小鼠急性缺血性脑中风后小胶质细胞增生来源的研究

发布时间：2018-04-28 02:03

本文选题：脑中风 + 小胶质细胞增生　；参考：《兰州大学》2013年博士论文

【摘要】：小胶质细胞是中枢神经系统(Central nervous system, CNS)重要的免疫效应细胞,它们通过监测微环境的变化,参与维持中枢神经系统的稳态平衡。缺血性脑中风能引起小胶质细胞的迅速激活,活化小胶质细胞在形态、抗原表达、功能行为等方面发生改变,尤其是他们在损伤区发生细胞增殖和聚集现象,小胶质细胞的这些反应被称为“小胶质细胞增生”。目前对这些增殖的小胶质细胞的来源仍有争议,有研究者认为小胶质细胞增生主要是通过小胶质细胞的自我更新得以维持。而另外一些报道称骨髓来源的一些祖细胞参与了小胶质细胞增生的过程,但这些研究都是基于辐射骨髓移植动物模型,而辐射和骨髓移植可能会带来血脑屏障的破坏等人为的影响,因此这些现象在生理条件下能否发生仍不清楚。本论文利用中风这一通常病理条件下既有血脑屏障破坏的的疾病模型,研究了小胶质细胞在缺血后增生的主要来源。为了避免辐射等人为因素对动物正常生理活动的影响,本实验建立了两种血液嵌合模型,并利用双光子成像技术研究了缺血性脑中风后亚急性期内增殖小胶质细胞的起源和动态变化,以及诱导其激活和增殖的影响因素。本论文的研究结果表明,正常健康动物体内血液细胞无法通过完整的血脑屏障。然而脑中风血脑屏障受损后,少量血液来源的Cx3crlGFP/+细胞能迁移进入大脑实质。虽然这些迁入的细胞与脑实质内小胶质细胞一样有荧光标记,但是它们表现出与本地小胶质细胞不同的表型特征和动力学反应。缺血损伤后进入脑实质的血源细胞数量很少,前5天发生迁移的细胞数量增加,随后逐渐减少。由于这些迁移细胞无法进行自我增殖,并且随着损伤时间的推移逐渐发生凋亡,因此血源迁移细胞无法长期存活。与此相反,免疫组织化学染色和双光子活体成像结果显示,缺血激活的本地小胶质细胞持续向损伤区聚集并能进行分裂增殖,而且这些细胞在损伤后一周内保持持续增加的趋势。因此,本地小胶质细胞的自我增殖是小胶质细胞增生的主要来源。另外,研究还发现血源Cx3erlGFP/+细胞的迁移和本地小胶质细胞的激活和增殖与损伤区血脑屏障的开放范围有关。本论文的研究结果揭示了血源Cx3erlGFP/+迁移细胞和本地小胶质细胞代表着两类不同的细胞种群,这两类细胞可能具有不同的功能和治疗潜力。
[Abstract]:Microglia are important immune effector cells in central nervous system (CNS). They play an important role in maintaining the homeostasis of CNS by monitoring the changes of microenvironment. Ischemic stroke can cause the rapid activation of microglia, the activation of microglia in morphology, antigen expression, functional behavior and other changes, especially in the injured areas of cell proliferation and aggregation. These reactions in microglia are called microglial proliferation. At present, the origin of these proliferating microglia is still controversial. Some researchers believe that microglial proliferation is mainly maintained through the self-renewal of microglia. Other reports suggest that some progenitor cells from bone marrow are involved in the process of microglia proliferation, but these studies are based on radiation bone marrow transplantation animal models. Radiation and bone marrow transplantation may result in the damage of blood-brain barrier and so on, so it is not clear whether these phenomena can occur under physiological conditions. In this study, the main sources of microglia proliferation after ischemia were studied by using the model of stroke, which is a common pathological disease with the destruction of the blood-brain barrier. In order to avoid the effects of human factors such as radiation on the normal physiological activities of animals, two blood chimeric models were established. The origin and dynamic changes of proliferative microglia during the subacute phase after ischemic stroke and the factors influencing their activation and proliferation were studied by using two-photon imaging technique. The results of this study suggest that blood cells in healthy animals cannot pass through the complete blood-brain barrier. However, after stroke the blood-brain barrier is damaged, a small number of blood-derived Cx3crlGFP/ cells can migrate into the brain's parenchyma. Although these migrating cells have the same fluorescence labeling as microglia in brain parenchyma, they exhibit different phenotypic characteristics and dynamic responses than native microglia. The number of hematopoietic cells entering the cerebral parenchyma was very small after ischemia injury, and the number of cells migrating increased in the first 5 days, then decreased gradually. These migration cells could not survive for a long time because they could not self-proliferate and apoptosis gradually occurred with the damage time. In contrast, immunohistochemical staining and two-photon imaging showed that ischemic activated native microglia continued to accumulate into the damaged area and to divide and proliferate. And these cells continued to increase for a week after injury. Therefore, the self-proliferation of native microglia is the main source of microglial proliferation. In addition, we also found that the migration of blood-derived Cx3erlGFP/ cells and the activation and proliferation of native microglia were related to the opening of blood-brain barrier. The results of this study reveal that Cx3erlGFP/ migration cells and native microglia represent two different cell populations, and these two types of cells may have different functions and therapeutic potential.
【学位授予单位】：兰州大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：R743.3

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