LOX激活及力学刺激提高体外构建软骨的力学强度

In views of many advantages suitable for clinical translation, in vitro engineered cartilage has provided a promising approach for repair and functional reconstruction of cartilage defects. Previously, we have successfully established a series of crucial techniques for in vitro cartilage regeneration. However, the poor mechanical properties of in vitro engineered cartilage severely impede its clinical translation. Our recent results indicated that the low levels of cross-linking in cartilage matrix macromolecules was one of important reasons that caused poor mechanical strength of in vitro engineered cartilage, and that inhibiting the activity of lysyl oxidase (LOX, the unique key enzyme for collagen cross-linking) could significantly reduce the mechanical properties of in vitro engineered cartilage. Besides, it was also testified that mechanical stimulation could remarkably improve the mechanical strength of in vitro engineered cartilage and up-regulate the expression of LOX, and the effect of mechanical stimulation could be completely blocked by the inhibitor of LOX activity. Nevertheless, several important issues still need to be elucidated, for example: can mechanical preperties of in vitro engineered cartilage be enhanced by activating LOX? How does mechanical stimulation regulate the expression LOX? Which signaling pathway plays an important role in this process? Are there cooperative effects in enhancing mechanical properties of in vitro engineered cartilage between mechanical stimulation and LOX activation? In this project, these questions will be systematically investigated, the crucial parameters will be optimized, and thus the improved techniques for in vitro cartilage regeneration may be established. By these investigations, it is expected that the mechanical strength of in vitro engineered cartilage can be significantly enhanced, which apparently helps to promote the clinical translation of in vitro engineered cartilage.

体外构建技术的诸多优势已使其成为软骨组织工程临床转化研究的重要趋势。本项目组目前已建立了体外软骨构建的关键技术平台，但力学强度不足问题严重阻碍了这一技术的临床转化。项目组研究发现，体外软骨强度不足主要与其基质大分子交联水平低下有关，抑制交联关键酶-赖氨酰氧化酶（LOX）活性能显著降低体外构建软骨的力学强度。研究中还发现，力学刺激能显著提高构建软骨的力学强度且能上调LOX的表达，而抑制LOX活性能完全阻断力学刺激的这一作用。尽管如此，仍有许多关键科学问题尚未阐明，例如：上调LOX活性是否有助于体外构建软骨力学强度的提高？力学刺激如何调控了LOX的表达？其主要信号通路与分子机制是什么？力学刺激与LOX激活对于提高体外软骨力学性能是否存在协同效应？本项目就是要通过对这些关键科学问题的深入研究及关键技术参数优化，改进体外软骨构建核心技术，提高体外构建软骨的力学性能，推动其临床应用转化。

各种原因所造成的软骨缺损或损伤临床上非常常见，临床上又缺乏理想的软骨移植供体。基于体外构建技术为的软骨缺损修复成功提供了强有力的保障，但力学强度不足已成为目前阻碍体外构建软骨临床转化的主要瓶颈。项目组前期研究发现，体外软骨强度不足主要与其基质大分子交联水平低下有关，抑制交联关键酶—赖氨酰氧化酶（LOX）活性能显著降低体外构建软骨的力学强度。本项目在此基础上，深入开展系列研究，进一步明确了抑制LOX活性对体外构建软骨力学强度的影响；证实了不同模式的力学刺激环境会不同程度增加体外软骨构建的LOX活性及含量的表达；对于LOX信号通路上下游中有影响的因子进行初筛，确定了可能对LOX活性有影响的活性因子（TGF-β1、BMP-1）；应用软骨诱导培养体系结合不同力学刺激环境模拟，显著提升了体外构建软骨质和量；改进了静水压生物反应器，更精准地进行力学微环境仿生模拟；试制了动态生物反应器，系统正在进行优化；开展了应用LOX激活剂提高体外再生软骨力学性能的相关研究；针对组织工程软骨形态精确控制的问题，以阴茎植入体为研究模型，初步探索了力学刺激在增强软骨力学性能及再生软骨形态维持的影响。本项目相关研究成果已发表SCI收录论文10篇，总SCI影响因子55.830 分，国内外学术合作与交流10人次，培养研究生14人，全面完成了各项研究任务与考核指标。本项目研究成果明确了LOX活性对再生软骨力学性能的影响，并开展了应用LOX激活剂提高体外再生软骨力学性能的相关研究，为解决体外再生软骨力学性能不足及形态维持难题提供了新的途径，对推进组织工程软骨的临床转化具有重要意义。