Print this pageThe Role Of OB-Cadherin In Vascular Smooth Muscle Cell Migration and Proliferation
Thomas S Monahan, Haig Panossian, Nicholas D Andersen, Jeffrey A Kalish, Mauricio A Contreras, Matthew D Phaneuf, Christiane J Ferran, Frank W LoGerfo
Beth Israel Deaconess Medical Center, Boston, MA
Introduction and Objectives:
Intimal Hyperplasia (IH), the pathologic migration and proliferation of vascular smooth muscle cells (VSMC), is a common cause of vein graft failure in cardiovascular surgery. Previous studies suggest that specific genetic signaling events initiate the pathogenesis of intimal hyperplasia. We have previously discovered that the cell surface adhesion molecule, OB-cadherin, is up-regulated in vein grafts after implantation. The aim of the present study is to characterize the role of OB-cadherin in VSMC migration and proliferation.
Methods:
Cephalic vein interposititon grafts were implanted in a canine model. These grafts were excised at predetermined time points. The expression of OB-cadherin was determined by immunohistochemistry. Cellular proliferation was determined by the Alamar Blue assay in the presence of 30% FBS. Migration was determined by serum induced migration of calcein-labeled VSMCs across a fluorescently opaque 8µm pore-size membrane. OB-cadherin mRNA levels were determined by quantitative RT-PCR. OB-cadherin was inhibited with either an antagonist, or by mRNA knock-down with siRNA.
Results:
Explanted vein grafts stained strongly for OB-cadherin in the intima, media and adventitia compared to control veins. Exposure of VSMCs grown in tissue culture to 10 ng/ml TNF-αλπηα increased OB-cadherin mRNA in a time dependent manner. The increase in mRNA expression reached statistical signifigance at 8 hours. Incubation with 10 µg/ml OB-cadherin antagonist decreased cellular migration by 32%. Treatment with the same concentration of antagonist decreased cellular proliferation by 2.1 fold (p<0.05) after 6 days. 24-hour transfection with 50 nM siRNA decreased VSMC OB-cadherin mRNA by 71%. OB-cadherin knock-down resulted in a 4.1 fold decrease in 11-day cellular proliferation (p<0.05). No change in proliferation was observed until five days after transfection.
Conclusions:
OB-cadherin is upreguated in VSMC after vein bypass grafting. This upregulation is due in part to stimulation with TNF-αλπηα. Inhibition of OB-cadherin attenuates both VSMC migration and proliferation.