Particularities of blood vessels correlate with VEGF expression in human renal medulla

Abstract

In the normal kidney, VEGF is constitutively expressed in podocytes and tubular epithelial cells of the renal cortex and medulla. This study determined the particularities of renal vascularization and VEGF expression in renal medulla using immunohistochemical methods on normal kidneys samples taken from 28 patients. Sections were stained with routine haematoxylin‐eosin method and immunohistochemically for VEGF, CD34, CD31 and SMA. All cases presented an intense immunoreaction for VEGF in the cells lining the nephron tubular system, the higher immunoreaction intensity in the collecting and distal tubules, but weak or moderate in the proximal tubules. The Henle loop cells showed a negative immunoreaction. The VEGF immunostaining was significantly higher in outer than inner medulla. In outer portion of outer medulla we identified using vascular markers, two types of vascular plexus: peritubular plexus around contort and collector tubules of outer zone of outer medulla and segmentary capillary plexal nodes near vasa recta. The strong positive immunoreaction for VEGF in the collecting ducts and distal tubules epithelial cells suggest a relationship between VEGF expression and adjacent straight vessels (vasa recta), with important roles in gradient concentration, being known that VEGF was initially named vascular permeability factor.