Hu Ying, Arulpragasam Ajanthy, Plant Giles W, Hendriks William T J, Cui Qi, Harvey Alan R
School of Anatomy and Human Biology, The University of Western Australia, Crawley, WA 6009, Australia.
Exp Neurol. 2007 Oct;207(2):314-28. doi: 10.1016/j.expneurol.2007.07.001. Epub 2007 Aug 8.
When grafted onto the cut optic nerve, chimeric peripheral nerve (PN) sheaths reconstituted with adult Schwann cells (SCs) support the regeneration of adult rat retinal ganglion cell (RGC) axons. Regrowth can be further enhanced by using PN containing SCs transduced ex vivo with lentiviral (LV) vectors encoding a secretable form of ciliary neurotrophic factor (CNTF). To determine whether other neurotrophic factors or different cell types also enhance RGC regrowth in this bridging model, we tested the effectiveness of (1) adult SCs transduced with brain-derived neurotrophic factor (BDNF) or glial cell line-derived neurotrophic factor (GDNF), and (2) fibroblasts (FBs) genetically modified to express CNTF. SCs transduced with LV-BDNF and LV-GDNF secreted measurable and bioactive amounts of each of these proteins, but reconstituted grafts containing LV-BDNF or LV-GDNF transduced SCs did not enhance RGC survival or axonal regrowth. LV-BDNF modified grafts did, however, contain many pan-neurofilament immunolabeled axons, many of which were also immunoreactive for calcitonin gene-related peptide (CGRP) and were presumably of peripheral sensory origin. Nor-adrenergic and cholinergic axons were also seen in these grafts. There were far fewer axons in LV-GDNF engineered grafts. Reconstituted PN sheaths containing FBs that had been modified to express CNTF did not promote RGC viability or regeneration, and PN reconstituted with a mixed population of SCs and CNTF expressing FBs were less effective than SCs alone. These data show that both the type of neurotrophic factor and the cell types that express these factors are crucial elements when designing bridging substrates to promote long-distance regeneration in the injured CNS.
当移植到切断的视神经上时，用成年雪旺细胞（SCs）重建的嵌合周围神经（PN）鞘可支持成年大鼠视网膜神经节细胞（RGC）轴突的再生。通过使用含有经慢病毒（LV）载体离体转导的SCs的PN，可进一步增强再生，该慢病毒载体编码一种可分泌形式的睫状神经营养因子（CNTF）。为了确定其他神经营养因子或不同细胞类型是否也能增强这种桥接模型中的RGC再生，我们测试了以下两种情况的有效性：（1）用脑源性神经营养因子（BDNF）或胶质细胞系源性神经营养因子（GDNF）转导的成年SCs，以及（2）经基因改造以表达CNTF的成纤维细胞（FBs）。用LV-BDNF和LV-GDNF转导的SCs分泌了可测量且具有生物活性的这些蛋白质，但含有LV-BDNF或LV-GDNF转导的SCs的重建移植物并未增强RGC的存活或轴突再生。然而，LV-BDNF修饰的移植物中确实含有许多泛神经丝免疫标记的轴突，其中许多轴突对降钙素基因相关肽（CGRP）也有免疫反应，推测其来自外周感觉神经。在这些移植物中也可见去甲肾上腺素能和胆碱能轴突。在LV-GDNF工程化的移植物中轴突要少得多。含有经修饰以表达CNTF的FBs的重建PN鞘并不能促进RGC的存活或再生，并且用SCs和表达CNTF的FBs的混合群体重建的PN比单独使用SCs的效果要差。这些数据表明，在设计促进受损中枢神经系统长距离再生的桥接底物时，神经营养因子的类型以及表达这些因子的细胞类型都是关键因素。
