Torrente Y, El Fahime E, Caron N J, Del Bo R, Belicchi M, Pisati F, Tremblay J P, Bresolin N
Centro Dino Ferrari, Institute of Clinical Neurology, University of Milan, Milan, Italy.
Cell Transplant. 2003;12(1):91-100. doi: 10.3727/000000003783985115.
Migration of transplanted myogenic cells occurs during both embryogenesis and regeneration of skeletal muscles and is important for successful myoblast transplantation, but little is known about factors that promote chemotaxis of these cells. Tumor necrosis factor-alpha (TNF-alpha) is known to induce chemotactic effect on several cell types. In this study, we investigated its influence on the in vitro and in vivo motility of C2C12 and primary myoblasts. In the in vitro test performed in the blind-well Boyden chambers, we showed that TNF-alpha (50-400 U/ml) significantly enhanced the ability of myogenic cells to migrate. The dose-response curve for this factor was bell shaped, with maximum activity in the 200 U/ml range. In the in vivo test, intramuscular administration of TNF-alpha was performed by an Alzet pump connected to a perforated polyethylene microtube inserted in the tibialis anterior (TA) of CD1 mice. In these experiments, myoblasts were injected under the muscle epimysium. The recipient mice were immunosuppressed with FK506. Our results showed that, 5 days after myoblast transplantation, cells migrated further in the muscles infused with TNF-alpha than in the muscles not exposed to TNF-alpha. TNF-alpha not only has a chemotactic activity but may also modify cell migration via its action on matrix metalloproteinase (MMP) expression. The proteolytic activities of the MMPs secreted in the muscles were thus also assessed by gelatin zymography. The results showed an increased of MMP-2 and MMP-9 transcripts in the TNF-alpha-infused muscles injected with myogenic cells. Myoblast migration during transplantation may be enhanced by overlapping gradients of several effector molecules such as TNF-alpha, interferon-gamma (INF-gamma), and interleukins, released at the site of muscle injury. We propose that TNF-alpha may promote myoblast migration directly through chemotactic activity and indirectly by enhancing MMP activity at the site of muscle injury.
移植的成肌细胞迁移发生在胚胎发育和骨骼肌再生过程中，对成肌细胞移植的成功至关重要，但对于促进这些细胞趋化性的因素知之甚少。已知肿瘤坏死因子-α（TNF-α）对几种细胞类型具有诱导趋化作用。在本研究中，我们调查了其对C2C12和原代成肌细胞体外和体内运动性的影响。在盲孔博伊登小室中进行的体外试验中，我们发现TNF-α（50-400 U/ml）显著增强了成肌细胞的迁移能力。该因子的剂量反应曲线呈钟形，在200 U/ml范围内活性最高。在体内试验中，通过连接到插入CD1小鼠胫前肌（TA）的多孔聚乙烯微管的Alzet泵进行TNF-α的肌肉内给药。在这些实验中，将成肌细胞注射到肌外膜下。受体小鼠用FK506进行免疫抑制。我们的结果表明，成肌细胞移植5天后，在注入TNF-α的肌肉中细胞迁移比未暴露于TNF-α的肌肉中更远。TNF-α不仅具有趋化活性，还可能通过其对基质金属蛋白酶（MMP）表达的作用来改变细胞迁移。因此，还通过明胶酶谱法评估了肌肉中分泌的MMP的蛋白水解活性。结果显示，在注射了成肌细胞的注入TNF-α的肌肉中，MMP-2和MMP-9转录本增加。移植过程中成肌细胞的迁移可能通过在肌肉损伤部位释放的几种效应分子如TNF-α、干扰素-γ（INF-γ）和白细胞介素的重叠梯度而增强。我们提出，TNF-α可能直接通过趋化活性促进成肌细胞迁移，并通过增强肌肉损伤部位的MMP活性间接促进迁移。
