胶质细胞干细胞/前体细胞特性的研究进展

Glial cells function as neural stem cells and progenitor cells

胶质细胞是脑内数量最多的神经细胞,包括星形胶质细胞、少突胶质前体细胞、NG2胶质细胞等多种类型,具有维持神经系统内环境稳态、支持和营养神经元、调控神经信号传导等多种重要功能。近年来,随着研究的深入,越来越多的证据表明某些特定的胶质细胞在一定条件下表现出干细胞的特性,发挥干细胞的功能。例如,在病理损伤条件下,星形胶质细胞和少突胶质前体细胞均会被活化而出现增殖、分化,体外分离培养可自我更新形成神经球。这些活化的星形胶质细胞和少突胶质前体细胞形成的神经球能够被诱导分化为星形胶质细胞、少突胶质细胞和神经元。此外,通过强制性表达外源基因能将星形胶质细胞和NG2胶质细胞转分化为神经元,这可能也是其干细胞特性的一种体现。本文在已有研究的基础上,总结了放射状胶质细胞、少突胶质前体细胞、星形胶质细胞、NG2胶质细胞与其它类型胶质细胞的干细胞特性、干细胞特性形成的条件、它们可能产生的子代细胞以及涉及的分子信号调控通路。深入探讨胶质细胞的干细胞特性及生理功能,有利于促进其在神经系统损伤修复领域的临床应用。

Glial cells, including astrocytes, oligodendrocyte progenitor ceils （OPCs）, NG2-glia, etc, are broadly distributed throughout the central nervous system （CNS）. Also, it has been well known that glial cells play multi-roles in physiological and pathological pro- cesses in the CNS, such as maintaining homeostasis, providing neurotrophins for neurons and regulating neural signal transmission. Recently, increasing evidence showed that glial cells may also function as neural stem/progenitor cells and contribute to adult neuro- genesis or neuroregeneration. In pathological conditions, for instance, astrocytes and OPCs could be activated to proliferate and differ- entiate. When cultured in vitro, they could form neurospheres which possess the ability to differentiate into astrocytes, oligodendro- cytes and neurons. Additionally, forced expression of exogenous genes in astrocytes and NG2-glia can successfully reprogram them into neurons, which may also be suggestive of their stem/progenitor cell features. Here, we review current knowledge of the stem cell- like properties of glial ceils, including what types of glial cells can function as stem/progenitor cells, how they can acquire the stem/ progenitor potential and what progenies can be produced. These insights may foster a better understanding of glial cell biology and function in physiological or pathological processes in the CNS and lead to the idea of using the stem/progenitor-like glial cells as endogenous cell source for neural repair.