Muscle satellite cells:one of the important factors in the occurrence and development of sarcopenia

Sarcopenia,or muscle loss,has been one of the hot topics in the medical field in recent years.Due to limited attention and effective treatments for sarcopenia in the past,many patients,especially the elderly,suffered irreversible damage to their motor function caused by sarcopenia.However,recent scientific studies have found that the occurrence and development of sarcopenia are closely related to the function and quantity of muscle satellite cells.This article briefly discusses the relationship between muscle satellite cells and sarcopenia.

Crosstalk among canonical Wnt and Hippo pathway members in skeletal muscle and at the neuromuscular junction

Skeletal muscles are essential for locomotion,posture,and metabolic regulation.To understand physiological processes,exercise adaptation,and muscle-related disorders,it is critical to understand the molecular pathways that underlie skeletal muscle function.The process of muscle contra ction,orchestrated by a complex interplay of molecular events,is at the core of skeletal muscle function.Muscle contraction is initiated by an action potential and neuromuscular transmission requiring a neuromuscular junction.Within muscle fibers,calcium ions play a critical role in mediating the interaction between actin and myosin filaments that generate force.Regulation of calcium release from the sarcoplasmic reticulum plays a key role in excitation-contraction coupling.The development and growth of skeletal muscle are regulated by a network of molecular pathways collectively known as myogenesis.Myogenic regulators coordinate the diffe rentiation of myoblasts into mature muscle fibers.Signaling pathways regulate muscle protein synthesis and hypertrophy in response to mechanical stimuli and nutrient availability.Seve ral muscle-related diseases,including congenital myasthenic disorders,sarcopenia,muscular dystrophies,and metabolic myopathies,are underpinned by dys regulated molecular pathways in skeletal muscle.Therapeutic interventions aimed at preserving muscle mass and function,enhancing regeneration,and improving metabolic health hold promise by targeting specific molecular pathways.Other molecular signaling pathways in skeletal muscle include the canonical Wnt signaling pathway,a critical regulator of myogenesis,muscle regeneration,and metabolic function,and the Hippo signaling pathway.In recent years,more details have been uncovered about the role of these two pathways during myogenesis and in developing and adult skeletal muscle fibers,and at the neuromuscular junction.In fact,research in the last few years now suggests that these two signaling pathways are interconnected and that they jointly control physiological and pathophysiological processes in muscle fibers.In this review,we will summarize and discuss the data on these two pathways,focusing on their concerted action next to their contribution to skeletal muscle biology.However,an in-depth discussion of the noncanonical Wnt pathway,the fibro/a dipogenic precursors,or the mechanosensory aspects of these pathways is not the focus of this review.

Biological Characteristics of Skeletal Muscle Satellite Cells and Its Application Prospects in Muscle Trauma Repair

As the only source of stem cells, satellite cells play and extraordinary role in the remediation process of skeletal muscle after injury. This paper overviewed the biological characteristic of skeletal muscle satellite cells and its role in repairing muscle injury, and put forward the prospects of its application in muscle trauma repair.

Effects of Soybean Isoflavones on In vitro Antioxidative Capacity of Satellite Cells of Porcine Skeletal Muscles

A synthetic isoflavone （ISO-S） or genistein was added in culture medium at different concentrations （0, 10, 20, 30, 40, and 80 p.mol L^-1） to investigate the effects of soybean isoflavones on antioxidative capacity of porcine skeletal muscle satellite cells. After 48 h incubation, the suspension was cryopreserved for the determination of superoxide dismutase （SOD）, catalase （CAT）, glutathione peroxidase （GSH-Px） activities, and malondialdehyde （MDA） content. The mRNA levels of SOD, CAT, and GSH-Px gene in cells were detected with Taqman fluorescent probe method. The results showed that the content of MDA and the activities and the mRNA levels of SOD of porcine skeletal muscle satellite cells were influenced by supplemented soybean isoflavone （P〈0.05） when adding 10-80 μmol L^-1 ISO-S or genistein in the medium. The MDA contents, SOD and CAT activities and their mRNA expression levels of porcine skeletal muscle cells responded quadratically （P〈 0.05） as the level of ISO-S or genistein increased. Pre-incubation of porcine skeletal muscle satellite cells with ISO-S or genistein at 10-40 pmol L-1 elevated the activities and the mRNA expression levels of SOD and CAT in cells concurrently and decreased the cellular content of MDA （P〈 0.05）. The results indicated that pre-incubation of ISO-S or genistein at 10- 40μmol L^-1 could improve the antioxidative capacity of porcine skeletal muscle satellite cells.

MicroRNA-22 inhibits proliferation and promotes differentiation of satellite cells in porcine skeletal muscle

Pig is an important economic animal in China. Improving meat quality and meat productivity is a long time issue in animal genetic breeding. Micro RNAs(mi RNAs) are short non-coding RNAs that participate in various biological processes, such as muscle development and embryogenesis. mi R-22 differentially expresses in embryonic and adult skeletal muscle. However, the underlying mechanism is unclear. In this study, we investigated mi R-22 function in proliferation and differentiation of porcine satellite cells(PSCs) in skeletal muscle. Our data show that mi R-22 expressed in both proliferation and differentiated PSCs and is significantly upregulated(P<0.05) during differentiation. After treated with the mi R-22 inhibitor, PSCs proliferation was significantly increased(P<0.05), as indicated by the up-regulation(P<0.01) of cyclin D1(CCND1), cyclin B1(CCNB1) and down-regulation(P<0.05) of P21. Conversely, over-expression of mi R-22 resulted in opposite results. Differentiation of PSCs was significantly suppressed(P<0.05), evidenced by two major myogenic markers: myogenin(Myo G) and myosin heavy chain(My HC), after transfecting the PSCs with mi R-22 inhibitor. Opposite results were demonstrated in the other way around by transfection with mi R-22 mimics. In conclusion, the data from this study indicated that mi R-22 inhibited the PSCs proliferation but promoted their differentiation.

Impact of Bovine Skeletal Muscle Satellite Cell Differentiation by Small Interfering RNA Targeting Myogenin Gene

To examine the effect of myogenin gene on the differentiation of bovine skeletal muscle satellite cell, we constructed small interfering RNA plasmid vector to obtain myogenin knockdown bovine skeletal muscle cells, then used cell transfection, real time RCR and Western Blot to detect the influence of myogenin to cell differentiation. Results showed that the knockdown of myogenin significantly decreased its expression and other muscle-specific genes. Compared to the control, it could differentiate into few myotubes when challenged by low serum in the medium. These findings provided an important theoretical basis for further explore of the genetic mechanism in adult skeletal muscle, the remedy of muscle injuries and the cultivation of high-yield transgenic cattle.

Protective Effect of ATP on Skeletal Muscle Satellite Cells Damaged by H_2O_2

This study investigated the protective effect of ATP on skeletal muscle satellite cells damaged by H2O2 in neonatal rats and the possible mechanism. The skeletal muscle satellite cells were randomly divided into four groups： normal group, model group（cells treated with 0.1 mmol/L H2O2 for 50 s）, protection group（cells treated with 16, 8, 4, 2, 1, 0.5, or 0.25 mmol/L ATP for 24 h, and then with 0.1 mmol/L H2O2 for 50 s）, proliferation group（cells treated with 16, 8, 4, 2, 1, 0.5, or 0.25 mmol/L ATP for 24 h）. MTT assay, FITC＋PI＋DAPI fluorescent staining, Giemsa staining and immunofluorescence were performed to examine cell viability and apoptosis, and apoptosis-related proteins. The results showed that the survival rate of skeletal muscle satellite cells was decreased and the apoptosis rate was increased after H2O2 treatment（P〈0.01）. Different doses of ATP had different effects on skeletal muscle satellite cells damaged by H2O2： the survival rate of muscle satellite cells treated with ATP at 4, 2, or 1 mmol/L was increased. The protective effect was most profound on cells treated with 2 mmol/L ATP. Immunofluorescence showed that ATP could increase the number of Bcl-2-positive cells（P〈0.01） and decrease the number of the Bax-positive cells（P〈0.01）. It was concluded that ATP could protect skeletal muscle satellite cells against H2O2 damage in neonatal rats, which may be attributed to the up-regulation of the expression of Bcl-2 and down-regulation of Bax, resulting in the suppression of apoptosis.

Skeletal muscle atrophy,regeneration,and dysfunction in heart failure:Impact of exercise training

This review highlights some established and some more contemporary mechanisms responsible for heart failure(HF)-induced skeletal muscle wasting and weakness.We first describe the effects of HF on the relationship between protein synthesis and degradation rates,which determine muscle mass,the involvement of the satellite cells for continual muscle regeneration,and changes in myofiber calcium homeostasis linked to contractile dysfunction.We then highlight key mechanistic effects of both aerobic and resistance exercise training on skeletal muscle in HF and outline its application as a beneficial treatment.Overall,HF causes multiple impairments related to autophagy,anabolic-catabolic signaling,satellite cell proliferation,and calcium homeostasis,which together promote fiber atrophy,contractile dysfunction,and impaired regeneration.Although both wasting and weakness are partly rescued by aerobic and resistance exercise training in HF,the effects of satellite cell dynamics remain poorly explored.

Denervated muscle extract promotes recovery of muscle atrophy through activation of satellite cells. An experimental study

Purpose: The objective of the present study was to determine whether a denervated muscle extract(DmEx) could stimulate satellite cell response in denervated muscle.Methods: Wistar rats were divided into 4 groups: normal rats, normal rats treated with DmEx, denervated rats, and denervated rats treated with DmEx. The soleus muscles were examined using immunohistochemical techniques for proliferating cell nuclear antigen, desmin, and myogenic differentiation antigen(MyoD), and electron microscopy was used for analysis of the satellite cells.Results: The results indicate that while denervation causes activation of satellite cells, DmEx also induces myogenic differentiation of cells localized in the interstitial space and the formation of new muscle fibers. Although DmEx had a similar effect in nature on innervated and denervated muscles, this response was of greater magnitude in denervated vs. intact muscles.Conclusion: Our study shows that treatment of denervated rats with DmEx potentiates the myogenic response in atrophic denervated muscles.

IGF-1, bFGF EXPRESSION AND VASCULAR REGENERATION IN ACUTE INFARCTED CANINE MYOCARDIUM AFTER AUTOLOGUS SKELETAL MUSCLE SATELLITE CELL IMPLANTATION

Objective To study the cell growth factor secretion and vascular regeneration in acute in-farcted myocardium after autologous skeletal muscle satellite cell implantation. Methods Autologous skeletal muscle satellite cells from adult mongrel canine were implanted into the acute myocardial infarct site via the ligated left anterior descending (LAD) artery. Specimens were harvested at 2, 4 , 8 weeks after implantation for the expression of insulin-like growth factor-1 (IGF-1), basic fibroblast growth factor ( bFGF) and the vascular density. Results The expression of IGF-1, bFGF and the vascular density in skeletal muscle satellite cell implant group were higher than that in the control group. Conclusion The skeletal muscle satellite cells, after being implanted into the acute myocardial infarction, not only showed myocardial regeneration, but also showed the ability to secrete the cell factors, hence representing a positive effect on the regeneration of the infarcted myocardium.

THE IMPROVEMENT OF INFARCTED MYOCARDIAL CONTRACTILE FORCE AFTER AUTOLOGOUS SKELETAL MUSCLE SATELLITE CELL IMPLANTATION

Objective To study the improvement of infarcted myocardial contractile force after autologous skeletal muscle satellite cell implantation via intracoronary arterial perfusion. Methods Skeletal muscle cells were harvested from gluteus max of adult mongrel dogs and the cells were cultured and expanded before being labeled with DAPI (4’, 6-diamidino-2-phenylindone). The labeled cells were then implanted into the acute myocardial infarct site via the ligated left anterior descending (LAD) coronary artery. Specimens were taken at 2nd, 4th, 8th week after myoblast implantation for histologic and contractile force evaluation, respectively. Results The satellite cells with fluorescence had been observed in the infarct site and also in papi- llary muscle with consistent oriented direction of host myocardium. A portion of the implanted cells had differen- tiated into muscle fibers. Two weeks after implantation, the myocardial contractile force showed no significant difference between the cell implant group and control group. At 4 and 8 week, the contractile force in the cell implant group was better than that in control group. Conclusion The skeletal muscle satellite cells, implanted into infarct myocardium by intracoronary arterial perfusion, could disseminate through the entire infarcted zone with myocardial regeneration and improve the contractile function of the infarcted myocardium.

Time-dependent gene expression analysis after mouse skeletal muscle contusion

Background:Though the mechanisms of skeletal muscle regeneration are deeply understood,those involved in muscle contusion,one of the most common muscle injuries in sports medicine clinics,are not.The objective of this study is to explore the mechanisms involved in muscle regeneration after contusion injury.Methods:In this study,a total of 72 mice were used.Eight of them were randomly chosen for the control group,while the rest were subjected to muscle contusion.Subsequently,their gastrocnemius muscles were harvested at different time points.The changes in muscle morphology were assessed by hematoxylin and eosin(HE) stain.In addition,the gene expression was analyzed by real-time polymerase chain reaction.Results:The data showed that the expression of many genes,i.e.,specific markers of immune cells and satellite cells,regulatory factors for muscle regeneration,cytokines,and chemokines,increased in the early stages of recovery,especially in the first 3 days.Furthermore,there were strict rules in the expression of these genes.However,almost all the genes returned to normal at 14 days post-injury.Conclusion:The sequence of immune cells invaded after muscle contusion was neutrophils,M1 macrophages and M2 macrophages.Some CC(CCL2,CCL3,and CCL4) and CXC(CXCL10) chemokines may be involved in the chemotaxis of these immune cells.HGF may be the primary factor to activate the satellite cells after muscle contusion.Moreover,2 weeks are needed to recover when acute contusion happens as used in this study.

Barriers in contribution of human mesenchymal stem cells to murine muscle regeneration

AIM: To study regeneration of damaged human and murine muscle implants and the contribution of added xenogeneic mesenchymal stem cells(MSCs).METHODS: Minced human or mouse skeletal muscle tissues were implanted together with human or mouse MSCs subcutaneously on the back of non-obese diabetic/severe combined immunodeficient mice. The muscle tissues(both human and murine) were minced with scalpels into small pieces(< 1 mm3) and aliquoted in portions of 200 mm3. These portions were either cryopreserved in 10% dimethylsulfoxide or freshly implanted. Syngeneic or xenogeneic MSCs were added to the minced muscles directly before implantation. Implants were collected at 7, 14, 30 or 45 d after transplantation and processed for(immuno)histological analysis. The progression of muscle regeneration was assessed using a standard histological staining(hematoxylin-phloxinsaffron). Antibodies recognizing Pax7 and von Willebrand factor were used to detect the presence of satellite cells and blood vessels, respectively. To enable detection of the bone marrow-derived MSCs or their derivatives we used MSCs previously transduced with lentiviral vectors expressing a cytoplasmic LacZ gene. X-gal staining of the fixed tissues was used to detect β-galactosidase-positive cells and myofibers.RESULTS: Myoregeneration in implants of fresh murine muscle was evident as early as day 7, and progressed with time to occupy 50% to 70% of the implants. Regeneration of fresh human muscle was slower. These observations of fresh muscle implants were in contrast to the regeneration of cryopreserved murine muscle that proceeded similarly to that of fresh tissue except for day 45(P < 0.05). Cryopreserved human muscle showed minimal regeneration, suggesting that the freezing procedure was detrimental to human satellite cells. In fresh and cryopreserved mouse muscle supplemented with LacZ-tagged mouse MSCs, β-galactosidase-positive myofibers were identified early after grafting at the wellvascularized periphery of the implants. The contribution of human MSCs to murine myofiber formation was, however, restricted to the cryopreserved mouse muscle implants. This suggests that fresh murine muscle tissue provides a suboptimal environment for maintenance of human MSCs. A detailed analysis of the histological sections of the various muscle implants revealed the presence of cellular structures with a deviating morphology. Additional stainings with alizarin red and alcian blue showed myofiber calcification in 50 of 66 human muscle implants, and encapsulated cartilage in 10 of 81 of murine muscle implants, respectively.CONCLUSION: In mouse models the engagement of human MSCs in myoregeneration might be underestimated. Furthermore, our model permits the dissection of speciesspecific factors in the microenvironment.

运动联合益生菌干预2型糖尿病大鼠糖脂代谢、氧化应激及骨骼肌卫星细胞成肌分化水平的变化

目的观察运动联合益生菌干预2型糖尿病大鼠糖脂代谢、氧化应激及骨骼肌卫星细胞表达的影响。方法8周龄SPF级SD雄性大鼠60只,随机选择10只大鼠为正常对照组(NC组),造模组大鼠腹腔注射链脲佐菌素,建立2型糖尿病大鼠模型,随机分为模型组(TN组)、运动+糖尿病组(YTN组)、益生菌+糖尿病组(GTN组)、运动+益生菌+糖尿病组(YGTN组),6周的递增负荷有氧跑台运动(第1周跑台速度为15 m/min,持续30 min;第2周跑台速度为15 m/min,持续60 min;第3~6周跑台速度为19.3 m/min,运动时间持续60 min,持续训练到第6周,每周5 d);GTN组和YGTN组在训练前1 h灌胃10.0 mL/(kg·d)的Lactibiane Iki益生菌溶液(浓度为10~7 CFU/mL)。最后,测定大鼠糖脂代谢指标、氧化应激指标及骨骼肌卫星细胞蛋白的表达。结果(1)TN组、YTN组、GTN组和YGTN组大鼠空腹血糖(fasting plasma glucose,FBG)、血清胰岛素(fasting serum insulin,FINS)、糖化血红蛋白(hemoglobin A1c,HBA1C)和胰岛素抵抗指数(homeostasis model assessment-insulin resistance index,HOMA-IR)水平均高于NC组(P<0.01),其中,YGTN组大鼠FBG水平均低于TN组、YTN组、GTN组(P<0.05);YTN组、GTN组和YGTN组大鼠血清FINS水平均与TN组比较均有所下降(P<0.01);YGTN组大鼠血清HBA1C水平均低于TN组、YTN组和GTN组水平(P<0.01);YGTN组大鼠HOMA-IR指数与TN组、YTN组和GTN组比较下降较显著(P<0.01)。结果表明有氧运动联合益生菌干预组大鼠FBG、FINS、HBA1C和HOMA-IR含量下降较明显。(2)TN组大鼠血清总胆固醇(total cholesterol,T-CHO)、甘油三酯(triglyceride,TG)、低密度脂蛋白胆固醇(low density lipoprotein cholesterol,LDL)和游离脂肪酸(free fatty acid,FFA)水平均高于NC组(P<0.05),YGTN组大鼠血清T-CHO、TG、LDL和FFA水平均低于TN组(P<0.05),基本上恢复到NC组的水平。TN组大鼠血清高密度脂蛋白胆固醇(high density lipoprotein cholesterol,HDL)水平低于NC组(P<0.05),YGTN组大鼠血清HDL水平高于TN组(P<0.05),基本上恢复到NC组水平。结果表明有氧运动联合益生菌干预糖尿病大鼠,可降低糖尿病大鼠血清T-CHO、TG、LDL、FFA含量,提高HDL水平较明显。(3)TN组大鼠血清丙二醛(malondialdehyde,MDA)和游离8-异前列腺素F2α(8-iso-prostaglandin F2α,8-isoPGF2α)水平均高于NC组(P<0.05或P<0.01),YGTN组大鼠血清MDA和8-isoPGF2α水平均低于TN组(P<0.05或P<0.01);TN组大鼠血清过氧化氢酶(catalase,CAT)、超氧化物歧化酶(superoxide dismutase,SOD)、谷胱甘肽过氧化物酶(glutathione peroxidase,GSH-Px)和总抗氧化能力(total antioxidant capacity,T-AOC)水平均低于NC组(P<0.01),YGTN组大鼠血清CAT、SOD、GSH-Px和T-AOC水平均高于NC组(P<0.01),但基本上恢复到NC组的水平。(4)TN组大鼠骨骼肌卫星细胞配对盒基因7(paired box gene 7,Pax7)、成肌分化因子(myogenic determination gene,MyoD)、肌细胞生成素(myogenin,MyoG)和生肌因子5(myogenic factor 5,Myf5)蛋白表达均低于NC组(P<0.05或P<0.01),YGTN组大鼠骨骼肌Pax7、MyoD、MyoG和Myf5蛋白表达均高于TN组(P<0.05或P<0.01);基本上恢复到NC组水平。TN组大鼠骨骼肌生成抑制素(myostatin,MSTN)蛋白表达高于NC组(P<0.05),YGTN组大鼠骨骼肌MSTN蛋白表达低于TN组(P<0.05),基本上恢复到NC组水平。结论益生菌和有氧运动具有减轻胰岛素抵抗,改善血脂和氧化激的作用,在改善2型糖尿病大鼠血糖和胰岛素水平具有协同作用。此外,有氧运动联合益生菌干预促进了肌细胞的分化,可能对防止T2DM引起肌肉质量的流失和力量下降以及肌肉组织的并发症发挥一定的作用。

MMP14调控骨骼肌卫星细胞分化的分子机制研究

旨在分析基质金属蛋白酶14(MMP14)调控骨骼肌卫星细胞分化的分子机制。本试验取10只4周龄C57/BL6雌性小鼠,利用胶原酶消化法分离骨骼肌卫星细胞。首先,对骨骼肌卫星细胞进行诱导分化,利用qRT-PCR和Western blot试验分析MMP14在骨骼肌卫星细胞增殖期和分化期表达量的变化。应用siRNA抑制MMP14蛋白表达,分为试验组(si-MMP14)和对照组(si-NC),每组3个重复:首先诱导细胞分化,应用免疫荧光和qRT-PCR分析试验组和对照组细胞分化水平的差异;随后取增殖期细胞进行蛋白组学测序,结合生物信息学分析鉴定差异蛋白,并筛选MMP14调控的关键差异蛋白和通路。本研究结果表明:1)MMP14在卫星细胞增殖期表达上调,在分化期表达下调;抑制MMP14蛋白会抑制肌管生成,表现为肌管融合指数下降。2)通过蛋白组学分析筛选到549个差异蛋白,其中有66个上调蛋白和483个下调蛋白,差异蛋白主要富集在细胞黏附、脂肪酸代谢以及AMPK通路等,参与调控细胞命运决定、组蛋白甲基化和染色质结构等生物学过程。3)通过蛋白互作关系网络分析发现MMP14与肌源性分化相关蛋白、脂肪生成相关蛋白以及异染色质结构调控蛋白直接互作,抑制MMP14可导致肌分化转录因子(PAX7、MYOD)和H3-K9甲基转移酶(SETDB1、SUV39H1)下调,而成脂分化转录因子(JUN、C/EBPβ)上调。本研究初步分析了MMP14调控骨骼肌卫星细胞分化的机制,MMP14可能通过H3-K9组蛋白甲基化参与卫星细胞命运决定以及成肌与成脂分化的转换,且这种调控作用发生在卫星细胞细胞分化启动前。本研究结果为骨骼肌发育研究提供理论依据。

理筋手法调控兔骨骼肌损伤修复中瘢痕形成的作用机制

背景:理筋手法能够促进骨骼肌修复,治疗骨骼肌损伤。但骨骼肌损伤在修复过程中的纤维化形成、瘢痕组织增生等与损伤修复质量密切相关。开展理筋手法对纤维化形成、瘢痕组织增生的调控作用研究,有利于阐述理筋手法提高骨骼肌损伤修复质量的相关机制。目的:探索理筋手法提高兔骨骼肌损伤后修复质量的作用机制,为临床治疗提供科学依据。方法:45只健康成年日本大耳白兔随机分为空白组、模型组、理筋组,每组15只。其中模型组和理筋组均进行腓肠肌打击造模;造模后理筋组于第3天开始进行理筋手法干预,1次/d,15 min/次。各组在造模后的第7,14,21天分别处死5只兔进行观察。苏木精-伊红染色法观察腓肠肌形态及炎性细胞量,Masson染色法观察腓肠肌胶原纤维量,ELISA法检测腓肠肌白细胞介素6和白细胞介素10的表达量,Western blot和RT-PCR检测配对盒基因7、成肌分化因子、肌细胞生成素、肌动蛋白α、转化生长因子β1、Ⅰ型胶原蛋白的蛋白及mRNA表达,免疫组织化学法检测Ⅰ型胶原蛋白的表达。结果与结论:①苏木精-伊红染色及Masson染色结果显示,与模型组比较,理筋组各观察点炎性细胞浸润减少,胶原纤维量减少(P<0.01),肌纤维逐渐愈合;②ELISA结果显示,与模型组比较,理筋组白细胞介素6表达持续降低(P<0.05),而白细胞介素10在造模后第7天时升高(P<0.05),随后呈下降趋势(P<0.05);③Western blot和RT-PCR结果显示,与模型组比较,理筋组造模后第14天配对盒基因7、成肌分化因子、肌细胞生成素的蛋白及mRNA表达量均显著升高(P<0.05),而第21天时却较之前下降(P<0.05);理筋组各观察点肌动蛋白α、转化生长因子β1、Ⅰ型胶原蛋白的蛋白及mRNA表达量相较于模型组均显著降低(P<0.05);④免疫组化结果显示,理筋组各观察点Ⅰ型胶原蛋白的表达量相较于模型组均显著降低(P<0.05);⑤结果表明,理筋手法能够通过抑制炎症、促进肌卫星细胞的增殖分化、减少纤维化的生成,从而提高兔骨骼肌损伤的修复质量。

骨骼肌再生过程中卫星细胞调控机制及其生态位信号的作用

背景:卫星细胞是骨骼肌包含的一种特定的成体干细胞群,可促进损伤骨骼肌的再生重建,但其具体机制尚不完善。目的:综述骨骼肌再生过程中卫星细胞调控作用以及卫星细胞与其生态位信号相互作用的机制,旨在总结现有知识的基础上提供新的研究思路和角度。方法:检索Web of Science、PubMed、中国知网(CNKI)、万方、维普等数据库2002年1月至2022年6月发表的文献。英文检索词:muscle,skeletal muscle,muscle injury,stem cells,satellite cells,muscle repair等;中文检索词:骨骼肌,骨骼肌再生,骨骼肌重建,卫星细胞,生态位等。共纳入66篇文献进行整理和分析。结果与结论:(1)卫星细胞存在于骨骼肌中,其既有助于损伤后新肌纤维的形成,亦有助于已存在的成年肌纤维有效生长。(2)卫星细胞中的静止卫星细胞被激活后,骨骼肌再生过程中卫星细胞的增殖、分化和融合形成肌纤维等步骤均会受到其内在不同机制调控作用的影响。(3)卫星细胞可与所处生态位信号中的肌纤维、细胞外基质、骨骼肌交界位、纤维生成祖细胞、免疫细胞以及内皮细胞相互作用促进卫星细胞的激活和增殖和分化,进而实现骨骼肌的有效再生。(4)未来研究可能的突破口:机体内卫星细胞的分裂模式;调控卫星细胞转移相关机制;卫星细胞在体内分化或自我更新的具体时间;卫星细胞和骨骼肌交界位的相互作用机制。(5)此次综述可为骨骼肌损伤重建的领域及其创新提供一定的理论参考价值。

骨骼肌中卫星细胞衰老生物学机制及潜在的应对策略

背景:卫星细胞是一种肌源性干细胞,位于肌纤维膜与基底膜之间,但尚未有综述完全揭示卫星细胞衰老机制及其潜在应对策略,这对于当前减缓骨骼肌老化的策略应用难以起到有效的指导效果。目的:综述骨骼肌中卫星细胞衰老的机制及其相关减缓其衰老的应对策略。方法:检索各数据库时间截至2023年5月,包括Web of Science、PubMed、中国知网、万方和维普数据库。英文检索词:“Skeletal muscle,satellite cells,aging,mechanism,solution strategye”;中文检索词:“骨骼肌,卫星细胞,衰老,老化,机制,应对策略”。经过严格按照纳入和排除标准进行筛选,最终纳入78篇文献进行综述分析。结果与结论:①卫星细胞位于肌纤维膜与基底膜之间,具有增殖和分化潜能,通常处于静息状态,但在肌肉组织受刺激时会被激活并参与修复和恢复正常组织结构的过程,衰老会导致卫星细胞数量减少,并引发肌力和耐力的下降等症状。②卫星细胞衰老的机制主要涉及再生能力下降、串扰能力随生态位变化、年龄依赖性损失和异质性变化,衰老的卫星细胞数量减少以及活性降低会导致肌肉再生速度变慢和损伤恢复时间增加,且在分化过程中可能出现错误,从而导致肌肉质量下降和功能退化。③针对卫星细胞衰老的应对策略主要包括调节体内卫星细胞的受体环境、外源手段干预促进卫星细胞再生、人体肌肉模型构建和运动和饮食干预诱导卫星细胞增殖等,这些策略具有一定的潜力,可以为卫星细胞的再生和治疗骨骼肌疾病提供新的思路和方法。④未来的研究建议深入探究卫星细胞衰老机制,探究卫星细胞与生态位之间的相互作用,研究卫星细胞与免疫系统和线粒体功能等因素的关系,开发应用人体肌肉模型来提高研究深度和准确性。

FoxO1对牛骨骼肌细胞增殖、凋亡和分化的调控

【目的】骨骼肌是动物机体的重要组成成分,其生长发育直接影响畜禽肉产量,叉头转录因子O1(forkhead box protein O1,FoxO1)作为重要的转录调控因子,其与骨骼肌生长发育密切相关。探究过表达FoxO1对牛骨骼肌细胞增殖、凋亡与分化的作用,为肉牛遗传改良提供基础材料。【方法】采集牛的多个组织样品,提取其RNA并反转录,利用实时荧光定量PCR(qPCR)构建FoxO1组织表达谱。利用酶消化法分离得到牛骨骼肌细胞,通过观察其分化后肌管的形成以及qPCR检测其分化标志基因的表达情况来检验所分离细胞的分化性能。利用免疫荧光技术对牛骨骼肌细胞进行FoxO1亚细胞定位。设计并包装牛FoxO1过表达腺病毒,以提高牛骨骼肌细胞内FoxO1的表达。利用EdU染色检测过表达FoxO1对细胞相对增殖率的影响。利用流式细胞术检测过表达FoxO1对细胞周期分布的影响。利用qPCR检测过表达FoxO1对牛骨骼肌细胞增殖、凋亡和分化相关基因表达水平的影响。【结果】组织表达谱结果显示FoxO1在多个组织中均有表达,其在成年牛的背脂中表达量最高,在背最长肌组织中表达量最低,且FoxO1在犊牛背最长肌组织中的表达量要极显著高于成年牛的(P<0.01)。亚细胞定位结果显示FoxO1在牛骨骼肌细胞的细胞核和细胞质内均有表达,其细胞核内荧光强度高于细胞质。成功构建FoxO1过表达载体,并完成FoxO1重组过表达腺病毒的包装与扩繁,在感染牛骨骼肌细胞后,能显著提高FoxO1表达水平(P<0.01)。EdU检测显示过表达FoxO1会显著降低细胞增殖率(P<0.01),流式细胞周期检测显示过表达FoxO1会显著增加G1期细胞数并减少S期和G2期细胞数,抑制细胞G1/S期的转化,并减少G2期细胞的形成。利用qPCR进一步检测发现,增殖相关基因PCNA、CDK1、CDK2、CCNA2、CCNB1、CCND1和CCNE2均极显著下调(P<0.01),促凋亡相关基因BAD和BAX显著上调以及抑凋亡基因BCL2显著下调(P<0.05)。过表达FoxO1导致牛骨骼肌细胞肌管形成量减少,qPCR检测结果发现,骨骼肌分化相关基因MYOD、MYOG、MYF5、MYF6和MYHC的表达量显著下调(P<0.05)。【结论】FoxO1在牛的不同组织中均有表达,是一个广泛存在的转录调控因子,并且在背最长肌组织生长发育不同阶段存在表达差异,起到阶段调控作用。FoxO1在细胞核和细胞质中均发挥重要的转录调控作用,特别是在细胞核内。过表达FoxO1可能通过抑制细胞增殖相关基因和肌细胞分化相关基因的表达,从而抑制牛骨骼肌细胞的增殖与分化,并且可能通过上调促凋亡基因的表达和下调抑凋亡基因的表达来促使牛骨骼肌细胞凋亡的发生。

转化生长因子-β参与骨骼肌损伤修复的机制探讨及研究进展

骨骼肌损伤是临床上常见的疾病,对其修复机制的深入了解对于制定有效的治疗策略至关重要。本文聚焦于TGF-β在骨骼肌损伤修复中的关键作用,介绍了其家族成员的多样性和信号传导途径,探讨在骨骼肌损伤后TGF-β的表达与调控部分,解析了其早期表达动态和调控因素,深入研究TGF-β对骨骼肌修复的影响,揭示了其在炎症调节、细胞活化与增殖以及纤维化等方面的关键作用。特别关注了其在肌肉再生中的作用机制及在细胞水平上的调控机制。此外,对TGF-β在骨骼肌损伤修复中的潜在临床应用进行了讨论,探索了将其作为治疗靶点和调控剂的发展与应用。然而,当前研究中仍存在争议与不足,如TGF-β的双重作用和个体差异对治疗的影响。未来的研究方向应包括深入挖掘信号通路的细节以及生物标志物的发现。通过克服这些挑战,TGF-β在骨骼肌损伤修复中的潜在临床应用有望迎来新的突破,为患者提供更为个体化和有效的治疗策略。