EXPRESSION OF VASCULAR ENDOTHELIAL GROWTH-FACTOR AND ITS RECEPTORS INHUMAN RENAL ONTOGENY AND IN ADULT KIDNEY

Vascular endothelial growth factor (VEGF) may modulate vascular permea bility, chemotaxis for monocytes, and protease activity. In addition, VEGF may play a role in embryonic and tumor angiogenesis. In fetal mou se kidney, VEGF mRNA and protein expression have been demonstrated. Th is finding led to the hypothesis that VEGF might be involved in renal growth and development. To further elucidate the role of VEGF in human kidney, expression of VEGF and its receptors, the specific tyrosine k inase receptors, fit-1 and KDR, were studied. In fetal (6-24 gestation al wk; mesonephros and metanephros) and adult kidney, VEGF mRNA and pr otein could be colocalized in glomerular epithelia and collecting duct cells by in situ hybridization and immunohistology. By reverse transc ription-polymerase chain reaction, mRNA of three VEGF isoforms, VEGF(1 21), VEGF(165), and VEGF(189), were found in fetal kidney and cortex, isolated glomeruli, and medulla of adult human kidney. KDR and fit-1 m RNA were coexpressed in endothelia of glomeruli and in peritubular cap illaries in fetal and adult kidney. These data support the assumption that VEGF and its receptors may influence renal ontogenesis. We specul ate that the constitutive expression of VEGF in adult kidney may be re quired for the function of VEGF receptor positive-fenestrated endothel ia in glomeruli and postglomerular vessels. The expression of VEGF in collecting duct and of its receptors in medullary capillaries may in a ddition be relevant for maintaining medullary osmolality.