Mori Tetsuji, Buffo Annalisa, Götz Magdalena
Institute for Stem Cell Research, GSF-National Research Center for Environment and Health, D-85764 Neuherberg/Munich, Germany.
Curr Top Dev Biol. 2005;69:67-99. doi: 10.1016/S0070-2153(05)69004-7.
Astroglial cells are the most frequent cell type in the adult mammalian brain, and the number and range of their diverse functions are still increasing. One of their most striking roles is their function as adult neural stem cells and contribution to neurogenesis. This chapter discusses first the role of the ubiquitous glial cell type in the developing nervous system, the radial glial cells. Radial glial cells share several features with neuroepithelial cells, but also with astrocytes in the mature brain, which led to the name "radial glia." At the end of neurogenesis in the mammalian brain, radial glial cells disappear, and a subset of them transforms into astroglial cells. Interestingly, only some astrocytes maintain their neurogenic potential and continue to generate neurons throughout life. We discuss the current knowledge about the differences between the adult astroglial cells that remain neurogenic and act as neural stem cells and the majority of other astroglial cells that have apparently lost the capacity to generate neurons. Additionally, we review the changes in glial cells upon brain lesion, their dedifferentiation and recapitulation of radial glial properties, and the conditions under which reactive glia may reinitiate some neurogenic potential. Given that the astroglial cells are not only the most frequent cell type in an adult mammalian brain, but also the key cell type in the wound reaction of the brain to injury, it is essential to further understand their heterogeneity and molecular specification, with the final aim of using this unique source for neuronal replacement. Therefore, one of the key advances in the field of neurobiology is the discovery that astroglial cells can generate neurons not only during development, but also throughout adult life and potentially even after brain lesion.
星形胶质细胞是成年哺乳动物大脑中最常见的细胞类型，其多样功能的数量和范围仍在不断增加。它们最显著的作用之一是作为成年神经干细胞的功能以及对神经发生的贡献。本章首先讨论在发育中的神经系统中普遍存在的胶质细胞类型——放射状胶质细胞的作用。放射状胶质细胞与神经上皮细胞有几个共同特征，但也与成熟大脑中的星形胶质细胞有共同特征，这就导致了“放射状胶质细胞”这个名称。在哺乳动物大脑神经发生结束时，放射状胶质细胞消失，其中一部分转化为星形胶质细胞。有趣的是，只有一些星形胶质细胞保持其神经发生潜能，并在一生中持续产生神经元。我们讨论了目前关于仍具有神经发生能力并作为神经干细胞的成年星形胶质细胞与大多数明显已失去产生神经元能力的其他星形胶质细胞之间差异的知识。此外，我们回顾了脑损伤后胶质细胞的变化、它们的去分化以及放射状胶质细胞特性的重现，以及反应性胶质细胞可能重新启动一些神经发生潜能的条件。鉴于星形胶质细胞不仅是成年哺乳动物大脑中最常见的细胞类型，而且是大脑损伤伤口反应中的关键细胞类型，进一步了解它们的异质性和分子特征至关重要，最终目标是利用这一独特来源进行神经元替代。因此，神经生物学领域的一项关键进展是发现星形胶质细胞不仅在发育过程中，而且在成年期甚至脑损伤后都能产生神经元。
