M.Sc Thesis


M.Sc StudentGabriel Zarbiv
SubjectTissue Engineering of Blood Vessels: Improvement of Cell
Adhesion and Characterization of Polymer
Immunogenicity
DepartmentDepartment of Biotechnology and Food Engineering
Supervisor Full Professors Machluf Marcelle


Abstract

Background: Patients in need of coronary artery bypass surgery often lack the suitable autologous tissue to serve as vascular conduits for bypass of occluded vessels. The present research is based on the hypothesis that acellularized porcine carotid arteries can function as scaffolds for vascular grafts and can be seeded with vascular cells.

Methods: The cellular content of carotid arteries, 4-5 mm in diameter, was removed using 0.05% trypsin, followed by 1% Triton X-100 and 1% ammonium hydroxide. The acellularization process was evaluated using histologic and immunohistologic staining, DNA extraction and scanning electron microscopy. Optimization of smooth muscle cells (SMC) seeding and growth on the scaffold was examined using static and dynamic techniques. Optimization of endothelial cells adhesion and growth was examined by the use of several coatings for the luminal side of the scaffold. A bioreactor for co-culture of both cells was also designed. Finally, the in vivo response for the acellularized scaffold was examined by implanting the polymer subcutaneously in mice and characterizing the immune response up to eight weeks post implantation.

Results: All the analyses revealed that no cellular residues remained in the vessel wall after the acellularization process. Centrifugal seeding and dynamic growth were the optimal combination for SMC, while optimal adhesion and growth of endothelial cells were accomplished using a matrix secreted by corneal cells as a substrate for the cells. The use of the bioreactor supported the uniform seeding of both cells but was insufficient for a proper long-term culture. From the in vivo studies it was clear that the immune response to the polymer was mild in the first two weeks post implantation, while 8 weeks post implantation a fibrous capsule, which may be correlated to the site of implantation, was observed surrounding the polymer.

Conclusion: Acellularized porcine arteries can be used as compatible scaffolds for engineering of small caliber vascular grafts.