| Neural stem cells (NSCs) are defined as undifferentiated cells that are able to self-renew as well as generate the three major types of cells that constitute the central nervous system (CNS): neurons, astrocytes, and oligodendrocytes (pluripotency). It has long been believed that stem cells are not present in the adult mammalian central nervous system. However, many lines of recent evidence have violated this long-standing dogma and shown that adult brain cells do exist that exhibit the capacity both to self-renew and to generate differentiated progeny in vitro and in vivo. Furthermore, in addition to findings that demonstrate the presence of NSCs in the adult mammalian nervous system, there are strong evidences that neurogenesis persists into adulthood in the special area such as the olfactory bulb and hippocampus in the brain of mammals, including humans. This new evidence has precipitated enthusiastic discussions about the biological significance of NSCs and neurogenesis in adult mammalian brains: The presence of NSCs in the adult mammalian brain,.and the persistence of neurogenesis into adulthood in some specialized areas, led us to ask why the self-repairing activity of the adult mammalian CNS is so poor, despite the presence of endogenous NSCs. In fact, cells with NSCs-like properties are likely to occur throughout the adult CNS, but they are able to give rise to neurons in only a few restricted areas in vivo, i.e., the subventricular zone (SVZ) in the wall of the lateral ventricle and the subgranular zone of the hippocampal dentate gyrus. Very poor regenerative capability of the adult mammalian CNS could be explained as follows: first, theneuronal differentiation of endogenous NSCs may be inhibited by microenvironmental factors present in most areas of the adult CNS. Second, the number of endogenous NSCs could be too small to self-repair effectively. To overcome these difficulties, it would be helpful to pursue investigation into the elucidation of the regulatory mechanisms underlying the differentiation and self-renewal of NSCs, which would reveal how self-repairing neurogenesis is inhibited in the adult mammalian brain and might also enable us to activate the endogenous NSCs in situ or control the functional differentiation of transplanted NSCs.Due to the microenvironment of brains of animals, if we want to study the mechanisms of differentiation of NSCs, we had better culture and expanse NSCs in vitro. Now three methods have been established to culture NSCs: 1. the establishment of clonogenic expansion of NSCs by neurosphere formation. This excellent culture method enables us to define the NSCs experimentally and to quantify the multilineage potency and self-renewing ability of these cells. Furthermore, cultured in this method, NSCs can proliferate in an undifferentiated state in vitro, allowing them to be expanded mitotically and harvested in bulk. 2. clonol monolayer culture method. This culture system is not intended for the expansion of NSCs in vitro; instead, it provides a powerful method of assaying lineage potential starting from single NSCs or intermediate progenitor cells. 3. slice culture method. The roles and morphology of NSCs in the developing fetal cerebral cortex have been characterized dynamically by using this culture technique that can mimic the in vivo situation. In this experiments we wanted to observe the differentiation of NSCs responsing to stimulation in vitro, so we expected to culture NSCs with Reynolds's neurospheres culture method.Recent studies have indicated that μ -mercaptoethanol(BME), a kind of antioxidant, can induce bone marrow stromal cells from mesoderm to differentiate into neuron-like cells, and make them express neuron-specific enolase, NeuN,neurofilament-M, and tau. The retractile cell bodies extended long processes terminating in typical growth cones and filopodia. During the differentiation, expression of nestin was detected transiently. However, the role of BME in inducing the differentiation of NSCs hasn't been reported. In our ex...
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