Department of Neurosurgery, 3rd Faculty of Medicine, Charles University, Prague, Czech Republic.
BMC Neurosci. 2012 Jun 6;13:57. doi: 10.1186/1471-2202-13-57.
Vascular endothelial growth factor (VEGF) is not only a potent angiogenic factor but it also promotes axonal outgrowth and proliferation of Schwann cells. The aim of the present study was to quantitatively assess reinnervation of musculocutaneous nerve (MCN) stumps using motor and primary sensory neurons after plasmid phVEGF transfection and end-to-end (ETE) or end-to-side (ETS) neurorrhaphy. The distal stump of rat transected MCN, was transfected with plasmid phVEGF, plasmid alone or treated with vehiculum and reinnervated following ETE or ETS neurorrhaphy for 2 months. The number of motor and dorsal root ganglia neurons reinnervating the MCN stump was estimated following their retrograde labeling with Fluoro-Ruby and Fluoro-Emerald. Reinnervation of the MCN stumps was assessed based on density, diameter and myelin sheath thickness of regenerated axons, grooming test and the wet weight index of the biceps brachii muscles.
Immunohistochemical detection under the same conditions revealed increased VEGF in the Schwann cells of the MCN stumps transfected with the plasmid phVEGF, as opposed to control stumps transfected with only the plasmid or treated with vehiculum. The MCN stumps transfected with the plasmid phVEGF were reinnervated by moderately higher numbers of motor and sensory neurons after ETE neurorrhaphy compared with control stumps. However, morphometric quality of myelinated axons, grooming test and the wet weight index were significantly better in the MCN plasmid phVEGF transfected stumps. The ETS neurorrhaphy of the MCN plasmid phVEGF transfected stumps in comparison with control stumps resulted in significant elevation of motor and sensory neurons that reinnervated the MCN. Especially noteworthy was the increased numbers of neurons that sent out collateral sprouts into the MCN stumps. Similarly to ETE neurorrhaphy, phVEGF transfection resulted in significantly higher morphometric quality of myelinated axons, behavioral test and the wet weight index of the biceps brachii muscles.
Our results showed that plasmid phVEGF transfection of MCN stumps could induce an increase in VEGF protein in Schwann cells, which resulted in higher quality axon reinnervation after both ETE and ETS neurorrhaphy. This was also associated with a better wet weight biceps brachii muscle index and functional tests than in control rats.
血管内皮生长因子（VEGF）不仅是一种有效的血管生成因子，而且还能促进轴突的生长和雪旺细胞的增殖。本研究的目的是定量评估质粒 phVEGF 转染后肌皮神经（MCN）残端的再神经支配，使用运动和初级感觉神经元进行端对端（ETE）或端侧（ETS）神经吻合。将大鼠切断的 MCN 远端残端用质粒 phVEGF、质粒单独或用载体处理，然后进行 ETE 或 ETS 神经吻合 2 个月后进行转染。用荧光 Ruby 和荧光 Emerald 逆行标记后，估计重新支配 MCN 残端的运动和背根神经节神经元数量。根据再生轴突的密度、直径和髓鞘厚度、梳理试验和肱二头肌湿重指数评估 MCN 残端的再神经支配。
在相同条件下进行免疫组织化学检测显示，与仅转染质粒或用载体处理的对照组相比，转染质粒 phVEGF 的 MCN 残端 Schwann 细胞中 VEGF 增加。与对照组相比，ETE 神经吻合后，转染质粒 phVEGF 的 MCN 残端被数量适中的运动和感觉神经元重新支配。然而，转染质粒 phVEGF 的 MCN 残端的有髓轴突形态计量质量、梳理试验和肱二头肌湿重指数明显更好。与对照组相比，转染质粒 phVEGF 的 MCN ETS 神经吻合导致更多的运动和感觉神经元重新支配 MCN。值得注意的是，进入 MCN 残端的侧支芽数量增加。与 ETE 神经吻合一样，phVEGF 转染导致有髓轴突形态计量质量、行为测试和肱二头肌湿重指数显著提高。
我们的结果表明，MCN 残端的质粒 phVEGF 转染可以诱导 Schwann 细胞中 VEGF 蛋白的增加，这导致 ETE 和 ETS 神经吻合后轴突再神经支配的质量更高。这也与比对照组更好的肱二头肌湿重指数和功能测试相关。
