Deselülerize Miyokard-Elastomer Yamaların Hazırlanması ve In Vitro Performanslarının İncelenmesi

Abstract

Heart failure is the final stage of most cardiovascular diseases, such as myocardial infarction. Unlike other tissues such as bone and skin, heart tissue does not have the ability to regenerate and repair itself. This causes irreversible cell death in the heart muscles of infarcted patients. In recent years, cardiac tissue engineering offers a promising therapeutic treatment for regeneration of myocardial tissue patches. Within the scope of myocardial tissue engineering, stem cells, cell sheet technologies, decellularized and synthetic cardiac patches are widely investigated. The synthesis of scaffolds within high mechanical strength and have no immune effects is critical for this treatment method to provide recellularization and regeneration of cardiac tissue patches. Within the scope of this thesis studies, hybrid and composite cardiac patches were prepared and characterized for cardiac muscle regeneration and static and dynamic cell culture performances with human cardiomyocytes were examined. In the first stage of the study, myocardial sections dissected from bovine heart tissues were decellularized in two different methods by chemically and supercritical CO2 fluid system. Decellularization process was characterized via histological stainings, biochemical analysis, structural analysis, chemical analysis, thermal analysis and macro and nano mechanical analysis. Myocardial tissue scaffolds obtained by chemical decellularization were compared with the tissue scaffolds obtained by the supercritical CO2 fluid method, and the advantage of the supercritical CO2 fluid method in the decellularization effect was demonstrated. In the second stage of the thesis, decellularized tissue scaffolds were reinforced with poly(glycerol-sebacate) (PGS) polymer to obtain cardiac patches in hybrid form. The hybrid cardiac patches were analyzed chemically, thermally, morphologically, microscopically and mechanically. It has been proven that the PGS polymer can be crosslinked within decellularized tissues by chemically, thermally and microscopically. In addition, the weakened mechanical properties of native myocardial tissue after decellularization and lyophilization were improved by hybrid forms. In the next step, cardiac patches in composite form were synthesized by doping with poly(glycerol-sebacate) (PGS) polymer and carbon nanotube geometries in to decellularized scaffolds. Composite cardiac patches were characterized by chemically and mechanically and microscope and tomography images were taken, and conductivity measurements were performed. It has been demonstrated by chemically and microscopically that PGS polymer can be crosslinked within decellularized tissues with the addition of carbon nanotubes. Through tomography analysis, it has been shown that carbon nanotubes are homogeneously dispersed within the structure. In addition to improved mechanical properties, composite cardiac patches have been reported to be conductive compared to hybrid cardiac patches. Finally, all cardiac patches were recellularized with human cardiomyocyte cells; static and dynamic in vitro cultures studies were performed. Cytotoxicity analyzes of the obtained cardiac patches were performed, and after seeding of cardiomyocyte cells on cardiac patches, cell metabolic activities, cell viability, cell behavior, GAG secretions and gene expressions were examined. The results of static culture conditions were compared with the dynamic culture which scaffolds exposed to mechanical stimulation. The positive effects of dynamic culture conditions on cell behavior compared to static conditions have been reported.