The effect of biochemical stimulation on mechanical properties of collagen-based tissue engineered blood vessels
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The successful creation of a living blood vessel substitute for bypass surgery can overcome current problems associated with grafting the patient’s own vascular tissue. A fully biological vessel comprised of smooth muscle cells (SMC's) in collagen is an attractive alternative due to its potential for long-term remodeling and vasoactivity, but these vessels are limited by inherent physical weaknesses. This study determines how the mechanical properties of tissue engineered blood vessels made with the collagen/SMC method can be improved by biochemical stimulation. Vessels were prepared by embedding rat aortic smooth muscle cells in a collagen gel and culturing the constructs for two weeks to allow matrix remodeling. Experimental vessels were treated with transglutaminase and cultured in media supplemented with ascorbic acid, TGF-beta, and insulin. Mechanical properties of these vessels were measured by using tensile testing of ring samples from the vessels and applying internal pressure loads over whole constructs. The treated vessels demonstrated statistically significant improvements in both ultimate tensile strength and burst pressure relative to control vessels. These results indicate that biochemical stimulation can facilitate improvements in mechanical properties of tissue engineered blood vessels.