Enhanced endothelialization for tissue engineering

University Of Texas Arlington, Arlington TX

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Abstract

[unreadable] DESCRIPTION (provided by applicant): Biodegradable polymers including poly(l-lactic acid) (PLLA) have been used to develop cardiovascular prostheses such as vascular grafts and stents. However, implant-associated thrombosis, inflammation, and restenosis are still a major obstacle for the patency of these prostheses. Our long-term goal is to reduce these complications by rapid endothelialization. Our hypothesis is that rapid endothelialization on the prosthetic surfaces is possible by incorporation of the prosthetic materials with endothelial cell (EC) adhesion (fibronectin) and growth factors (vascular endothelial growth factor, VEGF) and by seeding of genetically modified ECs with growth factor receptors (VEGF receptors, KDR/flk-1) on the prosthetic surfaces. Specifically, aim #1 is to incorporate fibronectin and VEGF onto PLLA surfaces using different immobilized techniques: coating, cross-linking, and electrostatic self-assembly (ESA). Cell adhesion and proliferation on these surfaces will be investigated using PicoGreen DNA assays, whereas cell retention under physiological flow conditions will be studied using an in vitro parallel flow system. To assess whether seeded cells maintain functional characteristics of ECs, we will determine: (1) the cellular uptake of acetylated LDL (ac-LDL), (2) histamine-mediated release of von Willerbrand factor (vWF), and (3) the expression of vWF (endothelial marker) and endothelium constitutive NO synthase (ecNOS) using immunocytochemistry. Aim #2 is to develop genetically modified ECs with VEGF receptors (KDR/flk-1 plasmids) using Lipofectamine(tm) transfection reagent. Expression of transduced genes will be confirmed using Western blotting. Aim #3 is to seed genetically modified ECs on the optimal surface developed in Aim #1 and evaluate their performance. EC adhesion, retention, proliferation, and functionality will be assessed as described in Aim #1. The proposed biodegradable PLLA materials will have several benefits as these materials will stimulate the vessel healing by creating a vessel wall-protecting neoendothelium and thus can be used in the future as a way to modify surfaces for vascular tissue engineering. We believe that surface modification with the combination of adhesion and growth factors and gene transfer of growth factor receptors used in our strategies will improve endothelialization, and thereby reduce the body's adverse reactions toward the prostheses. [unreadable] [unreadable]