Recurrent Inflammatory Myoblastic Tumour of the Vocal Cord: A Rare Case Report from Malaysia

Inflammatory myoblastic tumour (IMT) is a rare benign neoplasm that can affect any part of the body including the head and neck. When it is affecting the head and neck region, the clinical presentations can mimic other common head and neck pathology. If the tumour involves the upper airway it can cause stridor and hoarseness. Other presenting features are neck swelling and dysphagia. This tumour may mimic other chronic granulomatous diseases. This case report described a rare IMT arising from the vocal cord and presents with hoarseness and stridor for six months duration. The patient has no known risk factors. Despite surgical resection, the tumour recurred within six month and further surgical resection was performed, but yet the tumour recurred after one year following second surgery. She was then further treated with mass excision by Endolaryngeal Microsurgery (ELMS) with steroid laryngeal injection. Currently she is still being followed up and remains asymptomatic.

Interactions between myoblasts and macrophages under high glucose milieus result in inflammatory response and impaired insulin sensitivity

BACKGROUND Skeletal muscle handles about 80% of insulin-stimulated glucose uptake and become the major organ occurring insulin resistance(IR).Many studies have confirmed the interactions between macrophages and skeletal muscle regulated the inflammation and regeneration of skeletal muscle.However,despite of the decades of research,whether macrophages infiltration and polarization in skeletal muscle under high glucose(HG)milieus results in the development of IR is yet to be elucidated.C2C12 myoblasts are well-established and excellent model to study myogenic regulation and its responses to stimulation.Further exploration of macrophages'role in myoblasts IR and the dynamics of their infiltration and polarization is warranted.AIM To evaluate interactions between myoblasts and macrophages under HG,and its effects on inflammation and IR in skeletal muscle.METHODS We detected the polarization status of macrophages infiltrated to skeletal muscles of IR mice by hematoxylin and eosin and immunohistochemical staining.Then,we developed an in vitro co-culture system to study the interactions between myoblasts and macrophages under HG milieus.The effects of myoblasts on macrophages were explored through morphological observation,CCK-8 assay,Flow Cytometry,and enzyme-linked immunosorbent assay.The mediation of macrophages to myogenesis and insulin sensitivity were detected by morphological observation,CCK-8 assay,Immunofluorescence,and 2-NBDG assay.RESULTS The F4/80 and co-localization of F4/80 and CD86 increased,and the myofiber size decreased in IR group(P<0.01,g=6.26).Compared to Mc group,F4/80+CD86+CD206-cells,tumor necrosis factor-α(TNFα),inerleukin-1β(IL-1β)and IL-6 decreased,and IL-10 increased in McM group(P<0.01,g>0.8).In McM+HG group,F4/80+CD86+CD206-cells,monocyte chemoattractant protein 1,TNFα,IL-1βand IL-6 were increased,and F4/80+CD206+CD86-cells and IL-10 were decreased compared with Mc+HG group and McM group(P<0.01,g>0.8).Compered to M group,myotube area,myotube number and E-MHC were increased in MMc group(P<0.01,g>0.8).In MMc+HG group,myotube area,myotube number,E-MHC,GLUT4 and glucose uptake were decreased compared with M+HG group and MMc group(P<0.01,g>0.8).CONCLUSION Interactions between myoblasts and macrophages under HG milieus results in inflammation and IR,which support that the macrophage may serve as a promising therapeutic target for skeletal muscle atrophy and IR.

Anti-Diabetic Activity of an Extract of Syzygium Jambolanum - A Review

Syzygium jambolanum is a promising natural treatment for diabetes.The potential benefits of S jambolanum for diabetes include lowering blood sugar levels,increasing insulin sensitivity,protecting pancreatic beta cells,and slowing the absorption of glucose into the bloodstream.The anti-diabetic activity of the crude extract of S jambolanum was evaluated in L6 myotubes and the lipid deposition in tissue was measured using Nile red Staining.Nile red staining confirmed that a considerable quantity of lipids had been deposited in the tissue treated with a crude extract of S jambolanum,comparable to the quantity of lipids deposited with a standard drug known as Rosiglitazone.This study analyzed the anti-diabetic activity of a crude extract of S jambolanum to understand its potential as a feedstock for extracting bioactive constituents to screen for bioactive molecules in the treatment of diabetes.

Identification of transition factors in myotube formation from proteome and transcriptome analyses

Muscle fibers are the main component of skeletal muscle and undergo maturation through the formation of myotubes.During early development,a population of skeletal muscle satellite cells(SSCs)proliferate into myoblasts.The myoblasts then undergo further differentiation and fusion events,leading to the development of myotubes.However,the mechanisms involved in the transition from SSCs to myotube formation remain unclear.In this study,we characterized changes in the proteomic and transcriptomic expression profiles of SSCs,myoblasts(differentiation for 2 d)and myotubes(differentiation for 10 d).Proteomic analysis identified SLMAP and STOM as potentially associated with myotube formation.In addition,some different changes in MyoD,MyoG,Myosin7 and Desmin occurred after silencing SLMAP and STOM,suggesting that they may affect changes in the myogenic marker.GO analysis indicated that the differentiation and migration factors SVIL,ENSCHIG00000026624(AQP1)and SERPINE1 enhanced the transition from SSCs to myoblasts,accompanied by changes in the apoptotic balance.In the myoblast vs.myotube group,candidates related to cell adhesion and signal transduction were highly expressed in the myotubes.Additionally,CCN2,TGFB1,MYL2 and MYL4 were identified as hub-candidates in this group.These data enhance our existing understanding of myotube formation during early development and repair.

Effects of areca nut consumption on cell differentiation of osteoblasts, myoblasts, and fibroblasts

Areca nut is used worldwide as a hallucinogenic addicting drug along the tropical belt.Arecoline,a toxic compound,is the most important alkaloid in areca nuts.The adverse effects of oral uptake and chewing of areca nut are well known.For example,the possibility of cancer caused by chewing areca nuts is widely discussed.Chewing areca nut has other adverse effects on other organs,including abnormal cell differentiation,oral cancer,and several other diseases.The use of areca nut is also associated with low birthweight.Skeletal musculature is the largest organ in the body and is attached to the bones.During embryo development,the differentiation of bone and muscle cells is critical.In this article,we reviewed the effects of areca nut and arecoline on embryonic cell differentiation,particularly osteoblasts,myoblasts,and fibroblasts.

Micro RNA transcriptome of skeletal muscle during yak development reveals that miR-652 regulates myoblasts differentiation and survival by targeting ISL1

The growth and development of skeletal muscle also determine the meat production of yak, ultimately affecting the economic benefits. Hence, improving growth performance is a top priority in the yak industry. Skeletal muscle development is a complex process involving the regulation of several genes, including microRNAs(miRNAs). However,the transcription of miRNAs in yak skeletal muscle during prenatal to postnatal stages is unknown. We used small RNA sequencing(small RNA-Seq) to determine the global miRNAs of longissimus dorsi muscle from yak(the samples were collected from three fetuses and three adults). Totally 264 differently expressed miRNAs(|log2(fold change)|>1and P-value≤0.05) were detected between the two groups. Gene Ontology(GO) and Kyoto Encyclopedia of Genes and Genomes(KEGG) analysis showed that differently expressed miRNAs-targeted genes participated in pathways associated with muscle development, such as MAPK, PI3K-Akt, and Hippo signaling pathways, etc. MiR-652, which was up-regulated in the fetal group, was transfected into C2C12 myoblasts to examine its role. miR-652 promoted(P≤0.05)proliferation and differentiation, but inhibited(P≤0.001) apoptosis at early period. Furthermore, miR-652 reduced(P≤0.001) the proportion of C2C12 myoblasts in the G1 phase while increasing(P≤0.01) the proportion of cells in the S and G2 phases. Dual-luciferase reporter assays indicated that ISL1 served as a target of miR-652. In general, these findings expand our understanding of yak skeletal muscle miRNAs, and suggested that miR-652 probably regulated myogenesis by regulating ISL1.

Genetic Cell Therapy in Anti-Aging Regenerative Cosmetology

As post-WWII baby boomer approaching age 80, Anti-Aging Regenerative Cosmetology (AARC) has been developed and patented for beautifying and strengthening the human body using live cells;to enhance the appearance and function of various bodily parts to provide health and aestheticism of human being throughout life. It is a combined cosmetic and preventive medicine to intervene with and to correct the undesirable phenotypic expression of aging. The intrinsic properties of myoblasts and foreskin fibroblasts in development and regeneration are harnessed to formulate a genetic cell therapy program which is safe and efficacious as previously been tested in FDA Phase III clinical trials. Myoblasts are selected for strength development and foreskin fibroblasts for tenacity and smooth-to-the-touch. Both cell types are highly mitotic and non-carcinogenic. In additional to providing large quantities of nuclei as regenerative gene medicine, and of mitochondria as energy generators, myoblasts secret tumor necrosis factor alpha (TNF-α) for skin whitening and melanoma prevention. Myoblasts, because of their small size, spindle shape, and resilience, grow readily on collagen and laminin within wrinkles of skin surfaces, thus enhancing the color, luster, and texture of the skin “plated” with them. Alternatively, they can be injected subcutaneously as cell filler to reduce wrinkles. Intramuscular injection of myoblasts can augment the size, shape, consistency, tone, and strength of muscle groups, improving the lines, contours, and vitality to sculpt a youthful appearance. By improving cell genetics and organ functions, the program holds promise to sustain the human subject in good health and appearance, with a good quality of life and life prolongation.

碱性成纤维生长因子和神经生长因子对骨骼肌成肌细胞增殖作用的研究

生长因子，因其与多种病理生理状态有关，已受到国内外学者的普遍重视，但多关注于对神经系统发育和再生的研究。有关生长因子对肌细胞生长发育作用的研究，国内尚未见报道。作者应用肌细胞无血清培养技术，观察了碱性成纤维生长因子（ｂＦＧＦ）和神经生长因子（ＮＧＦ）...

Benefit of stem cells and skeletal myoblast cells in dilated cardiomyopathies

Although some authors suggest that there is mitotic division in the heart,most cardiomyocytes do not have the capacity to regenerate after myocardial infarction and when this occurs there is a deterioration of contractile function,and if the area of infarction is extensive ventricular remodeling may occur,leading to the development of heart failure.Cell transplantation into the myocardium with the goal of recovery of cardiac function has been extensively studied in recent years. The effects of cell therapy are based directly on the cell type used and the type of cardiac pathology.For myocardial ischemia in the hibernating myocardium, bone marrow cells have functional benefits,however these results in transmural fibrosis are not evident. In these cases there is a benefit of implantation with skeletal myoblasts,for treating the underlying cause of disease,the loss of cell contractility.

Skeletal myoblast based delivery of angiogenic growth factors:a comparison between angiopoietin-1 and VEGF gene delivery for therapeutic angiogenesis in the heart

Objectives This study investigated the efficacy of human skeletal myoblasts (SkM) mediated either human vascular endothelial growth factor-165 (hVEGF165) or angiopoietin-1 (Ang-1) on vascular development and myocardial regional perfusion. Methods A porcine heart model of chronic infarction was created in 28 female swine by coronary artery ligation. The animals were randomized into: (1) group-1, DMEM injected (n=6), (2) group-2, Ad-null transduced SkM transplanted (n=6), (3) group-3, Ad-hVEGF165 transduced SkM transplanted (n=8), and (4) group-4, Ad-Ang-1 transduced SkM (n=8). Three weeks later, 5 ml DMEM containing 3×108 SkM carrying exogenous genes were intramyocardially injected into 20 sites in left ventricle in groups-2, -3 and -4. Animals in group-1 were injected 5 ml DMEM without cells. Animals were kept on 5 mg/kg cyclosporine per day for 6 weeks. Regional blood flow was measured using fluorescent microspheres. The heart was explanted at 2, 6 and 12 weeks after transplantation for histological studies. Results Histological examination showed survival of lac-z expressing myoblasts in host tissue. Capillary density based on Von Willebrand factor-VIII (vWF-VIII) at low power field (×100) was 57.13±11.85 in group-3 at 6 weeks and declined to 32.1±5.21 at 12 weeks, while it was 39.9±10.26 at 6 weeks and increased to 45.14±6.54 at 12 weeks in group-4. The mature blood vessel index was highest in group- 4 at 6 and 12 weeks after transplantation. The regional blood flow in the center and peri-infarct area was significantly increased in animals of groups-3 and -4. Conclusions SkM carrying either hVEGF165 or Ang-1 induced neovascularization with increased blood flow. Ang-1 overexpression resulted in mature and stable blood vessel formation and may be a more potent arteriogenic inducer for neovascularization.

Modified methods for culturing myoblasts of rats: Combination of multi-enzymatic digestion and double purification

BACKGROUND： With developments of tissue engineering and genetic engineering, we aim to culture myoblasts, which are characterized by high purity, high quality and high production, for wide application in neural regeneration researches. OBJECTIVE： To modify traditional dissociation method in order to obtain myoblasts, which are characterized by high purity, high quality and high production, and explore the biological properties under in vitro culture. DESIGN： Observational study. SETTING： Basic Institute of Academy of Military Medical Sciences of Chinese PLA. MATERIALS： Four neonatal Wistar rats of 5 days old, both genders and mean body mass of 10 g were selected in this study. The main reagents and devices were detailed as follows： DMEM medium （Gibco Company）, fetus bovine serum （FBS, Hycolne Company）, collagenase Ⅱ （Sigma Company）, trypsin （Sigma Company）, dispase Ⅱ （Sigma Company）, desmin antibody （Fuzhou Maixin Company）, antibody Ⅱ and ABC kit （Wuhan Baster Biotechnology Company）, desk centrifuge （KUBATO, Japan）, and inverted phase contrast microscope （LEICA DMIRB, Germany）. METHODS： The experiment was carried out in the Basic Institute of Academy of Military Medical Sciences of Chinese PLA from June to October 2006. Neonatal rats were sacrificed under sterile condition to obtain skeletal muscles of limbs, which were washed with cold PBS （containing benzylpenicillin and estreptomicina）, and muscular tissue was sheared into pieces. Then, those muscular pieces were added with mixed digestive enzyme （containing 2 g/L collagenase Ⅱ ＋ 5 g/L dispase Ⅱ ＋ 0.28 g/L CaCl2） as twice volume as pieces, dealt with mechanical pipetting for 5 minutes and cultured in CO2 incubator for 10 minutes. The operation was done for three times and the muscular pieces were digested for 45 minutes in total. Moreover, cells were suspended again in order to obtain myoblasts from skeletal muscle of neonatal rats. In addition, myoblasts were purified with differential attachment technique and enzyme digestion so as to observe morphological characteristics and growth, draw growth curve, analyze surface structure under scanning electron microscope, and evaluate with Desmin immunohistochemical staining. MAIN OUTCOME MEASURES： Morphological characteristics and growth ofmyoblasts cultured in vitro. RESULTS： ①Growth of myoblasts of skeletal muscle： Primary cells had well growth, mature and differentiation. The positive rate of Desmin was 94% and purification of cells was ideal. Growth curve of cells demonstrated that myoblasts which were characterized by high purification started proliferation plentiful through transient growth lag phase （about at one or two days after inoculation）. If myoblasts were not dealt with any interventions, they might become sarcotubule gradually at 3 - 5 days after proliferative phase. During this period, myoblasts maintained a monocaryon-bipolarity state under inverted phase contrast microscope. Furthermore, the growth of cells was the strongest and reproductive activity was the most powerful. This suggested that myotube started to form; in addition, muscle fiber of contractility might form under a well culturing condition. ②Immunocytochemical stain with desmin antibody： Interzonal fiber of desmin from myoblasts showed strongly positive reaction. Positive staining existed in cytoplasm had a high nucleus-cytoplasm ratio. However, myoblasts showed negative or mildly positive reaction. CONCLUSION： It is ideal for modified multi-enzymatic digestion and double purification method to dissociate and purify myoblasts of skeletal muscle; meanwhile, these two methods are both the effective ways to provide convenient conditions to obtain seed cells for neural regeneration researches.

Human myoblast genome therapy

Human Myoblast Genome Therapy (HMGT) is a platform technology of cell transplantation, nuclear transfer, and tissue engineering. Unlike stem cells, myoblasts are differentiated, immature cells destined to become muscles. Myoblasts cultured from satellite cells of adult muscle biopsies survive, develop, and function to revitalize degenerative muscles upon transplantation. Injection injury activates regeneration of host myofibers that fuse with the engrafted myoblasts, sharing their nuclei in a common gene pool of the syncytium. Thus, through nuclear transfer and complementation, the normal human genome can be transferred into muscles of patients with genetic disorders to achieve phenotype repair or disease prevention. Myoblasts are safe and efficient gene transfer vehicles endogenous to muscles that constitute 50% of body weight. Results of over 280 HMGT procedures on Duchenne Muscular Dystrophy (DMD) subjects in the past 15 years demonstrated absolute safety. Myoblast-injected DMD muscles showed improved histology. Strength increase at 18 months post-operatively averaged 123%. In another application of HMGT on ischemic cardiomyopathy, the first human myoblast transfer into porcine myocardium revealed that it was safe and effective. Clinical trials on approximately 220 severe cardiomyopathy patients in 15 countries showed a <10% mortality. Most subjects received autologous cells implanted on the epicardial surface during coronory artery bypass graft, or injected on the endomyocardial surface percutaneously through guiding catheters. Significant increases in left ventricular ejection fraction, wall thickness, and wall motion have been reported, with reduction in perfusion defective areas, angina, and shortness of breath. As a new modality of treatment for disease in the skeletal muscle or myocardium, HMGT emerged as safe and effective. Large randomized multi-center trials are under way to confirm these preliminary results. The future of HMGT is bright and exciting.

Stem cell transplantation for treating Duchenne muscular dystrophy A Web of Science-based literature analysis

OBJECTIVE： To identify global research trends in stem cell transplantation for treating Duchenne muscular dystrophy using a bibliometric analysis of Web of Science. DATA RETRIEVAL： We performed a bibliometric analysis of studies on stem cell transplantation for treating Duchenne muscular dystrophy from 2002 to 2011 retrieved from Web of Science. SELECTION CRITERIA： Inclusion criteria： （a） peer-reviewed published articles on stem cell transplantation for treating Duchenne muscular dystrophy indexed in Web of Science; （b） original research articles, reviews, meeting abstracts, proceedings papers, book chapters, editorial material, and news items; and （c） publication between 2002 and 2011. Exclusion criteria： （a） articles that required manual searching or telephone access; （b） documents that were not published in the public domain; and （c） corrected papers. MAIN OUTCOME MEASURES： （1）Annual publication output; （2） distribution according to subject areas; （3） distribution according to journals; （4） distribution according to country; （5） distribution according to institution; （6） distribution according to institution in China; （7） distribution according to institution that cooperated with Chinese institutions; （8） top-cited articles from 2002 to 2006; （9） top-cited articles from 2007 to 2011. RESULTS： A total of 318 publications on stem cell transplantation for treating Duchenne muscular dystrophy were retrieved from Web of Science from 2002 to 2011, of which almost half derived from American authors and institutes. The number of publications has gradually increased over the past 10 years. Most papers appeared in journals with a focus on gene and molecular research, such as Molecular Therapy, Neuromuscular Disorders, and PLoS One. The 10 most-cited papers from 2002 to 2006 were mostly about different kinds of stem cell transplantation for muscle regeneration, while the 10 most-cited papers from 2007 to 2011 were mostly about new techniques of stem cell transplantation for treating Duchenne muscular dystrophy. CONCLUSION： The publications on stem cell transplantation for treating Duchenne muscular dystrophy were relatively few. It also needs more research to confirm that stem cell therapy is a reliable treatment for Duchenne muscular dystrophy.

MicroRNA bta-miR-365-3p inhibits proliferation but promotes differentiation of primary bovine myoblasts by targeting the activin A receptor type Ⅰ

Background: MicroRNAs act as post-transcriptional regulators that repress translation or degrade mRNA transcripts.Each microRNA has many mRNA targets and each mRNA may be targeted by several microRNAs. Skeletal muscles express a plethora of microRNA genes that regulate muscle development and function by controlling the expression of protein-coding target genes. To expand our understanding of the role of microRNA, specifically btamiR-365-3 p, in muscle biology, we investigated its functions in regulating primary bovine myoblast proliferation and differentiation.Results: Firstly, we found that bta-miR-365-3 p was predominantly expressed in skeletal muscle and heart tissue in Chinese Qinchuan beef cattle. Quantitative PCR and western blotting results showed that overexpression of btamiR-365-3 p significantly reduced the expression levels of cyclin D1(CCND1), cyclin dependent kinase 2(CDK2) and proliferating cell nuclear antigen(PCNA) but stimulated the expression levels of muscle differentiation markers, i.e.,MYOD1, MYOG at both mRNA and protein level. Moreover, downregulation of bta-miR-365-3 p increased the expression of CCND1, CDK2 and PCNA but decreased the expression of MYOD1 and MYOG at both mRNA and protein levels. Furthermore, flow cytometry, EdU proliferation assays and immunostaining results showed that increased levels of bta-miR-365-3 p suppressed cell proliferation but promoted myotube formation, whereas decreased levels of bta-miR-365-3 p resulted in the opposite consequences. Finally, we identified that activin A receptor type I(ACVR1) could be a direct target of bta-miR-365-3 p. It was demonstrated that bta-miR-365-3 p can bind to the 3'UTR of ACVR1 gene to regulate its expression based on dual luciferase gene reporter assays.Consistently, knock-down of ACVR1 was associated with decreased expressions of CDK2, CCND1 and PCNA but increased expression of MYOG and MYOD1 both at mRNA and protein level.Conclusion: Collectively, these data suggested that bta-miR-365-3 p represses proliferation but promotes differentiation of bovine myoblasts through several biological mechanisms involving downregulation of ACVR1.

Culture and Identification of Myoblasts Isolated from Duck Embryos

Using embryonic myoblasts to research the formation and de-velopmental mechanisms of skeletal muscle is becoming a research hotspot. This study aimed to establish a method of isolation, culture and identification of my-oblasts in duck embryos. [Method] Pectoral and leg muscle samples were isolated from the embryos of Gaoyou duck at 13 d of hatching, then disassociated with col-lagenase and trypsin and purified via differential adhesion. The isolated cells were cultured in vitro and detected for the expression of Pax7 protein using immunofluo-rescence technique. [Result] Myoblasts were obtained successful y both from pectoral and leg muscles in duck embryos and these cells proliferated strongly and differen-tiated wel . Immunofluorescence staining showed that more than 95% cells could express Pax7 protein. [Conclusion] In summary, we report the successful establish-ment of a complete system for the isolation, purification, identification and culture of myoblasts from duck embryos.

Growth and differentiation factor-11 is developmentally regulated in skeletal muscle and inhibits myoblast differentiation

Growth and differentiation factor-11 (GDF-11) is a secreted protein that is closely related to myostatin, a known inhibitor of skeletal muscle development. The role of GDF-11 in regulating skeletal muscle growth remains unclear and the pattern of expression during post-natal growth has not been reported. Therefore, we sought to determine the expression of GDF-11 during post-natal growth and its effect on myoblast proliferation and differentiation. We collected gastrocnemius muscles from male and female mice at 2, 3, 4, 6, 12, 20 and 32 weeks of age (n = 6 per sex and age). In addition, gastrocnemius muscles were col- lected from male wild-type and myostatin knockout mice at 4, 6, 12 and 20 weeks of age (n = 6 per age and genotype). RNA was extracted and reverse tran- scribed. Northern analysis identified an expected 4.4 kb mRNA transcript for GDF-11 in gastrocnemius muscles of mice. The concentration of GDF-11 mRNA, as determined by quantitative PCR, was increased in gastrocnemius muscles from 2 to 6 weeks—a period of rapid postnatal muscle growth—and remained higher in male than female mice from 4 to 20 weeks of age (P gastrocnemius muscles of myostatin knockout compared with wild-type mice (P < 0.05), which may suggest a compensatory mecha- nism for the lack of myostatin. In support, recombi- nant GDF-11 inhibited differentiation of C2C12 mur- ine myoblasts and those isolated from myostatin knockout and wild-type mice (P < 0.05). Inhibited dif-ferentiation of C2C12 myoblasts was associated with decreased mRNA expression of early and late mo- lecular markers of differentiation (MyoD, myogenin, IGF-II, desmin and MyHC, P < 0.05). Our results suggest that GDF-11 regulates growth of skeletal muscles by inhibiting myoblast differentiation in an autocrine/paracrine manner and, perhaps, also plays a role in regulating sexually dimorphic growth.

Role of Mutant TBP in Regulation of Myogenesis on Muscle Satellite Cells

In polyglutamine(PolyQ)diseases,mutant proteins cause not only neurological problems but also peripheral tissue abnormalities.Among all systemic damages,skeletal muscle dystrophy is the severest.Previously by studying knock-in(KI)mouse models of spinal cerebellar ataxia 17(SCA17),it was found that mutant TATA box binding protein(TBP)decreases its interaction with myogenic differentiation antigen,thus reducing the expression of skeletal muscle structural proteins and resulting in muscle degeneration.In this paper,the role of mutant TBP in myogenesis was investigated.Single myofibers were isolated from tibialis anterior muscles of wild type(WT)and SCA17KI mice.The 1TBP18 staining confirmed the expression of mutant TBP in muscle satellite cells in SCA17Ki mice.In the BaCl2-induced TA muscle injury,H&E cross-section staining showed no significant change in myofibril size before and after BaCl2 treatment,and there was no significant difference in centralized nuclei between WT and SCA17KI mice,suggesting that mutant TBP had no significant effect on muscle regeneration.In the cultured primary myoblasts from WT and SCA17KI mice in vitro,representative BrdU immunostaining showed no significant difference in proliferation of muscle satellite cells.The primary myoblasts were then induced to differentiate and immunostained for eMyHC,and the staining showed there was no significant difference in differentiation of primary myoblasts between WT and SCA1KI mice.Our findings confirmed that mutant TBP had no significant effect on myogenesis.

Ryanodine receptor RyR1-mediated elevation of Ca^(2+)concentration is required for the late stage of myogenic differentiation and fusion

Background:Cytosolic Ca^(2+)plays vital roles in myogenesis and muscle development.As a major Ca^(2+)release channel of endoplasmic reticulum(ER),ryanodine receptor 1(RyR1)key mutations are main causes of severe congenital myopathies.The role of RyR1 in myogenic differentiation has attracted intense research interest but remains unclear.Results:In the present study,both RyR1-knockdown myoblasts and CRISPR/Cas9-based RyR1-knockout myoblasts were employed to explore the role of RyR1 in myogenic differentiation,myotube formation as well as the potential mechanism of RyR1-related myopathies.We observed that RyR1 expression was dramatically increased during the late stage of myogenic differentiation,accompanied by significantly elevated cytoplasmic Ca^(2+)concentration.Inhibition of RyR1 by siRNA-mediated knockdown or chemical inhibitor,dantrolene,significantly reduced cytosolic Ca^(2+)and blocked multinucleated myotube formation.The elevation of cytoplasmic Ca^(2+)concentration can effectively relieve myogenic differentiation stagnation by RyR1 inhibition,demonstrating that RyR1 modulates myogenic differentiation via regulation of Ca^(2+)release channel.However,RyR1-knockout-induced Ca^(2+)leakage led to the severe ER stress and excessive unfolded protein response,and drove myoblasts into apoptosis.Conclusions:Therefore,we concluded that Ca^(2+)release mediated by dramatic increase in RyR1 expression is required for the late stage of myogenic differentiation and fusion.This study contributes to a novel understanding of the role of RyR1 in myogenic differentiation and related congenital myopathies,and provides a potential target for regulation of muscle characteristics and meat quality.

Change of p16^(INK4a) and PNCA Protein Expression in Myocardium after Injection of hIGF-1 Gene Modified Skeletal Myoblasts into Post-infarction Rats

This study examined the change of p16^INK4a and PNCA protein expression in myocardium after injection of hIGF-1 gene modified skeletal myoblasts into post-infarction rats. HIGF-1 gene modified skeletal myoblasts （hIGF-1-myoblasts） were injected into hind limb muscles of 18 post-infraction rats （experimental group）. Primary-myoblasts were injected into 18 post-infraction rats （control group） and 12 non-infarction rats （sham group）. Expression of p16INK4a and PCNA pro- tein in myocardiums were separately detected immunocytochemically 1, 2 and 4 weeks after the inuection. The level of hIGF-1 and rIGF-1 protein in serum and myocardium were detected by en- zyme-linked immunosorbent assay （ELISA）. Compared with the sham group, the percentage of p^16INK4a and PCNA positive cells reached a peak after 1 week in the control group and the experimental group （P〈0.01）. Moreover, the percentage of p16^INK4a-positive cells in the experimental group was lower than in control group whereas the percentage of PCNA-positive cells was lower in the control group than in the experimental group （P〈0.01）. The percentage of p16^INK4a-positive cells in the experimental group and the percentage of PCNA-positive cells in the control group were close to that in the sham group from the 2nd week （P〉0.05）. ELISA analysis disclosed that the myocardium level of rIGF-1 protein increased gradually in the controls and especially in the experimental group （P〈0.01）. The serum level of rIGF-1 decreased significantly in post-infraction rats, but these conditions were improved in the experimental group （P〈0.01）. The hIGF-1 protein in serum and myocar- dium were detected from the 1st week to the 4th week in the experimental group. Statistical analysis revealed significant associations of myocardium level of hIGF-1 protein with expression of p^16INK4a and PCNA protein （r=–0.323, P〈0.05; r=0.647, P〈0.01）. It is concluded that genetically hIGF-1-myoblast provides a means for constant synthesis and release of hIGF-1. It could not only improve the expression of rIGF-1 and PCNA protein in myocardium, but also suppress the expression of p16^INK4a protein for 30 days in post-infraction rats. Myoblasts-mediated IGF-1 gene therapy may provide a new alternative for the clinical treatment of heart failure.

Preclinical stem cell therapy in Chagas Disease: Perspectives for future research

Chagas cardiomyopathy still remains a challenging problem that is responsible for high morbidity and mortality in Central and Latin America. Chagas disease disrupts blood microcirculation via various autoimmune mechanisms, causing loss of cardiomyocytes and severe impairment of heart function. Different cell types and delivery approaches in Chagas Disease have been studied in both preclinical models and clinical trials. The main objective of this article is to clarify the reasons why the benefits that have been seen with cell therapy in preclinical models fail to translate to the clinical setting. This can be explained by crucial differences between the cellular types and pathophysiological mechanisms of the disease, as well as the differences between human patients and animal models. We discuss examples that demonstrate how the results from preclinical trials might have overestimated the efficacy of myocardial regeneration therapies. Future research should focus, not only on studying the best cell type to use but, very importantly, understanding the levels of safety and cellular interaction that can elicit efficient therapeutic effects in human tissue. Addressing the challenges associated with future research may ensure the success of stem cell therapy in improving preclinical models and the treatment of Chagas disease.