Departments of Mechanical Engineering, Bioengineering, and Cardiothoracic Surgery, Stanford University, Stanford, CA, USA.
J Mech Behav Biomed Mater. 2014 Jan;29:529-43. doi: 10.1016/j.jmbbm.2013.10.009. Epub 2013 Oct 28.
Living systems can grow, develop, adapt, and evolve. These phenomena are non-intuitive to traditional engineers and often difficult to understand. Yet, classical engineering tools can provide valuable insight into the mechanisms of growth in health and disease. Within the past decade, the concept of incompatible configurations has evolved as a powerful tool to model growing systems within the framework of nonlinear continuum mechanics. However, there is still a substantial disconnect between the individual disciplines, which explore the phenomenon of growth from different angles. Here we show that the nonlinear field theories of mechanics provide a unified concept to model finite growth by means of a single tensorial internal variable, the second order growth tensor. We review the literature and categorize existing growth models by means of two criteria: the microstructural appearance of growth, either isotropic or anisotropic; and the microenvironmental cues that drive the growth process, either chemical or mechanical. We demonstrate that this generic concept is applicable to a broad range of phenomena such as growing arteries, growing tumors, growing skin, growing airway walls, growing heart valve leaflets, growing skeletal muscle, growing plant stems, growing heart valve annuli, and growing cardiac muscle. The proposed approach has important biological and clinical applications in atherosclerosis, in-stent restenosis, tumor invasion, tissue expansion, chronic bronchitis, mitral regurgitation, limb lengthening, tendon tear, plant physiology, dilated and hypertrophic cardiomyopathy, and heart failure. Understanding the mechanisms of growth in these chronic conditions may open new avenues in medical device design and personalized medicine to surgically or pharmacologically manipulate development and alter, control, or revert disease progression.
生命系统可以生长、发育、适应和进化。这些现象对于传统工程师来说是直观的，而且常常难以理解。然而，经典的工程工具可以为健康和疾病中的生长机制提供有价值的见解。在过去的十年中，不兼容配置的概念已经发展成为一种强大的工具，可以在非线性连续介质力学的框架内对生长系统进行建模。然而，探索生长现象的各个学科之间仍然存在很大的脱节，它们从不同的角度研究生长现象。在这里，我们表明力学的非线性场论提供了一个统一的概念，可以通过单个张量内部变量（二阶生长张量）来模拟有限生长。我们回顾了文献，并通过两个标准对现有的生长模型进行了分类：生长的微观结构外观，无论是各向同性还是各向异性；以及驱动生长过程的微观环境线索，无论是化学的还是机械的。我们证明了这个通用的概念适用于广泛的现象，如生长的动脉、生长的肿瘤、生长的皮肤、生长的气道壁、生长的心脏瓣膜叶、生长的骨骼肌、生长的植物茎、生长的心脏瓣膜环和生长的心肌。所提出的方法在动脉粥样硬化、支架内再狭窄、肿瘤侵袭、组织扩张、慢性支气管炎、二尖瓣反流、肢体延长、肌腱撕裂、植物生理学、扩张型和肥厚型心肌病以及心力衰竭等方面具有重要的生物学和临床应用。了解这些慢性疾病中的生长机制可能会为医疗器械设计和个性化医学开辟新的途径，以手术或药物方式操纵发育并改变、控制或逆转疾病进展。
