“分步式”骨组织工程移植策略的研究

Mesenchymal stem cell (MSC) based bone tissue engineering (BTE) strategy can fullfil the ever-increasing clinical need for the bone defect treatment in China. However, the major bottlenecking problem for the clinical translation of BTE is the poor celluar survival rate of tissue engineered bone graft (TEB) after the in vivo transplantation, leading to the compromised defect healing efficacy. Based on our preliminary study showing that the additional transplantation of MSC resulted in the better defect healing, we propose a novel "two-step" BTE transplantation strategy, where the first step aims to implant TEB with pro-angiogenic treatment into the defect site to promote the vascualarizaiton and construct a pro-healing microenvironment for bone regeneration and the second step aims to deliver MSC with pro-osteogenic treatment to the defect site after sufficient vascular network has been generated in order to supplement osteogenic cell pools for bone regeneration. In this study, we will develop and optimize this "two-step" BTE transplantation strategy and investigate its underlying mechanism: (1) to develop the first-step transplantation strategy by optimizing the three dimensional structure of scaffold and investigating the suitable hypoxial culture conditions for TEB; (2) to develop the second-step transplantation strategy by investigating the optimal time point for MSC transplantation and optimizing the osteogenic priming condition of MSC; and (3) to study its underlying mechanism by comparing it with current one-step BTE transplantation strategy at the tissue, cell and molecular levels. The development of two-step BTE transplantation strategy will help to boost up the healing efficacy of BTE technology and minimize the individual variation of BTE treatment, on the other hand, it can supplement the current knowleage of BTE research and can be highly useful as a reference for developing tissue engineering strategies for other tissue defect treatment.

使用间充质干细胞（MSC）的骨组织工程（BTE）技术可满足我国骨科治疗的巨大临床需求，但其临床转化的主要瓶颈在于组织工程骨（TEB）植入体内后细胞存活率低、疗效有限。基于预实验发现第二次移植MSC可促进成骨，我们首次提出BTE"分步式"移植的新理念：第一步移植促血管化预处理的TEB，以促进缺损部位血管化，构建有利骨再生的微环境；第二步在充分血管化后移植促成骨化预处理的MSC，以促进骨再生。本课题拟研究和建立该"分步式"移植策略，并阐明其作用机理：①通过优化支架材料结构和研究TEB低氧培养条件，建立高效的促血管化预处理方案，用于第一步移植，②通过探讨MSC的合适移植时间点和成骨诱导条件，研究第二步移植策略，③与现有移植策略对比，从组织、细胞、分子水平研究其作用机理。"分步式"移植策略可提高BTE疗效，减少个体差异，加速临床转化；且是对现有BTE理论的重要补充，对其他组织修复有重要借鉴意义。

使用间充质干细胞的骨组织工程技术可满足我国骨科治疗的巨大临床需求，但其临床转化的主要瓶颈在于组织工程骨植入体内后细胞存活率低、疗效有限。基于预实验发现第二次移植MSC可促进成骨，我们首次提出BTE“分步式”移植的新理念，通过探索优化骨组织工程种子细胞的移植策略，提高种子细胞移植后的存活，以期提高骨缺损修复的效率，为临床治疗提供新的思路。.胶原(collagen, Col)是细胞外基质的主要组成部分，具有良好的生物相容性和可降解性；我们以胶原为支架构建大鼠骨缺损模型，检测术后局部及全身炎症情况，探讨了分步式骨组织工程的可行性及细胞二期移植的最佳时间点；通过慢病毒感染BMSCs，活体成像分析观察BMSCs移植入体内后的存活情况，结合远期的骨修复效果，对分步式骨组织工程的成骨机制进行了研究。.“分步式”移植策略可提高BTE疗效，减少个体差异，加速临床转化；且是现有BTE理论的重要补充，对其他组织修复有重要借鉴意义。