Pete H. Gueldner , Cyrus J. Darvish , Isabelle K.M. Chickanosky , Emma E. Ahlgren , Ronald Fortunato , Timothy K. Chung , Keshava Rajagopal , Chandler C. Benjamin , Spandan Maiti , Kumbakonam R. Rajagopal , David A. Vorp
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The objective of this work was to test this novel hypothesis for porcine thoracic aorta.</p><p><strong>Methods:</strong> Three tissue specimens from freshly harvested porcine thoracic aorta were treated with either collagenase or elastase to selectively degrade structural proteins in the tissue, or with phosphate buffer saline (control). The tissue mass and volume of each specimen were measured before and after treatment to allow for density calculation, then mechanically tested to failure under uniaxial extension.</p><p><strong>Results:</strong> Protease treatments resulted in statistically significant tissue density reduction (sham vs. collagenase p = 0.02 and sham vs elastase p = 0.003), which in turn was significantly and directly correlated with both ultimate tensile strength (sham vs. collagenase p = 0.02 and sham vs elastase p = 0.03) and tangent modulus (sham vs. collagenase p = 0.007 and sham vs elastase p = 0.03).</p><p><strong>Conclusions:</strong> This work demonstrates for the first time that tissue stiffness and tensile strength are directly correlated with tissue density in proteolytically-treated aorta. 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引用次数: 0
摘要
简介主动脉夹层或破裂的死亡率很高,因此迫切需要更好地预测这些事件,以改善患者管理和临床疗效。从生物力学角度来看,这些事件代表了局部作用壁应力超过局部组织强度的情况。根据最近有关聚合物的报道,我们假设主动脉组织的破坏强度和刚度与组织质量密度直接相关。这项工作的目的是测试猪胸主动脉的这一新假设:方法:用胶原酶或弹性蛋白酶选择性地降解组织中的结构蛋白,或用磷酸盐缓冲盐水(对照组)处理新鲜采集的猪胸主动脉的三个组织标本。在处理前后测量每个样本的组织质量和体积,以便计算密度,然后在单轴伸展条件下进行机械测试,直至失效:蛋白酶处理导致组织密度明显降低(假胶原酶与弹性蛋白酶对比 p = 0.02,假弹性蛋白酶与弹性蛋白酶对比 p = 0.003),这反过来又与极限拉伸强度(假胶原酶与弹性蛋白酶对比 p = 0.02,假弹性蛋白酶与弹性蛋白酶对比 p = 0.03)和切线模量(假胶原酶与弹性蛋白酶对比 p = 0.007,假弹性蛋白酶与弹性蛋白酶对比 p = 0.03)明显直接相关:这项研究首次证明,经蛋白水解处理的主动脉组织硬度和拉伸强度与组织密度直接相关。这些发现是了解主动脉组织失效机制的重要一步,并有可能通过密度测量进行无创主动脉强度评估,从而对临床治疗产生影响。
Aortic tissue stiffness and tensile strength are correlated with density changes following proteolytic treatment
Introduction: Dissection or rupture of the aorta is accompanied by high mortality rates, and there is a pressing need for better prediction of these events for improved patient management and clinical outcomes. Biomechanically, these events represent a situation wherein the locally acting wall stress exceed the local tissue strength. Based on recent reports for polymers, we hypothesized that aortic tissue failure strength and stiffness are directly associated with tissue mass density. The objective of this work was to test this novel hypothesis for porcine thoracic aorta.
Methods: Three tissue specimens from freshly harvested porcine thoracic aorta were treated with either collagenase or elastase to selectively degrade structural proteins in the tissue, or with phosphate buffer saline (control). The tissue mass and volume of each specimen were measured before and after treatment to allow for density calculation, then mechanically tested to failure under uniaxial extension.
Results: Protease treatments resulted in statistically significant tissue density reduction (sham vs. collagenase p = 0.02 and sham vs elastase p = 0.003), which in turn was significantly and directly correlated with both ultimate tensile strength (sham vs. collagenase p = 0.02 and sham vs elastase p = 0.03) and tangent modulus (sham vs. collagenase p = 0.007 and sham vs elastase p = 0.03).
Conclusions: This work demonstrates for the first time that tissue stiffness and tensile strength are directly correlated with tissue density in proteolytically-treated aorta. These findings constitute an important step towards understanding aortic tissue failure mechanisms and could potentially be leveraged for non-invasive aortic strength assessment through density measurements, which could have implications to clinical care.
期刊介绍:
The Journal of Biomechanics publishes reports of original and substantial findings using the principles of mechanics to explore biological problems. Analytical, as well as experimental papers may be submitted, and the journal accepts original articles, surveys and perspective articles (usually by Editorial invitation only), book reviews and letters to the Editor. The criteria for acceptance of manuscripts include excellence, novelty, significance, clarity, conciseness and interest to the readership.
Papers published in the journal may cover a wide range of topics in biomechanics, including, but not limited to:
-Fundamental Topics - Biomechanics of the musculoskeletal, cardiovascular, and respiratory systems, mechanics of hard and soft tissues, biofluid mechanics, mechanics of prostheses and implant-tissue interfaces, mechanics of cells.
-Cardiovascular and Respiratory Biomechanics - Mechanics of blood-flow, air-flow, mechanics of the soft tissues, flow-tissue or flow-prosthesis interactions.
-Cell Biomechanics - Biomechanic analyses of cells, membranes and sub-cellular structures; the relationship of the mechanical environment to cell and tissue response.
-Dental Biomechanics - Design and analysis of dental tissues and prostheses, mechanics of chewing.
-Functional Tissue Engineering - The role of biomechanical factors in engineered tissue replacements and regenerative medicine.
-Injury Biomechanics - Mechanics of impact and trauma, dynamics of man-machine interaction.
-Molecular Biomechanics - Mechanical analyses of biomolecules.
-Orthopedic Biomechanics - Mechanics of fracture and fracture fixation, mechanics of implants and implant fixation, mechanics of bones and joints, wear of natural and artificial joints.
-Rehabilitation Biomechanics - Analyses of gait, mechanics of prosthetics and orthotics.
-Sports Biomechanics - Mechanical analyses of sports performance.