Ludwin S K, Szuchet S
Department of Pathology, University of Western Ontario, London, Canada.
Glia. 1993 Aug;8(4):219-31. doi: 10.1002/glia.440080402.
The ability of isolated mature post-myelination ovine oligodendrocytes to myelinate was investigated in tissue culture and in vivo. In culture, although the cells adhered preferentially to rat dorsal root ganglia (DRG) axons, sent out processes that encircled and wrapped them, proliferated, and synthesised myelin proteins (MBP), no myelination was found. This failure to find myelination occurred despite the fact that the oligodendrocytes both in the present experiments and in previous studies elaborated membranous structures that have been shown chemically and structurally to be similar to normal central nervous system myelin. These findings contrasted with those seen when neonatal rodent glial cells were added to similar DRG neuron cultures, in which myelination readily occurred. When the same adult ovine oligodendrocytes were transplanted into the brains of Shiverer mice, normal compact myelin was formed, proving that the cells were capable of myelination and suggesting that cross-species incompatibility was probably not a major factor in the lack of myelination in vitro. It is possible that the failure of ovine oligodendrocytes to myelinate DRG axons is due either to the relatively low number of supporting glial cells, such as astrocytes or microglia which may be necessary for satisfactory myelination, or that some other factor in the microenvironment is lacking; in any event, these results point to the complexity of oligodendrocyte-axon interactions. It is clear that each of the events, from adherence to proliferation to wrapping and the myelin compaction may be under the control of a different signal and may operate through a distinct mechanism, even though each process is dependent on the other. The results also point to the potential usefulness of this model system for deciphering such signals and mechanisms.
在组织培养和体内研究了分离的成熟髓鞘形成后绵羊少突胶质细胞的髓鞘形成能力。在培养中，尽管细胞优先黏附于大鼠背根神经节（DRG）轴突，发出环绕并包裹它们的突起，进行增殖并合成髓鞘蛋白（MBP），但未发现髓鞘形成。尽管在本实验和先前研究中，少突胶质细胞都形成了膜性结构，经化学和结构分析显示与正常中枢神经系统髓鞘相似，但仍未发现髓鞘形成。这些发现与将新生啮齿动物神经胶质细胞添加到类似的DRG神经元培养物中时的情况形成对比，在后者中髓鞘形成很容易发生。当将相同的成年绵羊少突胶质细胞移植到颤抖小鼠的大脑中时，形成了正常的致密髓鞘，证明这些细胞具有髓鞘形成能力，并表明跨物种不相容性可能不是体外缺乏髓鞘形成的主要因素。绵羊少突胶质细胞未能使DRG轴突形成髓鞘，可能是由于支持性神经胶质细胞（如星形胶质细胞或小胶质细胞）数量相对较少，而这些细胞对于令人满意的髓鞘形成可能是必需的，或者是微环境中缺乏其他某些因素；无论如何，这些结果表明少突胶质细胞与轴突相互作用的复杂性。显然，从黏附到增殖再到包裹和髓鞘压实的每一个事件都可能受不同信号的控制，并可能通过不同的机制起作用，尽管每个过程都相互依赖。这些结果还表明该模型系统在破译此类信号和机制方面具有潜在的用途。
