外泌体递送的miR-1-5p增强间充质干细胞保护骨髓瘤相关骨损伤的作用及机制研究

Multiple myeloma (MM) is an incurable hematological malignancy, whose characteristic pathological changes are osteolytic lesions. Soluble cytokine in the bone marrow niche, e.g. IL-6, considerably contributes toMM progression. Mesenchymal stem cells (MSCs) exert osteoprotective effects by osteogenesis and paracrine action, thereby providing new strategy for cell therapy in MM. The miRNAs in exosome secreted by MSCs were shown to play a key role in regulating the development of MM-related osteolytic lesions. Bioinformatics prediction reveals that miR-1-5p may be a candidate target miRNA of IL-6. Besides, we found that MSCs transfected by miR-1-5p have increased the level of miR-1-5p in their secreted exosomes and exhibited significantly enhanced inhibitory effects on tumor growth and bone injury, but the underlying mechanism remains to be clarified. Thus, we hypothesis that exosomal miR-1-5p derived from MSCs could confer osteoprotective activities by targeting IL-6 in MM cells. This study will construct double reporter gene system in MSCs and MM cell lines, and employ molecular imaging to monitor the in vivo and in vitro therapeutic efficacy of MSCs transfected by miR-1-5p in MM. We will disclose the mechanism of MSCs-induced osteoprotective actions in MM-related bone disease through exosomal miR-1-5p. Collectively, our study will provide novel approaches to target therapy of MM.

多发性骨髓瘤（MM）是目前不可治愈的血液系统恶性疾病，溶骨性损害是其典型特征。骨髓微环境中的可溶性细胞因子，如IL-6在MM进展中的作用不容忽视。间充质干细胞（MSCs）可通过成骨分化和旁分泌发挥骨保护作用，为治疗MM提供新的思路。研究称MSCs分泌的外泌体miRNAs可调控MM骨损伤过程。生物信息学预测miR-1-5p是IL-6的候选靶miRNA，我们发现转染miR-1-5p升高MSCs外泌体miR-1-5p的水平，增强其抑制肿瘤细胞生长和骨损伤的能力，但具体机制尚待揭示。据此，我们推测外泌体递送miR-1-5p靶定MM细胞中的IL-6介导MSCs发挥骨保护作用。本项目将筛选表达双报告基因的MSCs和MM细胞株，利用分子影像技术监测外泌体递送的miR-1-5p介导MSCs体内和体外治疗MM的效果，并探索该过程在MM相关骨损伤中的具体调控机制，为MM提供新的靶向治疗策略和方向。

多发性骨髓瘤（MM）是目前不可治愈的血液系统恶性疾病，骨髓中浆细胞浸润是其典型特征。骨髓微环境中的可溶性细胞因子，如IL-6在MM进展中的作用不容忽视。胎盘间充质干细胞（hpMSCs）可通过成骨分化和旁分泌发挥抗瘤作用，为治疗MM提供新的思路，但其具体机制尚不清楚。在本研究中，我们利用芯片技术检测MM患者和正常捐献者的骨髓浆细胞的miRNA表达谱，发现miR-1-5p在MM患者中低表达。功能实验表明，miR-1-5p抑制MM细胞生长、促进其凋亡。接着，分离和提取hpMSCs细胞条件培养基中的exosome后，我们发现，exosome来源的miR-1-5p可增强hpMSCs抑制MM细胞生长和促进其凋亡的作用。我们利用分子成像技术实时监测小鼠体内和体外的成瘤情况,数据显示：与对照组相比，外泌体来源的miR-1-5p可以有效降低小鼠的成瘤能力。进一步研究表明，hpMSCs的外泌体来源的miR-1-5p通过靶定并负向调控骨髓微环境中的可溶性细胞因子IL-6发挥抗骨髓瘤细胞生长的作用。因此，该研究表明exosome来源的miR-1-5p通过靶定IL-6增强hpMSCs抑制MM细胞的生长和促进其凋亡的能力，这为MM的治疗提供了新的策略和方向。