The Fralin Life Science Research Institute and The Metabolic Phenotyping Core at Virginia Tech supported this work.

Os estudos em animais foram realizados sob um protocolo aprovado pelo Institutional Animal Care e usar Comité na Virginia Polytechnic Institute e State University. 1. Instalação (Time: ~ 45 min) <ol><li> Lojas de congelados descongelamento de tripsina a 0,25%, tampão de isolamento para mitocôndrias (IBM) 1 e IBM2 em um banho de água a 37 ° C. </li><li> Enxágüe copos e instrumentos de dissecação em etanol a 70%, seguido por água de alta pureza. </li><li> Preparar a solução de tripsina a 0,05% a partir de 0,25% estoque de tripsina diluindo 1 parte de tripsina em 4 partes IBM1. </li><li> Misturar protease e fosfatase cocktail inibidor com tampão de lise celular (1: 100 rácio) num tubo de microcentrífuga de 1,5 ml com tampa de rosca. </li><li> Alíquotas de 5 ml (5 ml / rato) de tripsina a 0,05% para um tubo de plástico de 15 ml. </li><li> Ajuste motorizado homogeneizador de tecidos a 80 RPM. </li></ol> 2. Isolamento de mitocôndrias Músculo Esquelético (Tempo: ~ 90 min) <ol><li> Euthanize um rato por CO 2 </sub&gt; inalação, seguido por deslocação cervical. </li><li> Remover músculo vermelho do músculo gastrocnémio e quadríceps, que inclui o sóleo (~ 75-100 mg no total) tal como descrito nas etapas a seguir: <ol><li> Descasque a pele para o mouse. </li><li> Remova a almofada de gordura sobre o ponto de origem do quadríceps. Corte o tendão do quadríceps que está ligado à patela com uma tesoura de ponta fina. Nota: O quadríceps é identificado por sua posição anatômica na porção anterior do fêmur proximal. </li><li> Lentamente cortar o aponeurosis entre o osso e os quadríceps, evitando a artéria femoral, para libertar os quadríceps do osso. Corte o tendão com uma tesoura de ponta fina no ponto de origem no fêmur para liberar o músculo quadríceps e coloque o músculo quadríceps em refrigerados PBS. </li><li> Remover o tecido adiposo visível sobre o quadríceps com uma tesoura. Virar o quadríceps de forma que a parte do músculo que se recobre o fémur é virado up. Abra o músculo quadríceps com uma pinça em um movimento de ventilação. Retire as duas porções musculares vermelhas visíveis de cada lobo com uma tesoura de ponta fina e coloque em um copo contendo 5 ml de refrigerados IBM1. Nota: músculo quadríceps aparecem como dois lobos com uma tira de músculo vermelho localizado perto da borda lateral de cada lóbulo. </li><li> Corte a pele que recobre o tendão de Aquiles com tesouras com ponta fina e descascar a pele na direção do mouse. Cortar o tendão de Aquiles exposta e descasque o músculo em direcção ao corpo do rato. </li><li> Corte o tendão no côndilos lateral e medial do fêmur com uma tesoura de ponta fina para libertar o gastrocnêmio e coloque o gastrocnêmio anexado aos seus tendões em refrigerados PBS. </li><li> Virar o gastrocnêmio sobre e descolar o músculo sóleo e coloque no copo contendo 5 ml de refrigerados IBM1. Fan abrir o gastrocnêmio. Remova os três porções visuais vermelhas musculares (duas tiras vermelhas lateral e um medial superficial) com tesoura de ponta finas e transferi-los para o copo contendo 5 ml de refrigerados IBM1. </li></ol></li><li> Remover outro ~ 75-100 mg de vermelho de músculo a outra perna do rato (conforme descrito no passo 2.2) e colocar num tubo de microcentrífuga de 1,5 ml com protease e fosfatase cocktail inibidor e tampão de lise celular (50 mM Tris-HCl, 1 mM de EDTA, 150 mM de NaCl, 1% de dodecil sulfato de sódio, 0,5% de desoxicolato de sódio, 1% de polioxietileno (9) nonilfeniléter, ramificada. Imediatamente piscar-congelar esta segunda amostra em azoto líquido para posterior utilização em transferência Western (ver passo 6.1). </li><li> Colocar uma superfície de plástico pré-gelada, plana sobre gelo em um balde grande. Pour uma gota de IBM1 sobre a superfície de plástico e utilizar uma pinça para colocar todo o músculo vermelho segmentado (passo 2.2.4 e 2.2.7) em IBM1 gota. Picar o tecido muscular durante 2 minutos usando 3 individuais lâminas de barbear borda, alterando lâminas de barbear a cada 40 seg. </li><li> Transferir o tecido moído para um novo recipiente com 5 ml de IBM1 fresco, mantendo a superfície de plástico sobre o the proveta e raspando o músculo para a proveta com uma lâmina de barbear. Tome esta solução e drená-lo através de um filtro de células 100 mm colocados em um tubo de 50 ml. </li><li> Seque o tecido com um limpador tarefa delicada e, em seguida, transferi-la para 5 ml de solução de tripsina a 0,05%. Use pinças para remover o tecido a partir da tarefa do limpador. </li><li> Incubar o tecido muscular em gelo durante 30 min em solução de tripsina a 0,05%. </li><li> Rodar as tubo de 15 ml contendo mistura de tripsina / músculo a 200 xg durante 3 min a 4 ° C. </li><li> Despeje o sobrenadante tripsina em um recipiente de resíduos e ressuspender o sedimento com 3 ml de gelo frio IBM1. Transferir o tecido para um tubo de 45 ml homogeneizador de vidro. Lavar as 15 ml tubo cônico com mais 1,5 ml IBM1 para recolher qualquer amostra restante e adicione ao tubo de homogeneizador de vidro. </li><li> Colocar o tubo homogeneizador de vidro para um copo ou recipiente de plástico a meio caminho cheio de gelo de modo que o homogeneizador de vidro move-se minimamente no interior da taça. </li><li&gt; Homogeneizar a mistura tecido / IMB1 com o pilão de PTFE ligados a um homogeneizador de tecido accionada por motor com 10 passagens a 80 rpm. Segure a parte inferior de cada passagem para ~ 2 seg. </li><li> Transferir o homogeneizado de tecido para um novo tubo de 15 mL cónico e enxaguar o tubo homogeneizador de vidro com 6,5 ml de IBM1. Verter a IBM1 para dentro do tubo cónico de 15 ml contendo homogeneizado de tecido. </li><li> Girar o tubo de 15 ml a 700 g durante 10 min a 4 ° C. Delicadamente despeje o sobrenadante para um tubo de centrífuga de alta resistência vidro e descartar o pellet. </li><li> Girar o sobrenadante do passo anterior a 8000 xg durante 10 min a 4 ° C. </li><li> Remover o sobrenadante e re-IBM1 suspender o sedimento, adicionando-se lentamente 500 ul de IBM2. Cortar a extremidade de uma ponta de pipeta e homogeneizar suavemente o sedimento em IBM2 com mistura e agitação movimentos. Adicionar mais 4,5 ml de IBM2 à mistura após a pelete é totalmente suspenso. Nota: Evite trituração excessiva ao quebrar pedaços maiores de pelotas como tHis pode danificar as membranas mitocondriais. </li><li> Girar o homogenato / tecido IBM2 a 8000 xg durante 10 min a 4 ° C. Nota: Esta etapa pode ser repetida num tubo de centrífuga limpo de alta resistência, para a quantificação mais precisa da proteína de mitocôndrias isoladas no Passo 4, uma vez de BSA residual pode contribuir para o conteúdo de proteína total. </li><li> Remover o sobrenadante e suavemente, mas completamente re-suspender o sedimento, adicionando dois incrementos de 25 ul de IBM2 com uma ponta de pipeta com a ponta cortada. Agitar suavemente o sedimento e misturar após cada adição de 25 ul de IBM2. Coloque este estoque mitocondrial no gelo. </li></ol> 3. A homogeneização da Whole Tissue Lysate (Tempo: ~ 45 min; pode ser feito durante Passo 7) <ol><li> Remover o músculo do que foi colocada em azoto líquido a partir do passo 2.3 e incubar à temperatura ambiente até estarem completamente descongelados. </li><li> Picar o tecido para ~ 30 segundos em gelo com uma tesoura de ponta fina. </li><li> Adicione duas colheres de 100 ul de ZircoÓxido nio Beads para o tubo de microcentrífuga de 1,5 ml com tampa de rosca a partir do passo 3.2 que contém o tecido picada. Homogeneizar o tecido em um homogeneizador de tecidos moinho de esferas usando dois a três ciclos de 5 min a uma velocidade de 4-6 configuração (ajuste médio). </li><li> Girar-se a mistura a partir do passo 3.3 a 12.000 xg durante 10 min a 4 ° C. Remover o sobrenadante utilizando uma ponta de pipeta de 1.000 ul, após a centrifugação e transferência para um tubo de microcentrífuga de 1,5 ml. Desprezar o pelete e colocar o sobrenadante em gelo. </li></ol> 4. Determinação da proteína (Tempo: ~ 30 min) <ol><li> Determinar a concentração de proteína de lisado de todo o tecido (passo 3.4) e da mitocondrial (passo 2.17) utilizando o kit de ensaio de proteínas BCA de acordo com as especificações do fabricante. </li></ol> 5. As mitocôndrias Membrane Integridade; Citrato sintase (CS) Atividade (Tempo: ~ 15 min) <ol><li> Faça dois separados 1: 20 diluições do estoque mitocondrial em água de alta pureza. Adicionar0,1% de Triton X-100 para uma amostra e sonicate-lo em um nível baixo (765 Watts, amplitude de 2). Deixe a outra diluição no gelo. Recolocar a amostra de gelo após sonicação. </li><li> Realizar um ensaio de citrato sintase tanto com a não-sonicada e sonicada diluições mitocondriais utilizando um ensaio espectrofotométrico conforme anteriormente descrito 11,12. </li><li> Determinar a percentagem de membranas mitocôndrias intactas, utilizando as seguintes equações: (CS atividade não-sonicado ÷ sonicado atividade CS) * 100 </li></ol> 100- N- (percentagem obtida a partir de cima) 6. As mitocôndrias Qualidade de isolamento; Western Blotting (Horário: De acordo com Lab Protocol) <ol><li> Realizar Western blotting em todo o lisado de tecido e mitocôndrias isoladas como anteriormente descrito 12. Nota: O uso de anticorpos primários para GAPDH (1: 1000 de diluição em 5% de BSA / TBS-T) e COXIV (1: 1000 de diluição em 5% de gordura não-leite / TBS-T), seguido por anti-cabra, e anticorpos secundários de coelho, respectivamente (1: 10.000). </li></ol> 7. respirométrico Ensaio Run (Time: ~ 90 min) <ol><li> Realizar ensaios respirométricos desejados utilizando baseado O 2 tecnologia de medição do consumo de microplaca, como descrito anteriormente (ver artigo do companheiro e Rogers et al 8). </li><li> Determinar a relação de controle respiratório (RCR) dividindo Estado 3 por Estado 4o (RCR) ou dividindo 3U Estado por Estado 4o. Use o (média) ponto médio, ou o mais elevado (estado 3) e taxas mais baixas (4o Estado) a partir de vestígios ponto-a-ponto ao determinar RCR. </li></ol>

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George Rogers is an employee of Seahorse Bioscience that produces the instrument for which this protocol was modified.

Os métodos aqui apresentados proporcionam uma descrição detalhada de um procedimento de isolamento de quantidades mínimas mitocondrial (~ 75-100 mg) de rato músculo esquelético. Este procedimento de isolamento é capaz de produzir alto funcionamento, as mitocôndrias puro (~ 450 mg) como evidenciado pela O2 taxas de consumo, valores RCR, atividade da citrato sintase máxima e expressão de proteína de immunoblotting. Importante, as mitocôndrias isoladas a partir deste processo pode ser usado para múl...

The primary function of mitochondria is to produce ATP from oxidative phosphorylation. However, mitochondria have many other important cellular functions including but not limited to: the production and detoxification of reactive oxygen species, the regulation of cytoplasmic and mitochondrial calcium, organelle trafficking, ionic homeostasis, and involvement in apoptosis1,2. Therefore, it is not surprising that dysfunctional mitochondria play a role in many disease pathologies, such as aging, neurodegenerative diseases, cardiovascular disease, cancer, obesity, and diabetes3,4. Importantly, skeletal muscle mitochondria specifically are involved in many of these pathologies3-5.
Mitochondrial respiration assays using isolated mitochondria allow for the assessment of electron transport chain and oxidative phosphorylation function, and the determination of mechanism(s) of action of drugs and proteins that modulate metabolism. Mitochondrial isolation procedures exist for multiple tissue and cell types for a variety of species6,7. However, these procedures often require large quantities of tissue/cells for a high quality mitochondria yield necessary for classic respirometric assays. 
Microplate based respirometirc assays allow for high throughput measurements using minimal quantities of isolated mitochondria, often just several &#181;g per well8. Therefore, we present a modification of previously published methods7 to allow for high quality mitochondria to be isolated from smaller quantities of mouse skeletal muscle for use in microplate based respirometirc assays. In addition, methods are provided to establish the quality of the mitochondrial isolation preparation and the integrity of the mitochondrial membranes. Given that skeletal muscle mitochondria are involved in many pathological conditions, the measurement of O2 consumption in mechanistically driven studies is becoming more prevalent in biomedical research9,10.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>Essentially Fatty</td>
			<td rowspan="2">Sigma Aldrich</td>
			<td rowspan="2">A6003</td>
			<td rowspan="2">N/A</td>
		</tr>
		<tr>
			<td>Acid Free- BSA</td>
		</tr>
		<tr>
			<td>Tris/HCl</td>
			<td>Promega</td>
			<td>H5123</td>
			<td>N/A</td>
		</tr>
		<tr>
			<td>KCL</td>
			<td>Sigma Aldrich</td>
			<td>P9541</td>
			<td>N/A</td>
		</tr>
		<tr>
			<td>Tris Base</td>
			<td>Promega</td>
			<td>H5135</td>
			<td>N/A</td>
		</tr>
		<tr>
			<td>EDTA</td>
			<td>Sigma Aldrich</td>
			<td>E6511</td>
			<td>N/A</td>
		</tr>
		<tr>
			<td>EGTA</td>
			<td>Sigma Aldrich</td>
			<td>E4378</td>
			<td>N/A</td>
		</tr>
		<tr>
			<td>Sucrose</td>
			<td>Sigma Aldrich</td>
			<td>S7903</td>
			<td>N/A</td>
		</tr>
		<tr>
			<td>D-Mannitol</td>
			<td>Sigma Aldrich</td>
			<td>63559</td>
			<td>N/A</td>
		</tr>
		<tr>
			<td>Trypsin-EDTA (0.25%), phenol red</td>
			<td>Thermo Scientific</td>
			<td>25200-056</td>
			<td>N/A</td>
		</tr>
		<tr>
			<td>Sodium Chloride 
			White Crystals or Crystalline Powder 
			&#8805;99.0 %</td>
			<td>Fisher Scientific</td>
			<td>BP3581</td>
			<td>N/A</td>
		</tr>
		<tr>
			<td>Sodium dodecyl sulfate</td>
			<td>Sigma Aldrich</td>
			<td>L3771&#160;</td>
			<td>N/A</td>
		</tr>
		<tr>
			<td>Sodium deoxycholate</td>
			<td>Sigma Aldrich</td>
			<td>D6750&#160;</td>
			<td>N/A</td>
		</tr>
		<tr>
			<td>Polyoxyethylene (12) nonylphenyl ether, branched</td>
			<td>Sigma Aldrich</td>
			<td>238651</td>
			<td>N/A</td>
		</tr>
		<tr>
			<td>Single Edge Razor Blades</td>
			<td>Fisher Scientific</td>
			<td>12-640</td>
			<td>N/A</td>
		</tr>
		<tr>
			<td>Falcon- 100 uM Nylon Cell Strainers</td>
			<td>Fisher Scientific</td>
			<td>352360</td>
			<td>N/A</td>
		</tr>
		<tr>
			<td rowspan="2">Halt Protease &#38; Phosphatse Inhibitor Cocktail</td>
			<td rowspan="2">Thermo Scientific</td>
			<td rowspan="2">1861284</td>
			<td rowspan="2">N/A</td>
		</tr>
		<tr>
		</tr>
		<tr>
			<td rowspan="2">1.5mL microcentrifuge tubes with screw cap</td>
			<td rowspan="2">Thermo Scientific</td>
			<td rowspan="2">3474</td>
			<td rowspan="2">N/A</td>
		</tr>
		<tr>
		</tr>
		<tr>
			<td rowspan="2">Zirconium Oxide beads</td>
			<td rowspan="2">Fisher Scientific</td>
			<td rowspan="2">C9012112</td>
			<td rowspan="2">N/A</td>
		</tr>
		<tr>
		</tr>
		<tr>
			<td>GAPDH antibody (1D4)</td>
			<td>Santa Cruz Biotechnology</td>
			<td>sc-59540</td>
			<td>N/A</td>
		</tr>
		<tr>
			<td>Anti- COXIV antibody</td>
			<td>Cell Signaling</td>
			<td>4844s</td>
			<td>Any mitochondrial inner membrane protein will suffice</td>
		</tr>
		<tr>
			<td rowspan="2">Peroxidase conjugated affinipure Donkey, Anti Rabbit IgG (H+L)</td>
			<td rowspan="2">Jackson ImmunoResearh</td>
			<td rowspan="2">711-035-152</td>
			<td rowspan="2">N/A</td>
		</tr>
		<tr>
		</tr>
		<tr>
			<td rowspan="2">Peroxidase conjugated affinipure Goat, Anti Mouse IgG (H+L)</td>
			<td rowspan="2">Jackson ImmunoResearh</td>
			<td rowspan="2">115-001-003</td>
			<td rowspan="2">N/A</td>
		</tr>
		<tr>
		</tr>
		<tr>
			<td>Triton-X100</td>
			<td>Sigma Aldrich</td>
			<td>X100</td>
			<td>N/A</td>
		</tr>
		<tr>
			<td>Pierce BCA Protein Assay Kit&#160;</td>
			<td>Thermo Scientific</td>
			<td>23225</td>
			<td>N/A</td>
		</tr>
		<tr>
			<td>Pyruvic Acid, 98%</td>
			<td>Sigma Aldrich</td>
			<td>107360</td>
			<td>Store at 4&#176;C,pH to 7.4 with KOH prior to use in respirometric assay</td>
		</tr>
		<tr>
			<td>Succinic Acid</td>
			<td>Sigma Aldrich</td>
			<td>S9512</td>
			<td>Store at room temperature, pH to 7.4 with KOH prior to use in respirometric assay</td>
		</tr>
		<tr>
			<td>L(-) Malic Acid, BioXtra, &#8805;95%</td>
			<td>Sigma Aldrich</td>
			<td>M6413</td>
			<td>Store at room temperature, to 7.4 with KOH prior to use in respirometric assay</td>
		</tr>
		<tr>
			<td rowspan="2">L-Glutamic acid</td>
			<td rowspan="2">Sigma Aldrich</td>
			<td rowspan="2">G1251</td>
			<td rowspan="2">Store at room temperature, to 7.4 with KOH prior to use in respirometric assay, to 7.4 with KOH prior to use in respirometric assay</td>
		</tr>
		<tr>
		</tr>
		<tr>
			<td>Palmitoyl L-carnitine chloride</td>
			<td>Sigma Aldrich</td>
			<td>P1645</td>
			<td>Store at -20&#176;C</td>
		</tr>
		<tr>
			<td>Oligomycin A, &#8805; 95% (HPLC)</td>
			<td>Sigma Aldrich</td>
			<td>75351</td>
			<td>Store at -20&#176;C</td>
		</tr>
		<tr>
			<td>Carbonyl cyanide 4-(trifluoromethoxy)</td>
			<td rowspan="3">Sigma Aldrich</td>
			<td rowspan="3">C2920</td>
			<td rowspan="3">Store at 2-8&#176;C</td>
		</tr>
		<tr>
			<td>phenylhydrazone</td>
		</tr>
		<tr>
			<td>&#8805;98% (TLC), powder [FCCP]</td>
		</tr>
		<tr>
			<td>Antimycin A from streptomyces sp.</td>
			<td>Sigma Aldrich</td>
			<td>A8674</td>
			<td>Store at -20&#176;C</td>
		</tr>
		<tr>
			<td rowspan="2">Adenosine 5&#8242;-diphosphate monopotassium salt dehydrate [ADP]</td>
			<td rowspan="2">Sigma Aldrich</td>
			<td rowspan="2">A5285</td>
			<td rowspan="2">Store at -20&#176;C, to 7.4 with KOH prior to use in respirometric assay</td>
		</tr>
		<tr>
		</tr>
		<tr>
			<td>Rotenone</td>
			<td>Sigma Aldrich</td>
			<td>R8875</td>
			<td>Store at room temperature</td>
		</tr>
	</tbody>
</table>

isolation of mitochondria from minimal quantities of mouse skeletal muscle for high throughput microplate respiratory measurements

Disfuncionais mitocôndrias do músculo esquelético desempenha um papel no metabolismo alterado observado com o envelhecimento, obesidade e diabetes tipo II. Ensaios respirométricos mitocondriais isoladas a partir de preparações mitocondriais permitir a avaliação da função mitocondrial, bem como a determinação do mecanismo (s) de acção de drogas e proteínas que modulam o metabolismo. Procedimentos de isolamento atuais requerem muitas vezes grandes quantidades de tecido para produzir mitocôndrias de alta qualidade necessários para ensaios respirométricos. Os métodos aqui apresentados descrevem como de alta qualidade mitocôndrias purificadas (~ 450 mg) pode ser isolado a partir de quantidades mínimas (~ 75-100 mg) de rato músculo esquelético para utilização em medições respiratórias alto rendimento. Nós determinamos que nosso método de isolamento produz 92,5 ± 2,0% mitocôndrias intacto medindo atividade da citrato sintase espectrofotometria. Além disso, a análise de Western blot em mitocôndrias isoladas resultou na expressão fraca da cytosoproteína lic, GAPDH, e a expressão robusta da proteína mitocondrial, COXIV. A ausência de uma banda proeminente GAPDH nas mitocôndrias isoladas é indicativo de pouca contaminação a partir de fontes não-mitocondriais durante o procedimento de isolamento. Mais importante ainda, a medição da taxa de consumo de O2 com a tecnologia de micro-placa de base e a determinação do índice de controlo respiratório (RCR) para ensaios respirométricos acoplados mostra altamente acopladas (RCR;&gt; 6 para todos os ensaios) e mitocôndrias funcionais. Em conclusão, a adição de um passo de picagem separado e reduzindo significativamente accionada por motor de velocidade de homogeneização de um método previamente relatado que permitiu o isolamento de alta qualidade e de mitocôndrias purificadas a partir de pequenas quantidades de rato músculo esquelético que resulta em mitocôndrias altamente acopladas que respiram com elevada função durante microplacas ensaios respirometirc.

Atividade da citrato sintase serve como uma medida para a integridade da membrana, uma vez sintase de citrato é localizado na membrana mitocondrial interna, e, portanto, não devem estar presentes nas suspensões de mitocôndrias com membranas intactas. A Figura 1 representa a actividade da sintase de citrato em amostras não sonicada mitocondriais em comparação com sonicada amostras do mesmo isolamento. Sonicando os resultados mitocôndria em um aumento estatisticamente significativo na atividade da...

Watch this Scientific Journal Video about Isolation of Mitochondria from Minimal Quantities of Mouse Skeletal Muscle for High Throughput Microplate Respiratory Measurements at JoVE.com

Isolation of Mitochondria from Minimal Quantities of Mouse Skeletal Muscle for High Throughput Microplate Respiratory Measurements

Here, we present a modification of a previously reported method that allows for the isolation of high quality and purified mitochondria from smaller quantities of mouse skeletal muscle. This procedure results in highly coupled mitochondria that respire with high function during microplate based respirometirc assays.

Isolamento de mitocôndrias de quantidades mínimas de Rato Músculo Esquelético para medições High Throughput Microplate respiratórias

Dysfunctional skeletal muscle mitochondria play a role in altered metabolism observed with aging, obesity and Type II diabetes. Mitochondrial ...

isolation-mitochondria-from-minimal-quantities-mouse-skeletal-muscle

Research

JoVE Journal

Biology

12.7K visualizações.  Virginia Tech. Here, we present a modification of a previously reported method that allows for the isolation of high quality and purified mitochondria from smaller quantities of mouse skeletal muscle. This procedure results in highly coupled mitochondria that respire with high function during microplate based respirometirc assays.

Vídeo: Isolation of Mitochondria from Minimal Quantities of Mouse Skeletal Muscle for High Throughput Microplate Respiratory Measurements

Adult and Embryonic Skeletal Muscle Microexplant Culture and Isolation of Skeletal Muscle Stem Cells

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.

The micro-dissected explants technique is a robust and reliable method for isolating proliferative skeletal muscle cells from juvenile, adult or embryonic muscles as a source of skeletal muscle stem cells. Uniquely, these cells have been clonally derived to produce skeletal muscle stem cell lines used for in vivo transplantation.

Adultas e embrionárias Cultura Microexplant Músculo Esquelético e isolamento de células-tronco musculares

Cultured embryonic and adult skeletal muscle cells have a number of different uses. The micro-dissected explants technique described in this chapter is a ...

Biologia

Mitochondrial Isolation from Skeletal Muscle

Mitochondria are organelles controlling the life and death of the cell. They participate in key metabolic reactions, synthesize most of the ATP, and regulate a number of signaling cascades2,3. Past and current researchers have isolated mitochondria from rat and mice tissues such as liver, brain and heart4,5. In recent years, many researchers have focused on studying mitochondrial function from skeletal muscles.
Here, we describe a method that we have used successfully for the isolation of mitochondria from skeletal muscles 6. Our procedure requires that all buffers and reagents are made fresh and need about 250-500 mg of skeletal muscle. We studied mitochondria isolated from rat and mouse gastrocnemius and diaphragm, and rat extraocular muscles. Mitochondrial protein concentration is measured with the Bradford assay. It is important that mitochondrial samples be kept ice-cold during preparation and that functional studies be performed within a relatively short time (~1 hr). Mitochondrial respiration is measured using polarography with a Clark-type electrode (Oxygraph system) at 37&deg;C7. Calibration of the oxygen electrode is a key step in this protocol and it must be performed daily. Isolated mitochondria (150 &mu;g) are added to 0.5 ml of experimental buffer (EB). State 2 respiration starts with addition of glutamate (5mM) and malate (2.5 mM). Then, adenosine diphosphate (ADP) (150 &mu;M) is added to start state 3. Oligomycin (1 &mu;M), an ATPase synthase blocker, is used to estimate state 4. Lastly, carbonyl cyanide p-[trifluoromethoxy]-phenyl-hydrazone (FCCP, 0.2 &mu;M) is added to measurestate 5, or uncoupled respiration 6. The respiratory control ratio (RCR), the ratio of state 3 to state 4, is calculated after each experiment. An RCR &ge;4 is considered as evidence of a viable mitochondria preparation.
In summary, we present a method for the isolation of viable mitochondria from skeletal muscles that can be used in biochemical (e.g., enzyme activity, immunodetection, proteomics) and functional studies (mitochondrial respiration).

This protocol describes a procedure to study the respiration of mitochondria isolated from skeletal muscles. This method was adapted from Scorrano et al. (2007). The mitochondrial isolation procedure requires about 2 hours. The mitochondrial respiration can be completed in about 1 hour.

Isolamento mitocondrial do músculo esquelético

Mitochondria are organelles controlling the life and death of the cell. They participate in key metabolic reactions, synthesize most of the ATP, and ...

Purification of Progenitors from Skeletal Muscle

Skeletal muscle contains multiple progenitor populations of distinct embryonic origins and developmental potential. Myogenic progenitors, usually residing in a "satellite cell position" between the myofiber plasma membrane and the laminin-rich basement membrane that ensheaths it, are self-renewing cells that are solely committed to the myogenic lineage1,2. We have recently described a second class of vessel associated progenitors that can generate myofibroblasts and white adipocytes, which responds to damage by efficiently entering proliferation and provides trophic support to myogenic cells during tissue regeneration3,4. One of the most trusted assays to determine the developmental and regenerative potential of a given cell population relies on their isolation and transplantation5-7. To this end we have optimized protocols for their purification by flow cytometry from enzymatically dissociated muscle, which we will outline in this article. The populations obtained using this method will contain either myogenic or fibro/adipogenic colony forming cells: no other cell types are capable of expanding in vitro or surviving in vivo delivery. However, when these populations are used immediately after the sort for molecular analysis (e.g qRT-PCR) one must keep in mind that the freshly sorted subsets may contain other contaminant cells that lack the ability of forming colonies or engrafting recipients.

Method for the enzymatic dissociation, surface labeling and purification by flow cytometry of fibro/adipogenic and myogenic progenitors from murine skeletal muscle.

Purificação de Progenitores do músculo esquelético

Skeletal muscle contains multiple progenitor populations of distinct embryonic origins and developmental potential. Myogenic progenitors, usually residing ...

Isolation and Culture of Individual Myofibers and their Satellite Cells from Adult Skeletal Muscle

Muscle regeneration in the adult is performed by resident stem cells called satellite cells. Satellite cells are defined by their position between the basal lamina and the sarcolemma of each myofiber. Current knowledge of their behavior heavily relies on the use of the single myofiber isolation protocol. In 1985, Bischoff described a protocol to isolate single live fibers from the Flexor Digitorum Brevis (FDB) of adult rats with the goal to create an in vitro system in which the physical association between the myofiber and its stem cells is preserved 1. In 1995, Rosenblattmodified the Bischoff protocol such that myofibers are singly picked and handled separately after collagenase digestion instead of being isolated by gravity sedimentation 2, 3. The Rosenblatt or Bischoff protocol has since been adapted to different muscles, age or conditions 3-6. The single myofiber isolation technique is an indispensable tool due its unique advantages. First, in the single myofiber protocol, satellite cells are maintained beneath the basal lamina. This is a unique feature of the protocol as other techniques such as Fluorescence Activated Cell Sorting require chemical and mechanical tissue dissociation 7. Although the myofiber culture system cannot substitute for in vivo studies, it does offer an excellent platform to address relevant biological properties of muscle stem cells. Single myofibers can be cultured in standard plating conditions or in floating conditions. Satellite cells on floating myofibers are subjected to virtually no other influence than the myofiber environment. Substrate stiffness and coating have been shown to influence satellite cells' ability to regenerate muscles 8, 9 so being able to control each of these factors independently allows discrimination between niche-dependent and -independent responses. Different concentrations of serum have also been shown to have an effect on the transition from quiescence to activation. To preserve the quiescence state of its associated satellite cells, fibers should be kept in low serum medium 1-3. This is particularly useful when studying genes involved in the quiescence state. In serum rich medium, satellite cells quickly activate, proliferate, migrate and differentiate, thus mimicking the in vivo regenerative process 1-3. The system can be used to perform a variety of assays such as the testing of chemical inhibitors; ectopic expression of genes by virus delivery; oligonucleotide based gene knock-down or live imaging. This video article describes the protocol currently used in our laboratory to isolate single myofibers from the Extensor Digitorum Longus (EDL) muscle of adult mice (6-8 weeks old).

Isolation and culture of myofibers is the gold standard in vitro system to study the transition of satellite cells through quiescence, activation and differentiation. Importantly, the single myofiber culture system preserves the myofiber/stem cell association, which is an essential component of the muscle stem cell niche.

Isolamento e Cultura de miofibras individuais e suas células satélites do músculo esquelético

Muscle  regeneration in the adult is performed by resident stem cells called satellite  cells. Satellite cells are defined by  their position between the ...

Isolation of Blood-vessel-derived Multipotent Precursors from Human Skeletal Muscle

Since the discovery of mesenchymal stem/stromal cells (MSCs), the native identity and localization&#160;of MSCs have been obscured by their retrospective isolation in culture. Recently, using fluorescence-activated cell sorting (FACS), we and other researchers prospectively identified and purified three subpopulations of multipotent precursor cells associated with the vasculature of human skeletal muscle. These three cell populations: myogenic endothelial cells (MECs), pericytes (PCs), and adventitial cells (ACs), are localized respectively to the three structural layers of blood vessels: intima, media, and adventitia. All of these human blood-vessel-derived stem cell (hBVSC) populations not only express classic MSC markers but also possess mesodermal developmental potentials similar to typical MSCs. Previously, MECs, PCs, and ACs have been isolated through distinct protocols and subsequently characterized in separate studies. The current isolation protocol, through modifications to the isolation process and adjustments in the selective cell surface markers, allows us to simultaneously purify all three hBVSC subpopulations by FACS from a single human muscle biopsy. This new method will not only streamline the isolation of multiple BVSC subpopulations but also facilitate future clinical applications of hBVSCs for distinct therapeutic purposes.

Blood vessels within human skeletal muscle harbor several multi-lineage precursor populations that are ideal for regenerative applications. This isolation method allows simultaneous purification of three multipotent precursor cell populations respectively from three structural layers of blood vessels: myogenic endothelial cells from intima, pericytes from media, and adventitial cells from adventitia.

Isolamento de Blood-derivado do navio Multipotentes Precursores do músculo-esquelético humano

Since the discovery of mesenchymal stem/stromal cells (MSCs), the native identity and localization&#160;of MSCs have been obscured by their retrospective ...

High-throughput Screening for Chemical Modulators of Post-transcriptionally Regulated Genes

Both transcriptional and post-transcriptional regulation have a profound impact on genes expression. However, commonly adopted cell-based screening assays focus on transcriptional regulation, being essentially aimed at the identification of promoter-targeting molecules. As a result, post-transcriptional mechanisms are largely uncovered by gene expression targeted drug development. Here we describe a cell-based assay aimed at investigating the role of the 3&#39; untranslated region (3&#8217; UTR) in the modulation of the fate of its mRNA, and at identifying compounds able to modify it. The assay is based on the use of a luciferase reporter construct containing the 3&#8217; UTR of a gene of interest stably integrated into a disease-relevant cell line. The protocol is divided into two parts, with the initial focus on the primary screening aimed at the identification of molecules affecting luciferase activity after 24 hr of treatment. The second part of the protocol describes the counter-screening necessary to discriminate compounds modulating luciferase activity specifically through the 3&#8217; UTR. In addition to the detailed protocol and representative results, we provide important considerations about the assay development and the validation of the hit(s) on the endogenous target. The described cell-based reporter gene assay will allow scientists to identify molecules modulating protein levels via post-transcriptional mechanisms dependent on a 3&#8217; UTR.

Here we describe a cell-based reporter gene assay as a valuable tool to screen chemical libraries for compounds modulating post-transcriptional control mechanisms exerted through 3&#8217; UTR.

Rastreio de alto rendimento para moduladores químicos de Genes Post-transcriptionally Regulamentados

Both transcriptional and post-transcriptional regulation have a profound impact on genes expression. However, commonly adopted cell-based screening assays ...

Isolation of Intact Mitochondria from Skeletal Muscle by Differential Centrifugation for High-resolution Respirometry Measurements

Mitochondria are involved in cellular energy metabolism and use oxygen to produce energy in the form of adenosine triphosphate (ATP). Differential centrifugation at low- and high-speed is commonly used to isolate mitochondria from tissues and cultured cells. Crude mitochondrial fractions obtained by differential centrifugation are used for respirometry measurements. The differential centrifugation technique is based on the separation of organelles according to their size and sedimentation velocity. The isolation of mitochondria is performed immediately after tissue harvesting. The tissue is immersed in an ice-cold homogenization medium, minced using scissors and homogenized in a glass homogenizer with a loose-fitting pestle. The differential centrifugation technique is efficient, fast and inexpensive and the mitochondria obtained by differential centrifugation are pure enough for respirometry assays. Some of the limitations and disadvantages of isolated mitochondria, based on differential centrifugation, are that the mitochondria can be damaged during the homogenization and isolation procedure and that large amounts of the tissue biopsy or cultured cells are required for the mitochondrial isolation.

Here, a quadriceps muscle specimen is taken from an anaesthetized pig and mitochondria are isolated by differential centrifugation. Then, the respiratory rates of mitochondrial respiratory chain complexes I, II and IV are determined using high-resolution respirometry.

Isolamento de mitocôndrias intactas de Músculo Esquelético por centrifugação diferencial para medições Respirometria de alta resolução

Mitochondria are involved in cellular energy metabolism and use oxygen to produce energy in the form of adenosine triphosphate (ATP). Differential ...

Isolation and Characterization of Exosomes from Skeletal Muscle Fibroblasts

Exosomes are small extracellular vesicles released by virtually all cells and secreted in all biological fluids. Many methods have been developed for the isolation of these vesicles, including ultracentrifugation, ultrafiltration, and size exclusion chromatography. However, not all are suitable for large scale exosome purification and characterization. Outlined here is a protocol for establishing cultures of primary fibroblasts isolated from adult mouse skeletal muscles, followed by purification and characterization of exosomes from the culture media of these cells. The method is based on the use of sequential centrifugation steps followed by sucrose density gradients. Purity of the exosomal preparations is then validated by western blot analyses using a battery of canonical markers (i.e., Alix, CD9, and CD81). The protocol describes how to isolate and concentrate bioactive exosomes for electron microscopy, mass spectrometry, and uptake experiments for functional studies. It can easily be scaled up or down and adapted for exosome isolation from different cell types, tissues, and biological fluids.

This protocol illustrates the 1) the isolation and culture of primary fibroblasts from the adult mouse gastrocnemius muscle as well as 2) purification and characterization of exosomes using a differential ultracentrifugation method combined with sucrose density gradients followed by western blot analyses.

Isolamento e Caracterização de Exossomos de Fibroblastos de Músculo Esquelético

Exosomes are small extracellular vesicles released by virtually all cells and secreted in all biological fluids. Many methods have been developed for the ...

Isolation of High Quality Murine Atrial and Ventricular Myocytes for Simultaneous Measurements of Ca2+ Transients and L-Type Calcium Current

Mouse models play a crucial role in arrhythmia research and allow studying key mechanisms of arrhythmogenesis including altered ion channel function and calcium handling. For this purpose, atrial or ventricular cardiomyocytes of high quality are necessary to perform patch-clamp measurements or to explore calcium handling abnormalities. However, the limited yield of high-quality cardiomyocytes obtained by current isolation protocols does not allow both measurements in the same mouse. This article describes a method to isolate high-quality murine atrial and ventricular myocytes via retrograde enzyme-based Langendorff perfusion, for subsequent simultaneous measurements of calcium transients and L-type calcium current from one animal. Mouse hearts are obtained, and the aorta is rapidly cannulated to remove blood. Hearts are then initially perfused with a calcium-free solution (37 &#176;C) to dissociate the tissue at the level of intercalated discs and afterwards with an enzyme solution containing little calcium to disrupt extracellular matrix (37 &#176;C). The digested heart is subsequently dissected into atria and ventricles. Tissue samples are chopped into small pieces and dissolved by carefully pipetting up and down. The enzymatic digestion is stopped, and cells are stepwise reintroduced to physiologic calcium concentrations. After loading with a fluorescent Ca2+-indicator, isolated cardiomyocytes are prepared for simultaneous measurement of calcium currents and transients. Additionally, isolation pitfalls are discussed and patch-clamp protocols and representative traces of L-type calcium currents with simultaneous calcium transient measurements in atrial and ventricular murine myocytes isolated as described above are provided.

Isolation of High Quality Murine Atrial and Ventricular Myocytes for Simultaneous Measurements of Ca2+ Transients and L-Type Calcium Current

Mouse models allow studying key mechanisms of arrhythmogenesis. For this purpose, high quality cardiomyocytes are necessary to perform patch-clamp measurements. Here, a method to isolate murine atrial and ventricular myocytes via retrograde enzyme-based Langendorff perfusion, which allows simultaneous measurements of calcium-transients and L-type calcium current, is described.

Isolamento de miócitos murinos atrial e ventricular de alta qualidade para medidas simultâneas de Ca2+ transitórios e corrente de cálcio tipo L

Mouse models play a crucial role in arrhythmia research and allow studying key mechanisms of arrhythmogenesis including altered ion channel function and ...

Preparation of Rat Skeletal Muscle Homogenates for Nitrate and Nitrite Measurements

Nitrate ions (NO3-) were once thought to be inert end products of nitric oxide (NO) metabolism. However, previous studies demonstrated that nitrate ions can be converted back to NO in mammals through a two-step reduction mechanism: nitrate being reduced to nitrite (NO2-) mostly by oral commensal bacteria, then nitrite being reduced to NO by several mechanisms including via heme- or molybdenum-containing proteins. This reductive nitrate pathway contributes to enhancing NO-mediated signaling pathways, particularly in the cardiovascular system and during muscular exercise. The levels of nitrate in the body before such utilization are determined by two different sources: endogenous NO oxidation and dietary nitrate intake, principally from plants. To elucidate the complex NO cycle in physiological circumstances, we have examined further the dynamics of its metabolites, nitrate and nitrite ions, which are relatively stable compared to NO. In previous studies skeletal muscle was identified as a major storage organ for nitrate ions in mammals, as well as a direct source of NO during exercise. Therefore, establishing a reliable methodology to measure nitrate and nitrite levels in skeletal muscle is important and should be helpful in extending its application to other tissue samples. This paper explains in detail the preparation of skeletal muscle samples, using three different homogenization methods, for nitrate and nitrite measurements and discusses important issues related to homogenization processes, including the size of the samples. Nitrate and nitrite concentrations have also been compared across four different muscle groups.

We present protocols for three different methods for the homogenization of four different muscle groups of rat skeletal muscle tissue to measure and compare the levels of nitrate and nitrite. Furthermore, we compare different sample weights to investigate whether tissue sample size affects the results of homogenization.

Preparação de Homogeneizados do Músculo Esquelético de Rato para Medições de Nitrato e Nitrito

Nitrate ions (NO3-) were once thought to be inert end products of nitric oxide (NO) metabolism. However, previous studies demonstrated that nitrate ions ...