Aloisi F, Agresti C, D'Urso D, Levi G
Istituto Superiore di Sanita, Neurobiology Section, Rome, Italy.
Proc Natl Acad Sci U S A. 1988 Aug;85(16):6167-71. doi: 10.1073/pnas.85.16.6167.
The differentiation of bipotential precursors of oligodendrocytes (OL) and type-2 astrocytes (AS) was followed in primary cultures from 8-day postnatal rat cerebellum by labeling the cells with the antibodies LB1 (which binds to the surface disialoganglioside GD3 present in glial precursors, type-2 AS, and immature OL), O4 (a marker of immature and mature OL binding to surface sulfatide), anti-galactocerebroside (GalCer, a marker of OL), and anti-glial fibrillary acidic protein (GFAP, a marker of AS). Two hours after plating, hardly any LB1+, GFAP+ cells were detectable, 40% of the O4+ cells were GalCer+, and none of the O4+ cells were GFAP+. Upon culturing cells plated at a density of 1 x 10(5) cells per cm2 in the presence of fetal calf serum, most of the LB1+ precursors differentiated into type-2 AS, even if most of them had already expressed the O4 antigen. Thus, in culture, most type-2 AS seem to derive from progenitor cells that were differentiating in vivo into OL. In higher density cultures (2.5 x 10(5) cells per cm2), however, many precursors differentiated into GalCer+ OL, rather than into AS. As a possible source of the signals responsible for the behavior of the glial precursors in high-density cultures, we focused our attention on type-1 AS, the most abundant cell type in the cultures. We found that, in low-density cultures maintained for 5-7 days in a medium conditioned by type-1 AS, the proliferation of the precursors was enhanced and their differentiation into OL or AS was prevented. In contrast, when cerebellar cells were coplated with type-1 AS dissociated from purified cultures, not only did the precursors proliferate more than in control cultures, but also a larger proportion of them differentiated into GalCer+ OL. In conclusion, type-1 AS appear to facilitate the differentiation of bipotential glial precursors into OL through direct cell-cell interactions. The influence of type-1 AS on the differentiation of the LB1+ and O4+ precursors is supported also by experiments with glial cortical cultures.
通过用抗体LB1（与神经胶质前体细胞、2型星形胶质细胞和未成熟少突胶质细胞表面存在的双唾液酸神经节苷脂GD3结合）、O4（一种与表面硫酸脑苷脂结合的未成熟和成熟少突胶质细胞标志物）、抗半乳糖脑苷脂（GalCer，少突胶质细胞标志物）和抗神经胶质纤维酸性蛋白（GFAP，星形胶质细胞标志物）对细胞进行标记，在出生后8天大鼠小脑的原代培养物中追踪少突胶质细胞（OL）和2型星形胶质细胞（AS）双能前体细胞的分化。接种后两小时，几乎检测不到LB1+、GFAP+细胞，40%的O4+细胞是GalCer+，且没有O4+细胞是GFAP+。在含有胎牛血清的条件下，以每平方厘米1×10⁵个细胞的密度接种细胞进行培养时，即使大多数LB1+前体细胞已经表达了O4抗原，它们中的大多数仍分化为2型星形胶质细胞。因此，在培养中，大多数2型星形胶质细胞似乎来源于在体内正向少突胶质细胞分化的祖细胞。然而，在更高密度的培养物（每平方厘米2.5×10⁵个细胞）中，许多前体细胞分化为GalCer+少突胶质细胞，而不是星形胶质细胞。作为高密度培养物中负责神经胶质前体细胞行为的信号的可能来源，我们将注意力集中在1型星形胶质细胞上，它是培养物中最丰富的细胞类型。我们发现，在由1型星形胶质细胞条件培养基维持5 - 7天的低密度培养物中，前体细胞的增殖增强，并且它们向少突胶质细胞或星形胶质细胞的分化受到抑制。相反，当小脑细胞与从纯化培养物中分离的1型星形胶质细胞共培养时，不仅前体细胞的增殖比对照培养物中更多，而且它们中更大比例的细胞分化为GalCer+少突胶质细胞。总之，1型星形胶质细胞似乎通过直接的细胞间相互作用促进双能神经胶质前体细胞向少突胶质细胞的分化。大脑皮质神经胶质培养物实验也支持1型星形胶质细胞对LB1+和O4+前体细胞分化的影响。
