基于适配体捕获骨髓间充质干细胞归巢至骨表面成骨的策略研究

Aging is associated with a reduction in bone marrow MSC numbers and a deficiency in the bone marrow microenvironment that supports bone formation process.Bone regeneration by the means of induction of osteogenesis from MSCs offers a rational therapeutic option. However, this approach is problematic due to the transplanted MSC do not preferentially home to bone.Our previous research has identified the aptamer with specific affinity to BMSCs. On the basis of our previous research, we propose a new therapeutic strategy of attaching aptamer to alendronate to target BMSCs to the bone surface and to induce the osteogenesis. First, we synthetise the Aptamer-alendronate compound (Ap-Al), and inject Ap-Al into the rat through caudal vein, so that we can observe the tissue-specific distribution of Ap-Al and its deposition on the bone surface.Then we anchor the BMSCs with Ap-Al, and transplant the BMSCs-Ap-Al into the osteoporotic rats model (OVX rats or aged rats). We can observe the migration, homing, differentiation and metabolism of the BMSCs after the transplantation, and find out if the BMSCs can be captured to the bone surface, if BMSCs can differentiate into osteoblasts, and if diffentiation of BMSCs can increase the bone formation and prevent the bone loss. Thus we can provide a new strategy for the treatment of osteoporosis.

衰老与骨髓腔间充质干细胞(BMSCs)数量减少和骨髓中促进骨形成的微环境缺乏有关;因此通过移植BMSC促进成骨是一种治疗策略,然而移植的MSC不会自动归巢到骨发挥作用。本课题在我们前期研究鉴定出BMSCs特异性结合适配体(Aptamer)基础上,提出Aptamer连接alendronate捕获BMSCs至骨表面进行成骨的新策略。先在体外合成Aptamer-alendronate复合物( Ap-Al),尾静脉注射至大鼠,观察Ap-Al在体内组织分布及其在骨表面的沉积状况。进而在体外用Ap-Al锚定BMSCs,移植BMSCs于大鼠,检测BMSCS是否被捕获至骨表面。最后用Ap-Al锚定的BMSCs移植于骨质疏松模型(去卵巢大鼠、老年大鼠),观察移植后BMSCs移行、归巢、分化及骨代谢状况,确定BMSCS是否能被捕获至骨表面并分化为成骨细胞,促进骨形成,从而阻止骨丢失。为临床治疗提供新靶点。

课题组成功构建BMSCs 靶向载体 Aptamer-alendronate 复合物（Ap-Al），在体外证实复合物（Ap-Al）可以靶向结合BMSCs；构建含BMSCs的复合物Ap-Al-BMSCs，进一步在动物实验中证实复合物Ap-Al-BMSCs可以靶向结合到股骨骨表面；最后在大鼠绝经后 OP 模型中注射复合物Ap-Al-BMSCs，观察到复合物Ap-Al-BMSCs可以显著促进骨形成，缓解了大鼠绝经后骨丢失。本项目构建了适配体捕获BMSCs归巢至骨表面成骨的复合物，为骨质疏松症治疗提供新途径。（本部分结果已经整理完毕，正在投稿中）。.研究筛选成骨诱导过程中小鼠骨髓基质干细胞（BMSCs）差异表达miRNAs：基因芯片筛选表达差异的miR-483-3p，分析发现miR-483-3p在成骨诱导后高表达。在12月龄小鼠的股骨骨髓腔中注射BMSC靶向适配体mir-483-3P后，骨表面成骨细胞数量显著升高，表现出较高的骨密度、骨小梁体积、骨小梁厚度、胫骨最大负荷和刚度，以及较低的骨小梁分离度。以上结果表明，在老年小鼠中过表达mir-483-3p可促进骨形成。（本部分结果已经整理完毕，正在投稿中）.发现GDF11与与神经性厌食患者骨密度负相关，而GDF8与之无相关性，分别以腰椎骨密度、股骨颈骨密度和总骨密度作为因变量，考虑年龄、BMI、脂重、瘦重、25羟-维生素D、雌激素、GDF8和GDF11为自变量，在进行多元线性回归分析中，发现是GDF11作为BMD的独立决定因素被纳入，而GDF8被排除。研究揭示了GDF8和GDF11与神经性厌食患者骨密度的关系，已发表论文在Clin Endocrinol (Oxf). 2019 （IF 值= 2.897）；并筛选出人IGSF23基因突变导致骨代谢异常疾病的作用机制，为骨质疏松症治疗提供新途径、新思路，已发表论文在Cell Prolif.2019（IF 值= 5.039），