人胚胎干细胞定向分化为神经前体细胞

Differentiation of Human Embryonic Stem Cells to Neural Progenitors

采用单层贴壁分化的方法在无血清条件下诱导同源饲养层培养的人胚胎干细胞定向分化,得到了高比例的神经前体细胞(97.5±0.83)%(P<0.05)。这些神经前体细胞具有分化为神经元、星形胶质细胞和少突胶质细胞的能力。在长期的传代培养中发现,随着培养时间的延长,nestin阳性的神经前体细胞比例下降,同时发育能力也发生了变化。在传代培养的早期,神经前体细胞发育为神经元的比例很高,几乎没有胶质细胞分化出来。随着培养时间的延长,胶质细胞的比例逐渐上升。这与体内神经系统的发育过程非常相似。进一步研究发现具有bHLH(basic helix-loop-helix)结构域的转录因子neurogenein2(Ngn2)和Olig2可能在这一变化中起重要作用。因此,人胚胎干细胞来源的神经前体细胞能够模拟体内神经发育的模式,为在体外研究人的神经发育和再生医学奠定了基础。

Human embryonic stem cells （hES）, derived from the inner cell mass of the pre-implantation embryo, may serve as a valuable experimental tool for early human neurogenesis, due to their capacity for multipotency and self-renewal. They may also provide an unlimited cell source for cell replacement therapy. Neural progenitors differentiated from hES cells have considerable therapeutic potential for use in drug screening studies, or cell-based therapies for neurodegenerative diseases, because of their ability to generate defined neuronal cell types. However, for clinical application, generating a highly purified and homologous population of neural progenitors from hES cells without contamination remains a challenge. In this study, we identified an adherent culture system for efficiently differentiating neural progenitors from hES cells, cultured on homogenous feeder layers. These neural progenitors can differentiate into neurons, astrocytes and oligodendrocytes. During prolonged propagation, similar to in vivo embryonic neural progenitors, the differentiation potential of the neural progenitors shifts from neuronal to glial fate. We demonstrated that the proneural transcription factor neurogenein2 （Ngn2）, and the basic helix-loop-helix transcription factor Olig2, are critical to the transition from neurogenesis to gliogenesis. Therefore, neural progenitors derived from hES cells can mimic the developmental pattern of the central nervous system and provide options for regeneration medicine.