Collagen is at the heart of any and all questions concerning semilunar valvular leaflet composition, structure, and function. Whether during development, physiological homeostasis, or pathological degeneration, it is the structural-mechanical state of the heart valve leaflet collagen network that ultimately confers valvular function, and the difference between health and disease. In the current study, the effects of physiologically relevant strain states on collagen catabolism are investigated in porcine aortic and pulmonary valve leaflets. Application of bacterial collagenase to the tissues which acts to simulate collagen degradation by endogenous matrix metalloproteinases, biaxial stress relaxation, and histology are all used to serve as measures of functional and compositional collagen catabolism. Current stress-relaxation results are used in conjunction with previous equibiaxial testing to confirm that a mechanism exists to prevent collagen catabolism when stretched at physiologically relevant strain states. Collectively, these in vitro results indicate that biaxial strain states are capable of impacting the susceptibility of valvular collagens to catabolism, and that at physiological strain states, a protective mechanism exists to effectively block collagen catabolism. The results of the study will be broadly applicable to clarify the roles of tissue microarchitecture and load transmission in a variety of other developmental, homeostatic, or pathogenic tissue processes such as tumor growth, embryogenesis, thrombi formation, and atherogenesis.

胶原蛋白是任何有关半月瓣小叶组成，结构和功能的问题的核心。无论是在发育，生理稳态还是病理性退化过程中，最终赋予瓣膜功能以及健康与疾病之间差异的是心脏瓣膜小叶胶原蛋白网络的结构-机械状态。在目前的研究中，在猪主动脉和肺动脉瓣小叶中研究了生理相关的应变状态对胶原分解代谢的影响。细菌胶原酶在组织上的施加，其通过内源性基质金属蛋白酶模拟胶原降解，双轴应力松弛和组织学，均被用作功能性和组成性胶原分解代谢的量度。当前的应力松弛结果与先前的等双轴测试结合使用，以确认存在一种机制，可以在生理相关的应变状态下拉伸时防止胶原蛋白分解代谢。总的来说，这些体外结果表明双轴应变状态能够影响瓣膜胶原对分解代谢的敏感性，并且在生理应变状态下，存在有效地阻断胶原分解代谢的保护机制。该研究的结果将广泛应用于阐明组织微体系结构和负荷传递在各种其他发育，体内平衡或致病性组织过程中的作用，例如肿瘤生长，胚胎发生，血栓形成和动脉粥样硬化。