载药纳米颗粒定向缓释促进M2型巨噬细胞极化增强老年脑内髓鞘损伤修复能力的研究

China has seen an annually increase of 2 to 3 millions of population aged over 65 years since 2009. Aged population, therefore, poses an increasingly heavy burden to China both economically and socially, and this situation made biomedical research on aging a burning issue. In response to injury the regeneration efficiency declines with progressive aging for all organs in our body, and not surprisingly, the myelin repair efficiency also decreases with aging. The applicant and colleagues have recently shown that when the old animals were exposed to young environment, their myelin repair efficiency can be rejuvenated to the level almost the same as that of the young ones. Macrophage is the main cell type associated with such enhancement. Moreover, our recent work showed that macrophage polarization to M2 phenotype drives myelin repair ability enhancement. These results suggest that macrophages can be the target for myelin enhancing therapy. So far there is no effective therapy to enhance myelin repair in the aged central nervous system. To explore whether shifting macrophages polarisation towards M2 phenotype can enhance myelin repair efficiency in the aged brain, using Nanoparticle targeted drug delivery technique, together with in vitro cell culture and brain slice culture, this project will try to explore new strategy to push macrophage polarization towards M2 phenotype in vitro. In order to test whether the results obtained from mice can be translated into human conditions potentially, we plan to explore whether shifting macrophages obtained from bone marrow of healthy human volunteers can also enhance myelin repair efficiency in animal brain slice culture model. This project will not only deepen our understanding on how macrophage polarization towards M2 type changes with aging but also provide new clues to enhance myelin repair ability through encouraging M2 macrophage polarization in demyelination disorders such as secondary progressive multiple sclerosis in the old central nervous system.

随着逐渐衰老，包括神经髓鞘的全身组织损伤后修复能力均逐步下降。申请人近期揭示，年轻的巨噬细胞能增强老年受损髓鞘的修复能力，说明巨噬细胞是增强老年髓鞘损伤修复的药物靶点。但如何提高老年受损髓鞘的修复能力至今尚无有效治疗方法。我们最近发现，M2型巨噬细胞可促进年轻髓鞘损伤的修复。为验证促进巨噬细胞向M2型极化可以增强老年损伤髓鞘修复的新假说，本研究拟采用载药纳米颗粒定向缓释技术精确调控巨噬细胞向M2型极化这一核心技术，结合细胞和脑片培养，揭示巨噬细胞向M2型极化的老龄化特点，明确何种亚型M2型巨噬细胞可促进髓鞘修复，并比较小鼠和人骨髓来源M2型巨噬细胞促髓鞘修复的特征以验证结果是否有临床转化的潜力。本研究将为研究治疗诸如继发性进展性多发性硬化症等老年脱髓鞘疾病的新方法提供新思路。

研究内容1：根据研究计划，本项目首先证实了纳米颗粒缓释的有效性，纳米颗粒是能够缓慢释放的（见附图1）。进而揭示了巨噬细胞／小胶质细胞极化的增龄性变化特点。采用在体细胞毒素溶血卵磷脂诱导脱髓鞘，在电子显微镜下观察，以促进复髓鞘效率为指标，确定了最佳的M2型巨噬细胞来源、年龄及亚型。结果显示，M2型巨噬细胞的确能在脱髓鞘动物模型上提高髓鞘修复的效率。实验室通过筛选小胶质细胞分泌的物质，得到3种明显促进少突胶质细胞前体细胞增殖的化合物和1种促进少突胶质细胞分化的物质。最后，采用脱髓鞘动物模型，在体验证了极化小胶质细胞的促进复髓鞘的效率。这部分工作由于应用老年动物，在体动物研究工作量大，需要做电镜观察，试验周期很长，结果正在准备投稿。预计2018年发表论文。本项目结果表明，抗体引导的定向纳米颗粒载药技术具有缓释、保鲜、定向释放等优点，在髓鞘损伤修复等再生医学中具有重要的应用前景。..研究内容2：基底前脑胆碱能神经元对多种神经功能有调节作用，那么，基底前脑胆碱能神经元是否对脓毒症引起的炎症反应是否有作用？为探索这一问题，我们采用光遗传技术，特异激活基底前脑胆碱能神经元，结果发现激活基底前脑胆碱能神经元对严重的全身性炎症-脓毒症具有显著的抗炎效应，这一结果为脓毒症的治疗提供了新的思路，为刺激脑区来抗炎提供了新的作用靶点，具有潜在的重要临床应用前景。这篇论文的创新性在于首次报道了刺激基底前脑胆碱能神经元具有显著的抗炎效应。论文发表于重症医学领域的顶级期刊Critical Care Medicine (Impact Factor 7.4) 上。

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