牙周膜细胞外泌体在招募骨髓基质细胞参与应力介导骨改建中的作用及机制研究

Tension force-induced bone formation is the critical factor in maintaining long-term stability of orthodontic treatment. Recent studies demonstrated bone marrow stromal cells (BMSCs) may participate in the tension force-induced bone formation during orthodontic treatment. However, the specific mechanism is still unclear so far. As a new type of intercellular information messenger, exosome has been demonstrated to have the capability to promote the mobilization of BMSCs, which may play important roles in various physiological and pathological processes, for instance, the formation of pre-metastatic niche and injured blood vessel repair. Our preliminary data showed that periodontal ligament cells (PDLCs) under the tension force secreted exosomes, and these exosomes further enhanced the migration ability of BMSCs. The results suggested that the PDLCs-derived exosomes educated BMSCs, and enhanced the recruitment of BMSCs to the alveolar bone for further osteogenesis. The present project is aimed to investigate: (1) the role of PDLCs-derived exosomes in mediating recruitment of BMSCs; (2) the molecular mechanisms by which exosomes recruite the BMSCs; (3) the in vivo demonstration of the role of PDLCs-derived exosomes under the tension force in bone modeling during orthodontic treatment, and the potentials of PDLCs-derived exosomes for the clinical applications. Our research may not only further unravel the mechanism of bone formation in the tension site during orthodontic treatment, but also pave the way for developing novel approach for the controllabl eorthodontic treatment.

在正畸治疗过程中，张应力诱导成骨是影响正畸治疗效果的重要因素。近来研究表明骨髓基质细胞（BMSCs）可能参与正畸牙张力侧成骨过程，但BMSCs具体招募机制仍不清楚。外泌体作为一种新发现的胞间通讯方式，目前被证实可通过“驯化（educating）”BMSCs参与其招募过程，并在肿瘤转移前微环境预备、血管损伤修复等生理病理过程中发挥重要作用。课题组前期预实验结果显示，受张应力刺激后的牙周膜细胞可通过释放外泌体增强BMSCs的趋化迁移能力，提示正畸张应力下牙周膜细胞的外泌体可能通过“驯化”BMSCs，促进其被招募至张力侧牙周组织处参与成骨。本课题旨在研究：(1) 张应力下牙周膜细胞外泌体在介导BMSCs招募过程中的作用；(2) 张应力下牙周膜细胞外泌体“驯化”BMSCs的具体分子机制；(3) 利用体内正畸牙移动动物模型验证张应力下牙周膜细胞外泌体在正畸骨塑建中的作用，并论证其潜在治疗价值。

项目背景. 张应力诱导成骨是影响正畸牙移动的重要因素，研究表明骨髓基质细胞（BMSCs）可能参与这一过程。在肿瘤相关研究中，外泌体能够传递信号分子以促进细胞迁移。牙周膜细胞（PDLCs）存在于具有机械敏感特性的牙周膜中，课题组前期实验发现PDLCs在张应力刺激下外泌体释放增加。本研究在此基础上继续探索，探讨牙周膜细胞外泌体在招募骨髓基质细胞参与应力骨改建过程的调控作用和机制。..主要研究内容.1 收集和鉴定张应力刺激下的PDLCs外泌体，并分析浓度，确定产量。.2 检测PDLCs在张应力刺激下释放的外泌体对BMSCs的迁移、增殖等生物学行为的作用.3 分析PDLCs外泌体中RNA的功能，通过高通量测序miRNA得到差异表达的miRNA。进一步通过生物信息学方法预测外泌体miRNA相关靶基因及潜在相互作用的蛋白质。.4 研究细胞因子参与PDLCs招募BMSCs参与应力骨改建的作用和机制。..重要结果及关键数据.1 PDLCs在张应力刺激下释放的外泌体能够促进BMSCs迁移，但对增殖无显著影响。.2 通过高通量测序和生信分析预测，张应力刺激下PDLCs分泌的外泌体可能经差异表达的miRNA调控PI3K等信号通路增强靶细胞迁移。.3 FGF2和SDF-1这2种细胞因子牙移动的张力侧的牙周膜中表达上调，CREB转录因子通过调控FGF2和SDF-1表达促进BMSCs的迁移和成骨分化。..科学意义. 本研究揭示张应力刺激下的牙周膜细胞通过释放外泌体招募骨髓基质细胞参与骨改建的机制，为研究张力区牙周组织中信息传递提出新的实验依据，同时也为加快牙周骨改建进程，从而提高正畸治疗效果提供新的靶点。

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