Basic study for regenerative medicine in muscular dystrophy by myogenic stem cells

肌肉萎缩症是一种遗传性疾病，其特征是严重的肌肉退化和再生，导致严重的肌肉无力和日常生活残疾。从Duchenne肌营养不良症（DMD）的基因缺陷——肌营养不良蛋白（dystrophin）的克隆，分离出许多肌营养不良症的相关基因，部分阐明了导致这些疾病的复杂发病机制。然而，临床上安全有效的治疗这些疾病的方法尚未开发出来。骨髓间充质干细胞是一种独特的肌源性干细胞。在这里，我们研究骨髓移植（BMT）作为一种安全的血液系统疾病的治疗工具是否成为治疗肌肉萎缩症的潜在疗法。从绿色荧光蛋白（GFP）小鼠中分离出总骨髓细胞作为供体细胞。我们将这些细胞移植到两种类型的肌肉萎缩症中…肌营养不良蛋白缺陷型DMD模型小鼠（mdx）和层粘连蛋白-α2缺陷型1A型先天性肌营养不良模型小鼠（dy）。除了mdx小鼠中一些GFP阳性肌纤维中的肌营养不良蛋白恢复外，BMT未能对肌肉性能和肌肉病理产生显著改善。与之形成鲜明对比的是，BMT显著延长了小鼠的寿命。BMT显著改善了dy小鼠包括呼吸肌在内的肌肉生理功能。免疫组化分析显示，超过60%的肌纤维呈gfp阳性，超过80%的肌纤维表达层粘连蛋白-α2。这些发现表明，一些基底膜破坏的肌营养不良症（如MDC 1A）比质膜破坏的肌营养不良症（如DMD）对BMT的反应更敏感。因此，我们进一步研究了BMT对另一种肌营养不良小鼠模型Fukuyama型先天性肌营养不良（Fukuyama type congenital muscular dystrophy， FCMD）的疗效，Fukuyama型先天性肌营养不良表现为严重的基底膜破坏。与mdx小鼠相比，BMT后ffcmd模型小鼠膈肌gfp阳性肌纤维增加。此外，我们发现对野生型小鼠肌肉基底膜破坏的处理显著增加了BMT后许多gfp阳性肌纤维。我们的研究结果可能为临床安全有效地治疗肌营养不良开辟了道路。少

Muscular dystrophies are inherited disorders characterized by severe muscular degeneration and regeneration, resulting in severe muscular weakness and disability in daily living. From the cloning of dystrophin, the gene deficient in Duchenne muscular dystrophy (DMD), many responsible genes for muscular dystrophies have been isolated and complex pathogenesis leading to these disorders have been partially clarified. Clinically safe and effective treatment of these disorders, however, has not been developed yet. Mesenchymal stem cells derived from bone marrow have shown to be a distinct population of myogenic stem cells. Here we investigated whether the bone marrow transplantation (BMT), which has been widely applied as a safe therapeutic tool for hematological disorders, become a therapeutic potential for muscular dystrophy. Total bone marrow cells from green fluorescent protein (GFP) mice have been isolated as donor cells. We transplanted these cells into two types of muscular dystrophy … More models; dystrophin-deficient DMD model mice (mdx) and laminin-α2-deficient congenital muscular dystrophy type 1A (MDC1A) model mice (dy). BMT failed to produce significant improvement in muscle performance and muscular pathology, except for the restoration of dystrophin in some GFP positive myofibers in the mdx mice. In sharp contrast, BMT has led to a significant increase of life span in the dy mice. Physiological function of muscles including respiratory muscles in the dy mice has significantly improved by BMT. Immunohistochemical analysis of diaphragm from the dy mice after BMT, exhibited that over 60% myofibers were GFP-positive and over 80% myofibers expressed laminin-α2. These findings gave rise to a possibility that some muscular dystrophies with basement membrane disruption, such as MDC 1A were more responsive to BMT than those with plasma membrane disruption, such as DMD. Thus we further investigated the efficacy of BMT on another mouse model of muscular dystrophy, Fukuyama type congenital muscular dystrophy (FCMD), which showed severe basement membrane disruption. Compared to the mdx mice, the FCMD model mice showed increased GFP-positive myofibers in diaphragm after BMT. Additionally, we found that a treatment of basement membrane disruption in muscles of wild-type mice significantly increased many GFP-positive myofibers after BMT. Our results may open the avenue for clinically safe and effective treatment for muscular dystrophy by BMT. Less