Effects of genotypically different strains of Helicobacter pylori on humanmicrovascular endothelial cells in vitro

Helicobacter pylori induces a number of disturbances in rodent gastric micr ocirculation in vivo. These events may result from direct necrotic or apopt otic damage to endothelial cells. This study therefore aimed to investigate the effects of genotypically different H, pylori strains on microvascular endothelial cell (MVEC) viability in vitro, Four H. pylori extracts were pr epared from strains with different cagA or vacA status. MVECs were plated i nto 96-well plates and coincubated with 50 mul of extract or vehicle for 24 , 48, 72, or 96 hr. An MTT assay quantified overall MVEC viability. The dua l labeling of MVECs with propidium iodide and Hoechst 33342 distinguished b etween necrotic and apoptotic cell death, respectively, and allowed total n umber of viable cells to be determined. All strains of H, pylori decreased cell viability after 72 and 96 hr. Neither necrosis or apoptosis was observ ed. Counting total number of viable cells revealed decreased cell prolifera tion with all strains when compared to controls, again reaching significanc e at 72 and 96 hr. In conclusion, both the MTT assay and the direct cell co unting technique demonstrated that all H. pylori strains induced cytostatic but not cytotoxic effects on MVECs. This suggests that microcirculatory di sturbances observed in vivo may not be the result of direct endothelial cel l damage. However, inhibition of angiogenesis may explain why ulcer healing is delayed in H. pylori-infected patients.