied. These are the first studies to lo calize PDGF A-chain expression in human kidney and suggest sites of ac tivity for PDGF A-chain in development, neoplasia, and in the renal ar terial sclerosis of aging.