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ENDOTHELIAL CELL GROWTH, SHEAR STABILITY, AND FUNCTION ON BIOMIMETIC PEPTIDE FLUOROSURFACTANT POLYMERS

Larsen, Coby Christian
http://rave.ohiolink.edu/etdc/view?acc_num=case1183690553

Abstract Details

2007, Doctor of Philosophy, Case Western Reserve University, Biomedical Engineering.
Cardiovascular disease, including coronary heart and peripheral arterial disease, is the leading cause of mortality in the United States. There is a pressing clinical need for suitable synthetic, small-diameter vascular prostheses for use in coronary and peripheral artery bypass grafting. Endothelial cells (ECs) are a vital component of native vasculature; their presence and antithrombotic function on the lumenal surface of vascular graft material would reduce or eliminate thrombosis and failure. In vivo, ECs adhere to extracellular matrix (ECM) proteins predominantly through integrin cell surface receptors. This adherence mechanism can be recapitulated by biomimetic constructs that present short, ECM-derived peptide sequences. The challenge for this approach when employed to facilitate adhesion of ECs to vascular graft material in a blood-contacting environment is that many of these same peptide sequences that bind ECs also bind platelets and lead to initiation of thrombosis. To overcome the thrombogenicity associated with platelet adhesion, we have investigated the use of two EC integrin-selective peptides to promote EC adhesion to ePTFE vascular graft material. We hypothesized that a fluorosurfactant polymer (FSP) presenting EC integrin-selective peptides would promote EC adhesion, growth, shear stability, and hemostatic function on ePTFE vascular graft material. For our studies, we used two cyclic peptides, cRGDfE and CRRETAWAC, that have high affinity and specificity for two of the primary EC integrins- αvβ3 and α5β1, respectively. As a first step to explore our hypothesis, we tested the affinity and specificity of cRGDf, CRRETAWAC, and an ECM-derived linear RGD sequence for prominent endothelial cell (αvβ3 and α5β1 integrins) and platelet (αIIbβ3 integrin) receptors. cRGDfE was found to have high affinity for the αvβ3 integrin; EC attachment to immobilized cRGDfE was predominantly αvβ3 integrin-mediated. Immobilized cyclic CRRETAWAC peptide promoted highly specific EC attachment through the α5β1 integrin. Linear RGD demonstrated moderate affinity for the αvβ3 integrin and a lower affinity for the α5β1 integrin. Solid-phase integrin binding experiments and platelet aggregometry demonstrated peptide affinity for platelet αIIbβ3 integrin in the following order: cRGDfE > RGD >> CRRETAWAC. As the next step in validating our hypothesis, we examined EC behavior, including adhesion, growth, shear stability, and hemostatic function, on RGD, cRGDfE, CRRETAWAC, and cRGDfE/CRRETAWAC combination FSPs. All peptide FSPs supported high efficiency EC attachment and proliferation; likewise, all peptide FSPs supported excellent EC retention under flow with no significant cell loss after 4 h of shear stress exposure. ECs adherent to CRRETAWAC and RGD FSP provided anti-thrombotic and fibrinolytic function. Uptake of acetylated low-density lipoprotein confirmed the EC phenotype of adherent cells on all peptide FSPs. Lastly, a modification, seeding, and perfusion chamber was designed and fabricated to permit in vitro adhesion, growth, and shear stability investigation of surface-modified ePTFE tubular conduits. A flow system employing these chambers was engineered and characterized. Pilot experiments indicate chamber feasibility for future modification, seeding, and in vitro assessment of peptide FSP modified ePTFE conduits. The CRRETAWAC FSP provides the most promise for promoting EC adhesion, growth, shear stability, and function on ePTFE vascular graft material while minimizing specific platelet adhesion. This EC-selective biomimetic construct has the potential to promote in vivo endothelialization without platelet adhesion and thrombosis. This research lays the groundwork for a successful clinical solution to the pressing need for a suitable small-diameter artificial vascular graft.
Roger Marchant (Advisor)
260 p.
Engineering, Biomedical
endothelial cell; fluorosurfactant polymer; ePTFE; small-diameter vascular graft; surface modification

Recommended Citations

Citations

  • Larsen, C. C. (2007). ENDOTHELIAL CELL GROWTH, SHEAR STABILITY, AND FUNCTION ON BIOMIMETIC PEPTIDE FLUOROSURFACTANT POLYMERS [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1183690553

    APA Style (7th edition)

  • Larsen, Coby. ENDOTHELIAL CELL GROWTH, SHEAR STABILITY, AND FUNCTION ON BIOMIMETIC PEPTIDE FLUOROSURFACTANT POLYMERS. 2007. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1183690553.

    MLA Style (8th edition)

  • Larsen, Coby. "ENDOTHELIAL CELL GROWTH, SHEAR STABILITY, AND FUNCTION ON BIOMIMETIC PEPTIDE FLUOROSURFACTANT POLYMERS." Doctoral dissertation, Case Western Reserve University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=case1183690553

    Chicago Manual of Style (17th edition)

case1183690553
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© 2007, all rights reserved.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.