miR-135介导的骨髓基质干细胞对眼眶骨缺损修复重建及调控机制研究

The orbital walls are adjacent to paranasal sinuses with poor blood supply, and the defects of the orbital walls are difficult to heal. Provious studies exhibit that induction of BMSC osteogenic differentiation improved the repair of orbital bone defects. At present, a group of microRNAs demonstrate to have an important role in BMSC osteogenic differentiation. Our pre-study show that microRNA-135 (miR-135), Satb2 and Hoxa2 acted as important regulators in the osteogenic differentiation of BMSCs: The expression levels of miR-135 and Satb2 gradually up-regulated while the expression of Hoxa2 down-regulated with time during BMSC osteogenic differentiation. Meanwhile, Satb2 could enhance miR-135 expression, whereas miR-135 inhibited the expression levels of Hoxa2. In addition, the overexpression of miR-135 could markedly promote BMSC osteogenic differentiation while the inhibition of miR-135 weaked the differentiation. This proposed study will systematically investigate the function and mechanisms of miR-135 in the osteogenic differentiation of BMSCs, and further evaluate the potentials of the composites of miR-135-mediated BMSCs and β-TCP scaffold in bone regeneration at the levels of gene, protein as well as animal models, which might provide new ideas for clinical reconstruction of orbital bone defects.

眼眶骨壁毗邻鼻窦空腔，血供差，缺损后难自愈。研究表明骨髓基质干细胞(BMSC)的成骨分化可促进眼眶骨缺损的修复，而微小RNAs在促干细胞成骨分化中起重要作用。本项目组前期发现miR-135与BMSC成骨分化关系密切,而且,在此过程中miR-135与两个重要成骨转录因子Satb2和Hoxa2的关系紧密：在成骨分化中，miR-135和Satb2的表达逐渐升高，而Hoxa2的表达逐渐降低；同时，Satb2能同向调节miR-135的表达，而miR-135反向调节Hoxa2的表达；另外，miR-135过表达明显促进BMSC成骨基因表达，而miR-135沉默则抑制其表达。本项目拟从基因、蛋白、小动物模型和大动物模型不同层次，进一步多角度探索miR-135促BMSC成骨分化的作用及其机制，并评估miR-135介导的BMSC复合支架材料在体内的异位和原位促成骨作用，以期为眼眶骨缺损的重建提供新思路。

眼眶骨壁毗邻鼻窦空腔，血供差，缺损后难自愈。研究表明骨髓间充质干细胞(BMSC)的成骨分化可促进眼眶骨缺损的修复，而微小RNAs在促干细胞成骨分化中起重要作用。本项目组发现miR-135与BMSC成骨分化关系密切,而且在此过程中miR-135与两个重要成骨转录因子Satb2和Hoxa2的关系紧密：在成骨分化中，miR-135和Satb2的表达逐渐升高，而Hoxa2的表达逐渐降低；同时，Satb2能同向调节miR-135的表达，而miR-135反向调节Hoxa2的表达；通过体外实验，本课题组发现过表达miR-135后促进成骨分化，反之敲除miR-135抑制成骨分化；转导了miR-135的rBMSC中Hoxa2蛋白水平降低，而转导了miR-135抑制剂的rBMSC中Hoxa2蛋白的表达水平逐渐升高，而Hoxa2 的mRNA水平无明显变化，表明miR-135可能是在转录后水平调节Hoxa2的表达；进一步的荧光素酶载体报告基因实验发现Hoxa2是miR-135的靶基因;在体内， miR-135 基因修饰的BMSC与PSed支架复合，裸鼠皮下分别异位植入复合支架材料后，切片HE染色示裸鼠肝肾等并无明显炎症反应。通过评估其在大鼠颅骨和犬眼眶骨缺损的修复重建效果，结果发现过表达miR-135后Hoxa2表达下调，可以显著促进体内新骨的形成，而敲除miR-135后Hoxa2表达上调则抑制体内新骨的形成，为解剖和生理功能上的骨缺损修复提供了新的实验基础。 ..论文发表方面：在此项目的资助下,课题组已在《Advanced Functional Materials》、《Biomaterials》等SCI 收录杂志发表论文13 篇（均标注有本项目的资助编号，且本项目的负责人均为发表论文的通讯作者或共同通讯作者）。..学术交流方面：我们多次参加全国眼科年会和全国眼科基础研究大会以及眼科相关的各种学术会议。..研究生培养方面：从事本项目研究的研究生共6名，已毕业3名。