Limits to the durability of arterial elastic tissue.
To engineer a better blood vessel, we must identify which structural, mechanical, and biological features of the native vessel must be replicated to ensure long-term survival of the implant. In this study, we tested autoclave-purified elastic tissue from along the pig thoracic aorta under long-term static and cyclic loading to identify factors that affected its durability. Samples were tested in water or in sucrose, which enhances viscoelasticity. Samples failed between 50% and 80% extension, which is lower than the failure extension in shorter, quasi-static tensile tests. Cyclic loading had a small effect on the durability of samples tested in water. Samples from the distal thoracic aorta and samples pre-treated in 70% ethanol showed enhanced durability. Failure between 50% and 80% extension appears associated with structural features of the individual fibre, and indirect evidence suggests it may be due to failure of the microfibrils, not the elastin. Cross-linked elastin may be necessary but insufficient to prevent failure. Durability appears also affected by regional differences in tissue structure, possibly the three-dimensional fibre organization. These results suggest ensuring normal fibre synthesis and organization may be crucial to the design of a successful vascular implant.
Lillie
M A
MA
Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4. lillie@zoology.ubc.ca
Gosline
J M
JM
D000818:Animals; D001013:Aorta, Thoracic / Q000166:cytology* / Q000378:metabolism; D001158:Arteries / Q000473:pathology*; D001672:Biocompatible Materials / Q000737:chemistry*; D003094:Collagen / Q000737:chemistry; D004547:Elastic Tissue / Q000378:metabolism / Q000502:physiology*; D004548:Elasticity; D004549:Elastin / Q000737:chemistry; D000431:Ethanol / Q000737:chemistry; D012044:Regression Analysis; D013314:Stress, Mechanical; D013395:Sucrose / Q000737:chemistry; D013552:Swine; D013718:Tensile Strength; D023822:Tissue Engineering
D001672:Biocompatible Materials; D000431:Ethanol; D013395:Sucrose; D003094:Collagen; D004549:Elastin