M.Sc Thesis


M.Sc StudentAddie Dvir
SubjectTissue Engineering of Blood Vessels Based on Acellularized
Collagen Matrix
DepartmentDepartment of Biotechnology and Food Engineering
Supervisors Full Professors Machluf Marcelle
Professor Flugelman Moshe


Abstract

Background: Availability of autologous venous and arterial conduits for bypass surgery is limited. The present research is based on the hypothesis that carotid artery harvested from porcine can be processed to function as scaffold for vascular graft and can be seeded with human vascular cells.

Methods:  Porcine carotid arteries 3-4mm in diameter were used for all studies. To reduce immunogenecity, cellular content of the arteries was eliminated using 0.1% or 0.05% trypsin in combination with triton X-100 (1%) and Ammonium Hydroxide (1%) as detergents. Content of elastin and collagen was evaluated in the processed arteries (PA) using histochemical staining, morphometric analysis and biochemical quantification. The PA’s were assessed for their biomechanical properties, by testing stress relaxation characteristics and ultimate stress. Burst pressure of the PA was tested using an intra-luminal balloon. Finally the PA’s were seeded with primary human endothelial and smooth muscle cells.

Results: The H&E staining demonstrated complete elimination of cells from the vessel wall when combining trypsin and detergent processing. The biochemical analysis of the scaffolds, demonstrates that the elastin content is reduced by 52±2% with 0.05% Trypsin and by 69±2.3% with 0.1%Trypsin. Collagen content was reduced by 20% in all methods. The mechanical analysis, demonstrated correlating results, where the strength of the constructs was reduced by 20%. Mechanical strength was recovered after three months of culturing the PA with HSMC. Complete Endothelial lining of the PA was observed three weeks post seeding with wet-SEM and fluorescent microscopy. 

Conclusions: Based on our data, processed porcine arteries can be considered, after in vivo testing, as small caliber vascular grafts.