核酸适配体aptamer原位募集骨髓间充质干细胞在兔胫骨缺损修复中的研究

Recruiting bone marrow mesenchymal stem cells (BMSCs) at the bone defect site by specific chemoattractants for in situ regeneration is a hot issue in clinical bone defect repair. But the chemoattractants currently used also bind to other cells or factors besides BMSCs, resulting in side effect on bone tissue repair. Nucleic acid aptamer targeted to BMSCs which is generated by a method called systematic evolution of ligands by exponential enrichment (SELEX) provides a new way for bone defect in situ repair. We synthetized an aptamer according to the references and ours previous research showed that this aptamer binds to human BMSCs with high affinity and specificity. In this study, we will fabricate a bone tissue engineering scaffold by grafting the nucleic acid aptamer to recruit BMSCs and block the scaffold using polyethylene glycol to weaken the nonspecific adsorption of the scaffold to other cells or factors. The effect of this bone tissue engineering scaffold will be tested in vitro and in vivo to examine its ability of recruiting BMSCs and repairing bone defect in situ. This study is not only expected to provide a quick and efficient method to raise the efficiency and effect of bone defect repair, but also provide a new idea for other tissue repair. At the same time, the introduction of specific aptamer to tissue engineering, also broaden the application of aptamer in biomedical field.

在缺损部位利用化学引诱物募集骨髓间充质干细胞（BMSCs）进行原位修复，是骨缺损修复的一大研究热点。但目前常用的化学引诱物存在特异性低的缺陷，影响骨组织修复的效果。通过指数富集的配体系统进化技术筛选出的、对BMSCs具有高特异性作用的核酸适配体aptamer，为骨缺损原位修复提供了新的思路。我们根据文献调研合成了特异性aptamer，并通过预实验证明该aptamer对人BMSCs具有高特异性识别黏附作用。在本研究中，拟将该aptamer接枝到骨组织工程支架上，对BMSCs进行募集。同时以聚乙二醇对骨组织工程支架进行封闭，削弱支架对其它细胞或因子的非特异性吸附。在体外和体内考查该支架原位募集BMSCs的能力及对骨缺损修复的作用。本研究如获成功，可望提高骨组织修复的效果，也为其它组织修复提供思路。同时首次将特异性aptamer引入组织工程，进一步拓宽了aptamer在生物医学领域的应用。

在缺损部位利用化学引诱物募集骨髓间充质干细胞（BMSCs）进行原位修复，是骨缺损修复的一大研究热点。选择高特异性的引诱导物是该过程的关键步骤之一。在本研究中，我们使用针对BMSCs表面特征标记物CD271的特异性抗体作为引诱物，通过生物素-链霉亲和素之间的特异性作用，将CD271抗体接枝到多巴胺涂覆的壳聚糖微球表面进行生物功能化。在体外实验中，我们发现CD271抗体修饰的微球可以有效地对BMSCs进行捕获，从不同种类的细胞中也能高效地筛选出BMSCs，并进一步快速增殖。在体内实验中，Micro-CT 扫描分析及H&E染色等结果表明，CD271抗体修饰的微球可以快速地促进骨组织愈合，达到提高骨修复效率的作用。该研究为骨组织工程及其他组织工程修复，生物材料表面功能化提供了有效的方法和思路。