Antioxidant-inhibitable angiotensin II effects on human vascular endothelial cell migration

As is known, vascular smooth muscle cell migration is stimulated by angiotensin II. To evaluate the possible peptide effect on human vascular endothelial cell (HUVEC) migration, HUVECs were obtained from umbilical cord veins and cultured in Dulbecco's HAT medium. After 4-5 passages HUVECs were seeded at high density in Boyden chambers modified by the insertion of a polyethyleneterephthalate membrane (porosity = 8 μm). HUVEC migration was then quantified as the mean number of migrated cells observed in five high-power fields. In further experiments, “endothelial wound repair” was also assessed, i.e. “wounds” were inflicted by dragging a sterile pipette tip across cell monolayers and the number of cells migrating into the “wounded area” after various time up to 12 hours was quantified by light microscopy. Results: the addition of angiotensin II at various concentrations reduced HUVEC migration by at least 50%. Such effect was abolished by the AT1 receptor inhibitor losartan and the antioxidant N-acetyl-L-cysteine (NAC). In contrast, AT2 receptor inhibition was completely ineffective. Angiotensin II also reduced the so-called “wound repair”, i.e. markedly reduced HUVEC ability to migrate into wound areas and delayed wound closure. Also in this case, the angiotensin II effect was blocked by losartan and NAC but not AT2 receptor inhibition. In conclusion, angiotensin II strongly reduces HUVEC migration in vitro. This effect of angiotensin II is inhibited by losartan and NAC, suggesting oxidative mechanisms are activated by the peptide in the vascular endothelium and might markedly affect endothelial response to injuries.