The proposed research will study a novel approach for treating heart valve disease via the use of heart valve replacements with trileaflet polyurethane prostheses that are endothelial seeded using blood outgrowth endothelial cells (BOEC). We will investigate the AbioCor polyurethane valve (ABV), manufactured by Abiomed (Danvers, MA). The ABV has been used in more than 7,000 human subjects. BOEC seeded ABV are hypothesized to be efficacious for resisting the principal causes of polyurethane heart valve failure, which include thrombosis, calcification and oxidative degradation of leaflet surfaces.
Aim 1. Synthesize and characterize a novel two component photoactivated complex for surface modifying polyurethane heart valve leaflets with cholesterol to hypothetically increase BOEC adhesion under high flow and high shear. Our synthetic methods will use a two step approach using: 1) A photo- activatable polyallylamine-benzophone compound, referred to as PBPC, to activate the surface of polyurethane heart valve leaflets for the subsequent attachment to the photo-linked PBPC of, 2) a cholesterol-derivatized polyallylamine, biochemically modified with thiol-reactive groups and ionogenic groups--this 2nd component of the complex is referred to as CPB. The goal of these studies will be to create a candidate set of PBPC-CPB formulations for investigation in Aims 2&3.
Aim 2. In vitro investigations of polyurethane surfaces modified with PBPC-CPB to promote BOEC adhesion. These studies will assess adhesion mechanisms, BOEC phenotype stability, endothelial function and activation with various candidate CPB. We will then study ABV modified with lead CPB compounds and BOEC seeded with mitral valve flow simulations. Taken together, these studies will be used to both understand adhesion mechanisms and guide formulation changes in candidate PBPC-CPBs that will result in optimal in vivo cell adhesion in Aim 3 described below.
Aim 3. In vivo studies (using sheep) of BOEC seeding that will investigate optimal PBPC-CPB formulations. Two in vivo model systems will be studied: 1) An aortic button model implant that will assess BOEC adhesion, phenotype stability and thrombo-resistance in 2 week studies. Explants will also be studied for extent of cell coverage, endothelial phenotype stability, the presence of nonendothelial cell types, endothelial activation, and platelet and fibrin thrombus depositon. 2) Mitral valve replacements in sheep with ABV surface modified with PBPC-CPB and BOEC seeded and nonmodified controls will be carried out for 150 days with the goal of assessing both BOEC adhesion and phenotype stability, and therapeutic efficacy for preventing thrombus, calcification and oxidative degradation.
Project Narrative Heart valve disease affects millions and is only treatable by cardiac surgery. In addition current artificial heart valves fail frequently due to thrombosis and primary material failure. This proposal will investigate a novel approach for a heart valve replacement by studying a trileaflet polyurethane valve that is seeded with autologous blood outgrowth endothelial cells.
