Division of Neuroscience, University of Alberta, Edmonton, Alberta T6G 2S2, Canada.
Division of Neuroscience, University of Alberta, Edmonton, Alberta T6G 2S2, Canada.
Exp Neurol. 2021 Jul;341:113717. doi: 10.1016/j.expneurol.2021.113717. Epub 2021 Apr 8.
Schwann cells are essential for peripheral nerve regeneration but, over short distances in acellular nerve grafts, extracellular matrix (ECM) molecules can support growth. The ECM molecules are present also on denervated muscle surfaces where they can support nerve growth. In this study, we addressed the efficacy of the ECM molecules of denervated muscle to support nerve fiber regeneration and muscle reinnervation. In the hindlimb of Sprague-Dawley rats, the proximal stump of the transected posterior tibial nerve, was cross-sutured to the distal nerve stump (NN) of each of three denervated muscles, tibialis anterior, extensor digitorum longus, and soleus, or implanted onto the denervated muscles' surfaces (N-M), proximal or distal to the endplate zone. Recordings of muscle and motor unit (MU) isometric forces and silver/cholinesterase histochemical staining of longitudinal muscle cryosections were used to determine the numbers of reinnervated MUs and the spatial course of regenerating nerve fibers, respectively. MU numbers declined significantly after N-M (>50%) as compared to those after NN. Muscle forces were reduced despite each nerve reinnervating up to three times the normal MU muscle fiber number. Regenerating nerves 'streamed' from the N-M site either proximal or distal to endplate zones toward the denervated intramuscular endoneurial tubes, with reduced numbers reinnervating endplates. We conclude that there is preferential reinnervation through the endoneurial tube and that it is important to drive implanted nerve fibers to enter endoneurial tubes for optimal muscle reinnervation. Schwann cells play the essential role in guiding regenerating nerve fibers to reinnervate denervated muscle fibers.
许旺细胞对于周围神经再生是必需的，但在去细胞神经移植物的短距离内，细胞外基质（ECM）分子可以支持生长。 ECM 分子也存在于去神经的肌肉表面，在那里它们可以支持神经生长。在这项研究中，我们研究了去神经肌肉的 ECM 分子支持神经纤维再生和肌肉再支配的效果。在 Sprague-Dawley 大鼠的后肢中，横断的后胫神经的近端残端被交叉缝合到三个去神经肌肉（胫骨前肌、趾长伸肌和比目鱼肌）的远端神经残端（NN），或者植入到去神经肌肉的表面（N-M），近端或远端到终板区。记录肌肉和运动单位（MU）等长力和纵向肌肉冷冻切片的银/胆碱酯酶组织化学染色，分别用于确定再支配 MU 的数量和再生神经纤维的空间轨迹。与 NN 相比，N-M 后 MU 数量显著下降（>50%）。尽管每条神经再支配的 MU 肌纤维数量增加了多达三倍，但肌肉力量仍降低。再生神经从 N-M 部位向去神经的肌内神经内膜管的近端或远端“流动”，向去神经的肌内神经内膜管的再支配终板数量减少。我们得出结论，存在通过神经内膜管的优先再支配，并且对于最佳的肌肉再支配，将植入的神经纤维引导到神经内膜管中非常重要。许旺细胞在引导再生神经纤维再支配去神经的肌纤维方面发挥着至关重要的作用。
