Characterization of Collagen and Elastin Remodeling in Engineered Arteries

We have shown that elongation of arteries perfused ex vivo is possible by applying moderate axial strain (∼8%) daily. In 9 days we were able to elongate porcine carotid arteries 48 ± 3% while being perfused under subphysiological conditions, retaining a 20 ± 3% increase when removed from the system and unloaded (p < 0.005). General appearance, viability and vasoactive function were similar to fresh and control (perfused but not elongated) arteries. Mechanical properties (ultimate stress and strain, elastic modulus) were insignificantly different than fresh arteries. To investigate the effects of pressure and flow rate on elongation and remodeling, we elongated arteries under the same elongation protocol, but with physiological flow, pressure and viscosity. Arteries were able to elongate 50 ± 1% in the system, but only retained an 8 ± 1% length increase when unloaded (p < 0.005). The increase in wet weight (29 ± 13%) was similar to that seen in previous elongation experiments (40 ± 18%), as was the increase in the total collagen content 30% vs. 34% previously). Data are also presented on mechanical properties, and elastin arrangement.