Siironen J, Sandberg M, Vuorinen V, Röyttä M
Department of Pathology and Medical Biochemistry, University of Turku, Finland.
Lab Invest. 1992 Jul;67(1):80-7.
The regeneration of transected peripheral nerve is thought to happen with the help of cell-cell and cell-extracellular matrix interactions. We studied the role of axon in controlling the expression of extracellular matrix genes in transected peripheral nerve.
Left sciatic nerves were transected in a total of 132 rats. In half of the animals, regeneration was allowed to occur, while in the other half regeneration was prevented. The expression of type I and III collagen and fibronectin genes was studied proximally and distally to the site of transection up to 8 weeks after the injury both with and without axonal reinnervation. For Northern blotting, the endoneuriums of 10 animals from both groups were used at each time point. For in situ hybridization, transverse sections of the nerves were used to observe cellular source of the mRNA. In addition, immunohistochemistry was performed in sequential sections in order to identify the cells expressing the studied extracellular matrix genes.
Northern hybridization showed the highest expression of type I and III collagens in the distal stumps of transected nerves 7 to 14 days after nerve transection both with and without axonal reinnervation. The proximal site of the injury showed strong expression of the extracellular matrix genes which lasted markedly longer than in the distal site. In situ hybridizations showed that epi-, peri-, and endoneurium are active for producing type I collagen. S-100 immunohistochemistry suggested that the cell type responsible for the production of type I collagen in the endoneurium during the peripheral nerve regeneration is endoneurial fibroblast.
During peripheral nerve regeneration the expression of the extracellular matrix genes does not seem to be simply related to the presence of axons. Endoneurial fibroblasts contribute to the production of collagen type I and apparently to that of fibronectin, which thus is not totally derived from plasma.
人们认为，横断的周围神经的再生是在细胞-细胞和细胞-细胞外基质相互作用的帮助下发生的。我们研究了轴突在控制横断的周围神经中细胞外基质基因表达方面的作用。
总共132只大鼠的左侧坐骨神经被横断。在一半的动物中，允许再生发生，而在另一半动物中，再生被阻止。在损伤后长达8周的时间里，在有和没有轴突再支配的情况下，研究了横断部位近端和远端I型和III型胶原蛋白以及纤连蛋白基因的表达。对于Northern印迹分析，在每个时间点使用两组中10只动物的神经内膜。对于原位杂交，使用神经的横切片来观察mRNA的细胞来源。此外，在连续切片上进行免疫组织化学，以鉴定表达所研究的细胞外基质基因的细胞。
Northern杂交显示，在神经横断后7至14天，无论有无轴突再支配，横断神经的远端残端中I型和III型胶原蛋白的表达最高。损伤的近端部位显示细胞外基质基因的强烈表达，其持续时间明显长于远端部位。原位杂交显示，神经外膜、神经束膜和神经内膜都积极参与I型胶原蛋白的产生。S-100免疫组织化学表明，在周围神经再生过程中，神经内膜中负责产生I型胶原蛋白的细胞类型是神经内膜成纤维细胞。
在周围神经再生过程中，细胞外基质基因的表达似乎并不简单地与轴突的存在相关。神经内膜成纤维细胞有助于I型胶原蛋白的产生，显然也有助于纤连蛋白的产生，因此纤连蛋白并非完全来自血浆。
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