Name: facs-isolation and culture of fibro-adipogenic progenitors and muscle stem cells from unperturbed and injured mouse skeletal muscle
Uploaded: 2022-06-08T14:30:00
Description: Watch this Scientific Journal Video about FACS-Isolation and Culture of Fibro-Adipogenic Progenitors and Muscle Stem Cells from Unperturbed and Injured Mouse Skeletal Muscle at JoVE.com

We would like to thank Tom Cheung (The Hong Kong University of Science &#38; Technology) for advice on MuSC isolation. This work was funded by the NIAMS-IRP through NIH grants AR041126 and AR041164.

All animal experiments performed were conducted in compliance with institutional guidelines approved by the Animal Care and Use Committee (ACUC) of the National Institute of Arthritis, Musculoskeletal, and Skin Diseases (NIAMS). Investigators performing this protocol must adhere to their local animal ethics guidelines.
NOTE: This protocol describes in detail how to isolate FAPs and MuSCs from hind limb and injured tibialis anterior (TA) muscles of adult male and female mice (3-6 months) and pr...

<ol>
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Establishing efficient and reproducible protocols for the identification and isolation of pure adult stem cell populations is the first and most critical step toward understanding their function. Isolated FAPs and MuSCs can be used to conduct multiomics analysis in transplantation experiments as a potential treatment for muscular diseases or can be genetically modified for disease modeling in stem cell therapy. 
The protocol described here provides standardized guidelines for the identificatio...

The skeletal muscle is the largest tissue in the body, accounting for ~40% of adult human weight, and is responsible for maintaining posture, generating movement, regulating basal energy metabolism, and body temperature1. Skeletal muscle is a highly dynamic tissue and possesses a remarkable ability to adapt to a variety of stimuli, such as mechanical stress, metabolic alterations, and daily environmental factors. In addition, skeletal muscle regenerates in response to acute injury, leading to complete restoration of its morphology and functions2. Skeletal muscle plasticity mainly relies upon a population of resident muscle stem cells (MuSCs), also termed satellite cells, which are located between the myofiber plasma membrane and the basal lamina2,3. Under normal conditions, MuSCs reside in the muscle niche in a quiescent state, with only a few divisions to compensate for cellular turnover and to replenish the stem cell pool4. In response to injury, MuSCs enter the cell cycle, proliferate, and either contribute to the formation of new muscle fibers or return to the niche in a self-renewal process2,3. In addition to MuSCs, homeostatic maintenance and regeneration of the skeletal muscle rely upon the support of a population of muscle resident cells named fibro-adipogenic progenitors (FAPs)5,6,7. FAPs are mesenchymal stromal cells embedded in the muscle connective tissue and capable of differentiating along fibrogenic, adipogenic, osteogenic, or chondrogenic lineage5,8,9,10. FAPs provide structural support for MuSCs as they are a source of extracellular matrix proteins in the muscle stem cell niche. FAPs also promote long-term maintenance of the skeletal muscle by secreting cytokines and growth factors that provide trophic support for myogenesis and muscle growth6,11. Upon acute muscle injury, FAPs rapidly proliferate to produce a transient niche that supports the structural integrity of the regenerating muscle and provides a favorable environment to sustain MuSCs proliferation and differentiation in a paracrine manner5. As regeneration proceeds, FAPs are cleared from the regenerative muscle by apoptosis, and their numbers gradually return to basal level12. However, in conditions favoring chronic muscle injury, FAPs override pro-apoptotic signaling and accumulate in the muscle niche, where they differentiate into collagen-producing fibroblasts and adipocytes, leading to ectopic fat infiltrates and fibrotic scar formation12,13.
Due to their multipotency and their regenerative abilities, FAPs and MuSCs have been identified as prospective targets in regenerative medicine for the treatment of skeletal muscle disorders. Therefore, to investigate their function and therapeutic potential, it is important to establish efficient and reproducible protocols for the isolation and culture of FAPs and MuSCs.
Fluorescence-activated cell sorting (FACS) can identify different cell populations based on morphological characteristics such as size and granularity, and permits cell-specific isolation based on the use of antibodies directed against cell surface markers. In adult mice, MuSCs express the vascular cell adhesion molecule 1 (VCAM-1, also known as CD106)14,15 and &#945;7-Integrin15, while FAPs express the platelet-derived growth factor receptor &#945; (PDGFR&#945;) and the stem cell antigen 1 (Sca1 or Ly6A/E)5,6,9,12,16,17. In the protocol described here, MuSCs were identified as CD31-/CD45-/Sca1-/VCAM-1+/&#945;7-Integrin+, while FAPs were identified as CD31-/CD45-/Sca1+/VCAM-1-/&#945;7-Integrin-. Alternatively, PDGFR&#945;EGFP mice were employed to isolate FAPs as CD31-/CD45-/PDGFR&#945;+/VCAM-1-/&#945;7-Integrin- events18,19. Furthermore, we compared the overlapping between the fluorescent signal of PDGFR&#945;-GFP+ cells to cells identified by the surface marker Sca1. Our analysis showed that all GFP-expressing cells were also positive for Sca1, indicating that either approach can be employed for the identification and isolation of FAPs. Finally, staining with specific marker antibodies confirmed the purity of each cell population.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>5 mL Polypropylene Round-Bottom Tube</td>
			<td>Falcon</td>
			<td>352063</td>
			<td></td>
		</tr>
		<tr>
			<td>5 mL Polystyrene Round-Bottom Tube with Cell-Strainer Cap</td>
			<td>Falcon</td>
			<td>352235</td>
			<td></td>
		</tr>
		<tr>
			<td>20 G BD Needle 1 in. single use, sterile</td>
			<td>BD Biosciences&#160;</td>
			<td>305175</td>
			<td></td>
		</tr>
		<tr>
			<td>anti-Alpha 7 Integrin PE (clone:R2F2) (RatIgG2b)</td>
			<td>The University of British Columbia</td>
			<td>53-0010-01</td>
			<td></td>
		</tr>
		<tr>
			<td>APC anti-mouse CD31 Antibody</td>
			<td>BioLegend</td>
			<td>102510</td>
			<td></td>
		</tr>
		<tr>
			<td>APC anti-mouse CD45 Antibody</td>
			<td>BioLegend</td>
			<td>103112</td>
			<td></td>
		</tr>
		<tr>
			<td>BD FACSMelody Cell Sorter</td>
			<td>BD Biosciences&#160;</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>BD Luer-Lok tip control syringe, 10-mL</td>
			<td>BD Biosciences&#160;</td>
			<td>309604</td>
			<td></td>
		</tr>
		<tr>
			<td>Biotin anti-mouse CD106 Antibody</td>
			<td>BioLegend</td>
			<td>105703</td>
			<td></td>
		</tr>
		<tr>
			<td>C57BL/6J&#160; mouse (Female and Male)</td>
			<td>The Jackson Laboratory</td>
			<td>000664</td>
			<td></td>
		</tr>
		<tr>
			<td>B6.129S4-Pdgfratm11(EGFP)Sor/J mouse</td>
			<td>The Jackson Laboratory</td>
			<td>007669</td>
			<td></td>
		</tr>
		<tr>
			<td>Corning BioCoat Collagen I 6-well Clear Flat Bottom TC-treated Multiwell Plate</td>
			<td>Corning</td>
			<td>356400</td>
			<td></td>
		</tr>
		<tr>
			<td>Corning BioCoat Collagen I 12-well Clear Flat Bottom TC-treated Multiwell Plate</td>
			<td>Corning</td>
			<td>356500</td>
			<td></td>
		</tr>
		<tr>
			<td>Corning BioCoat Collagen I 24-well Clear Flat Bottom TC-treated Multiwell Plate</td>
			<td>Corning</td>
			<td>356408</td>
			<td></td>
		</tr>
		<tr>
			<td>DAPI Solution (1 mg/mL)</td>
			<td>ThermoFisher Scientific</td>
			<td>62248</td>
		</tr>
		<tr>
			<td>Disposable Aspirating Pipets, Polystyrene, Sterile</td>
			<td>VWR</td>
			<td>414004-265</td>
			<td></td>
		</tr>
		<tr>
			<td>Donkey anti-Goat IgG (H+L) Highly Cross-Adsorbed Secondary Antibody, Alexa Fluor 488</td>
			<td>ThermoFisher Scientific</td>
			<td>A-11055</td>
			<td></td>
		</tr>
		<tr>
			<td>Falcon 40 &#181;m Cell Strainer, Blue, Sterile</td>
			<td>Corning</td>
			<td>352340</td>
			<td></td>
		</tr>
		<tr>
			<td>Falcon 60 mm TC-treated Cell Culture Dish, Sterile</td>
			<td>Corning</td>
			<td>353002</td>
			<td></td>
		</tr>
		<tr>
			<td>Falcon Centrifuge Tubes, Polypropylene, Sterile, Corning, 15-mL</td>
			<td>VWR</td>
			<td>352196</td>
			<td></td>
		</tr>
		<tr>
			<td>Falcon Centrifuge Tubes, Polypropylene, Sterile, Corning, 50-mL</td>
			<td>Corning</td>
			<td>352070</td>
			<td></td>
		</tr>
		<tr>
			<td>Falcon Round-Bottom Tubes, Polypropylene, Corning</td>
			<td>VWR</td>
			<td>60819-728</td>
			<td></td>
		</tr>
		<tr>
			<td>Falcon Round-Bottom Tubes, Polystyrene, with 35um Cell Strainer Cap Corning</td>
			<td>VWR</td>
			<td>21008-948</td>
			<td></td>
		</tr>
		<tr>
			<td>Fibroblast Growth Factor, Basic, Human, Recombinant (rhFGF, Basic)</td>
			<td>Promega</td>
			<td>G5071</td>
			<td></td>
		</tr>
		<tr>
			<td>FlowJo 10.8.1</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Gibco Collagenase, Type II, powder</td>
			<td>ThermoFisher Scientific</td>
			<td>17101015</td>
			<td></td>
		</tr>
		<tr>
			<td>Gibco Dispase, powder</td>
			<td>ThermoFisher Scientific</td>
			<td>17105041</td>
			<td></td>
		</tr>
		<tr>
			<td>Gibco DMEM, high glucose, HEPES</td>
			<td>ThermoFisher Scientific</td>
			<td>12430054</td>
			<td></td>
		</tr>
		<tr>
			<td>Gibco Fetal Bovine Serum, certified, United States</td>
			<td>ThermoFisher Scientific</td>
			<td>16000044</td>
			<td></td>
		</tr>
		<tr>
			<td>Gibco Ham&#39;s F-10 Nutrient Mix</td>
			<td>ThermoFisher Scientific</td>
			<td>11550043</td>
			<td></td>
		</tr>
		<tr>
			<td>Gibco Horse Serum, New Zealand origin</td>
			<td>ThermoFisher Scientific</td>
			<td>16050122</td>
			<td></td>
		</tr>
		<tr>
			<td>Gibco PBS, pH 7.4</td>
			<td>ThermoFisher Scientific</td>
			<td>10010023</td>
			<td></td>
		</tr>
		<tr>
			<td>Gibco PBS (10x), pH 7.4</td>
			<td>ThermoFisher Scientific</td>
			<td>70011044</td>
			<td></td>
		</tr>
		<tr>
			<td>Gibco Penicillin-Streptomycin-Glutamine (100x)</td>
			<td>ThermoFisher Scientific</td>
			<td>10378016</td>
			<td></td>
		</tr>
		<tr>
			<td>Goat anti-Mouse IgG1 cross-absorbed secondary antibody, Alexa Fluor 555</td>
			<td>ThermoFisher Scientific</td>
			<td>A-21127</td>
			<td></td>
		</tr>
		<tr>
			<td>Hardened Fine Scissors</td>
			<td>Fine Science Tools Inc</td>
			<td>14090-09</td>
			<td></td>
		</tr>
		<tr>
			<td>Invitrogen 7-AAD (7-Aminoactinomycin D)</td>
			<td>ThermoFisher Scientific</td>
			<td>A1310</td>
			<td></td>
		</tr>
		<tr>
			<td>Mouse PDGF&#160;R alpha Antibody</td>
			<td>R&#38;D Systems</td>
			<td>AF1062</td>
			<td></td>
		</tr>
		<tr>
			<td>Normal Donkey Serum</td>
			<td>Fisher Scientific</td>
			<td>NC9624464</td>
			<td></td>
		</tr>
		<tr>
			<td>Normal Goat Serum</td>
			<td>ThermoFisher Scientific</td>
			<td>31872</td>
			<td></td>
		</tr>
		<tr>
			<td>Pacific Blue anti-mouse Ly-6A/E (Sca 1) Antibody</td>
			<td>BioLegend</td>
			<td>108120</td>
			<td></td>
		</tr>
		<tr>
			<td>Paraformaldehyde, 16%</td>
			<td>Fisher Scientific</td>
			<td>NCC0528893</td>
			<td></td>
		</tr>
		<tr>
			<td>Pax7 mono-clonal mouse antibody (IgG1) (supernatant)</td>
			<td>Developmental Study Hybridoma Bank</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>PE/Cyanine7 Streptavidin</td>
			<td>BioLegend</td>
			<td>405206</td>
			<td></td>
		</tr>
		<tr>
			<td>Student Vannas Spring Scissors</td>
			<td>Fine Science Tools Inc</td>
			<td>91500-09</td>
			<td></td>
		</tr>
		<tr>
			<td>Student Dumont #5 Forceps</td>
			<td>Fine Science Tools Inc</td>
			<td>91150-20</td>
			<td></td>
		</tr>
		<tr>
			<td>Triton X-100</td>
			<td>Sigma-Aldrich</td>
			<td>T8787</td>
			<td></td>
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facs-isolation and culture of fibro-adipogenic progenitors and muscle stem cells from unperturbed and injured mouse skeletal muscle

Fibro-adipogenic progenitor cells (FAPs) are a population of skeletal muscle-resident mesenchymal stromal cells (MSCs) capable of differentiating along fibrogenic, adipogenic, osteogenic, or chondrogenic lineage. Together with muscle stem cells (MuSCs), FAPs play a critical role in muscle homeostasis, repair, and regeneration, while actively maintaining and remodeling the extracellular matrix (ECM). In pathological conditions, such as chronic damage and muscular dystrophies, FAPs undergo aberrant activation and differentiate into collagen-producing fibroblasts and adipocytes, leading to fibrosis and intramuscular fatty infiltration. Thus, FAPs play a dual role in muscle regeneration, either by sustaining MuSC turnover and promoting tissue repair or contributing to fibrotic scar formation and ectopic fat infiltrates, which compromise the integrity and function of the skeletal muscle tissue. A proper purification of FAPs and MuSCs is a prerequisite for understanding the biological role of these cells in physiological as well as in pathological conditions. Here, we describe a standardized method for the simultaneous isolation of FAPs and MuSCs from limb muscles of adult mice using fluorescence-activated cell sorting (FACS). The protocol describes in detail the mechanical and enzymatic dissociation of mononucleated cells from whole limb muscles and injured tibialis anterior (TA) muscles. FAPs and MuSCs are subsequently isolated using a semi-automated cell sorter to obtain pure cell populations. We additionally describe an optimized method for culturing quiescent and activated FAPs and MuSCs, either alone or in coculture conditions.

This protocol allows the isolation of approximately one million FAPs and up to 350,000 MuSCs from uninjured hind limbs of wild-type adult mice (3-6 months), corresponding to a yield of 8% for FAPs and 3% for MuSCs of total events. When sorting cells from damaged TA 7 days post-injury, two to three TA muscles are pooled to obtain up to 300,000 FAPs and 120,000 MuSCs, which correspond to a yield of 11% and 4%, respectively. Post-sort purity values are usually above 95% for FAPs and MuSCs.
The ga...

Watch this Scientific Journal Video about FACS-Isolation and Culture of Fibro-Adipogenic Progenitors and Muscle Stem Cells from Unperturbed and Injured Mouse Skeletal Muscle at JoVE.com

FACS-Isolation and Culture of Fibro-Adipogenic Progenitors and Muscle Stem Cells from Unperturbed and Injured Mouse Skeletal Muscle

The precise identification of fibro-adipogenic progenitor cells (FAPs) and muscle stem cells (MuSCs) is critical to studying their biological function in physiological and pathological conditions. This protocol provides guidelines for the isolation, purification, and culture of FAPs and MuSCs from adult mouse muscles.

Fibro-adipogenic progenitor cells (FAPs) are a population of skeletal muscle-resident mesenchymal stromal cells (MSCs) capable of differentiating along ...

Research

JoVE Journal

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