ABSTRACT
BACKGROUND: Satellite cells are tissue-specific stem cells primarily responsible for the regenerative capacity of skeletal muscle. Satellite cell function and maintenance are regulated by extrinsic and intrinsic mechanisms, including the ubiquitin-proteasome system, which is key for maintaining protein homeostasis. In this context, it has been shown that ubiquitin-ligase NEDD4-1 targets the transcription factor PAX7 for proteasome-dependent degradation, promoting muscle differentiation in vitro. Nonetheless, whether NEDD4-1 is required for satellite cell function in regenerating muscle remains to be determined. RESULTS: Using conditional gene ablation, we show that NEDD4-1 loss, specifically in the satellite cell population, impairs muscle regeneration resulting in a significant reduction of whole-muscle size. At the cellular level, NEDD4-1-null muscle progenitors exhibit a significant decrease in the ability to proliferate and differentiate, contributing to the formation of myofibers with reduced diameter. CONCLUSIONS: These results indicate that NEDD4-1 expression is critical for proper muscle regeneration in vivo and suggest that it may control satellite cell function at multiple levels.
Subject(s)
Muscle, Skeletal/metabolism , Proteasome Endopeptidase Complex/metabolism , Stem Cells , Ubiquitins/metabolism , Cell Differentiation , Muscle Development/physiology , Cell Proliferation/physiology , PAX7 Transcription Factor/genetics , PAX7 Transcription Factor/metabolismABSTRACT
Muscle fibres are multinuclear cells, and the cytoplasmic territory where a single myonucleus controls transcriptional activity is called the myonuclear domain (MND). MND size shows flexibility during muscle hypertrophy. The MND ceiling hypothesis states that hypertrophy results in the expansion of MND size to an upper limit or MND ceiling, beyond which additional myonuclei via activation of satellite cells are required to support further growth. However, the debate about the MND ceiling hypothesis is far from settled, and various studies show conflicting results about the existence or otherwise of MND ceiling in hypertrophy. The aim of this review is to summarise the literature about the MND ceiling in various settings of hypertrophy and discuss the possible factors contributing to a discrepancy in the literature. We conclude by describing the physiological and clinical significance of the MND ceiling limit in the muscle adaptation process in various physiological and pathological conditions.
Subject(s)
Humans , Muscle Fibers, Skeletal/physiology , Hypertrophy/pathology , Muscle, SkeletalABSTRACT
ABSTRACT Introduction: Skeletal muscle satellite cells are considered the unique source of stem cells for myogenic differentiation of adult skeletal muscle cells. Upon stimulation, the skeletal muscle satellite cell can be activated through specific signaling pathways, proliferate and differentiate into a muscle cell. An analysis of the effects of key signaling pathways could provide the basis for an in-depth study of skeletal muscle formation in athletes and muscle development. Objective: This paper analyzes the effects of key signaling pathways on skeletal muscle satellite cell proliferation and differentiation. Methods: We divided 32 athletes into four groups: control, stretching, experimental, and mixed groups. The control group received no training at all, the stretching group and the experimental group received stretching training on the right gastrocnemius. The mixed group also got weight climbing training in the stretching training, initial load 30% of the athlete's weight, increasing 25% each week until 100% of body weight, at the frequency of 3 times a week. After training, gene expression of live satellite cells was measured by intramuscular signaling. Results: The FGM level of the antagonistic group (3.56±0.21) was higher than in the control group (3.25±0.18). The gene expression of HGF mRNA was higher in the mixed group (2.16±0.24) followed by the antagonistic group (2.02±0.15), the stretching group (1.81±0.25), and the control group (1.03±0.06). Conclusion: Both stretching and antagonistic training can increase gene expression in signaling pathways. Antagonistic training significantly increased the expression of HGF, MGF, and mRNA. This activity can promote muscle bulking and skeletal muscle enlargements. Evidence Level II; Therapeutic Studies - Investigating the result.
RESUMO Introdução: As células satélites musculares esqueléticas são consideradas a única fonte de células-tronco para a diferenciação miogênica das células musculares esqueléticas adultas. Após a estimulação, a célula satélite muscular esquelética pode ser ativada através de vias de sinalização específicas, proliferar e diferenciar-se em célula muscular. Uma análise sobre os efeitos das principais vias de sinalização poderia estabelecer as bases para um estudo aprofundado da formação muscular esquelética nos atletas e do desenvolvimento muscular. Objetivo: Este artigo analisa os efeitos das principais vias de sinal na proliferação e diferenciação das células satélites musculares esqueléticas. Métodos: Dividimos 32 atletas em quatro grupos. Grupos controle, alongamento, experimental e grupo misto. O grupo controle não recebeu treinamento algum, o grupo de alongamento e o grupo experimental receberam treinamento de alongamento no gastrocnêmio direito. O grupo misto também obteve treinamento de escalada com peso no treino de alongamento, carga inicial de 30% do peso do atleta, aumentando 25% em cada semana até 100% do peso corporal. Na frequência de 3 vezes por semana. Após os treinos, a expressão genética das células satélites vivas foi medida por intermédio da sinalização proveniente de coleta intramuscular. Resultados: O nível de MGF do grupo antagônico (3.56±0.21) foi maior que no grupo controle (3.25±0.18). A expressão gênica do mRNA HGF foi maior no grupo misto (2.16±0.24) seguido pelo antagônico (2.02±0.15), o grupo de alongamento (1.81±0.25) e o grupo controle (1.03±0.06) Conclusão: Tanto o treinamento de alongamento quanto o treinamento antagônico podem aumentar a expressão genética nas vias de sinalização. O treinamento antagônico aumentou significativamente a expressão de HGF, MGF e mRNA. Essa atividade pode promover volume e hipertrofia muscular. Nível de evidência II; Estudos terapêuticos - investigação dos resultados do tratamento.
RESUMEN Introducción: Las células satélite del músculo esquelético se consideran la única fuente de células madre para la diferenciación miogénica de las células musculares esqueléticas adultas. Tras la estimulación, la célula satélite del músculo esquelético puede activarse a través de vías de señalización específicas, proliferar y diferenciarse en una célula muscular. Un análisis sobre los efectos de las vías de señalización clave podría sentar las bases para un estudio en profundidad de la formación del músculo esquelético en los atletas y del desarrollo muscular. Objetivo: Este trabajo examina los efectos de las vías de señalización clave en la proliferación y diferenciación de las células satélite del músculo esquelético. Métodos: Dividimos a 32 atletas en cuatro grupos. Grupos de control, de estiramiento, experimentales y mixtos. El grupo de control no recibió ningún entrenamiento, el grupo de estiramiento y el grupo experimental recibieron un entrenamiento de estiramiento en el gastrocnemio derecho. El grupo mixto también recibió entrenamiento de escalada con pesas en el entrenamiento de estiramiento, con una carga inicial del 30% del peso del atleta, aumentando un 25% cada semana hasta el 100% del peso corporal. Con una frecuencia de 3 veces por semana. Tras el entrenamiento, se midió la expresión génica de las células satélite vivas mediante la señalización de la recogida intramuscular. Resultados: El nivel de FGM del grupo antagonista (3,56±0,21) fue mayor que en el grupo de control (3,25±0,18). La expresión génica del ARNm del HGF fue mayor en el grupo mixto (2,16±0,24), seguido del grupo antagonista (2,02±0,15), el grupo de estiramiento (1,81±0,25) y el grupo de control (1,03±0,06) Conclusión: Tanto el entrenamiento de estiramiento como el antagonista pueden aumentar la expresión génica en las vías de señalización. El entrenamiento antagónico aumentó significativamente la expresión de HGF, MGF y mRNA. Esta actividad puede promover el aumento de volumen muscular y la hipertrofia. Nivel de evidencia II; Estudios terapéuticos - Investigación de resultados.
ABSTRACT
Objective To investigate the effect of incremental load training on AMP-activated protein kinase (AMPK) phosphorylation in skeletal muscle satellite cells of aged mice. Methods Experimental mice were divided into 3 groups: young control group (YC group, n=12), old control group (OC group, n=12) and old training group (OT group, n=12). The mice in OT group received incremental load training, and CD45-/CD31-/Sca1-/VCAM (CD106) + cells were isolated by flow cytometry sorting. Desmin, Myod myogenic staining and myogenic differentiation culture were used for identification of muscle satellite cells, and the p-AMPK level of muscle satellite cells was detected by immunohistochemistry combined with Western blotting method. Results The expression levels of AMPK and p-AMPK in skeletal muscle satellite cells in YC group were significantly higher than those in OC group (P0.05), while p-AMPK expression level in OT group was significant higher than that in OC group (P<0.05). Conclusions Incremental load training can promote AMPK phosphorylation of skeletal muscle satellite cells in aged mice, and improve energy metabolism of skeletal muscle in aged mice.
ABSTRACT
BACKGROUND: Duchenne muscular dystrophy (DMD) is a devastating genetic muscular disorder with no effective treatment that is caused by the loss of dystrophin. Human induced pluripotent stem cells (hiPSCs) offer a promising unlimited resource for cell-based therapies of muscular dystrophy. However, their clinical applications are hindered by inefficient myogenic differentiation, and moreover, the engraftment of non-transgene hiPSC-derived myogenic progenitors has not been examined in the mdx mouse model of DMD. METHODS: We investigated the muscle regenerative potential of myogenic progenitors derived from hiPSCs in mdx mice. The hiPSCs were transfected with enhanced green fluorescent protein (EGFP) vector and defined as EGFP hiPSCs. Myogenic differentiation was performed on EGFP hiPSCs with supplementary of basic fibroblast growth factor, forskolin, 6-bromoindirubin-3'-oxime as well as horse serum. EGFP hiPSCs-derived myogenic progenitors were engrafted into mdx mice via both intramuscular and intravenous injection. The restoration of dystrophin expression, the ratio of central nuclear myofibers, and the transplanted cells-derived satellite cells were accessed after intramuscular and systemic transplantation. RESULTS: We report that abundant myogenic progenitors can be generated from hiPSCs after treatment with these three small molecules, with consequent terminal differentiation giving rise to mature myotubes in vitro. Upon intramuscular or systemic transplantation into mdx mice, these myogenic progenitors engrafted and contributed to human-derived myofiber regeneration in host muscles, restored dystrophin expression, ameliorated pathological lesions, and seeded the satellite cell compartment in dystrophic muscles. CONCLUSIONS: This study demonstrates the muscle regeneration potential of myogenic progenitors derived from hiPSCs using non-transgenic induction methods. Engraftment of hiPSC-derived myogenic progenitors could be a potential future therapeutic strategy to treat DMD in a clinical setting.
Subject(s)
Humans , Animals , Male , Mice , Muscular Dystrophy, Duchenne/therapy , Induced Pluripotent Stem Cells/transplantation , Cell Differentiation , Cells, Cultured , Green Fluorescent Proteins , Disease Models, Animal , Mice, Inbred C57BLABSTRACT
@#Introduction: Exercise-induced muscle injury stimulates production of proinflammatory cytokines, e.g., TNF-α, resulting in impaired satellite-cell-dependent muscle regeneration. Omega-3 fatty acids emerge to possess anti-inflammatory properties. This study aims to analyze the effect of omega-3 fish oil administration on the levels of TNF-α, MyoD and myogenin expressions of satellite cells after injury. Methods: Twenty-nine adult male Wistar rats were randomized into five groups. Except for control groups, the rats underwent single bout of downhill running exercise and three groups were given low-to-high doses of omega-3 fish oil administration 2 hours after exercise. Blood samples were collected after 24 hours to measure the concentration of TNF-α using ELISA and then the soleus muscles were surgically removed after 72 hours to measure mRNA expressions of MyoD and myogenin using RT-PCR. Results: The results showed lower serum levels of TNF-α (166.83 ± 16.15 vs. 132.83 ± 25.44, 125.00 ± 17.26, 99.66 ± 32.00 pg/mL) and higher expressions of MyoD (0.47 ± 0.19 vs. 0.64 ± 0.20, 1.17 ± 0.16, 1.07 ± 0.14) and myogenin (0.45 ± 0.10 vs. 1.82 ± 0.35, 1.50 ± 0.34, 0.76 ± 0.20) in groups given low-to-high doses of omega-3 fish oil supplementation, respectively, compared to exercise group with no supplement at 72 hours after exercise. Conclusion: Our study suggests that omega-3 fish oil supplementation following muscle injury may accelerate myogenin expression and a low dose of supplementation achieves optimal effect in promoting muscle regeneration. .
ABSTRACT
Objective:To study the effect of treadmill exercise and massage shortly after acute injury on expression of key growth factor in muscle satellite cells activation, insulin-like growth factor-1 (IGF-1), and mitogen-activated protein kinase (MAPK) / mitogen-activated protein kinase kinase (MEK) / extracellular regulated protein kinases (ERK)1/2 signaling pathways in muscle satellite cell in rats. Methods:A total of 40 SPF male adult Sprague-Dawley rats were randomly divided into groups A (n = 8), B (n = 8), C (n = 8), D (n = 8) and E (n = 8). Group A did not receive any treatment, while the other rats were contused the gastrocnemius muscle with self-made impactor. Group B received no intervention, groups C and D received massage and treadmill exercise shortly after injury, respectively, while group E received both treadmill exercise and massage shortly after injury. As the model was established, samples of gastrocnemius were obtained from all the rats 24 hours after injury, and observed under HE staining, detected the expression of MyoD1 and MyoG mRNA with reverse transcription polymerase chain reaction (RT-PCR), and expression of IGF-1, p-MAPK, p-MEK and p-ERKI/2 protein with Western blotting. Results:The expression of MyoD1 mRNA was more in groups C, D and E than in group B, which was the most in group C; less expression of MyoG mRNA, which was the most in group E (P < 0.05). The expression of p-MAPK, p-MEK and p-EPK1/2 was more in groups C, D and E than in group B, which was the most in group D (P < 0.05). The expression of IGF-1 increased in group C compared with that in group B (P < 0.05), and it decreased in group D (P < 0.05). Conclusion:Early intervention of treadmill exercise and massage may promote the activation of muscle satellite cells in different ways.
ABSTRACT
Objective:To investigate the effects and mechanism of Tuina on denervation-induced atrophy. Methods:A total of 42 Sprague-Dawley rats were randomly divided into sham group (n = 6), model group (n = 18) and Tuina group (n = 18). The model group and Tuina group freed and excised right tibia nerve about one centimeter, while the sham group freed the right tibia nerve only. From the second day after operation, Tuina group accepted Tuina on the injured area, while the sham group and the model group were only fixed without any intervention. Six rats were sacrificed on the 14th, 21st and 28th day after operation in the model and Tuina groups, and the sham group was sacrificed on the 28th day after operation. The gastrocnemius muscles were measured wet weight ratio. The diameter and area of muscle cells were measured under HE staining. The expression of Pax7, MyoD, MyoG, microRNA-1, microRNA-133a and microRNA-206 in the gastrocnemius muscles were detected with reverse transcription real-time quantitative polymerase chain reaction. Results:Compared with the sham group, the wet weight ratio, the area of muscle cells (except the 14-day-Tuina group) and the diameter of muscle cells decreased at each time point in the model group and Tuina group (P < 0.05); compared with the model group, the wet weight ratio, muscle cell diameter and muscle cell area increased at each time point in Tuina group (P < 0.05). Compared with the sham group, the expression of Pax7 increased in the 14-day-model group (P < 0.05) and decreased in the 28-day-model group (P < 0.05), and it increased at each time point (except 28-day) in Tuina group (P < 0.05); compared with the model group, the expression of Pax7 increased at each time point in Tuina group (P < 0.05). Compared with the sham group, the expression of MyoD and MyoG increased at each time point in the model group and Tuina group (P < 0.05); compared with the model group, the expression of MyoD and MyoG increased at each time point (except 14-day) in Tuina group (P < 0.05). Compared with the sham group, the expression of microRNA-1 and microRNA-133a decreased, and microRNA-206 increased in the model group and Tuina group at 21-day (P < 0.05); compared with the model group, the expression of microRNA-1, microRNA-133a and microRNA-206 increased in Tuina group (P < 0.05). Conclusion:Tuina may activate the Pax7/MyoD/MyoG pathway by increasing the expression of muscle-specific microRNA, to promote the proliferation and differentiation of muscle satellite cells, and delay denervation-induced atrophy.
ABSTRACT
Objective To observe the change pattern of pericyte number at different time periods after mice skeletal muscle contusion and discuss its role in wound age estimation. Methods A mice gastrocnemius muscle contusion model was established. The form and number changes of pericytes at 1, 3, 5, 7, 9, 14, and 28 d post-injury were detected by multiple immunofluorescence staining. Results Compared with the slender shape of pericytes in normal skeletal muscles, pericytes in the contusion area had increased volume, rounder form and a round nuclei. Part of pericytes were found to express satellite cell markers paired-box transcription factor （Pax7） or myoblast determination 1 （MyoD1）. The changes of pericyte number in skeletal muscles after contusion were time-dependant, and showed unimodal distribution with the extension of wound age. In the central contusion area, the number of pericytes peaked at 5 d post-injury while in the peripheral contusion area, the number of pericytes peaked at 5 d and 7 d post-injury. Conclusion The number of pericytes in contusion area varies time-dependently after skeletal muscle contusion in mice and might be a reference index for muscle wound age estimation, and is involved in the repair and regeneration of skeletal muscle injury.
Subject(s)
Animals , Mice , Contusions , Disease Models, Animal , Muscle, Skeletal , Pericytes , Rats, Sprague-DawleyABSTRACT
OBJECTIVE: To explore the effect of electroacupuncture (EA) serum on expression of myogenic differentiation antigen (Myod) and autophagy-related protein Beclin 1 in cultured muscle satellite cells of rats under starvation conditions. METHODS: The primary multifidus muscle satellite cells of one male SD rat were isolated and cultured to obtain the 3rd generation of cells. The EA serum was got from the rat received EA stimulation of bilateral "Weizhong" (BL40, 2 Hz/10 Hz, 1 mA, duration of 20 min, once daily for 7 days). The cell suspension (2×104/well) of the 3rd generation of cultured cells was transferred to each well of a 96-well plate in medium containing 10% fetal bovine serum (FBS). Twelve duplicate wells were set up for the blank control serum (without FBS), 10% FBS, 10% EA serum, 20% EA serum and 30% EA serum groups and incubated for 12 h and 24 h, respectively. Each well was supplemented with 10 µL CCK-8 reagent to be incubated for 1 h again for observing the state of cell proliferation. After culturing the primary muscle satellite cells in serum-free medium for 12 h, the cells were randomly divided into serum-free group, 10% fetal bovine serum group and optimal concentration electroacupuncture serum group, and serum of corresponding concentration was added respectively. The expression levels of Beclin 1 and cell-proliferation-related protein Myod were detected by Western blot. RESULTS: CCK-8 assay displayed that the proliferation levels were significantly higher at 12 h and 24 h after serum intervention in the 10% FBS, 10% EA serum, 20% EA serum and 30% EA serum groups than that in the blank control serum group (P0.05). As a result, 10% EA serum was selected as the optimal concentration for Western blot tests. No significant difference was found in the expression levels of Myod and Beclin 1 proteins among the serum-free, 10% FBS and 10% EA serum groups before intervention (P>0.05), and there was a marked up-regulation of Myod expression and an obvious down-regulation of Beclin 1 expression at 12 h in both the 10% EA serum and 10% FBS groups in comparison with their own pre-intervention (P0.05). CONCLUSION: EA serum can promote proliferation of cultured muscle satellite cells under starvation conditions, which is related to its functions in regulating expression of Beclin 1 and cell-proliferation-related protein Myod.
ABSTRACT
Objective:To explore the effects and mechanism of electroacupuncture (EA) on expression of myostatin (MSTN), muscle-specific ring finger protein 1 (MuRF1/Trim63), F-box only protein 32 (Atrogin-1/ Fbxo32), myogenic differentiation antigen (Myod) and myogenin (Myog) in traumatic spinal cord injury (TSCI) rats. Methods:A total of 45 adult female Sprague-Dawley rats were randomly divided into sham operation group (n = 12) and operation group (n = 33). The TSCI model was established with the modified Allen's method. After modeling, there were 24 survival rats and they were randomly divided into model group (n = 12) and EA group (n = 12). EA group was electroacupunctured at Dazhui (DU 14), Mingmen (DU 4) and bilateral Zusanli (ST 36) for 10 minutes, once a day, six times a week for 28 days. Basso-Beattie-Bresnahan (BBB) score was tested before modeling, and three days, seven days, 14 days, 21 days and 28 days after modeling. The rats were measured their body mass before and 28 days after modeling. The ratio of gastrocnemius wet mass was calculated; the cross-sectional area (CSA) and fiber diameter were measured by HE staining; the expression of MSTN, Trim63, Fbxo32, Myod and Myog mRNA were tested with real-time quantitative polymerase chain reaction (qPCR). Results:Three days, seven days, 14 days, 21 days, and 28 days after modeling, the score of BBB was lower in the model group than in the sham operation group (P < 0.01); seven days, 14 days, 21 days, and 28 days after modeling, the score of BBB was higher in EA group than in the model group (P < 0.01). Compared with the sham operation group, the mass of rats, the gastrocnemius wet mass, the CSA and the diameter of the muscle fiber were smaller in the model group (P < 0.05), while the expression of MSTN, Trim63, Fbxo32, Myod and Myog mRNA were higher (P < 0.05). Compared with the model group, the mass of rats, the gastrocnemius wet mass, the CSA, the expression of Myod and Myog mRNA were higher (P < 0.05) in EA group, while the expression of MSTN, Trim63 and Fbxo32 mRNA were lower (P < 0.05). Conclusion:EA might delay the gastrocnemius atrophy in TSCI rats by down-regulating the expression of MSTN, Trim63, Fbxo32 mRNA and up-regulating the expression of Myod and Myog mRNA via controlling the differentiation of the muscle satellite cells and the degradation of protein in skeletal muscle cells.
ABSTRACT
OBJECTIVE: To analyze fibrous scar tissue inhibition capacity with the use of losartan, hydrocortisone and acetylsalicylic acid. METHOD: The sample consisted of 120 male heterogeneic Wistar rats with a muscle laceration model. The rats were divided into four groups of 30 animals each: control group, losartan group, ASA group and hydrocortisone group. The animals were anesthetized and a 2.5 cm longitudinal incision was made in the left thoracolumbar paravertebral region. The muscles were subjected to a Grade III lesion caused by applying Kelly hemostatic forceps for 60 seconds, followed by sectioning with scissors. The skin was sutured with 3-0 nylon monofilament thread. The animals were placed in individual cages with plenty of food and water. The losartan group received losartan diluted in water at a dose of 0.1 mg/mL (10 mg/kg/day), the ASA Group received a 3 mg/mL ASA solution (300 mg/kg/day), and the hydrocortisone group received a 0.2 mg/mL hydrocortisone solution (20 mg/kg/day). RESULTS: The control, losartan, hydrocortisone and aspirin groups had a fibrotic area of 0.95 ± 0.35 mm, 0.55 ± 0.34 mm, 0.93 ± 0.33 mm, and 0.66 ± 0.36 mm, respectively. We observed a significantly smaller fibrotic area in the losartan group compared to the control (p=0.01) and hydrocortisone (p=0.01) groups. There were no significant differences among the other groups. CONCLUSION: The healing of striated skeletal muscle produced less fibrous scar tissue when exposed to losartan in comparison to the control group or the hydrocortisone group. Level of Evidence I; Randomized double-blind placebo-controlled study.
OBJETIVO: Analisar a capacidade de inibição de formação de tecido cicatricial fibroso com losartana, hidrocortisona e AAS. MÉTODOS: A amostra consistiu em 120 ratos Wistar heterogênicos machos com modelo de laceração muscular. Os ratos foram distribuídos em quatro grupos de 30 animais: grupo controle, grupo losartana, grupo AAS e grupo hidrocortisona. Os animais foram anestesiados e submetidos a uma incisão em sentido longitudinal de 2,5 cm de extensão na região paravertebral toracolombar esquerda, e os músculos sofreram uma lesão grau III com pinça hemostática de Kelly durante 60 segundos e posterior secção com tesoura. A pele foi suturada com nylon monofilamentar 3-0. Os animais foram colocados em gaiolas individuais, com água e alimento à vontade. O grupo losartana recebeu losartana diluída em água na dose de 0,1 mg/ml (10 mg/kg/dia), o grupo AAS recebeu solução de AAS 3 mg/ml (300 mg/kg/dia), o grupo hidrocortisona recebeu solução de hidrocortisona 0,2 mg/ml (20 mg/kg/ dia). RESULTADOS: Os grupos controle, losartana, hidrocortisona e AAS apresentaram área fibrótica de0,95 ± 0,35 mm, 0,55 ± 0,34 mm, 0,93 ± 0,33 mm, 0,66 ± 0,36 mm, respectivamente. Observou-se área fibrótica significativamente menor do grupo losartana em comparação com o grupo controle (p = 0,01) e hidrocortisona (p = 0,01). Nos demais grupos não houve diferença significativa. CONCLUSÃO: A cicatrização do músculo estriado esquelético produziu menos tecido cicatricial fibroso quando exposto à losartana do que quando comparado com o grupo controle ou o grupo hidrocortisona. Nível de Evidência I; Estudo duplo-cego randomizado controlado por placebo.
OBJETIVO: Analizar la capacidad de inhibición de formación de tejido cicatricial fibroso con losartán, hidrocortisona y AAS (ácido acetilsalicílico). MÉTODOS: La muestra consistió en 120 ratas Wistar heterogéneas machos con modelo de laceración muscular. Las ratas fueron distribuidas en cuatro grupos de 30 animales: grupo control; grupo losartán; grupo AAS y grupo hidrocortisona. Los animales fueron anestesiados y sometidos a una incisión longitudinal de 2,5 cm de extensión en la región paravertebral toracolumbar izquierda y los músculos sufrieron una lesión de grado III con pinza hemostática de Kelly durante 60 segundos y posterior sección con tijera. La piel se suturó con monofilamento de nylon 3-0. Los animales fueron dispuestos en jaulas individuales con abundante comida y agua. El grupo losartán recibió losartán diluido en agua a una dosis de 0,1 mg/ml (10 mg/kg/día), el grupo AAS recibió solución de AAS de 3 mg/ml (dosis 300 mg/kg/día), el grupo hidrocortisona recibió solución hidrocortisona de 0,2 mg/ml (20 mg/kg/día). RESULTADOS: Los grupos control, losartán, hidrocortisona y AAS mostraron área fibrótica de 0,95 ± 0,35 mm, 0,55 ± 0,34 mm, 0,93 ± 0,33 mm, 0,66 ± 0,36 mm, respectivamente. Se observó área fibrótica significativamente menor del grupo losartán en comparación con el grupo control (p = 0,01) e hidrocortisona (p = 0,01). En los demás grupos no hubo diferencias significativas. CONCLUSIÓN: La cicatrización del músculo estriado esquelético produjo menos tejido cicatricial fibroso cuando fue expuesto a losartán que cuando fue comparado con el grupo control o el grupo hidrocortisona. Nivel de Evidencia I; Estudio doble ciego aleatorio controlado por placebo.
Subject(s)
Animals , Male , Regeneration/drug effects , Muscle, Skeletal/injuries , Losartan/administration & dosage , Losartan/pharmacology , Fibrosis/drug therapy , Hydrocortisone/administration & dosage , Hydrocortisone/pharmacology , Aspirin/administration & dosage , Aspirin/pharmacology , Analysis of Variance , Transforming Growth Factor beta , Treatment Outcome , Rats, Wistar , Recovery of Function , Animal ExperimentationABSTRACT
@# Objective To explore the effect of the combination of Tuina and treadmill training on denervation skeletal muscle atrophy. Methods A total of 80 Sprague-Dawley rats (one month old) were randomly divided into control group (n=40) and manipulation group (n=40). Their sciatic nerves were transected, and the manipulative group accepted treadmill training and kneading of Tuina, while the control group accepted no intervention. Their muscle wet weight ratio, muscle satellite cells and insulin-like growth factor I (IGF-I) positive cells count were measured, and HE staining of gastrocnemius muscle were observed one, two, three and four months after intervention, ten rats in each group. Results Compared with the control group, the muscle wet weight ratio decreased three months after intervention (F=4.590, P<0.05), muscle satellite cells increased three months after intervention (F=12.466, P<0.01), and IGF-I positive cells increased two, three and four months after intervention (F>6.489, P<0.05). HE staining showed the skeletal muscle injury relieved somehow.Conclusion The combination of Tuina and treadmill training can relieve denervation skeletal muscle injury, but it is not enough for skeletal muscle atrophy, which may associate with promoting the expression of muscle satellite cells and IGF-I.
ABSTRACT
Sarcopenia is characterized by a loss of skeletal muscle mass and a decrease in muscle strength and function.The major etiological factors of sarcopenia include lack of exercise,decline of neuromuscular function,malnutrition and so on.Sarcopenia is associated with decreased numbers and function of muscle stem cells(also known as satellite cells).Muscle stem cells have a strong ability of self-renewal,with multi-potency,immune privilege,and antioxidant and anti-inflammatory properties, and are capable of promoting skeletal muscle regeneration.The mechanisms underlying cell proliferation,differentiation and self-renewal of satellite cells are not clear,but the number and activity of satellite cells are related to sarcopenia.Satellite cells work together with a variety of proliferation and differentiation factors to regulate muscle cell formation and muscle repair.Especially noteworthy is that p38α binds to a large number of myogenic gene promoters to regulate the proliferation and differentiation of satellite cells.In animal experiments,muscle stem cell therapy has shown regeneration and repair of muscle cells.Studies on changes at the molecular and gene levels in muscle fibers and their environment will be of great significance for the prevention and treatment of muscular disorders in the elderly.
ABSTRACT
Objective To study the effect of contusion and exhaustive exercise on satellite cells' activation and Pax7/CBF1/DAPT contents in skeletal muscles of rats,and reveal the repair mechanism of the skeletal muscle injury.Methods Twenty-four seven-week-old male Sprague-Dawley(SD)rats were randomly divided into a control(C)group,an immediately after exhaustive exercise(E0)group,a 24 hours after exhaustive exercise(E24)group and a 48 hours after exhaustive exercise(E48)group,each of 6.Other 18 SD rats were randomly divided into 3 groups,6 rats in each group:an immediately after contusion group(D0),a 24h post-contusion group(D24)and a 48h post-contusion group(D48).All groups were killed at different time points after exhaustive exercise and the contusion respectively while the control group was at resting state,and their serum was extracted.The right gastrocnemius muscles were resected and divided into 2 parts:one was used immediately for culturing satellite cells,while the other was stored in the bridge at-80℃.All the serum and gastrocnemius muscles were tested for Pax7,CBF1 and DAPT contents using the enzyme-linked immunosorbent assay(ELISA).Moreover,three-day-old newborn rats were also slaughtered for the above experiment.Results The results of culture in vitro showed that one day after the culture began a small amount of spindle satellite cells could be seen in the newborn rats,but the satellite cells of other groups were growing slowly.However,on the third day and the fifth day,the spindle satellite cells of each group began to proliferate in quantity and reached the peak.Then all the satellite cells had a good proliferation until the seventh day after serial passage,and some patial fusions to microtubules occurred.The biggest cell number and proliferation rate was in newborn rats,but no skeletal muscle satellite cell was found in the control group.At the same time,the number and the proliferation rate of skeletal muscle satellite cells in contusion groups were significantly higher than the exhaustive exercise groups.The results of Elisa showed that the contents of CBF1 and Pax7 in skeletal muscles in exhaustive groups and contusion groups,were significantly upregulated,compared to the control group(P＜0.05).Amomg them,the CBF1 content in group D0,together with the Pax7 content in group D24 and D48,was significantly higher than that of the other groups(P＜0.05).On the other hand,the content of DAPT in skeletal muscles of exhaustive groups and contusion groups,compared to the control group,was significantly downregulated (P＜0.05).To be more specific,the value of group D0 was significantly lower than that of the other groups (P＜0.05).However,there was no significant difference in it among group E0,E24 and E48.Conclusions Contusion and exhaustive exercise can activate the skeletal muscle satellite cells to proliferate and differentiate.The number of activated skeletal muscle satellite cells in the contusion groups is significantly larger than that of exhaustive groups maybe due to the stronger stimulating by contusion.Both contusion and exhaustive exercise increase the contents of Pax7 and CBF1 in skeletal muscles,but decrease that of DAPT.The Pax7 and CBF1 may play a positive regulating role in terms of activating skeletal satellite cells and repairing skeletal muscle injury,while DAPT may play a negative regulating role.
ABSTRACT
Summary The skeletal muscle tissue has a remarkable ability to alter its plastic structural and functional properties after a harmful stimulus, regulating the expression of proteins in complex events such as muscle regeneration. In this context, considering that potential therapeutic agents have been widely studied, nutritional strategies have been investigated in order to improve the regenerative capacity of skeletal muscle. There is evidence of the modulatory action of fatty acids, such that oleic and linoleic acids, that are abundant in Western diets, on muscle function and trophism. Thus, fatty acids appear to be potential candidates to promote or impair the recovery of muscle mass and function during regeneration, since they modulate intracellular pathways that regulate myogenesis. This study is the first to describe and discuss the effect of fatty acids on muscle plasticity and trophism, with emphasis on skeletal muscle regeneration and in vitro differentiation of muscle cells.
Resumo O tecido muscular esquelético possui a notável capacidade plástica de alterar suas propriedades estruturais e funcionais após um estímulo lesivo, regulando a expressão de proteínas durante eventos complexos como a regeneração muscular. Nesse contexto, considerando que possíveis agentes terapêuticos vêm sendo amplamente estudados, estratégias nutricionais têm sido investigadas na perspectiva de melhorar a capacidade regenerativa do músculo esquelético. Há evidências da ação modulatória dos ácidos graxos, como os ácidos oleico e linoleico, que são abundantes nas dietas ocidentais, sobre a função muscular e o trofismo. Nesse sentido, os ácidos graxos parecem ser potenciais candidatos para promover ou prejudicar a recuperação da massa e a função muscular durante a regeneração, uma vez que modulam vias intracelulares reguladoras da miogênese. Este trabalho é o primeiro a descrever e discutir o efeito dos ácidos graxos sobre a plasticidade e o trofismo muscular, com ênfase na regeneração do músculo esquelético e na diferenciação de células musculares in vitro.
Subject(s)
Humans , Regeneration/physiology , Muscle, Skeletal/physiology , Fatty Acids/metabolism , Cell Differentiation/drug effects , Muscle, Skeletal/cytology , Muscle, Skeletal/metabolism , Muscle Fibers, Skeletal/cytology , Muscle Fibers, Skeletal/metabolism , Myoblasts, Skeletal/cytologyABSTRACT
Objective To explore any effect of calorie restriction on the proliferation of satellite cells in the skeletal muscles of elderly rats.Methods Twelve male C57BL rats aged 12 or 13 months were randomly divided in to an experimental group and a control group,each of 6.The control group was fed 75.09 kJ/d as normal,while the experimental group was provided with 45.05 kJ/d (60％ of normal).The intervention lasted for 15 weeks and each rat's weight was measured every week.After the intervention,limb muscle satellite cells were sorted by fluorescenceactivated cell sorting after digestion,and the cell cycle was analyzed.Western blotting was used to assess the expression of cyclin A,D1 and E.Results There was no significant difference in the average weight of the two groups before the experiment.After the 15 weeks the average weight of the experimental group had decreased significantly (to 19.5±0.4 g),and it was significantly lighter than that of the control group (31.9±0.5 g).The average percentage of the satellite cells in the G0/G1 phase had decreased significantly in the experimental group,but the percentage in the S phase had increased significantly.The expression of cyclin A and E was significantly greater in the experimental group compared with the control group,but the expression of cyclin D1 had decreased significantly.Conclusion Caloric restriction can delay the proliferation of satellite cells in the skeletal muscles of elderly mice.
ABSTRACT
This study evaluated the effect of muscle satellite cells (MSCs) overexpressing myogenin (MyoG) on denervated muscle atrophy. Rat MSCs were isolated and transfected with the MyoG-EGFP plasmid vector GV143. MyoG-transfected MSCs (MTMs) were transplanted into rat gastrocnemius muscles at 1 week after surgical denervation. Controls included injections of untransfected MSCs or the vehicle only. Muscles were harvested and analyzed at 2, 4, and 24 weeks post-transplantation. Immunofluorescence confirmed MyoG overexpression in MTMs. The muscle wet weight ratio was significantly reduced at 2 weeks after MTM injection (67.17±6.79) compared with muscles injected with MSCs (58.83±5.31) or the vehicle (53.00±7.67; t=2.37, P=0.04 and t=3.39, P=0.007, respectively). The muscle fiber cross-sectional area was also larger at 2 weeks after MTM injection (2.63×103±0.39×103) compared with MSC injection (1.99×103±0.58×103) or the vehicle only (1.57×103±0.47×103; t=2.24, P=0.049 and t=4.22, P=0.002, respectively). At 4 and 24 weeks post-injection, the muscle mass and fiber cross-sectional area were similar across all three experimental groups. Immunohistochemistry showed that the MTM group had larger MyoG-positive fibers. The MTM group (3.18±1.13) also had higher expression of MyoG mRNA than other groups (1.41±0.65 and 1.03±0.19) at 2 weeks after injection (t=2.72, P=0.04). Transplanted MTMs delayed short-term atrophy of denervated muscles. This approach can be optimized as a novel stand-alone therapy or as a bridge to surgical re-innervation of damaged muscles.
Subject(s)
Animals , Male , Muscular Atrophy/rehabilitation , Myogenin/metabolism , Cell Transplantation , Muscle, Skeletal/innervation , Satellite Cells, Skeletal Muscle/transplantation , Muscle Denervation/rehabilitation , Organ Size/genetics , Plasmids , Muscular Atrophy/etiology , Transfection , Gene Expression , Fluorescent Antibody Technique , Rats, Sprague-Dawley , Myogenin/genetics , Satellite Cells, Skeletal Muscle/cytology , Real-Time Polymerase Chain ReactionABSTRACT
Skeletal muscle is an important tissue of the human body .Besides the roles in the motion system , the respiratory system, and the circulatory system , skeletal muscle also can be a secreting tissue and participate in signal transduction .As the finding of satellite cell and its muscle formation , the viewpoint that skeletal muscle′s injure is irreversible has becoming an history .Using sat-ellite cells to form muscle can be used to treat injury of skeletal muscle .However , the process is affected by many factors , such as ex-tracellular matrix, regulation factors, age, disease, epigenetic and so on.This paper summarizes the latest study progress of satellite cell muscle formation .
ABSTRACT
Muscle stem cells, which are known as satellite cells have heterogeneous components of committed myogenic progenitors, non-committed satellite cells, and mesenchymal stem cells. This distinguishing organization of self-renewal and differentiation capacities encourages the remarkable regenerative ability of skeletal muscles. Lately it has been proved that the satellite cell is the derivation of muscle regeneration and with the self-renew function, it roles as a true muscle stem cell. Therefore, stem cell therapy using satellite cells is considered to be ideal therapy for muscular dystrophies, which is deficient in specific muscle protein and causes muscle degeneration. Especially, Duchenne Muscular Dystrophy (DMD), which is caused by mutations at the dystrophin gene, has been targeted by much research. In this article the satellite cell characteristics, regulation of cell function, and stem cell therapy for DMD and the present progressive clinical trials will be reviewed.