Effects of fibulin-5 on attachment, adhesion, and proliferation of primary human endothelial cells

Background: Fibulin-5 is a novel extracellular protein that is thought to act as a bridging peptide between elastin fibers and cell surface integrins in blood vessel wall. Fibulin-5 binding to endothelial cell (EC) surface integrins may effect cell proliferation and cell attachment to extracellular matrix (ECM) or to artificial surfaces. In this paper, we describe the effects of fibulin-5 on attachment, adhesion, and proliferation of primary human EC. After demonstrating that fibulin-5 over-expression inhibited EC proliferation, we tested the hypothesis that co-expression of fibulin-5 and VEGF₁₆₅ will lead to unique EC phenotype that will exhibit increased adherence properties and retain its proliferation capacity. Methods and results: Fibulin-5 and VEGF₁₆₅ gene transfer to primary human saphenous vein endothelial cells was accomplished using retroviral vectors encoding the two genes. Transgene expression was verified using immunohistochemistry, Western blotting, and ELISA. Fibulin 5 over-expression tended to improve immediate EC attachment (30 min after seeding) and improved significantly adhesion (>40%) under shear stress tested 24 h after EC seeding. The effects of fibulin-5 and VEGF₁₆₅ on EC proliferation in the presence or absence of basic FGF were also tested. EC expressing fibulin-5 had reduced proliferation while VEGF₁₆₅ co-expression ameliorated this effect. Conclusion: Fibulin-5 improved EC attachment to artificial surfaces. Dual transfer of fibulin-5 and VEGF₁₆₅ resulted in EC phenotype with increased adhesion and improved proliferation. This unique EC phenotype can be useful for tissue engineering on endovascular prostheses.