小鼠大脑可塑性 z-bo 2020-11-06 314

　　The early brain is plastic, that is, the brain circuits are easily reorganized to promote learning. However, the brain loses most of its plasticity in adulthood, and it cannot quickly recover the lost functions after suffering an injury, such as a stroke. Scientists have now successfully restored early plasticity in the brains of adult mice by transplanting juvenile nerve cells—thus treating their vision that was severely damaged during the experiment.

　　A new study published in the May issue of "Neural" shows that neurologists led by Sunil Gandhi of the University of California, Irvine, transplanted mouse embryonic stem cells into the brains of other mice. These cells are mainly inhibitory neurons, which can inhibit brain activity. Before the study began, the first author of the paper Melissa Davis (Melissa Davis) once said: "Researchers generally doubt whether the adult brain can disperse, integrate and restore plasticity to these cells." Scientists have been experimenting for many years. Continuously improving their experimental methods, the Irvine research team finally got the answer: These cells can be integrated in the brain, triggering large-scale neural circuit reorganization and restoring the high plasticity in the early developmental stage. The results of nerve signal tests and water maze tests show that cells implanted in mice with visual impairment can restore normal vision.

　　Although scientists have not yet tested whether the transplantation technique can be used for other neurological diseases, they believe that this technique has the potential to be used for many diseases and injuries, depending on how the new nerve cells restore plasticity. Researchers are still unclear whether the restoration of brain plasticity comes from the proliferation of transplanted cells or whether they trigger the plasticity of existing neurons. If the latter is the case, then the treatment will promote the remodeling of neural circuits to heal severe brain damage or stroke.

　　Because this neuron works best in previous experiments, the research team used inhibitory neurons in the study. But this special nerve cell is also the most potential for clinical application, because many mental diseases and neurological diseases are related to the imbalance of stimulation and inhibition, including epilepsy, schizophrenia and chronic pain. An experimental team led by Stewart Anderson of the Perelman School of Medicine at the University of Pennsylvania found that implanting inhibitory neurons taken from healthy mice into disease model mice can improve their symptoms. This new method can cause large-scale changes in the brain, and may be able to completely eradicate the disease. For those who do not respond to medical treatment, “adopting bold therapies such as nerve cell transplantation may change their destiny,” Anderson said.

　　There are still serious obstacles to the transplantation of internal nerve cells in the human body. First, transplanting mouse stem cells into humans may not be safe and effective. Scientists still don’t know how to transform human stem cells into neuron precursor cells needed for surgery. In addition, it takes at least one month for the transplanted cells received in the mouse brain to mature; in theory, human cells take longer, or even several years.

　　Despite all the obstacles, the experts are still eager to make a breakthrough. They believe that transplanting neurons in the future can provide a cell-based therapy that can effectively treat or even cure diseases related to aging and developmental diseases.