Regeneration of muscle fibers after myoblast injection into dystrophic muscle

点击翻译按钮获取中文摘要

1. Muscle regeneration : Muscle regeneration was evoked by a cold injury on the surface of slow (the anterior latissimus dorsi) and fast (the posterior latissimus dorsi) muscles of adult chickens. In the fibers with nerves intact, troponin was expressed 1 day earlier than dystrophin and changed to its adult isoform more than 2 weeks after the stage when dystrophin exhibited the same appearance as that in normal fibers. Further, although regenerating fibers in denervated muscle switched on the expression of troponin similarly to those in innervated muscle, many of them again reverted to an embryonic state. However, no difference was found in the dystrophin expression between regenerating fibers with nerves intact and those with nerves resected. These results indicate that the expression of troponin and dystrophin genes is regulated independently during regeneration and that nerves are required for the full development of the former protein while unnecessary for the latter.2. Culture of dissociated myoblasts : Microinjection of actin an myosin into cardiomyocytes in vitro revealed that incorporation of these monomeric proteins occurred preferentially at immature portions of developing myofibrils, where connectin was distributed faintly and uniformly. It seems that polymerization of actin and/or the addition of newly formed actin filaments occur in assoiation with myosin filaments in myofibrils and these of myosin arise from the A-I junctional regions of myofibrils.3. Muscle fiber formation after C2 cell injection : PKH26-labelled C2 cells were injected into the tibialis anterior muscle of mice (ScN and mdx). These transferred C2 cells were seen to fuse with myoblasts of the host muscle fibers and formed chimera fibers. This method will be useful for further basic investigations of gene therapy of genetic muscle diseases.