核壳结构明胶-脱钙骨基质微组织的构建及其对骨质疏松骨缺损的再生机理研究

Osteoporotic bone defects, of which major characteristics are osteoclast activation and bone lost, is the common hurdle of clinical treatment. Our previous research showed that traditional bone tissue engineering strategy received a compromised effects , due to the low survival and osteodifferentiation rate of implanted MSC during the early stage of treatment. The microtissue technology based on the hydrogel system might be able to overcome this problem, for the biomimetic environment of extracelluar matrix reducing the possible damage during the implantation, the uniformly distribution of seed cells and the advances of anigogenesis. However, the suboptimal mechanical property and osteoinductivity of hydrogel system make it unsuitable for bone reconstruction. Here we design a core-shell structured tissue engineered microtissue. Demineralized bone matrix(DBM) microcarrier, with well osteoconductivity and mechanical property, was chosen as the core materials, with which rhBMP2 was coated to enhance its osteoinductivity. Gelatin was used as the shell to support the growth of seed cells. The core-shell tissue engineered microtissue will be assembled to repair the osteoporotic bone defects in rat cranial defect mode. In vivo osteogenesis results will be assessed to study the possible mechanism including MSC survival rate and angiogenesis under osteoporotic condition.

以破骨细胞活跃、骨量丢失为主要特点的骨质疏松骨缺损是临床常见难题。申请人前期研究发现经典骨组织工程方法对其修复效果欠佳，主要原因可能是修复段破骨细胞活跃，而植入的外源性间充质干细胞（MSC）早期存活率低，成骨分化少，难与破骨细胞形成动态平衡。基于凝胶的微组织技术可体外模拟MSC三维生长环境，减少植入体内过程中种子细胞损伤，还可基于Bottom-up策略组装成细胞均一分布、利于微血管长入的移植物，进一步提高MSC早期体内存活率。但是单纯凝胶微组织力学性能及骨诱导活性较差，难适用于硬组织修复。为此我们拟使用具有良好骨传导性和力学性能的脱钙骨基质微载体作为内核，复合rhBMP2提高骨诱导性，明胶作为壳层为MSC提供三维生长环境，制备核壳结构组织工程微组织。然后利用其对骨质疏松大鼠颅骨缺损进行修复，评估体内修复效果并从干细胞存活率及血管化角度究其可能的骨再生机理，拓宽骨组织工程技术应用思路。

以破骨细胞活跃、骨量丢失为主要特点的骨质疏松骨缺损是临床常见难题。本课题针对如何提高间充质干细胞在体内成骨效率的科学问题，提出构建核壳结构微组织的解决方式；并通过对比经典骨组织工程移植物，研究核壳结构微组织bottom-up组装方式有无修复效果优势。在体外实验中，本项目发现脱钙骨基质DBM为核，明胶为壳的核壳结构微组织相比单纯明胶微组织有很明显的成骨矿化优势，体内大鼠颅骨缺损效果也与体外一致。据此开展研究，以通讯作者发表论文20篇，IF>8有8篇。因此核壳结构是一种非常有价值的微组织构建方式，并具备使用其他组织的构建可能。在本研究中，微组织能较好的保证植入初期种子细胞的存活及成骨分化，使其对于临界骨缺损仍然具有较好的修复效果。为后续深入研究微组织工程技术打下坚实基础。