研究人员发现发展大脑中的神经元干细胞

2001年2月15日纽约，2001年2月15日 - 有助于导致更好地了解和治疗脑疾病的脑病，哥伦比亚研究人员已经确定了一种脑细胞，在大脑的大多数先进地区产生神经元的脑细胞。在FeBuarary第9期的性质上发表的研究表明，这种称为桡骨神经胶质细胞的这种类型的细胞可以在大脑发育过程中产生其他新皮质细胞，并以名为柱的组排列，是Neocortex的基本处理单元。因此，桡骨胶质细胞或桡骨细胞是Neocortex中的一种神经元干细胞。也就是说，它们产生接收，处理和发送信息的各种其他类型的单元格。该发现可以显着辅助干细胞研究，该研究研究了这种前体细胞如何用于重新创建由中风，创伤，神经退行性疾病和其他事件缺失或受损的脑区域。研究人员说，在胚胎中发生径向神经胶质细胞产生和组织新科奇的初始过程。但他们补充说，但在大脑的其他部分和后来的其他部分中可能发生类似的东西。这种可能性可以在去年惊吓科学家的发现中揭示：大脑在整个生命中产生新的细胞，而不仅仅是在持续的前。"Our study... raises the possibility that radial glia should be examined for their potential to generate neurons [brain cells] later in life," said Arnold R. Kriegstein, M.D., Ph.D., professor of neurology and pathology in the Center for Neurobiology and Behavior, Columbia University College of Physicians & Surgeons. "If you can encourage the injured brain to generate neurons, you may be able to promote recovery." Ultimately, the findings could aid research on diseases that may reflect problems in neocortical development and organization, such as epilepsy, mental retardation, schizophrenia, dyslexia, and attention deficit disorder, Kriegstein said. The neocortex, usually called simply the cortex, is the main seat of thinking and reasoning in humans, a thin sheet of wrinkly tissue that covers the cerebral hemispheres, the top most part of the brain. It exists in all mammals, but it is most developed in humans. The cortex consists of millions of tiny distinct column-shaped regions, aptly called columns, side by side. Each column is a group of cells acting together as a processing unit, like a transistor in a computer. A group of columns also can work together to carry out a particular function, for instance, moving a finger or recalling a memory. In the embryo, each column grows starting from a group of precursor cells at its base. A precursor divides itself to create new cells. Most of the newcomers, as they mature, rise to sit on top of the column and of their previously created “sibling” cells – although some stray into other columns. As they rise, the cells crawl along long, thin fibers that serve as their guides, helping each find its proper place. The guide fibers are elongated arms of cells that sit at the bottom of the column. The Columbia group’s key finding is that the cells that provide the guiding fibers, the radial glial cells, are the same ones that generate the other cells. Each radial glial cell provides the guide fiber for its own progeny. Previously, scientists knew the radial glia provided the guide fiber, called a process, but not that it also produced the other cells in the column. Scientists incorrectly assumed that because these other cells are neurons, the type that conduct information, their parent cell could not be a radial glial cell, an entirely different cell type. The radial glia are part of a class of nervous system cells called glia, which support and electrically insulate the information-processing neurons. The researchers used several experiments to determine that the radial glia are neuronal stem cells involved in neocortical development. When researchers inserted a bit of DNA into the brains of living mouse embryos, the DNA invaded some brain cells and turned them bright green. This green color would be passed on to infected cell’s descendants, letting researchers identify lineages of related cells. Three days after starting the experiment, researchers found that a typical radial glial cell would have produced four or five immature neurons that were slowly crawling up the glial cell's process. A time-lapse movie, filmed as it occurred in thin slices of rat brain in a laboratory culture, provided the most direct evidence. Additional experiments confirmed it also happens in intact, living brains. This system appears to provide the foundation for how the developing cortex is organized, Dr. Kriegstein said. It also could be relevant in other parts of the brain and in adults. "Having shown radial glial cells produce neurons in cortex, one could speculate about whether this occurs elsewhere in the nervous system. Radial glia are also found elsewhere in adult brains, in areas where neurons are born in the adult. This may be a more general neural precursor cell." In addition, knowing that the radial glial cell produces the neurons in its column may be important for studying how information circuits form in the brain. The research was supported by the National Institutes of Health, the March of Dimes Birth Defects Foundation, the Lieber Center, and the Robert Lee and Clara Guthrie Patterson Trust.

###