Effects of elastase on the mechanical and failure properties of engineered elastin-rich matrices

• Published in: Journal of applied physiology (1985) Vol. 98; no. 4; pp. 1434 - 1441
• Main Authors: Black, Lauren D, Brewer, Kelly K, Morris, Shirley M, Schreiber, Barbara M, Toselli, Paul, Nugent, Matthew A, Suki, Bela, Stone, Phillip J
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Am Physiological Soc 01-04-2005; American Physiological Society
• Subjects: Animals; Biological and medical sciences; Blood vessels; Blood vessels and receptors; Cell culture; Cell Extracts - chemistry; Cells, Cultured; Elasticity; Elastin - chemistry; Elastin - physiology; Extracellular Matrix - chemistry; Extracellular Matrix - physiology; Extracellular Matrix - ultrastructure; Fundamental and applied biological sciences. Psychology; Injuries; Muscle, Smooth, Vascular - chemistry; Muscle, Smooth, Vascular - physiology; Muscular system; Pancreatic Elastase - chemistry; Rats; Rats, Sprague-Dawley; Stress, Mechanical; Tensile Strength; Vertebrates: cardiovascular system; Cell culture; smooth muscle cell; Rat; Elastin; Rodentia; Mechanical properties; Smooth muscle; storage modulus; In vitro; Structure function relationship; Artery; Biomechanics; Vertebrata; Mammalia; Blood vessel; Aorta; Extracellular matrix; Circulatory system; Lesion; loss modulus
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.00921.2004

1 Department of Biomedical Engineering, Boston University, Boston; and 2 Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts
Submitted 24 August 2004
; accepted in final form 20 December 2004
Pulmonary emphysema and vessel wall aneurysms are diseases characterized by elastolytic damage to elastin fibers that leads to mechanical failure. To model this, neonatal rat aortic smooth muscle cells were cultured, accumulating an extracellular matrix rich in elastin, and mechanical measurements were made before and during enzymatic digestion of elastin. Specifically, the cells in the cultures were killed with sodium azide, the cultures were lifted from the flask, cut into small strips, and fixed to a computer-controlled lever arm and a force transducer. The strips were subjected to a broadband displacement signal to study the dynamic mechanical properties of the samples. Also, quasi-static stress-strain curves were measured. The dynamic data were fit to a linear viscoelastic model to estimate the tissues' loss (G) and storage (H) modulus coefficients, which were evaluated before and during 30 min of elastase treatment, at which point a failure test was performed. G and H decreased significantly to 30% of their baseline values after 30 min. The failure stress of control samples was 15 times higher than that of the digested samples. Understanding the structure-function relationship of elastin networks and the effects of elastolytic injury on their mechanical properties can lead to the elucidation of the mechanism of elastin fiber failure and evaluation of possible treatments to enhance repair in diseases involving elastolytic injury.
storage modulus; loss modulus; cell culture; smooth muscle cell
Address for reprint requests and other correspondence: P. J. Stone, Dept. of Biochemistry, 715 Albany St., Boston, MA 02118 (E-mail: stone{at}biochem.bumc.bu.edu )