Role of hepatic stem cells in skeletal muscle hypertrophy following tenotomy in a rat model

近年来，有报道称在肥大的骨骼肌纤维中含有许多额外的细胞核。目前还不清楚这些额外的细胞核来自何处，因此，我们检查了肥大肌纤维中这些额外细胞核的来源。在肌细胞的细胞质中观察到转基因大鼠的肝细胞，推测其细胞核可能来源于肝细胞的融合。以上结果提示肝干细胞向成肌细胞分化的可能性。因此，对正常大鼠肥大肌肉组织中肝干细胞的实际存在进行了检验。除了肝干细胞分化成成肌细胞的可能性外…观察到增生性肌肉组织中存在白蛋白阳性细胞。然后用肌原素抗体进行双重染色，以确认白蛋白阳性细胞是否为成肌细胞。结果显示，白蛋白阳性细胞也表达肌原蛋白，这是已知的特异性肌原细胞。因此，本研究的结果表明，在肌腱切断后肥厚的过程中，肝干细胞成为肌肉细胞并与现存肌肉融合。

Recently, it was reported that many additional nuclei are included in hypertrophied skeletal muscle fibers. It is still uncertain as to where these additional nuclei are derived from, and so, the source of these additional nuclei in the hypertrophied muscle fibers was examined. Hepatocytes from the GFP transgenic rat were observed in the cytoplasm of the muscle cells, and the possibility that the additional nuclei were derived from the fusion of hepatocytes was suggested. From the above results, the possibility of hepatic stem cells differentiating into myoblasts was suggested. Therefore, the actual existence of hepatic stem cells in the hypertrophied muscle tissue was examined in the normal rat. In addition to the possibility of hepatic stem cells differentiating into myoblasts.. The presence of albumin-positive cells in the hypertrophic muscle tissue was observed. Double-staining with a myogenin antibody was then performed in order to confirm whether the albumin-positive cells were myoblasts. It was revealed that the albumin-positive cells also expressed myogenin, which is known to be specific to myogenic cells. Thus, the results of this study suggest that hepatic stem cells become muscle cells and also fuse with exiting muscles during the process of hypertrophy following a tenotomy.