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Elevated Muscle-Specific miRNAs in Serum of Myotonic Dystrophy Patients Relate to Muscle Disease Progress.
PUBLISHED: 04-28-2015
The discovery of reliable and sensitive blood biomarkers is useful for the diagnosis, monitoring and potential future therapy of diseases. Recently, microRNAs (miRNAs) have been identified in blood circulation and might have the potential to be used as biomarkers for several diseases and clinical conditions. Myotonic Dystrophy type 1 (DM1) is the most common form of adult-onset muscular dystrophy primarily characterized by muscle myotonia, weakness and atrophy. Previous studies have shown an association between miRNAs and DM1 in muscle tissue and, recently, in plasma. The aim of this study was to detect and assess muscle-specific miRNAs as potential biomarkers of DM1 muscle wasting, an important parameter in the disease's natural history. Disease stable or progressive DM1 patients with muscle weakness and wasting were recruited and enrolled in the study. RNA isolated from participants' serum was used to assess miRNA levels. Results suggest that the levels of muscle-specific miRNAs are correlated with the progression of muscle wasting and weakness observed in the DM1 patients. Specifically, miR-1, miR-133a, miR133b and miR-206 serum levels were found elevated in DM1 patients with progressive muscle wasting compared to disease stable DM1 patients. Based on these results, we propose that muscle-specific miRNAs might be useful molecular biomarkers for monitoring the progress of muscle atrophy in DM1 patients.
Authors: Bruno Gualano, Carlos Ugrinowitsch, Manoel Neves Jr., Fernanda R. Lima, Ana Lúcia S. Pinto, Gilberto Laurentino, Valmor A.A. Tricoli, Antonio H. Lancha Jr., Hamilton Roschel.
Published: 06-05-2010
Inclusion body myositis (IBM) is a rare idiopathic inflammatory myopathy. It is known to produces remarkable muscle weakness and to greatly compromise function and quality of life. Moreover, clinical practice suggests that, unlike other inflammatory myopathies, the majority of IBM patients are not responsive to treatment with immunosuppressive or immunomodulatory drugs to counteract disease progression1. Additionally, conventional resistance training programs have been proven ineffective in restoring muscle function and muscle mass in these patients2,3. Nevertheless, we have recently observed that restricting muscle blood flow using tourniquet cuffs in association with moderate intensity resistance training in an IBM patient produced a significant gain in muscle mass and function, along with substantial benefits in quality of life4. Thus, a new non-pharmacological approach for IBM patients has been proposed. Herein, we describe the details of a proposed protocol for vascular occlusion associated with a resistance training program for this population.
20 Related JoVE Articles!
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Profiling of Estrogen-regulated MicroRNAs in Breast Cancer Cells
Authors: Anne Katchy, Cecilia Williams.
Institutions: University of Houston.
Estrogen plays vital roles in mammary gland development and breast cancer progression. It mediates its function by binding to and activating the estrogen receptors (ERs), ERα, and ERβ. ERα is frequently upregulated in breast cancer and drives the proliferation of breast cancer cells. The ERs function as transcription factors and regulate gene expression. Whereas ERα's regulation of protein-coding genes is well established, its regulation of noncoding microRNA (miRNA) is less explored. miRNAs play a major role in the post-transcriptional regulation of genes, inhibiting their translation or degrading their mRNA. miRNAs can function as oncogenes or tumor suppressors and are also promising biomarkers. Among the miRNA assays available, microarray and quantitative real-time polymerase chain reaction (qPCR) have been extensively used to detect and quantify miRNA levels. To identify miRNAs regulated by estrogen signaling in breast cancer, their expression in ERα-positive breast cancer cell lines were compared before and after estrogen-activation using both the µParaflo-microfluidic microarrays and Dual Labeled Probes-low density arrays. Results were validated using specific qPCR assays, applying both Cyanine dye-based and Dual Labeled Probes-based chemistry. Furthermore, a time-point assay was used to identify regulations over time. Advantages of the miRNA assay approach used in this study is that it enables a fast screening of mature miRNA regulations in numerous samples, even with limited sample amounts. The layout, including the specific conditions for cell culture and estrogen treatment, biological and technical replicates, and large-scale screening followed by in-depth confirmations using separate techniques, ensures a robust detection of miRNA regulations, and eliminates false positives and other artifacts. However, mutated or unknown miRNAs, or regulations at the primary and precursor transcript level, will not be detected. The method presented here represents a thorough investigation of estrogen-mediated miRNA regulation.
Medicine, Issue 84, breast cancer, microRNA, estrogen, estrogen receptor, microarray, qPCR
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Assessing Functional Performance in the Mdx Mouse Model
Authors: Annemieke Aartsma-Rus, Maaike van Putten.
Institutions: Leiden University Medical Center.
Duchenne muscular dystrophy (DMD) is a severe and progressive muscle wasting disorder for which no cure is available. Nevertheless, several potential pharmaceutical compounds and gene therapy approaches have progressed into clinical trials. With improvement in muscle function being the most important end point in these trials, a lot of emphasis has been placed on setting up reliable, reproducible, and easy to perform functional tests to pre clinically assess muscle function, strength, condition, and coordination in the mdx mouse model for DMD. Both invasive and noninvasive tests are available. Tests that do not exacerbate the disease can be used to determine the natural history of the disease and the effects of therapeutic interventions (e.g. forelimb grip strength test, two different hanging tests using either a wire or a grid and rotarod running). Alternatively, forced treadmill running can be used to enhance disease progression and/or assess protective effects of therapeutic interventions on disease pathology. We here describe how to perform these most commonly used functional tests in a reliable and reproducible manner. Using these protocols based on standard operating procedures enables comparison of data between different laboratories.
Behavior, Issue 85, Duchenne muscular dystrophy, neuromuscular disorders, outcome measures, functional testing, mouse model, grip strength, hanging test wire, hanging test grid, rotarod running, treadmill running
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Isolation of Small Noncoding RNAs from Human Serum
Authors: Samantha Khoury, Pamela Ajuyah, Nham Tran.
Institutions: University of Technology, Sydney, University of Technology, Sydney, Royal Prince Alfred Hospital.
The analysis of RNA and its expression is a common feature in many laboratories. Of significance is the emergence of small RNAs like microRNAs, which are found in mammalian cells. These small RNAs are potent gene regulators controlling vital pathways such as growth, development and death and much interest has been directed at their expression in bodily fluids. This is due to their dysregulation in human diseases such as cancer and their potential application as serum biomarkers. However, the analysis of miRNA expression in serum may be problematic. In most cases the amount of serum is limiting and serum contains low amounts of total RNA, of which small RNAs only constitute 0.4-0.5%1. Thus the isolation of sufficient amounts of quality RNA from serum is a major challenge to researchers today. In this technical paper, we demonstrate a method which uses only 400 µl of human serum to obtain sufficient RNA for either DNA arrays or qPCR analysis. The advantages of this method are its simplicity and ability to yield high quality RNA. It requires no specialized columns for purification of small RNAs and utilizes general reagents and hardware found in common laboratories. Our method utilizes a Phase Lock Gel to eliminate phenol contamination while at the same time yielding high quality RNA. We also introduce an additional step to further remove all contaminants during the isolation step. This protocol is very effective in isolating yields of total RNA of up to 100 ng/µl from serum but can also be adapted for other biological tissues.
Bioengineering, Issue 88, small noncoding RNA isolation, microRNAs, human serum, qPCR, guanidinium thiocyanate , Phase Lock Gels, arrays
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Tissue Triage and Freezing for Models of Skeletal Muscle Disease
Authors: Hui Meng, Paul M.L. Janssen, Robert W. Grange, Lin Yang, Alan H. Beggs, Lindsay C. Swanson, Stacy A. Cossette, Alison Frase, Martin K. Childers, Henk Granzier, Emanuela Gussoni, Michael W. Lawlor.
Institutions: Medical College of Wisconsin, The Ohio State University, Virginia Tech, University of Kentucky, Boston Children's Hospital, Harvard Medical School, Cure Congenital Muscular Dystrophy, Joshua Frase Foundation, University of Washington, University of Arizona.
Skeletal muscle is a unique tissue because of its structure and function, which requires specific protocols for tissue collection to obtain optimal results from functional, cellular, molecular, and pathological evaluations. Due to the subtlety of some pathological abnormalities seen in congenital muscle disorders and the potential for fixation to interfere with the recognition of these features, pathological evaluation of frozen muscle is preferable to fixed muscle when evaluating skeletal muscle for congenital muscle disease. Additionally, the potential to produce severe freezing artifacts in muscle requires specific precautions when freezing skeletal muscle for histological examination that are not commonly used when freezing other tissues. This manuscript describes a protocol for rapid freezing of skeletal muscle using isopentane (2-methylbutane) cooled with liquid nitrogen to preserve optimal skeletal muscle morphology. This procedure is also effective for freezing tissue intended for genetic or protein expression studies. Furthermore, we have integrated our freezing protocol into a broader procedure that also describes preferred methods for the short term triage of tissue for (1) single fiber functional studies and (2) myoblast cell culture, with a focus on the minimum effort necessary to collect tissue and transport it to specialized research or reference labs to complete these studies. Overall, this manuscript provides an outline of how fresh tissue can be effectively distributed for a variety of phenotypic studies and thereby provides standard operating procedures (SOPs) for pathological studies related to congenital muscle disease.
Basic Protocol, Issue 89, Tissue, Freezing, Muscle, Isopentane, Pathology, Functional Testing, Cell Culture
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Generation of Induced Pluripotent Stem Cells from Muscular Dystrophy Patients: Efficient Integration-free Reprogramming of Urine Derived Cells
Authors: Muhammad Z. Afzal, Jennifer L. Strande.
Institutions: Medical College of Wisconsin.
Dystrophic cardiomyopathy is a poorly understood consequence of muscular dystrophy. Generating induced Pluripotent Stem Cells (iPSCs) from patients with muscular dystrophy is an invaluable cellular source for in vitro disease model systems and can be used for drug screening studies. Patient-derived urine cells have been used in successful reprogramming into induced pluripotent stem cells in order to model dystrophic cardiomyopathy1. Addressing the safety concerns of integrating vector systems, we present a protocol using a non-integrating Sendai virus vector for transduction of Yamanaka factors into urine cells collected from patients with muscular dystrophy. This protocol generates fully reprogrammed clones within 2–3 weeks. The pluripotent cells are vector-free by passage-13. These dystrophic iPSCs can be differentiated into cardiomyocytes and used either to study disease mechanisms or for drug screening.
Medicine, Issue 95, Stem cell biology, Urine derived Cells (UCs), Induced Pluripotent Stem Cells (iPSCs), reprogramming, Sendai Virus (SeV), viral transduction, iPSC-derived Cardiomyocytes (iCMs), regenerative medicine, Muscular Dystrophy (MD), dystrophic cardiomyopathy.
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Methods to Assess Subcellular Compartments of Muscle in C. elegans
Authors: Christopher J. Gaffney, Joseph J. Bass, Thomas F. Barratt, Nathaniel J. Szewczyk.
Institutions: University of Nottingham.
Muscle is a dynamic tissue that responds to changes in nutrition, exercise, and disease state. The loss of muscle mass and function with disease and age are significant public health burdens. We currently understand little about the genetic regulation of muscle health with disease or age. The nematode C. elegans is an established model for understanding the genomic regulation of biological processes of interest. This worm’s body wall muscles display a large degree of homology with the muscles of higher metazoan species. Since C. elegans is a transparent organism, the localization of GFP to mitochondria and sarcomeres allows visualization of these structures in vivo. Similarly, feeding animals cationic dyes, which accumulate based on the existence of a mitochondrial membrane potential, allows the assessment of mitochondrial function in vivo. These methods, as well as assessment of muscle protein homeostasis, are combined with assessment of whole animal muscle function, in the form of movement assays, to allow correlation of sub-cellular defects with functional measures of muscle performance. Thus, C. elegans provides a powerful platform with which to assess the impact of mutations, gene knockdown, and/or chemical compounds upon muscle structure and function. Lastly, as GFP, cationic dyes, and movement assays are assessed non-invasively, prospective studies of muscle structure and function can be conducted across the whole life course and this at present cannot be easily investigated in vivo in any other organism.
Developmental Biology, Issue 93, Physiology, C. elegans, muscle, mitochondria, sarcomeres, ageing
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The Neuromuscular Junction: Measuring Synapse Size, Fragmentation and Changes in Synaptic Protein Density Using Confocal Fluorescence Microscopy
Authors: Nigel Tse, Marco Morsch, Nazanin Ghazanfari, Louise Cole, Archunan Visvanathan, Catherine Leamey, William D. Phillips.
Institutions: University of Sydney, Macquarie University, University of Sydney.
The neuromuscular junction (NMJ) is the large, cholinergic relay synapse through which mammalian motor neurons control voluntary muscle contraction. Structural changes at the NMJ can result in neurotransmission failure, resulting in weakness, atrophy and even death of the muscle fiber. Many studies have investigated how genetic modifications or disease can alter the structure of the mouse NMJ. Unfortunately, it can be difficult to directly compare findings from these studies because they often employed different parameters and analytical methods. Three protocols are described here. The first uses maximum intensity projection confocal images to measure the area of acetylcholine receptor (AChR)-rich postsynaptic membrane domains at the endplate and the area of synaptic vesicle staining in the overlying presynaptic nerve terminal. The second protocol compares the relative intensities of immunostaining for synaptic proteins in the postsynaptic membrane. The third protocol uses Fluorescence Resonance Energy Transfer (FRET) to detect changes in the packing of postsynaptic AChRs at the endplate. The protocols have been developed and refined over a series of studies. Factors that influence the quality and consistency of results are discussed and normative data are provided for NMJs in healthy young adult mice.
Neuroscience, Issue 94, neuromuscular, motor endplate, motor control, sarcopenia, myasthenia gravis, amyotrophic lateral sclerosis, morphometry, confocal, immunofluorescence
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Isolation and Immortalization of Patient-derived Cell Lines from Muscle Biopsy for Disease Modeling
Authors: Jerome D. Robin, Woody E. Wright, Yaqun Zou, Stacy C. Cossette, Michael W. Lawlor, Emanuela Gussoni.
Institutions: UT Southwestern Medical Center, National Institute of Health, Medical College of Wisconsin, Boston Children's Hospital.
The generation of patient-specific cell lines represents an invaluable tool for diagnostic or translational research, and these cells can be collected from skin or muscle biopsy tissue available during the patient’s diagnostic workup. In this protocol, we describe a technique for live cell isolation from small amounts of muscle or skin tissue for primary cell culture. Additionally, we provide a technique for the immortalization of myogenic cell lines and fibroblast cell lines from primary cells. Once cell lines are immortalized, substantial expansion of patient-derived cells can be achieved. Immortalized cells are amenable to many downstream applications, including drug screening and in vitro correction of the genetic mutation. Altogether, these protocols provide a reliable tool to generate and preserve patient-derived cells for downstream applications.
Medicine, Issue 95, Biopsy, skeletal muscle, skin, tissue dissociation, myoblast purification, myoblast immortalization, cell freezing
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Cerebrospinal Fluid MicroRNA Profiling Using Quantitative Real Time PCR
Authors: Marco Pacifici, Serena Delbue, Ferdous Kadri, Francesca Peruzzi.
Institutions: LSU Health Sciences Center, University of Milan.
MicroRNAs (miRNAs) constitute a potent layer of gene regulation by guiding RISC to target sites located on mRNAs and, consequently, by modulating their translational repression. Changes in miRNA expression have been shown to be involved in the development of all major complex diseases. Furthermore, recent findings showed that miRNAs can be secreted to the extracellular environment and enter the bloodstream and other body fluids where they can circulate with high stability. The function of such circulating miRNAs remains largely elusive, but systematic high throughput approaches, such as miRNA profiling arrays, have lead to the identification of miRNA signatures in several pathological conditions, including neurodegenerative disorders and several types of cancers. In this context, the identification of miRNA expression profile in the cerebrospinal fluid, as reported in our recent study, makes miRNAs attractive candidates for biomarker analysis. There are several tools available for profiling microRNAs, such as microarrays, quantitative real-time PCR (qPCR), and deep sequencing. Here, we describe a sensitive method to profile microRNAs in cerebrospinal fluids by quantitative real-time PCR. We used the Exiqon microRNA ready-to-use PCR human panels I and II V2.R, which allows detection of 742 unique human microRNAs. We performed the arrays in triplicate runs and we processed and analyzed data using the GenEx Professional 5 software. Using this protocol, we have successfully profiled microRNAs in various types of cell lines and primary cells, CSF, plasma, and formalin-fixed paraffin-embedded tissues.
Medicine, Issue 83, microRNAs, biomarkers, miRNA profiling, qPCR, cerebrospinal fluid, RNA, DNA
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A Modified Precipitation Method to Isolate Urinary Exosomes
Authors: Rupesh Kanchi Ravi, Mahdieh Khosroheidari, Johanna K. DiStefano.
Institutions: Translational Genomics Research Institute (TGen).
Identification of biomarkers that allow early detection of kidney diseases in urine and plasma has been an area of active interest for several years. Urinary exosome vesicles, 40-100 nm in size, are released into the urine under normal conditions by cells from all nephron segments and may contain protein, mRNA and microRNA representative of their cell type of origin. Under conditions of renal dysfunction or injury, exosomes may contain altered proportions of these components, which may serve as biomarkers for disease. There are currently several methods available for isolation of urinary exosomes, and we have previously conducted an experimental comparison of each of these approaches, including three based on ultracentrifugation, one using a nanomembrane ultrafiltration concentrator, one using a commercial precipitation reagent and one using a modification of the precipitation technique using ExoQuick reagent that we developed in our laboratory. We found the modified precipitation method produced the highest yield of exosome particles, miRNA, and mRNA, making this approach suitable for the isolation of exosomes for subsequent RNA profiling. We conclude that the modified exosome precipitation method offers a quick, scalable, and effective alternative for the isolation of exosomes from urine. In this report, we describe our modified precipitation technique using ExoQuick reagent for isolating exosomes from human urine.
Medicine, Issue 95, Translational medicine, exosomes, urine, RNA, western blot, Tamm-Horsfall Protein
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Utility of Dissociated Intrinsic Hand Muscle Atrophy in the Diagnosis of Amyotrophic Lateral Sclerosis
Authors: Parvathi Menon, Steve Vucic.
Institutions: Westmead Hospital, University of Sydney, Australia.
The split hand phenomenon refers to predominant wasting of thenar muscles and is an early and specific feature of amyotrophic lateral sclerosis (ALS). A novel split hand index (SI) was developed to quantify the split hand phenomenon, and its diagnostic utility was assessed in ALS patients. The split hand index was derived by dividing the product of the compound muscle action potential (CMAP) amplitude recorded over the abductor pollicis brevis and first dorsal interosseous muscles by the CMAP amplitude recorded over the abductor digiti minimi muscle. In order to assess the diagnostic utility of the split hand index, ALS patients were prospectively assessed and their results were compared to neuromuscular disorder patients. The split hand index was significantly reduced in ALS when compared to neuromuscular disorder patients (P<0.0001). Limb-onset ALS patients exhibited the greatest reduction in the split hand index, and a value of 5.2 or less reliably differentiated ALS from other neuromuscular disorders. Consequently, the split hand index appears to be a novel diagnostic biomarker for ALS, perhaps facilitating an earlier diagnosis.
Medicine, Issue 85, Amyotrophic Lateral Sclerosis (ALS), dissociated muscle atrophy, hypothenar muscles, motor neuron disease, split-hand index, thenar muscles
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Adult and Embryonic Skeletal Muscle Microexplant Culture and Isolation of Skeletal Muscle Stem Cells
Authors: Deborah Merrick, Hung-Chih Chen, Dean Larner, Janet Smith.
Institutions: University of Birmingham.
Cultured embryonic and adult skeletal muscle cells have a number of different uses. The micro-dissected explants technique described in this chapter is a robust and reliable method for isolating relatively large numbers of proliferative skeletal muscle cells from juvenile, adult or embryonic muscles as a source of skeletal muscle stem cells. The authors have used micro-dissected explant cultures to analyse the growth characteristics of skeletal muscle cells in wild-type and dystrophic muscles. Each of the components of tissue growth, namely cell survival, proliferation, senescence and differentiation can be analysed separately using the methods described here. The net effect of all components of growth can be established by means of measuring explant outgrowth rates. The micro-explant method can be used to establish primary cultures from a wide range of different muscle types and ages and, as described here, has been adapted by the authors to enable the isolation of embryonic skeletal muscle precursors. Uniquely, micro-explant cultures have been used to derive clonal (single cell origin) skeletal muscle stem cell (SMSc) lines which can be expanded and used for in vivo transplantation. In vivo transplanted SMSc behave as functional, tissue-specific, satellite cells which contribute to skeletal muscle fibre regeneration but which are also retained (in the satellite cell niche) as a small pool of undifferentiated stem cells which can be re-isolated into culture using the micro-explant method.
Cellular Biology, Issue 43, Skeletal muscle stem cell, embryonic tissue culture, apoptosis, growth factor, proliferation, myoblast, myogenesis, satellite cell, skeletal muscle differentiation, muscular dystrophy
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Manual Muscle Testing: A Method of Measuring Extremity Muscle Strength Applied to Critically Ill Patients
Authors: Nancy Ciesla, Victor Dinglas, Eddy Fan, Michelle Kho, Jill Kuramoto, Dale Needham.
Institutions: Johns Hopkins University, Johns Hopkins Hospital , Johns Hopkins University, University of Maryland Medical System.
Survivors of acute respiratory distress syndrome (ARDS) and other causes of critical illness often have generalized weakness, reduced exercise tolerance, and persistent nerve and muscle impairments after hospital discharge.1-6 Using an explicit protocol with a structured approach to training and quality assurance of research staff, manual muscle testing (MMT) is a highly reliable method for assessing strength, using a standardized clinical examination, for patients following ARDS, and can be completed with mechanically ventilated patients who can tolerate sitting upright in bed and are able to follow two-step commands. 7, 8 This video demonstrates a protocol for MMT, which has been taught to ≥43 research staff who have performed >800 assessments on >280 ARDS survivors. Modifications for the bedridden patient are included. Each muscle is tested with specific techniques for positioning, stabilization, resistance, and palpation for each score of the 6-point ordinal Medical Research Council scale.7,9-11 Three upper and three lower extremity muscles are graded in this protocol: shoulder abduction, elbow flexion, wrist extension, hip flexion, knee extension, and ankle dorsiflexion. These muscles were chosen based on the standard approach for evaluating patients for ICU-acquired weakness used in prior publications. 1,2.
Medicine, Issue 50, Muscle Strength, Critical illness, Intensive Care Units, Reproducibility of Results, Clinical Protocols.
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Identifying Targets of Human microRNAs with the LightSwitch Luciferase Assay System using 3'UTR-reporter Constructs and a microRNA Mimic in Adherent Cells
Authors: Shelley Force Aldred, Patrick Collins, Nathan Trinklein.
Institutions: SwitchGear Genomics.
MicroRNAs (miRNAs) are important regulators of gene expression and play a role in many biological processes. More than 700 human miRNAs have been identified so far with each having up to hundreds of unique target mRNAs. Computational tools, expression and proteomics assays, and chromatin-immunoprecipitation-based techniques provide important clues for identifying mRNAs that are direct targets of a particular miRNA. In addition, 3'UTR-reporter assays have become an important component of thorough miRNA target studies because they provide functional evidence for and quantitate the effects of specific miRNA-3'UTR interactions in a cell-based system. To enable more researchers to leverage 3'UTR-reporter assays and to support the scale-up of such assays to high-throughput levels, we have created a genome-wide collection of human 3'UTR luciferase reporters in the highly-optimized LightSwitch Luciferase Assay System. The system also includes synthetic miRNA target reporter constructs for use as positive controls, various endogenous 3'UTR reporter constructs, and a series of standardized experimental protocols. Here we describe a method for co-transfection of individual 3'UTR-reporter constructs along with a miRNA mimic that is efficient, reproducible, and amenable to high-throughput analysis.
Genetics, Issue 55, MicroRNA, miRNA, mimic, Clone, 3' UTR, Assay, vector, LightSwitch, luciferase, co-transfection, 3'UTR REPORTER, mirna target, microrna target, reporter, GoClone, Reporter construct
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A Functional Motor Unit in the Culture Dish: Co-culture of Spinal Cord Explants and Muscle Cells
Authors: Anne-Sophie Arnold, Martine Christe, Christoph Handschin.
Institutions: University of Basel.
Human primary muscle cells cultured aneurally in monolayer rarely contract spontaneously because, in the absence of a nerve component, cell differentiation is limited and motor neuron stimulation is missing1. These limitations hamper the in vitro study of many neuromuscular diseases in cultured muscle cells. Importantly, the experimental constraints of monolayered, cultured muscle cells can be overcome by functional innervation of myofibers with spinal cord explants in co-cultures. Here, we show the different steps required to achieve an efficient, proper innervation of human primary muscle cells, leading to complete differentiation and fiber contraction according to the method developed by Askanas2. To do so, muscle cells are co-cultured with spinal cord explants of rat embryos at ED 13.5, with the dorsal root ganglia still attached to the spinal cord slices. After a few days, the muscle fibers start to contract and eventually become cross-striated through innervation by functional neurites projecting from the spinal cord explants that connecting to the muscle cells. This structure can be maintained for many months, simply by regular exchange of the culture medium. The applications of this invaluable tool are numerous, as it represents a functional model for multidisciplinary analyses of human muscle development and innervation. In fact, a complete de novo neuromuscular junction installation occurs in a culture dish, allowing an easy measurement of many parameters at each step, in a fundamental and physiological context. Just to cite a few examples, genomic and/or proteomic studies can be performed directly on the co-cultures. Furthermore, pre- and post-synaptic effects can be specifically and separately assessed at the neuromuscular junction, because both components come from different species, rat and human, respectively. The nerve-muscle co-culture can also be performed with human muscle cells isolated from patients suffering from muscle or neuromuscular diseases3, and thus can be used as a screening tool for candidate drugs. Finally, no special equipment but a regular BSL2 facility is needed to reproduce a functional motor unit in a culture dish. This method thus is valuable for both the muscle as well as the neuromuscular research communities for physiological and mechanistic studies of neuromuscular function, in a normal and disease context.
Neuroscience, Issue 62, Human primary muscle cells, embryonic spinal cord explants, neurites, innervation, contraction, cell culture
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MicroRNA Detection in Prostate Tumors by Quantitative Real-time PCR (qPCR)
Authors: Aida Gordanpour, Robert K. Nam, Linda Sugar, Stephanie Bacopulos, Arun Seth.
Institutions: University of Toronto, Sunnybrook Health Sciences Centre, Toronto, Canada, Sunnybrook Health Sciences Centre, Toronto, Canada, Sunnybrook Research Institute.
MicroRNAs (miRNAs) are single-stranded, 18–24 nucleotide long, non-coding RNA molecules. They are involved in virtually every cellular process including development1, apoptosis2, and cell cycle regulation3. MiRNAs are estimated to regulate the expression of 30% to 90% of human genes4 by binding to their target messenger RNAs (mRNAs)5. Widespread dysregulation of miRNAs has been reported in various diseases and cancer subtypes6. Due to their prevalence and unique structure, these small molecules are likely to be the next generation of biomarkers, therapeutic agents and/or targets. Methods used to investigate miRNA expression include SYBR green I dye- based as well as Taqman-probe based qPCR. If miRNAs are to be effectively used in the clinical setting, it is imperative that their detection in fresh and/or archived clinical samples be accurate, reproducible, and specific. qPCR has been widely used for validating expression of miRNAs in whole genome analyses such as microarray studies7. The samples used in this protocol were from patients who underwent radical prostatectomy for clinically localized prostate cancer; however other tissues and cell lines can be substituted in. Prostate specimens were snap-frozen in liquid nitrogen after resection. Clinical variables and follow-up information for each patient were collected for subsequent analysis8. Quantification of miRNA levels in prostate tumor samples. The main steps in qPCR analysis of tumors are: Total RNA extraction, cDNA synthesis, and detection of qPCR products using miRNA-specific primers. Total RNA, which includes mRNA, miRNA, and other small RNAs were extracted from specimens using TRIzol reagent. Qiagen's miScript System was used to synthesize cDNA and perform qPCR (Figure 1). Endogenous miRNAs are not polyadenylated, therefore during the reverse transcription process, a poly(A) polymerase polyadenylates the miRNA. The miRNA is used as a template to synthesize cDNA using oligo-dT and Reverse Transcriptase. A universal tag sequence on the 5' end of oligo-dT primers facilitates the amplification of cDNA in the PCR step. PCR product amplification is detected by the level of fluorescence emitted by SYBR Green, a dye which intercalates into double stranded DNA. Specific miRNA primers, along with a Universal Primer that binds to the universal tag sequence will amplify specific miRNA sequences. The miScript Primer Assays are available for over a thousand human-specific miRNAs, and hundreds of murine-specific miRNAs. Relative quantification method was used here to quantify the expression of miRNAs. To correct for variability amongst different samples, expression levels of a target miRNA is normalized to the expression levels of a reference gene. The choice of a gene on which to normalize the expression of targets is critical in relative quantification method of analysis. Examples of reference genes typically used in this capacity are the small RNAs RNU6B, RNU44, and RNU48 as they are considered to be stably expressed across most samples. In this protocol, RNU6B is used as the reference gene.
Cancer Biology, Issue 63, Medicine, cancer, primer assay, Prostate, microRNA, tumor, qPCR
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Purification and microRNA Profiling of Exosomes Derived from Blood and Culture Media
Authors: Marguerite K. McDonald, Kathryn E. Capasso, Seena K. Ajit.
Institutions: Drexel University College of Medicine.
Stable miRNAs are present in all body fluids and some circulating miRNAs are protected from degradation by sequestration in small vesicles called exosomes. Exosomes can fuse with the plasma membrane resulting in the transfer of RNA and proteins to the target cell. Their biological functions include immune response, antigen presentation, and intracellular communication. Delivery of miRNAs that can regulate gene expression in the recipient cells via blood has opened novel avenues for target intervention. In addition to offering a strategy for delivery of drugs or RNA therapeutic agents, exosomal contents can serve as biomarkers that can aid in diagnosis, determining treatment options and prognosis. Here we will describe the procedure for quantitatively analyzing miRNAs and messenger RNAs (mRNA) from exosomes secreted in blood and cell culture media. Purified exosomes will be characterized using western blot analysis for exosomal markers and PCR for mRNAs of interest. Transmission electron microscopy (TEM) and immunogold labeling will be used to validate exosomal morphology and integrity. Total RNA will be purified from these exosomes to ensure that we can study both mRNA and miRNA from the same sample. After validating RNA integrity by Bioanalyzer, we will perform a medium throughput quantitative real time PCR (qPCR) to identify the exosomal miRNA using Taqman Low Density Array (TLDA) cards and gene expression studies for transcripts of interest. These protocols can be used to quantify changes in exosomal miRNAs in patients, rodent models and cell culture media before and after pharmacological intervention. Exosomal contents vary due to the source of origin and the physiological conditions of cells that secrete exosomes. These variations can provide insight on how cells and systems cope with stress or physiological perturbations. Our representative data show variations in miRNAs present in exosomes purified from mouse blood, human blood and human cell culture media. Here we will describe the procedure for quantitatively analyzing miRNAs and messenger RNAs (mRNA) from exosomes secreted in blood and cell culture media. Purified exosomes will be characterized using western blot analysis for exosomal markers and PCR for mRNAs of interest. Transmission electron microscopy (TEM) and immunogold labeling will be used to validate exosomal morphology and integrity. Total RNA will be purified from these exosomes to ensure that we can study both mRNA and miRNA from the same sample. After validating RNA integrity by Bioanalyzer, we will perform a medium throughput quantitative real time PCR (qPCR) to identify the exosomal miRNA using Taqman Low Density Array (TLDA) cards and gene expression studies for transcripts of interest. These protocols can be used to quantify changes in exosomal miRNAs in patients, rodent models and cell culture media before and after pharmacological intervention. Exosomal contents vary due to the source of origin and the physiological conditions of cells that secrete exosomes. These variations can provide insight on how cells and systems cope with stress or physiological perturbations. Our representative data show variations in miRNAs present in exosomes purified from mouse blood, human blood and human cell culture media
Genetics, Issue 76, Molecular Biology, Cellular Biology, Medicine, Biochemistry, Genomics, Pharmacology, Exosomes, RNA, MicroRNAs, Biomarkers, Pharmacological, Exosomes, microRNA, qPCR, PCR, blood, biomarker, TLDA, profiling, sequencing, cell culture
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Transplantation of Induced Pluripotent Stem Cell-derived Mesoangioblast-like Myogenic Progenitors in Mouse Models of Muscle Regeneration
Authors: Mattia F. M. Gerli, Sara M. Maffioletti, Queensta Millet, Francesco Saverio Tedesco.
Institutions: University College London, San Raffaele Hospital.
Patient-derived iPSCs could be an invaluable source of cells for future autologous cell therapy protocols. iPSC-derived myogenic stem/progenitor cells similar to pericyte-derived mesoangioblasts (iPSC-derived mesoangioblast-like stem/progenitor cells: IDEMs) can be established from iPSCs generated from patients affected by different forms of muscular dystrophy. Patient-specific IDEMs can be genetically corrected with different strategies (e.g. lentiviral vectors, human artificial chromosomes) and enhanced in their myogenic differentiation potential upon overexpression of the myogenesis regulator MyoD. This myogenic potential is then assessed in vitro with specific differentiation assays and analyzed by immunofluorescence. The regenerative potential of IDEMs is further evaluated in vivo, upon intramuscular and intra-arterial transplantation in two representative mouse models displaying acute and chronic muscle regeneration. The contribution of IDEMs to the host skeletal muscle is then confirmed by different functional tests in transplanted mice. In particular, the amelioration of the motor capacity of the animals is studied with treadmill tests. Cell engraftment and differentiation are then assessed by a number of histological and immunofluorescence assays on transplanted muscles. Overall, this paper describes the assays and tools currently utilized to evaluate the differentiation capacity of IDEMs, focusing on the transplantation methods and subsequent outcome measures to analyze the efficacy of cell transplantation.
Bioengineering, Issue 83, Skeletal Muscle, Muscle Cells, Muscle Fibers, Skeletal, Pericytes, Stem Cells, Induced Pluripotent Stem Cells (iPSCs), Muscular Dystrophies, Cell Differentiation, animal models, muscle stem/progenitor cells, mesoangioblasts, muscle regeneration, iPSC-derived mesoangioblasts (IDEMs)
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Isolation, Culture, and Transplantation of Muscle Satellite Cells
Authors: Norio Motohashi, Yoko Asakura, Atsushi Asakura.
Institutions: University of Minnesota Medical School.
Muscle satellite cells are a stem cell population required for postnatal skeletal muscle development and regeneration, accounting for 2-5% of sublaminal nuclei in muscle fibers. In adult muscle, satellite cells are normally mitotically quiescent. Following injury, however, satellite cells initiate cellular proliferation to produce myoblasts, their progenies, to mediate the regeneration of muscle. Transplantation of satellite cell-derived myoblasts has been widely studied as a possible therapy for several regenerative diseases including muscular dystrophy, heart failure, and urological dysfunction. Myoblast transplantation into dystrophic skeletal muscle, infarcted heart, and dysfunctioning urinary ducts has shown that engrafted myoblasts can differentiate into muscle fibers in the host tissues and display partial functional improvement in these diseases. Therefore, the development of efficient purification methods of quiescent satellite cells from skeletal muscle, as well as the establishment of satellite cell-derived myoblast cultures and transplantation methods for myoblasts, are essential for understanding the molecular mechanisms behind satellite cell self-renewal, activation, and differentiation. Additionally, the development of cell-based therapies for muscular dystrophy and other regenerative diseases are also dependent upon these factors. However, current prospective purification methods of quiescent satellite cells require the use of expensive fluorescence-activated cell sorting (FACS) machines. Here, we present a new method for the rapid, economical, and reliable purification of quiescent satellite cells from adult mouse skeletal muscle by enzymatic dissociation followed by magnetic-activated cell sorting (MACS). Following isolation of pure quiescent satellite cells, these cells can be cultured to obtain large numbers of myoblasts after several passages. These freshly isolated quiescent satellite cells or ex vivo expanded myoblasts can be transplanted into cardiotoxin (CTX)-induced regenerating mouse skeletal muscle to examine the contribution of donor-derived cells to regenerating muscle fibers, as well as to satellite cell compartments for the examination of self-renewal activities.
Cellular Biology, Issue 86, skeletal muscle, muscle stem cell, satellite cell, regeneration, myoblast transplantation, muscular dystrophy, self-renewal, differentiation, myogenesis
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Probe-based Real-time PCR Approaches for Quantitative Measurement of microRNAs
Authors: Wilson Wong, Ryan Farr, Mugdha Joglekar, Andrzej Januszewski, Anandwardhan Hardikar.
Institutions: The University of Sydney, The University of Sydney.
Probe-based quantitative PCR (qPCR) is a favoured method for measuring transcript abundance, since it is one of the most sensitive detection methods that provides an accurate and reproducible analysis. Probe-based chemistry offers the least background fluorescence as compared to other (dye-based) chemistries. Presently, there are several platforms available that use probe-based chemistry to quantitate transcript abundance. qPCR in a 96 well plate is the most routinely used method, however only a maximum of 96 samples or miRNAs can be tested in a single run. This is time-consuming and tedious if a large number of samples/miRNAs are to be analyzed. High-throughput probe-based platforms such as microfluidics (e.g. TaqMan Array Card) and nanofluidics arrays (e.g. OpenArray) offer ease to reproducibly and efficiently detect the abundance of multiple microRNAs in a large number of samples in a short time. Here, we demonstrate the experimental setup and protocol for miRNA quantitation from serum or plasma-EDTA samples, using probe-based chemistry and three different platforms (96 well plate, microfluidics and nanofluidics arrays) offering increasing levels of throughput.
Molecular Biology, Issue 98, microRNA, ncRNA, probe-based assays, high-throughput PCR, Nanofluidics / Open Arrays, reverse-transcription, pre-amplification, qPCR
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