Abstract 1672: Fibronectin Influences the Impact of Anti-Restenotic Drugs on Human Coronary Artery Endothelial Cell Function
Re-endothelialization of the vessel wall after coronary artery stent placement is critical for reducing the occurrence of thrombosis and restenosis. Proliferation and migration of endothelial cells (ECs) into the stented region of the vessel requires interactions with the extracellular matrix (ECM). This process may be modified by the presence of anti-restenotic drugs from drug eluting stents (DES). Therefore, when examining the effect of these drugs on EC function, it is important to consider interactions between ECs with ECM. In this study, we compare the effects of two DES therapeutics, sirolimus (SRL) and paclitaxel (PTX), on adhesion, proliferation, migration and gene expression patterns of human coronary artery endothelial cells (HCAECs) in the presence of fibronectin. Fibronectin increases the IC50 for PTX on VEGF165 -induced migration of HCAECs in transwells. On uncoated transwells, the IC50 for PTX on VEGF165 (3ng/ml)-induced EC migration is 78 pM, compared to 4.3 nM in the presence of fibronectin. Fibronectin also reduces the maximal inhibition of PTX on cell proliferation by greater than 50%. The IC50 for SRL on VEGF165-induced EC migration in uncoated transwells is1.0 μM, compared to 8.6 μM in the presence of fibronectin. In contrast, fibronectin does not impact the inhibitory effect of SRL on HCAEC proliferation. We also evaluated the functional state of HCAECs using gene expression analysis. SRL significantly reduces the expression of endothelial cell nitric oxide synthase (eNOS), while PTX has no effect on eNOS expression. Furthermore, growth of HCAECs on fibronectin-coated wells results in a 2–3 fold increase in eNOS expression, compared to cells grown on uncoated wells. This level of induction remains present in PTX treated HCAEC, but is inhibited by SRL treatment. In contrast, PTX but not SRL is observed to induce the expression of RANTES, while IL-8 is observed to be induced in HCAECs by both drugs. Fibronectin does not have an effect on either of these inflammation markers. In conclusion, our results suggest that the effect of PTX on HCAEC proliferation may be ameliorated in the vessel due to the presence of fibronectin, whereas fibronectin has no impact on the inhibitory effect of SRL on HCAEC proliferation.