Approximately five million Americans suffer from heart failure. Although cardiac transplantation is the best treatment for patients with end-stage heart failure, there are not enough donor organs available. Mechanical assist devices improve the quality of life and prolong survival in patients with end-stage heart failure who cannot receive a heart transplant. However, the interaction between blood and the artificial device surface is thought to cause a coagulopathy, often resulting in bleeding and thromboembolic complications.AIMS: The specific aims of the study are to test the hypotheses that 1. Endothelial progenitor cells (EPCs) will adhere to the structured titanium surface of mechanical assist devices, 2. EPCs will be retained under physiologic sheer stresses, and 3. EPCs will convey a more biocompatible surface to titanium. METHODS: EPCs will be isolated from bone marrow of swine and cultured. Using an adeno-associated virus vector, EPCs will be transduced with green-fluorescent protein and seeded onto sintered titanium of HeartMate II cannula adapters. Cell adherence and viability will be assessed under various seeding conditions with scanning electron microscopy, confocal electron microscopy and a redox assay. Further, optimally seeded tubes will be subjected to various sheer stresses in a flow circuit by perfusing seeded cylinders with media and whole blood. The biocompatibility of EPC-coated titanium will be evaluated by five different methods: 1. AlamarBlue redox assay, 2. Nitric oxide synthesis quantification after exposure to shear stresses, 3. Staining intensity of endothelial nitric oxide synthase under different shears stresses, 4. Thrombomodulin expression and upregulation under shear stress by quantification of activated protein C formation, and 5. Quantification of platelet-adhesion to the cell-seeded titanium after exposure of the surface to whole blood using scanning electron microscopy with NIH image capture software. OBJECTIVES: Our objectives are to test the three hypotheses described under AIMS. It is our long-term goal to engineer a more biocompatible inner lining by seeding patients' own EPCs onto the titanium surface of mechanical assist devices.
|Program type||Postdoctoral Fellowship|
|Effective start/end date||07/01/2008 → 06/30/2010|