Inhibition of adhesion molecule expression on human venous endothelial cells by non-viral siRNA transfection

OBJECTIVE: Expression of adhesion molecule receptors on venous endothelial cells crucially influences the fate of venous grafts by mediating leukocyte-endothelium interactions. These interactions include adhesion of leuko-cytes to the endothelium, followed by transendothelial migration, leading to neointimal hyperplasia (NIH) and finally graft occlusion. Therefore, inhibition of adhesion molecule expression may be a promising strategy to improve the quality of venous grafts.We tested the efficiency of non-viral transfection of human venous endothe-lial cells (HVEC) with short interfering RNA (siRNA) to specifically down-regulate adhesion molecule expression. METHODS: Primary cultures of HVEC were examined for expression of the adhesion molecules ICAM1, VCAM1 and E-selectin (SELE) after non viral siRNA transfection. Adhesion molecule expression was measured by flow cytom-etry, real-time polymerase chain reaction and immunoblotting after stimulation with TNF-α, an inflammatory cytokine. RESULTS: Non-transfected cells showed a strong increase of adhesion molecule expression following cytokine stimulation (P < 0.01). Upon transfection with specific siRNAs a sixfold decrease in ICAM1 (P < 0.001) and SELE expression and cell positivity (P < 0.05) and a twofold decrease in VCAM1 expression and cell positiv-ity (P < 0.01) Pcould be observed. SiRNA-mediated gene suppression of adhesion molecules was also reflected by corresponding decreases in adhesion protein and transcript levels. CONCLUSIONS: The expression of adhesion molecules on HVECs can be effectively inhibited by specific siRNAs using a safe, non-viral transfection approach. This is a promising tool to pre-condition venous bypass grafts in order to interfere with endothelium-leukocyte interactions and to prohibit neointima thickening or ath-erosclerosis, which are regarded to be the most important causes of venous graft failure.