What Is a Neural Stem Cell?

Neural stem cells refer to neural stem cells, which have the potential to differentiate into neurons, astrocytes, and oligodendrocytes, which can generate a large number of brain cell tissues and self-renewal. And enough to provide a large population of brain tissue cells. ^[1]

Different classification according to differentiation potential and the type of daughter cells

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1.Release various kinds of tissues in the affected area

The traditional drug treatment is not satisfactory. Taking medicine can only temporarily control the disease. Once the medicine is stopped, the disease recurrence is even more serious. often

Cytokines are closely related to the proliferation and differentiation of neural stem cells. Different cytokines play an important role in the induction and differentiation of neural stem cells, but there is no cytokine that can induce neural stem cells to differentiate into functional nerve cells in vitro. Vegetarians, such as IL-1, IL-7, IL-9 and IL-11. Neurotrophic factors have an effect on the whole process of neural stem cell differentiation into terminal cells. If cultured neural stem cells are exposed to brain-derived neurotrophic factors, a large number of neural stem cells can

Neural stem cells

To show the characteristics of differentiated neurons. Growth factors such as epithelial growth factor, nerve growth factor, and basic fibroblast growth factor also affect neural stem cell differentiation. Neural stem cells have different effects on different types and concentrations of factors, and the combined application of multiple factors. The effects of the same factors are different at different stages of neural stem cell development and differentiation. For example, in the presence of epidermal growth factor and basic fibroblast growth factor, embryonic neural stem cells mainly differentiate into neurons, astrocytes and oligodendrocytes, and postnatal and adult brain neural stem cells, Regardless of the presence of epithelial growth factor and basic fibroblast growth factor, they mainly differentiate into astrocytes. These studies suggest that the induction of neural stem cells into functional cells by epithelial growth factor and basic fibroblast growth factor is complex.

Signal transduction is important in neural stem cell differentiation. As a signaling pathway, the Notch signaling system has not been fully elucidated. The Notch receptor is considered to be an integrated membrane protein, a conserved cell surface receptor, which is activated by contact with surrounding ligands, and its signaling pathway begins in the cytoplasmic region of the Notch receptor after binding to the ligand. It falls off the cell membrane and transfers to the nucleus, transmitting the signal to the downstream signal molecule. The signal transmission of this pathway is mainly through protein interactions, causing changes in transcription regulators or binding transcription regulators to target genes to achieve regulation of specific gene transcription. When the Notch pathway is activated, stem cells proliferate, and when Notch activity is inhibited, stem cells enter a differentiation program. These results indicate that finding a way to regulate the Notch signal pathway may precisely regulate the process and proportion of neural stem cells to differentiate into neural functional cells by changing Notch signals. In addition, the Janus kinase signal transduction transmitter and transcription activator (JAK-STAT) signaling system is also involved in the regulation of stem cells.

Application of neural stem cells: Neural stem cells play an important role in neural development and repair of damaged neural tissue. Neural stem cell transplantation is an effective method for repairing and replacing damaged brain tissue, and can rebuild some circuits and functions. In addition, neural stem cells can be used as gene vectors for gene therapy of intracranial tumors and other neurological diseases. The use of neural stem cells as gene therapy vectors makes up for some of the shortcomings of viral vectors. Wagner et al transplanted neural stem cells to the rat brain of Parkinson's disease model. The neural stem cells migrated in their brain tissue and repaired damaged brain tissue, and the tremor symptoms were significantly reduced. It may be that neural stem cells differentiate into dopaminergic neurons to play a therapeutic role. . Piccini and other neural tissue cells isolated from the aborted fetal brain were transplanted into the patient's brain to treat Parkinson's disease. As a result, more than half of the patients' symptoms were significantly improved, and the effect persisted. Multiple sclerosis is a neurological disease with a high incidence. In its rodent model, it was found that oligodendrocytes that produce myelin sheaths were destroyed or lost function. Neural stem cells were transplanted directly into the rat brain. A large-scale migration occurred in the brain. Among the differentiated oligodendrocytes, about 40% of the cells formed myelin sheaths, and their characteristics were very close to normal. Some of the animals receiving transplants also had typical symptoms. Improvement. Glioma is one of the difficulties in medical treatment. Surgical removal of the tumor is difficult and it is easy to relapse. Radiotherapy and chemotherapy have certain effects on the tumor. Because neural stem cells have a migration function, this property can be used to release drugs to the brain. Genetically modified mouse neural stem cells to secrete IL-4, which can activate the immune system and anti-tumor attacks on tumor cells. Experimental mice with gliomas received such cells and had a longer life span than before. The experimental mice treated were significantly prolonged. MRI imaging showed that the large tumors in the brains of the experimental mice showed signs of shrinking. Interestingly, even if the injected neural stem cells did not secrete IL-4, the experimental mice's lifespan would be extended. Ling et al. Believe that this is because neural stem cells can also secrete an unknown substance that can slow tumor cell division. In addition, neural stem cells also have certain practical value for judging the efficacy and toxicity of drugs. For example, neural stem cell culture technology can be used to observe the neural activity of certain natural compounds and synthetic compounds, providing a theoretical basis for the development of small molecule therapeutic drugs.

Problems in the application of neural stem cells: The vast majority of the established neural stem cell lines originate from rats, and there are obvious species between rats and humans.

Neural stem cells

Differences; insufficient sources of neural stem cells; some transplanted neural stem cells develop into brain tumors; non-selective expression of neural stem cells in transfection range and in situ regulation of transfected gene expression; the use of embryonic stem cells to replace neural stem cells has sociology and ethics Academic issues, etc. (The establishment of a neural stem cell line can provide neurons and glial cells indefinitely, solve the problem of insufficient fetal brain transplantation, avoid ethical disputes, and provide sufficient seed cells for replacement treatment after injury).

There is still much work to do about the source, isolation, culture and identification of neural stem cells, and the mechanism of neural stem cell induction, differentiation and migration needs further study. Through cell culture technology and genomic research, such as DNA microarray technology, to further determine the exact location of adult neural stem cells, drugs can be designed to specifically activate these cells. Further understanding the nature of neural stem cells and controlling differentiation genes. By regulating target genes, specific differentiated cells can be induced from neural stem cells to meet various needs. The discovery of lateral differentiation is of great significance to the research and application of neural stem cells. It is expected that neural stem cells can be isolated from autologous cells, which may solve the problem of the source of neural stem cells, and the application of neural stem cells will have broad prospects.