Muscular dystrophies are groups of inherited progressive diseases of the muscle caused by mutations of diverse genes related to normal muscle function. Although there is no current effective treatment for these devastating diseases, various molecular strategies have been developed to restore the expressions of the associated defective proteins. In preclinical animal models, both viral and nonviral vectors have been shown to deliver recombinant versions of defective genes. Antisense oligonucleotides have been shown to modify the splicing mechanism of mesenger ribonucleic acid to produce an internally deleted but partially functional dystrophin in an experimental model of Duchenne muscular dystrophy. In addition, chemicals can induce readthrough of the premature stop codon in nonsense mutations of the dystrophin gene. On the basis of these preclinical data, several experimental clinical trials are underway that aim to demonstrate efficacy in treating these de-vastating diseases.
Codon, Nonsense ; Dystrophin ; Genetic Therapy ; Models, Animal ; Models, Theoretical ; Muscles ; Muscular Dystrophies ; Muscular Dystrophy, Duchenne ; Oligonucleotides, Antisense ; Proteins ; RNA

OBJECTIVE: To investigate the effect of exercise and steroid to the muscle of animal model of Duchenne muscular dystrophy. METHOD: We used 15 mdx and 15 control mice. To grade exercise loading, control and mdx mice were divided into free-living, exercise and immobilization groups. Free-living and exercise groups were further divided into steroid-treated and sham-treated groups to evaluate the effect of steroid administration. We measured the apoptotic changes using in situ DNA nick-end labling (TUNEL), DNA fragmentation assay and western blots for Bcl-2 and BAX. RESULT: With TUNEL method, the largest number of myonuclei became positive in sham-treated exercise group while apoptosis was significantly reduced in steroid-treated exercise group in mdx mice. Steroid-treated free-living group showed higher rate of apoptotic change than sham-treated free-living group. With western blots for Bcl-2 and BAX, the value of BAX/Bcl-2 ratio was highest in sham-treated exercise group and among free living mdx mice, it was higher in steroid-treated group than sham-treated one. CONCLUSION: Apoptosis can be minimized in free living condition while exercise loading or immobilization can cause apoptotic change in muscular dystrophy animal model. Steroid administration induces apoptosis in free living muscle and it alleviates apoptotic damage caused by exercise loading in mdx mice.
Animals ; Apoptosis* ; Blotting, Western ; DNA ; DNA Fragmentation ; Immobilization ; In Situ Nick-End Labeling ; Mice ; Mice, Inbred mdx* ; Models, Animal ; Muscle, Skeletal* ; Muscular Dystrophies ; Muscular Dystrophy, Duchenne ; Social Conditions

Duchenne muscular dystrophy (DMD) is an X-linked, recessive and lethal genetic disease, which usually caused by gene mutations and the underlying mechanisms are complicated and diverse. The causal gene of DMD is the largest one in human that locates in the region of Xp21.2, encoding dystrophin. Currently there is no effective treatment for DMD patients. The treatment of DMD depends on gene mutation and molecular mechanism study of the disease, which requires reliable disease models such as mdx mouse model. Recently, researchers have increasingly discovered gene therapy strategies for DMD, and the efficacy has been demonstrated in DMD animal models. In addition, induced pluripotent stem cell technology can provide patient-specific cell source, offering a new platform for mechanism and therapy study of DMD.
Animals ; Disease Models, Animal ; Dystrophin ; genetics ; Genetic Therapy ; trends ; Humans ; Induced Pluripotent Stem Cells ; Mice ; Mice, Inbred mdx ; genetics ; Muscular Dystrophy, Duchenne ; genetics ; therapy

OBJECTIVETo construct the retroviral vector containing human micro-dystrophin gene and detect the expression of human micro-dystrophin in mdx mice bone marrow-derived mesenchymal stem cells (MSCs) after retrovirus infection.

METHODSRetroviral vector for micro-dystrophin gene was constructed and transferred into the packing cell PA317 mediated by Lipofectamine 2000. The retroviral supernatant containing the target genes were subsequently used to infect mdx mice MSCs. Micro-dystrophin expression was examined by methods of immunofluorescence staining and reverse transcriptase-polymerase chain reaction.

RESULTSMicro-dystrophin retroviral vector was successfully constructed and transferred into PA317 cells, and 48 h after infection with the recombinant retrovirus in mdx mice MSCs, 319 bp fragment could be detected by electrophoresis in the RT-PCR products. The red particles could be detected in some infected mdx mice MSCs with immunofluorescence staining. CONCLUSION mdx mice MSCs infected with retrovirus containing micro-dystrophin gene can express micro-dystrophin protein.

Animals ; Bone Marrow Cells ; cytology ; metabolism ; Dystrophin ; biosynthesis ; genetics ; Humans ; Mesenchymal Stromal Cells ; cytology ; metabolism ; Mice ; Mice, Inbred mdx ; Muscular Dystrophy, Animal ; metabolism ; Retroviridae Infections ; Transfection

OBJECTIVETo investigate the dynamic changes of dystrophin expression in mdx mice after bone marrow stem cells transplantation.

METHODSThe bone marrow stem cells of C57 BL/6 mice (aged 6 to 8 weeks) were injected intravenously into the mdx mice (aged 7 to 9 weeks), which were preconditioned with 7Gy gamma ray. The amount of dystrophin;expression in gastrocnemius was detected by immunofluorescence, reverse transcription-polymerase chain reaction and Western blot at week 5, 8, 12 and 16 after transplantation.

RESULTSAt week 5 after bone marrow stem cells transplantation, the dystrophin expression detected in mdx mice were very low; however, its expression increased along with time. At week 16 week, about 12% muscle cells of all transplanted mice expressed dystrophin. There were less centrally placed myonuclei than the control mdx mice, whereas peripheral myonuclei increased.

CONCLUSIONSAfter having been injected into mdx mice, the allogenic bone marrow stem cells have a trend to reach the injured muscle tissues and differentiate to fibers that can express dystrophin and the expression increased with time. The bone marrow stem cells participates in the repair and regeneration of the injured tissues permanently and constantly.

Animals ; Bone Marrow Cells ; cytology ; metabolism ; Cell Differentiation ; Disease Models, Animal ; Dystrophin ; biosynthesis ; Hematopoietic Stem Cell Transplantation ; Male ; Mice ; Mice, Inbred C57BL ; Mice, Inbred mdx ; Muscular Dystrophy, Duchenne ; metabolism ; surgery ; Transplantation, Homologous

OBJECTIVETo investigate the differentiation of rat bone marrow mesenchymal stem cells (MSCs) into myocytes and their expression of dystrophin/utrophin after transplantation in mdx mice.

METHODSBrdU-labeled fifth-passage rat MSCs were transplanted in mdx mice with previous total body gamma irradiation (7 Gy). At 4, 8, 12 and 16 weeks after the transplantation, the mice were sacrificed to detect dystrophin/BrdU and utrophin expressions in the gastrocnemius muscle using immunofluorescence assay, RT-PCR and Western blotting. Five normal C57 BL/6 mice and 5 mdx mice served as the positive and negative controls, respectively.

RESULTSFour weeks after MSC transplantation, less than 1% of the muscle fibers of the mdx mice expressed dystrophin, which increased to 15% at 16 weeks. Donor-derived nuclei were detected in both single and clusters of dystrophin-positive fibers. Some BrdU-positive nuclei were centrally located, and some peripherally within myofibers. Utrophin expression decreased over time after transplantation.

CONCLUSIONThe myofibers of mdx mice with MSC transplantation express dystrophin, which is derived partially from the transplanted MSCs. Dystrophin expression from the transplanted MSCs partially inhibits the upregulation of utrophin in mdx mouse muscle, showing a complementary relation between them.

Animals ; Bone Marrow Cells ; cytology ; Cell Differentiation ; physiology ; Dystrophin ; genetics ; metabolism ; Mesenchymal Stem Cell Transplantation ; Mesenchymal Stromal Cells ; cytology ; Mice ; Mice, Inbred C57BL ; Mice, Inbred mdx ; metabolism ; Muscle Fibers, Skeletal ; cytology ; metabolism ; Muscular Dystrophy, Animal ; metabolism ; therapy ; Rats ; Utrophin ; metabolism