| Stroke is the third largest cause of death and the leading cause of long-term disability in our country. And ischemic stroke is the most common type of cerebrovascular disorders. After acute cerebral infarction, the brain cells in the core will die in a short period of time. Thus lead to deficit of neurological function.Until now, there are no effective thrapy to it. How to rescue the dying neuron in penumbra is an important topic on research. Transplantation of nerve tissue, especially embryo neural stem cells, is considered to be a potential useful method in treatment of stroke.But moral problem and immunological rejection limited its use. Bone marrow stromal cells ( MSCs) are stem cells of nonhematopoietic tissues in bone marrow. These cells have the capacity of self-renewal and multipotentiality for differentiation. So, they can be used for cell and gene therapy. Because there is no moral problem and immunological rejection in autogenous MSCs transplantation, MSCs transplantation is more useful for treatment of related diseases. Some experiment researchs have discovered that MSCs can ameliorate neurological deficits after grafting into the ischemic brain of rats. It is proved that MSCs in vitro secret brain-derived neurotrophic factor (BDNF), and other neurotrophic factors continuously. These neurotrophic factors are essential for survival, growth and differentiation of cells. And it is also found that exogenous BDNF can upregulate the expression of TrkB, the receptor of BDNF, in neurons. The aim of our study is to explore whether the grafted MSCs in the brain play an important role in the protection of ischemia-reperfusion injured neurons through secretion of neurotrophic factors, such as BDNF. From the study on the relationship between MSCs and ischemia-reperfiision injured neurons, we focused the research on the protective effect of MSCs on ischemia-reperfusion injured neurons and its mechanism at the cellular and molecular levels. We also explored if purifed MSCs when transplanted into brain, could alleviate the neurological deficits in rats with ischemic brain injury through antiapoptotic and induction of angiogenesis.Part I The expression of BDNF in bone marrow stromal cells induced by injured hippocampal slices following ischemia-reperfusionBone marrow cells were obtained from adult male Sprague-Dawley (SD) rats. Then, MSCs were expanded, isolated, and purified. Cells used in the experiment were harvested from the fourth to sixth passage. Organotypic hippocampal slice cultures prepared from newborn rats were maintained in vitro for 9 days. Cultures were then exposed to 30 minutes of oxygen and glucose deprivation followed by oxygen-glucose re-supply to simulate ischemia-reperfusion. Experiments are divided into three groups: control group, ischemia-coculture group and normal-coculture group. Each group were cultured for 1, 3, and 7 days separately. Western blot and immunocytochemistry were applied to measure the expression of BDNF in MSCs.The results showed that: (1) BDNF was faintly expressed in cytoplasm of MSCs in control group.When MSCs were cocultured with hippocampal slices following ischemia-reperfusion, the expression of BDNF in MSCs was increased significantly as compared to that of control group and normal-coculture group (p<0.01, vs control group; /K0.05, 0.05, and 0.01, vs normal-coculture group on the first, third and seventh day of coculture separately).When cocultured with normal hippocampal slices , MSCs expressed BDNF at a lower level at any times of coculture.But its expression was also elevated on the third and seventh day of coculture compared to that of control group (p<0.05, 0.01 separately). (2) Western blot showed that BDNF was expressed in all groups. The result is similar to that of immunocytochemistry.Part II The protective effects of bone marrow stromal cells on hippocampal slices following ischemia-reperfusionBone marrow cells were obtained from adult male SD rats. Then, MSCs were expanded, isolated, and purified. Cells used in the experiment were harv...
|
PDF Full Text Request