Dynamic Endothelialization of Aortic Heart Valve Scaffolds.

摘要

Cardiovascular disease is the number one killer worldwide affecting both the heart and blood vessels. Valvular heart disease can arise from calcification, and structural deterioration resulting in a stenotic or regurgitant valve incapable of proper function. With approximately 275,000 valve replacements performed annually worldwide, the need for replacement heart valves is well established. Currently, treatment of valvular heart disease is limited to two options (mechanical and bioprosthetic). Both replacement valves have their own drawbacks, which have driven research in the bioengineering field to focus on the development of a tissue engineered heart valve (TEHV) capable of growth and self-repair.;A major hurdle in the creation of a viable TEHV lies in the need for a confluent surface layer of endothelial cells (EC) prior to implantation. ECs are needed in TEHVs because they provide a natural non-thrombogenic surface, and a permeability barrier between blood and the vessel wall. One major step in the TEHV paradigm lies in the development of a means for delivering cells to a heart valve scaffold with the purpose of achieving this confluent cell layer. As it stands now there is no recognized standard for EC seeding, though researchers have developed a number of different devices and protocols attempting to successfully achieve uniform cellular attachment.;The goal of this Master's thesis research was to design and create a dynamic cell-seeding device capable of seeding cells onto the surface of a decellularized porcine aortic heart valve scaffold. Once developed, the dynamic seeding device was to be used to create a protocol for optimizing cellular attachment and confluence on the heart valve surface. Additionally, following cell seeding, the next step in the TEHV paradigm is mechanical preconditioning prior to functional implantation. Utilizing a pulsatile heart valve bioreactor, seeded scaffolds were subjected to mechanical forces for the purpose of studying cellular retention and the effects of mechanical stimuli on cell morphology. Analysis of cellular attachment, retention, and viability was done through the use of Live/Dead Assay and Scanning Electron Microscopy (SEM). The results of both Live/Dead and SEM showed that the dynamic seeding device is capable of seeding porcine aortic endothelial cells onto the surface of aortic heart valve scaffolds and that the cells could be retained on the surface after undergoing physiologic bioreactor conditioning. The cells were found to respond to the conditioning, changing morphology and aligning in response to these mechanical forces.