The authors are grateful to Dr. Matthew Watt at the University of Melbourne and Dr. Anastasia Kralli at Johns Hopkins University for assistance adopting this protocol based on the work of Mokbel et al.6. We also thank Dr. Sabine Jordan for assistance developing and adopting this protocol in our laboratory. This work was funded by the National Institutes of Health R01s DK097164 and DK112927 to K.A.L.

This protocol follows the animal care guidelines of Scripps Research.
1. Collection and Processing of Muscle Tissue Explants
<ol>
	<li>The day prior to dissection, sterilize all dissection equipment (forceps, razor blades, and scissors) and prepare all required media: phosphate buffered saline (PBS), MB Plating media (12.5 mL of DMEM, 12.5 mL of HAMS F12, 20 mL of heat-inactivated fetal bovine serum (FBS), 5 mL of amniotic fluid medium supplement), and Coating Solution (24 mL of DMEM, 24 mL ...

<ol>
	<li>Srikanthan, P., Karlamangla, A. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Muscle+mass+index+as+a+predictor+of+longevity+in+older+adults.">Muscle mass index as a predictor of longevity in older adults.</a> American Journal of Medicine. 127 (6), 547-553 (2014).</li><li>Lee-Young, R. S., Kang, L., Ayala, J. E., Wasserman, D. H., Fueger, P. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+physiological+regulation+of+glucose+flux+into+muscle+in+vivo.">The physiological regulation of glucose flux into muscle in vivo.</a> Journal of Experimental Biology. 214 (2), 254-262 (2010).</li><li>Sj&#248;berg, K. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Exercise+increases+human+skeletal+muscle+insulin+sensitivity+via+coordinated+increases+in+microvascular+perfusion+and+molecular+signaling.">Exercise increases human skeletal muscle insulin sensitivity via coordinated increases in microvascular perfusion and molecular signaling.</a> Diabetes. 66 (6), 1501-1510 (2017).</li><li>Girgis, C. M., Clifton-Bligh, R. J., Mokbel, N., Cheng, K., Gunton, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vitamin+D+signaling+regulates+proliferation,+differentiation,+and+myotube+size+in+C2C12+skeletal+muscle+cells.">Vitamin D signaling regulates proliferation, differentiation, and myotube size in C2C12 skeletal muscle cells.</a> Endocrinology. 155 (2), 347-357 (2014).</li><li>Smith, J., Merrick, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Embryonic+skeletal+muscle+microexplant+culture+and+isolation+of+skeletal+muscle+stem+cells.">Embryonic skeletal muscle microexplant culture and isolation of skeletal muscle stem cells.</a> Methods in Molecular Biology. 633, 29-56 (2010).</li><li>Mokbel, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=K7del+is+a+common+TPM2+gene+mutation+associated+with+nemaline+myopathy+and+raised+myofibre+calcium+sensitivity.">K7del is a common TPM2 gene mutation associated with nemaline myopathy and raised myofibre calcium sensitivity.</a> Brain. 136 (2), 494-507 (2013).</li><li>Yaffe, D., Saxel, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Serial+passaging+and+differentiation+of+myogenic+cells+isolated+from+dystrophic+mouse+muscle.">Serial passaging and differentiation of myogenic cells isolated from dystrophic mouse muscle.</a> Nature. 270, 725-727 (1977).</li><li>Rando, T. A., Blau, H. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Primary+mouse+myoblast+purification,+characterization,+and+transplantation+for+cell-mediated+gene+therapy.">Primary mouse myoblast purification, characterization, and transplantation for cell-mediated gene therapy.</a> Journal of Cell Biology. 125 (6), 1275-1287 (1994).</li><li>Musar&#242;, A., Carosio, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+and+Culture+of+Satellite+Cells+from+Mouse+Skeletal+Muscle.">Isolation and Culture of Satellite Cells from Mouse Skeletal Muscle.</a> Methods in Molecular Biology. 1553, 155-167 (2017).</li><li>Smolina, N., Bruton, J., Kostareva, A., Sejersen, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assaying+mitochondrial+respiration+as+an+indicator+of+cellular+metabolism+and+fitness.">Assaying mitochondrial respiration as an indicator of cellular metabolism and fitness.</a> Methods in Molecular Biology. 1601, 79-87 (2017).</li><li>Elliott, B., Renshaw, D., Getting, S., Mackenzie, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+central+role+of+myostatin+in+skeletal+muscle+and+whole+body+homeostasis.">The central role of myostatin in skeletal muscle and whole body homeostasis.</a> Acta Physiologica. 205 (3), 324-340 (2012).</li><li>Smolina, N., Kostareva, A., Bruton, J., Karpushev, A., Sjoberg, G., Sejersen, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Primary+murine+myotubes+as+a+model+for+investigating+muscular+dystrophy.">Primary murine myotubes as a model for investigating muscular dystrophy.</a> BioMed Research International. , (2015).</li><li>Nedachi, T., Fujita, H., Kanzaki, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Contractile+C+2+C+12+myotube+model+for+studying+exercise-inducible+responses+in+skeletal+muscle.">Contractile C 2 C 12 myotube model for studying exercise-inducible responses in skeletal muscle.</a> American Journal of Physiology-Endocrinology and Metabolism. 295 (5), E1191-E1204 (2008).</li><li>Chen, M. B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impaired+activation+of+AMP-kinase+and+fatty+acid+oxidation+by+globular+adiponectin+in+cultured+human+skeletal+muscle+of+obese+type+2+diabetics.">Impaired activation of AMP-kinase and fatty acid oxidation by globular adiponectin in cultured human skeletal muscle of obese type 2 diabetics.</a> Journal of Clinical Endocrinology and Metabolism. 90 (6), 3665-3672 (2005).</li><li>Douillard-Guilloux, G., Mouly, V., Caillaud, C., Richard, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immortalization+of+murine+muscle+cells+from+lysosomal+&#945;-glucosidase+deficient+mice:+A+new+tool+to+study+pathophysiology+and+assess+therapeutic+strategies+for+Pompe+disease.">Immortalization of murine muscle cells from lysosomal &#945;-glucosidase deficient mice: A new tool to study pathophysiology and assess therapeutic strategies for Pompe disease.</a> Biochemical and Biophysical Research Communications. 388 (2), 333-338 (2009).</li><li>Varga, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Myotube+elasticity+of+an+amyotrophic+lateral+sclerosis+mouse+model.">Myotube elasticity of an amyotrophic lateral sclerosis mouse model.</a> Scientific Reports. 8 (1), 5917 (2018).</li><li>Kriebs, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Circadian+repressors+CRY1+and+CRY2+broadly+interact+with+nuclear+receptors+and+modulate+transcriptional+activity.">Circadian repressors CRY1 and CRY2 broadly interact with nuclear receptors and modulate transcriptional activity.</a> Proceedings of the National Academy of Sciences. 114 (33), 8776-8781 (2017).</li><li>Cho, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Perm1+enhances+mitochondrial+biogenesis,+oxidative+capacity,+and+fatigue+resistance+in+adult+skeletal+muscle.">Perm1 enhances mitochondrial biogenesis, oxidative capacity, and fatigue resistance in adult skeletal muscle.</a> FASEB Journal. 30 (2), 674-687 (2016).</li></ol>

Skeletal muscle is vital for the establishment and maintenance of metabolic homeostasis11. The study of muscle physiology is complicated by interindividual variability, as well as difficulty in obtaining samples, particularly in the case of human studies. Cultured primary myotubes have been shown to recapitulate many features of muscle physiology, including calcium homeostasis12, regeneration of damaged muscle tissue5, metabolic alterations in respon...

While often cited as an indication of overall metabolic health, multiple studies have shown that body mass index (BMI) in older adults is not consistently associated with higher risk of mortality. To date, the only factor shown to be consistent with reduced mortality in this population is increased muscle mass1. Muscle tissue represents one of the largest sources of insulin-sensitive cells in the body, and is therefore critical in the maintenance of overall metabolic homeostasis2. Activation of skeletal muscle tissue via exercise is associated with increases in both local insulin sensitivity and overall metabolic health3. While in vivo models are essential for studying muscle physiology and the impact of muscle function on integrated metabolism, primary cultures of myotubes provide a tractable system that reduces the complexity of animal studies.
Myoblasts derived from post-natal muscles can be used to study the impact of numerous treatment and growth conditions in a highly reproducible manner. This has long been recognized and several methods for myoblast isolation and culture have been described4,5,6,7,8,9. Some of these methods use neonatal muscles and yield relatively low numbers of myoblasts5,8, requiring several animals for larger scale studies. Also, most widely used methods for culturing myoblasts use &#34;pre-plating&#34; to enrich for myoblasts, which are less adherent than other cell types. We have found the alternative enrichment method described here to be much more efficient and reproducible for enriching a highly proliferative myoblast population. In summary, this protocol enables the isolation of highly proliferative myoblasts from young adult muscle explants, via outgrowth into culture media. Myoblasts can be harvested repeatedly, over several days, rapidly expanded, and induced to differentiate into myotubes. This protocol reproducibly generates a large number of healthy myoblast cells that robustly differentiate into spontaneously twitching myotubes. It has enabled us to study metabolism and circadian rhythms in primary myotubes of mice of a variety of genotypes. Finally, we include methods for preparing myotubes for the study of oxidative metabolism, using measurements of oxygen consumption rates in 96-well plates.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Coating Solution:</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM</td>
			<td>Gibco</td>
			<td>10569010</td>
			<td>Always add gentamicin (1:1000 by volume) prior to use; 24 mL</td>
		</tr>
		<tr>
			<td>HAMS F12</td>
			<td>Lonza</td>
			<td>12-615F</td>
			<td>Always add gentamicin (1:1000 by volume) prior to use; 24 mL</td>
		</tr>
		<tr>
			<td>Collagen</td>
			<td>Life Technologies</td>
			<td>A1064401</td>
			<td>1.7 mL</td>
		</tr>
		<tr>
			<td>Matrigel</td>
			<td>Fisher</td>
			<td>CB40234A</td>
			<td>1 mL</td>
		</tr>
		<tr>
			<td>Plating Media:</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM</td>
			<td>Gibco</td>
			<td>10569010</td>
			<td>Always add gentamicin (1:1000 by volume) prior to use; 12.5 mL</td>
		</tr>
		<tr>
			<td>HAMS F12</td>
			<td>Lonza</td>
			<td>12-615F</td>
			<td>Always add gentamicin (1:1000 by volume) prior to use; 12.5 mL</td>
		</tr>
		<tr>
			<td>Heat Inactivated FBS</td>
			<td>Life Technologies</td>
			<td>16000044</td>
			<td>20 mL; can be purchased as regular FBS and heat-inactivated by placing in a 40 &#176;C water bath for 20 minutes</td>
		</tr>
		<tr>
			<td>Amniomax</td>
			<td>Life Technologies</td>
			<td>12556023</td>
			<td>5 mL</td>
		</tr>
		<tr>
			<td>Myoblast Media:</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM</td>
			<td>Gibco</td>
			<td>10569010</td>
			<td>Always add gentamicin (1:1000 by volume) prior to use; 17.5 mL</td>
		</tr>
		<tr>
			<td>HAMS F12</td>
			<td>Lonza</td>
			<td>12-615F</td>
			<td>Always add gentamicin (1:1000 by volume) prior to use; 17.5 mL</td>
		</tr>
		<tr>
			<td>Heat Inactivated FBS</td>
			<td>Life Technologies</td>
			<td>16000044</td>
			<td>10 mL; can be purchased as regular FBS and heat-inactivated by placing in a 40 &#176;C water bath for 20 minutes</td>
		</tr>
		<tr>
			<td>Amniomax</td>
			<td>Life Technologies</td>
			<td>12556023</td>
			<td>5 mL</td>
		</tr>
		<tr>
			<td>Differentiation Media:</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM</td>
			<td>Gibco</td>
			<td>10569010</td>
			<td>Always add gentamicin (1:1000 by volume) prior to use; 24 mL</td>
		</tr>
		<tr>
			<td>HAMS F12</td>
			<td>Lonza</td>
			<td>12-615F</td>
			<td>Always add gentamicin (1:1000 by volume) prior to use; 24 mL</td>
		</tr>
		<tr>
			<td>Heat Inactivated Horse Serum</td>
			<td>Sigma</td>
			<td>H1138</td>
			<td>1.5 mL</td>
		</tr>
		<tr>
			<td>Insulin-Selenium-Transferrin</td>
			<td>Life Technologies</td>
			<td>41400045</td>
			<td>0.5 mL</td>
		</tr>
		<tr>
			<td>Other Materials:</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>PBS</td>
			<td>Gibco</td>
			<td>14040133</td>
			<td></td>
		</tr>
		<tr>
			<td>Gentamicin</td>
			<td>Sigma</td>
			<td>G1397</td>
			<td></td>
		</tr>
		<tr>
			<td>TrypLE</td>
			<td>Gibco</td>
			<td>12604013</td>
			<td></td>
		</tr>
		<tr>
			<td>DMSO</td>
			<td>Sigma</td>
			<td>472301</td>
			<td>Prepare as 10% DMSO in Myoblast Media for freezing cells</td>
		</tr>
		<tr>
			<td>Forceps</td>
			<td>Any</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Razor Blades</td>
			<td>Any</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Scissors</td>
			<td>Any</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Whatman paper</td>
			<td>VWR</td>
			<td>21427-648</td>
			<td></td>
		</tr>
		<tr>
			<td>60 mm plate</td>
			<td>VWR</td>
			<td>734-2318</td>
			<td></td>
		</tr>
		<tr>
			<td>10 cm plate</td>
			<td>VWR</td>
			<td>25382-428 (CS)</td>
			<td></td>
		</tr>
		<tr>
			<td>T25 Flasks</td>
			<td>ThermoFisher</td>
			<td>156367</td>
			<td></td>
		</tr>
		<tr>
			<td>T75 Flasks</td>
			<td>ThermoFisher</td>
			<td>156499</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge Tubes (15mL)</td>
			<td>BioPioneer</td>
			<td>CNT-15</td>
			<td></td>
		</tr>
		<tr>
			<td>Oxygen Consumption Rates:</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Seahorse XFe96 Analyzer</td>
			<td>Agilent</td>
			<td>Seahorse XFe96 Analyzer</td>
			<td>Instrument used to measure oxygen consumption rates read out by acidification of the extracellular media</td>
		</tr>
		<tr>
			<td>Seahorse XFe96 FluxPak</td>
			<td>Agilent</td>
			<td>102416-100</td>
			<td>96-well plates for use in XFe96 Analyzer</td>
		</tr>
		<tr>
			<td>Seahorse XF Cell Mito Stress Test Kit</td>
			<td>Agilent</td>
			<td>103015-100</td>
			<td>components may be purchased from other suppliers once assay is established; some recommendations are listed below</td>
		</tr>
		<tr>
			<td>Seahorse XF Palmitate-BSA FAO substrate</td>
			<td>Agilent</td>
			<td>102720-100</td>
			<td>components may be purchased from other suppliers once assay is established; some recommendations are listed below</td>
		</tr>
		<tr>
			<td>Palmitic acid</td>
			<td>Sigma</td>
			<td>P5585-10G</td>
			<td>for measurement of fatty acid oxidation</td>
		</tr>
		<tr>
			<td>carnitine</td>
			<td>Sigma</td>
			<td>C0283-5G</td>
			<td>for measurement of fatty acid oxidation</td>
		</tr>
		<tr>
			<td>Etomoxir</td>
			<td>Sigma</td>
			<td>E1905</td>
			<td>for measurement of fatty acid oxidation</td>
		</tr>
		<tr>
			<td>BSA</td>
			<td>Sigma</td>
			<td>A7030</td>
			<td>used as control or in conjugation with palmitic acid for use in measurement of fatty acid oxidation</td>
		</tr>
	</tbody>
</table>

isolation and differentiation of primary myoblasts from mouse skeletal muscle explants

Primary myoblasts are undifferentiated proliferating precursors of skeletal muscle. They can be cultured and studied as muscle precursors or induced to differentiate into later stages of muscle development. The protocol provided here describes a robust method for the isolation and culture of a highly proliferative population of myoblast cells from young adult mouse skeletal muscle explants. These cells are useful for the study of the metabolic properties of skeletal muscle of different mouse models, as well as in other downstream applications such as transfection with exogenous DNA or transduction with viral expression vectors. The level of differentiation and metabolic profile of these cells depends on the length of exposure, and composition of the media used to induce myoblast differentiation. These methods provide a robust system for the study of mouse muscle cell metabolism ex vivo. Importantly, unlike in vivo models, the methods described here provide a cell population that can be expanded and studied with high levels of reproducibility.

Following Section 1 of the provided protocol should yield primary cells emerging from the explants that will be visible under a standard light microscope (Figure 2). A heterogeneous cell population will be seen growing out of and surrounding each muscle tissue explant. Myoblasts will appear as small, round, bright spheres. Following Section 2 of the protocol will yield early harvests of myoblasts from tissue explants, which will contain few cells and will be ...

Watch this Scientific Journal Video about Isolation and Differentiation of Primary Myoblasts from Mouse Skeletal Muscle Explants at JoVE.com

Isolation and Differentiation of Primary Myoblasts from Mouse Skeletal Muscle Explants

Myoblasts are proliferating precursor cells that differentiate to form polynucleated myotubes and eventually skeletal muscle myofibers. Here, we present a protocol for efficient isolation and culture of primary myoblasts from young adult mouse skeletal muscles. The method enables molecular, genetic, and metabolic studies of muscle cells in culture.

Primary myoblasts are undifferentiated proliferating precursors of skeletal muscle. They can be cultured and studied as muscle precursors or induced to ...

This is a protocol for the isolation of primary mouse muscle stem cells for the study of metabolism ex vivo. This protocol provides a much larger population of stem cells compared to other protocols that we've tried in the past. And importantly, once we differentiate these stem cells into myotubes, they exhibit normal physiology, so things like circadian rhythms.When trying this procedure for the first time, take detailed notes and save several images because every tissue explant looks different and there will be variation in the outgrowth of myoblasts. Without visual demonstration, it is difficult to know if you're isolating the correct cells. We benefited from the generous help of others who showed us this method when we established it in our lab.After preparing the dish for dissection according to the manuscript, prepare a moist chamber by placing two to three sheets of thick absorbent paper into a plastic bag and use a pipette to wet the surface of the paper with sterile water. Place the chamber under UV light for five minutes to sterilize. Dissect the desired muscle from a four to eight-week-old mouse and rinse gently in PBS containing 40 micrograms per milliliter gentamycin to sterilize.Use sterile forceps to transfer the muscle to a sterile 10 centimeter non-coated Petri dish. Add 0.5 to one milliliter of plating media over the muscle such that the tissue is moist but not floating. Use a sterile scalpel or razor blade to gently slice the muscle into small fragments.Use forceps or a pipette to transfer the muscle fragments onto the surface of a pre-coated six centimeter plate. Very gently overlay an additional 0.8 milliliters of plating media over the tissue. Place the six centimeter dish containing the muscle fragments inside the moist chamber and return it to an incubator at 37 degrees Celsius and 5%carbon dioxide for 48 hours.Prepare and prewarm myoblast media, trypsin and PBS-gentamycin in a water bath at 37 degrees Celsius. To coat a T25 flask for each muscle group, add two milliliters of coating solution to the surface of the flask, shake gently to create an even coat on the surface, and incubate the flask at four degrees Celsius for one hour. Now with a pipette, remove the plating media from the muscle explants and gently rinse the muscle explants with two milliliters of PBS-gentamycin.Quickly remove the PBS and do not let the plate sit in the PBS. Then gently add one milliliter of PBS-gentamycin and place the plate in the 37 degree Celsius incubator for one minute. Use a P1000 pipette to collect the PBS with cells into a 15 milliliter centrifuge tube.Next, add one milliliter of trypsin to the plate and return it to the 37 degree Celsius incubator for three minutes. Gently tap the plates to dislodge the myoblasts. Collect the trypsin with cells and combine with the PBS collection.Add eight milliliters of myoblast media to the centrifuge tube and gently invert to mix. Gently overlay two milliliters of plating solution on the muscle plates and return the plates to the 37 degree Celsius incubator. Spin the centrifuge tubes containing cells in a centrifuge for three minutes at 200 times g.Aspirate the supernatant and keep approximately one milliliter in the tube. Gently add myoblast media, transfer the cells to the pre-coated flask and place the flask in the 37 degree Celsius incubator. Aspirate the media from P0 myoblast T25 flasks.Rinse the cells briefly with two milliliters of warm PBS-gentamycin then aspirate the PBS from the flask. Pipette two milliliters of warm PBS into each flask containing myoblasts. Place the flasks with PBS into the 37 degree Celsius incubator for three minutes.Then firmly tap the side of the flask to dislodge the cells. Check under a light microscope for freely floating myoblasts. Place the flasks upright in a tissue culture hood and rinse the bottom of the flasks with 10 milliliters of myoblast media two to three times to ensure all cells are dislodged.Collect the cell media mixture in a 15 milliliter centrifuge tube. Centrifuge for three minutes at 200 times g. Aspirate the media to leave around one milliliter in the tube being careful to avoid the cell pellet.Gently add an appropriate volume of myoblast media to the centrifuge tube and gently mix. Distribute the cell mixture to new T75 flasks six milliliters each. Add 10 milliliters of myoblast media to each new T75 flask.Gently shake the flasks horizontally to distribute the cells and place them in the incubator at 37 degrees Celsius overnight. In this protocol, primary cells emerged from the explants were observed under a standard light microscope. Early harvests of myoblasts appeared as small round and bright spheres.Differentiation of myoblasts took four to six days during which the morphology of the cells changed from single round spheres to elongated fused long multi-nucleated fibers. Fully differentiated myotubes were yielded which were ready for measurement of oxygen consumption rates. These cells can be used for a number of downstream applications.For instance, we frequently use them to study substrate flux in Seahorse instruments.

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16.3K Views.  Department of Molecular Medicine. This is a protocol for the isolation of primary mouse muscle stem cells for the study of metabolism ex vivo. This protocol provides a much larger population of stem cells compared to other protocols that we've tried in the past. And importantly, once we differentiate these stem cells into myotubes, they exhibit normal physiology, so things like circadian rhythms.When trying this procedure for the first time, take detailed notes and save several images because every tissue explant looks...