RESUMEN
The phenotypic differences among Duchenne muscular dystrophy patients, mdx mice, and mdx(5cv) mice suggest that despite the common etiology of dystrophin deficiency, secondary mechanisms have a substantial influence on phenotypic severity. The differential response of various skeletal muscles to dystrophin deficiency supports this hypothesis. To explore these differences, gene expression profiles were generated from duplicate RNA targets extracted from six different skeletal muscles (diaphragm, soleus, gastrocnemius, quadriceps, tibialis anterior, and extensor digitorum longus) from wild-type, mdx, and mdx(5cv) mice, resulting in 36 data sets for 18 muscle samples. The data sets were compared in three different ways: (1) among wild-type samples only, (2) among all 36 data sets, and (3) between strains for each muscle type. The molecular profiles of soleus and diaphragm separate significantly from the other four muscle types and from each other. Fiber-type proportions can explain some of these differences. These variations in wild-type gene expression profiles may also reflect biomechanical differences known to exist among skeletal muscles. Further exploration of the genes that most distinguish these muscles may help explain the origins of the biomechanical differences and the reasons why some muscles are more resistant than others to dystrophin deficiency.
Asunto(s)
Distrofina/genética , Regulación de la Expresión Génica , Mitocondrias Musculares/genética , Músculo Esquelético , Distrofia Muscular de Duchenne/genética , Animales , Distrofina/deficiencia , Perfilación de la Expresión Génica , Ratones , Ratones Endogámicos mdx , FenotipoRESUMEN
Cell-based therapy for Duchenne muscular dystrophy patients and mdx mice has proven to be a safe but ineffective form of treatment. Recently, a group of cells called muscle side population (SP) cells have been isolated based on their ability to efflux the DNA-binding dye Hoechst. To understand the potential of skeletal muscle SP cells to serve as precursors for muscle, SP cells from the two mice strains mdx(5cv) and C57BL/6N were isolated, transduced, and transplanted. Under coculture conditions with myogenic cells, some cells within the SP cell population can give rise to early Pax7-positive satellite cells and other later stage myogenic cells. Transduced SP cells were transplanted via the tail vein and were shown to successfully deliver enhanced GFP and human microdystrophin to the skeletal muscle of nonirradiated mdx(5cv) mice, thus demonstrating their ability to travel through the capillaries and enter into damaged muscle. These results demonstrate that i.v. delivery of genes via SP cells is possible and that these SP cells are capable of recapitulating the myogenic lineage. Because this approach shows definitive engraftment by using autologous transplantation of noninjured recipients, our data may have substantial implications for therapy of muscular dystrophy.
Asunto(s)
Distrofina/genética , Distrofina/metabolismo , Distrofia Muscular Animal/terapia , Mioblastos Esqueléticos/metabolismo , Mioblastos Esqueléticos/trasplante , Animales , División Celular , Células Cultivadas , Terapia Genética , Vectores Genéticos , Proteínas Fluorescentes Verdes , Humanos , Lentivirus/genética , Proteínas Luminiscentes/genética , Proteínas Luminiscentes/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos mdx , Distrofia Muscular Animal/metabolismo , Distrofia Muscular Animal/patología , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Regeneración , Transducción GenéticaRESUMEN
Adult bone marrow and skeletal muscle have been shown to contain a subpopulation of cells, called side population (SP) cells, that can be isolated with the fluorescence-activated cell sorter. We used a similar method to identify SP cells in the skin of adult mice. These cells express surface markers similar to SP cells isolated from skeletal muscle, but differ from bone marrow SP cells and do not express hematopoietic markers. When transplanted into nonirradiated mdx mice, nuclei from donor skin SP cells are found within myofibers that express dystrophin. Thus, adult skin SP cells can engraft in dystrophic skeletal muscle even in the absence of total body irradiation.