We acknowledge the Mayo Clinic Microscopy Cell Analysis Core Flow Cytometry Facility for assistance with FACS sorting.

All animal experimental procedures were performed under approval by the Mayo Clinic Institutional Animal Care and Use Committee.
1. Solution preparation 
<ol>
	<li>Prepare collagenase 2% (w/v) solution by dissolving collagenase II 2 g in 100 mL Hanks&#39; balanced salt solution (HBSS). Aliquot 200 &#181;L each for each use.</li>
	<li>Prepare neutralization medium by mixing 84 mL F-12 medium, 15 mL horse serum, and 1 mL penicillin/streptomycin.</li>
	<li>Prepare flow cytometry buffer by dissolving 500 mg of bovine serum albumin (BSA) and 400 &#181;L of 0.5 M EDTA in 100 mL of Dulbecco&#39;s phosphate-buffered saline (DPBS).</li>
</ol>
2. Dissection of epididymal fat pad and tissue dissociation
<ol>
	<li>Humanely euthanize (isoflurane/cervical dislocation) one male mouse. In this protocol, a four-month-old FVB mouse was used.</li>
	<li>Apply/spray 70% ethanol on the abdomen and expose the lower abdominal cavity using clean scissors and forceps.</li>
	<li>Locate epididymal fat pad (proximal/attached to testes). Hold the junction between testes and epididymal fat pad with blunt forceps and pull gently to liberate the epididymal fat pad.</li>
	<li>Remove testes by cutting using scissors and incubate epididymal fat pad in 5 mL of HBSS supplemented with 3% BSA in a 50 mL conical tube at room temperature for 15 min.</li>
	<li>Centrifuge at 150 x g for 7 min at 4 &#176;C.</li>
	<li>Take floating epididymal fat pad from the 50 mL conical tube and finely mince the tissue using clean scissors.</li>
	<li>Add 200 &#181;L collagenase 2% solution into 3.8 mL of HBSS in a 13 mL culture tube. Add the minced tissue and incubate in a rotating incubator at 5 rpm for 1 h at 37 &#176;C. Instead of a rotating incubator, cell culture incubator at 37 &#176;C can be alternatively used with occasional agitations.</li>
	<li>Transfer entire contents into a 50 mL conical tube and add 10 mL of neutralization medium. Mix gently by inverting the tube 2-3 times.</li>
	<li>Prepare another 50 mL conical tube fitted with a 70 &#181;m cell strainer. Filter the digested tissue into the new tube using the cell strainer.</li>
	<li>Transfer the flow-through to a 15 mL conical tube and centrifuge at 350 x g for 10 min at 4 &#176;C.</li>
	<li>Carefully remove the supernatant and resuspend cell pellets with 5 mL of DPBS. Centrifuge at 350 x g for 10 min at 4 &#176;C.</li>
	<li>Carefully remove the supernatant and add 50 &#181;L of flow cytometry buffer. Mix well by pipetting gently and keep cells on ice. Due to the volume of the cell pellets and small amount of residual supernatant, total volume of cells in the flow cytometry buffer will be greater than 50 &#181;L (approximately 100 &#181;L).</li>
</ol>
3. Antibody labeling and fluorescence activated cell sorting (FACS)
<ol>
	<li>After mixing the cells well with gentle pipetting, transfer 54 &#181;L of the cell suspension into a 1.7 mL microcentrifuge tube. Add 6 &#181;L of FcR blocking reagent and mix well by pipetting gently. Incubate at 4 &#176;C for 10 min. Save any leftover cells after taking 54 &#181;L and keep them in the ice to use as an unstained control in step 3.5 and step 3.6.</li>
	<li>During the incubation in step 3.1, prepare an antibody cocktail by combining 11 &#181;L each of anti-Sca1-APC, anti-Ter119-FITC, anti-CD31-FITC, and anti-CD45-FITC antibodies in a microcentrifuge tube. Mix well by gentle pipetting and keep on ice protected from light.</li>
	<li>After incubation with FcR blocking reagent for 10 min, add 40 &#181;L of the antibody cocktail and mix well by gentle pipetting. Incubate at 4 &#176;C for 10 min.</li>
	<li>Add 500 &#181;L of flow cytometry buffer supplemented with 1 &#181;g/mL of DAPI into the stained cells. Mix well by gentle pipetting and filter cells using a 5 mL test tube with cell strainer snap cap. Keep cells on ice.</li>
	<li>Add 500 &#181;L of flow cytometry buffer to remaining cells in step 3.1 and mix well by gentle pipetting. Filter cells using a 5 mL test tube with cell strainer snap cap. Keep these cells on ice and use as an unstained control in the following step.</li>
	<li>Take the stained cells and unstained control to FACS analysis or sorting instrument.
	<ol>
		<li>Identify and isolate the APC+/FITC-/DAPI- population with gating strategies shown in Figure 1. These cells represent viable Sca1+/Ter119-/CD31-/CD45- cells. Debris and cell aggregates are depleted using forward (FSC) and side scatter (SSC) plots. Then, DAPI- population is gated, followed by gating of APC+/FITC- population. Unstained controls should be used to aid in setting gating parameters.</li>
		<li>Collect the cells into 500 &#181;L of flow cytometry buffer in a 1.5 mL microcentrifuge tube. Moving forward, all procedures should be performed under sterile conditions to minimize a contamination. Approximately 50,000 &#8211; 100,000 cells are collected from one mouse.</li>
	</ol>
	</li>
	<li>Count cells using a hemocytometer to evaluate cell viability. Since cell aggregates can interfere with further downstream analyses, the presence of cell aggregates is also evaluated to ensure a minimal presence (&#60;5% of viable cell number) of these aggregates.</li>
</ol>

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	<li>Krotkiewski, M., Bjorntorp, P., Sjostrom, L., Smith, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impact+of+obesity+on+metabolism+in+men+and+women.+Importance+of+regional+adipose+tissue+distribution.">Impact of obesity on metabolism in men and women. Importance of regional adipose tissue distribution.</a> The Journal of Clinical Investigation. 72, 1150-1162 (1983).</li><li>Salans, L. B., Horton, E. S., Sims, E. 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P., Scheller, E. L., MacDougald, O. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adipose+tissue+stem+cells+meet+preadipocyte+commitment:+going+back+to+the+future.">Adipose tissue stem cells meet preadipocyte commitment: going back to the future.</a> Journal of Lipid Research. 53, 227-246 (2012).</li><li>Cho, D. S., Lee, B., Doles, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Refining+the+adipose+progenitor+cell+landscape+in+healthy+and+obese+visceral+adipose+tissue+using+single-cell+gene+expression+profiling.">Refining the adipose progenitor cell landscape in healthy and obese visceral adipose tissue using single-cell gene expression profiling.</a> Life Science Alliance. 2, 201900561 (2019).</li><li>Burl, R. 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=Deconstructing+Adipogenesis+Induced+by+beta3-Adrenergic+Receptor+Activation+with+Single-Cell+Expression+Profiling.">Deconstructing Adipogenesis Induced by beta3-Adrenergic Receptor Activation with Single-Cell Expression Profiling.</a> Cell Metabolism. 28, 300-309 (2018).</li><li>Hepler, C., 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=Identification+of+functionally+distinct+fibro-inflammatory+and+adipogenic+stromal+subpopulations+in+visceral+adipose+tissue+of+adult+mice.">Identification of functionally distinct fibro-inflammatory and adipogenic stromal subpopulations in visceral adipose tissue of adult mice.</a> eLife. 7, 39636 (2018).</li><li>Merrick, D., 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=Identification+of+a+mesenchymal+progenitor+cell+hierarchy+in+adipose+tissue.">Identification of a mesenchymal progenitor cell hierarchy in adipose tissue.</a> Science. 364, 2501 (2019).</li><li>Schwalie, P. C., 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=A+stromal+cell+population+that+inhibits+adipogenesis+in+mammalian+fat+depots.">A stromal cell population that inhibits adipogenesis in mammalian fat depots.</a> Nature. 559, 103-108 (2018).</li><li>Raajendiran, 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=Identification+of+Metabolically+Distinct+Adipocyte+Progenitor+Cells+in+Human+Adipose+Tissues.">Identification of Metabolically Distinct Adipocyte Progenitor Cells in Human Adipose Tissues.</a> Cell Reports. 27, 1528-1540 (2019).</li><li>De Matteis, R., 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=In+vivo+physiological+transdifferentiation+of+adult+adipose+cells.">In vivo physiological transdifferentiation of adult adipose cells.</a> Stem Cells. 27, 2761-2768 (2009).</li><li>Hanamsagar, R., 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=An+optimized+workflow+for+single-cell+transcriptomics+and+repertoire+profiling+of+purified+lymphocytes+from+clinical+samples.">An optimized workflow for single-cell transcriptomics and repertoire profiling of purified lymphocytes from clinical samples.</a> Scientific Reports. 10, 2219 (2020).</li><li>Marinovic, M. 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The authors have nothing to disclose.

Single cell RNA sequencing (scRNA-seq) is rapidly gaining traction as a powerful tool to simultaneously study diverse cell populations at the single cell level. Due to high costs associated with sample preparation and high throughput sequencing, it is imperative to optimize cellular inputs (high viability and purity) to increase the likelihood of experimental success. Some cell preparation protocols rely on removal of dead cells and debris using low-spin washes and column-based separation without FACS sorting14. Many of these methods, however, significantly reduce the number of viable recovered cells, and in many cases, dead cells are not completely removed14. This protocol outlines a simple method to isolate highly viable Sca1+ adipose progenitor cells containing minimal cellular debris, cell doublets, and dead cells. Although cells isolated using this protocol exhibited high viability, we still recommend minimizing time between cell isolation and further downstream analysis to maintain high viability. In addition, successful antibody labeling is critical to isolate Sca1+ adipose progenitor cells with high purity. Hence, determination of optimal concentration of antibodies is strongly recommended for each antibody, and dilution of the antibodies in step 3.2 can be adjusted accordingly.
This flow cytometry-based protocol is amenable to customization depending on individual interest in specific adipose progenitor cell sub-populations. Here, alternative antibody combinations can be used to identify and isolate the population(s) of interest. Indeed, due to extensive APC marker diversity, multiple labs studying APCs using scRNA-seq report isolating cells using other surface markers. &#173;For example, PDGFRA+/CD44+ cells, CD31-/CD45-/Ter119-/CD29+/CD34+/Sca1+ cells, and Pdgfrb+ cells have been isolated by FACS for downstream APC scRNA-seq analyses8,9,11. CD142+ subpopulations have also been characterized and are shown to exhibit limited adipogenic differentiation capacity and an ability to suppress adipogenesis10,11. In addition to Sca1, combinations of antibodies against CD55, CD81, and CD9 were recently used to prospectively isolate ASC and preadipocyte subpopulations (using this protocol) and study subpopulation molecular and functional heterogeneity7. Moreover, since adipose progenitor cells from other fat pads including inguinal fat pads and brown adipose tissues have been isolated using collagenase dissociation like the present protocol15,16,17, the present protocol may be applicable to isolation of adipose progenitor cells from other adipose tissues.
One caveat of the current approach is that it is tailored towards the isolation of immature APCs. Although the present protocol yields high viability APCs, the efficacy and efficiency of isolation of other adipose tissue resident cell types (i.e., immune cells, fibroblasts, endothelial cells, etc.) is unclear. Importantly, this protocol is not suitable for the isolation of mature adipocytes. Adipocytes have been extremely difficult to isolate using FACS due to their large cell size and fragility. Recently, isolation of mature adipocytes by FACS was reported using a large nozzle size (150 &#181;m) and low sheath pressure (6 psi) with a specific FSC/SSC gating strategy18. Future studies could perhaps merge this adipocyte isolation protocol with the protocol described here to establish a more comprehensive pipeline to isolate and study diverse cell types within adipose tissue.

Adipose tissue plays a key role in energy metabolism. Excess energy is stored in the form of lipids, and adipose tissue is capable of significant expansion or retraction depending on nutritional status and energetic demand. Expansion of adipose tissue can result from an increase in adipocyte size (hypertrophy) and/or from an increase in adipocyte number (hyperplasia); the latter process tightly regulated by proliferation and differentiation of adipose progenitor cells1,2. During obesity, adipose tissue excessively expands, and tissue dysfunction &#8211; including hypoxia, inflammation, and insulin resistance &#8211; often develops3,4. These complications are risk factors to many chronic diseases including hypertension, diabetes, cardiovascular diseases, stroke, and cancer5. Hence, limiting uncontrolled adipose tissue expansion and mitigating adipose tissue pathologies are top biomedical research priorities. During adipose tissue expansion, resident adipose tissue-derived stem cells (ASCs) proliferate and differentiate sequentially into preadipocytes (committed progenitor cells) and then into mature adipocytes6. Recent single-cell RNA-sequencing (scRNA-seq) studies show that these adipose progenitor cell (APC) populations (ASCs and preadipocytes) exhibit substantial molecular and functional heterogeneity7,8,9,10,11,12. For example, ASCs display a reduced adipogenic differentiation capacity, while also exhibiting higher proliferation and expansion capabilities, compared to preadipocytes7. Further molecular differences are reported within ASC and preadipocyte populations, although the functional relevance of these differences remains unclear7. Together, these data highlight the complexity of the adipose progenitor cell pool and underscore the need to develop and standardize tools to better understand and manipulate these critical cell populations.
This protocol details the isolation of high viability Sca1+ adipose progenitor cell populations from mouse epididymal fat pads that are suitable for sensitive downstream analyses, including single-cell studies (scRNA-sequencing) and cell culture. Isolation and dissociation of epididymal fat pads was performed as previously described7,13 with slight modifications that improve the viability of isolated APCs. In brief, dissociated cells from epididymal fat pads are stained with antibodies against Sca1, a marker for both ASCs and preadipocytes6,7, and other lineage (Lin) markers: Ter119 (erythroid cells), CD31 (endothelial cells), and CD45 (leukocytes). Viable Sca1+/Ter119-/CD31-/CD45-/DAPI- cells are then sorted by fluorescence activated cell sorting (FACS). Importantly, this protocol was validated by successful isolation and analysis of viable Sca1+/Lin- adipose progenitor cells reported in a recent single cell RNA sequencing study that identified functionally heterogeneous subpopulations within ASCs and preadipocytes7.

<table><tbody><tr><td>1.7 mL microcentrifuge tube</td><td>VWR</td><td>87003-294</td><td></td></tr><tr><td>13 mL culture tube</td><td>Thermo Fisher Scientific</td><td>50-809-216</td><td></td></tr><tr><td>15 mL conical tube</td><td>Greiner Bio-one</td><td>188 271</td><td></td></tr><tr><td>5 mL test tube with cell strainer snap cap</td><td>Thermo Fisher Scientific</td><td>08-771-23</td><td></td></tr><tr><td>50 mL conical tube</td><td>Greiner Bio-one</td><td>227 261</td><td></td></tr><tr><td>70 &amp;micro;m cell strainer</td><td>Thermo Fisher Scientific</td><td>22-363-548</td><td></td></tr><tr><td>Anti-CD31-FITC antibody</td><td>Miltenyi Biotec</td><td>130-102-519</td><td></td></tr><tr><td>Anti-CD45-FITC antibody</td><td>Miltenyi Biotec</td><td>130-102-491</td><td></td></tr><tr><td>Anti-Sca1-APC antibody</td><td>Miltenyi Biotec</td><td>130-102-833</td><td></td></tr><tr><td>Anti-Ter119-FITC antibody</td><td>Miltenyi Biotec</td><td>130-112-908</td><td></td></tr><tr><td>BSA</td><td>Gold Biotechnology</td><td>A-420-500</td><td></td></tr><tr><td>Collagenase type II</td><td>Thermo Fisher Scientific</td><td>17101-015</td><td></td></tr><tr><td>DAPI</td><td>Thermo Fisher</td><td>D1306</td><td></td></tr><tr><td>Dulbecco&#039;s phosphate-buffered saline (DPBS)</td><td>Thermo Fisher Scientific</td><td>14190-144</td><td></td></tr><tr><td>F-12 medium</td><td>Thermo Fisher Scientific</td><td>11765-054</td><td></td></tr><tr><td>FcR blocking reagent</td><td>Miltenyi Biotec</td><td>130-092-575</td><td></td></tr><tr><td>Hanks&#039; balanced salt solution (HBSS)</td><td>Thermo Fisher Scientific</td><td>14025-092</td><td></td></tr><tr><td>Horse serum</td><td>Thermo Fisher Scientific</td><td>16050-122</td><td></td></tr><tr><td>Penicillin-streptomycin</td><td>Thermo Fisher Scientific</td><td>15140-122</td><td></td></tr><tr><td>Propidium iodide solution</td><td>Miltenyi Biotec</td><td>130-093-233</td><td></td></tr></tbody></table>

preparation of adipose progenitor cells from mouse epididymal adipose tissues

Obesity and metabolic disorders such as diabetes, heart disease, and cancer, are all associated with dramatic adipose tissue remodeling. Tissue-resident adipose progenitor cells (APCs) play a key role in adipose tissue homeostasis and can contribute to the tissue pathology. The growing use of single cell analysis technologies &#8211; including single-cell RNA-sequencing and single-cell proteomics &#8211; is transforming the stem/progenitor cell field by permitting unprecedented resolution of individual cell expression changes within the context of population- or tissue-wide changes. In this article, we provide detailed protocols to dissect mouse epididymal adipose tissue, isolate single adipose tissue-derived cells, and perform fluorescence activated cell sorting (FACS) to enrich for viable Sca1+/CD31-/CD45-/Ter119- APCs. These protocols will allow investigators to prepare high quality APCs suitable for downstream analyses such as single cell RNA sequencing.

Four-month-old male FVB mice were used in this experiment. After exclusion of debris and doublets using FSC/SSC plots, viable cells (DAPI- population) were gated, followed by the selection of APC+/FITC- population (Figure 1). DAPI, APC, and FITC gates were drawn based on the unstained control. Gating strategies are shown in Figure 1.
After 1 h of sorting, the quality of isolation was quantitatively evaluated by flow cytometry analysis (Figures 2,3). The cells were stained with propidium iodide solution (1:100) for viability staining. Using the same gating for sorting, the cells maintained high viability and purity: 92.6 &#177; 2.2% single cells (third panel in Figure 2), 86.4 &#177; 3.0% viability (PI- cells), and 86.0 &#177; 2.8% APC+/FITC- cells (n= 4, average &#177; standard deviation). These percentages were defined as percentages of each gated population (single cells, PI- cells, and PI-/APC+/FITC- population, respectively, in Figure 2) relative to total cell number.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/61694/61694fig1v2.jpg" /> 
Figure 1: Isolation of viable Sca1+ adipose progenitor single cells by FACS. Gating strategies are shown in both stained cells and in an unstained control. <a href="https://www.jove.com/files/ftp_upload/61694/61694fig1v2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/61694/61694fig2v2.jpg" /> 
Figure 2: Representative flow cytometry analysis to assess post-isolation cell viability. Viability staining was performed using propidium iodide. <a href="https://www.jove.com/files/ftp_upload/61694/61694fig2v2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/61694/61694fig3.jpg" /> 
Figure 3: Quantification of percentage of cells 1 h post-isolation in flow cytometry analysis. Percentages of single cells, viable cells, and APC+/FITC- cells were quantified to evaluate purity and viability after isolation of cells. Data shown represents the average &#177; standard deviation. n=4. <a href="https://www.jove.com/files/ftp_upload/61694/61694fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Preparation of Adipose Progenitor Cells from Mouse Epididymal Adipose Tissues at JoVE.com

Preparation of Adipose Progenitor Cells from Mouse Epididymal Adipose Tissues

We present a simple method to isolate highly viable adipose progenitor cells from mouse epididymal fat pads using fluorescence activated cell sorting.

Obesity and metabolic disorders such as diabetes, heart disease, and cancer, are all associated with dramatic adipose tissue remodeling. Tissue-resident ...

preparation-adipose-progenitor-cells-from-mouse-epididymal-adipose

Nanyang Technological University

Research

JoVE Journal

Biology

5.5K Views.  Mayo Clinic. We present a simple method to isolate highly viable adipose progenitor cells from mouse epididymal fat pads using fluorescence activated cell sorting.

Video: Preparation of Adipose Progenitor Cells from Mouse Epididymal Adipose Tissues

Generation of Human Adipose Stem Cells through Dedifferentiation of Mature Adipocytes in Ceiling Cultures

Mature adipocytes have been shown to reverse their phenotype into fibroblast-like cells in vitro through a technique called ceiling culture. Mature adipocytes can also be isolated from fresh adipose tissue for depot-specific characterization of their function and metabolic properties. Here, we describe a well-established protocol to isolate mature adipocytes from adipose tissues using collagenase digestion, and subsequent steps to perform ceiling cultures. Briefly, adipose tissues are incubated in a Krebs-Ringer-Henseleit buffer containing collagenase to disrupt tissue matrix. Floating mature adipocytes are collected on the top surface of the buffer. Mature cells are plated in a T25-flask completely filled with media and incubated upside down for a week. An alternative 6-well plate culture approach allows the characterization of adipocytes undergoing dedifferentiation. Adipocyte morphology drastically changes over time of culture. Immunofluorescence can be easily performed on slides cultivated in 6-well plates as demonstrated by FABP4 immunofluorescence staining. FABP4 protein is present in mature adipocytes but down-regulated through dedifferentiation of fat cells. Mature adipocyte dedifferentiation may represent a new avenue for cell therapy and tissue engineering.

Mature adipocytes may represent an abundant source of stem cells through dedifferentiation, which leads to a homogenous population of fibroblast-like cells. Collagenase digestion is used to isolate mature adipocytes from human fat. The goal of our protocol is to obtain multipotent, dedifferentiated fat cells from human mature adipocytes.

Mature adipocytes have been shown to reverse their phenotype into fibroblast-like cells in vitro through a technique called ceiling culture. Mature ...

Developmental Biology

Isolation and Differentiation of Adipose-Derived Stem Cells from Porcine Subcutaneous Adipose Tissues

Obesity is an unconstrained worldwide epidemic. Unraveling molecular controls in adipose tissue development holds promise to treat obesity or diabetes. Although numerous immortalized adipogenic cell lines have been established, adipose-derived stem cells from the stromal vascular fraction of subcutaneous white adipose tissues provide a reliable cellular system ex vivo much closer to adipose development in vivo. Pig adipose-derived stem cells (pADSC) are isolated from 7- to 9-day old piglets. The dorsal white fat depot of porcine subcutaneous adipose tissues is sliced, minced and collagenase digested. These pADSC exhibit strong potential to differentiate into adipocytes. Moreover, the pADSC also possess multipotency, assessed by selective stem cell markers, to differentiate into various mesenchymal cell types including adipocytes, osteocytes, and chondrocytes. These pADSC can be used for clarification of molecular switches in regulating classical adipocyte differentiation or in direction to other mesenchymal cell types of mesodermal origin. Furthermore, extended lineages into cells of ectodermal and endodermal origin have recently been achieved. Therefore, pADSC derived in this protocol provide an abundant and assessable source of adult mesenchymal stem cells with full multipotency for studying adipose development and application to tissue engineering of regenerative medicine.

This protocol describes the isolation of pig adipose-derived stem cells (pADSC) from subcutaneous adipose tissues with examination of multipotency. The multipotent pADSC are used to delineate processes of adipocyte differentiation and study transdifferentiation into multiple cell lineages of mesodermal mesenchyme or further lineages of ectoderm and endoderm for regenerative studies.

Obesity is an unconstrained worldwide epidemic. Unraveling molecular controls in adipose tissue development holds promise to treat obesity or diabetes. ...

Isolation and Processing of Murine White Adipocytes for Transcriptome and Epigenome Analyses

Obesity is a complex disease influenced by genetics, epigenetics, the environment, and their interactions. Mature adipocytes represent the major cell type in white adipose tissue. Understanding how adipocytes function and respond to (epi)genetic and environmental signals is essential for identifying the cause(s) of obesity. RNA and chromatin have previously been isolated from adipocytes using enzymatic digestion. In addition, protocols have been developed for nuclear isolation, where purification is achieved by fluorescence-activated cell sorting (FACS) of adipocyte-specific transgenic reporters. One of the greatest challenges to achieving high yield and quality during such protocols is the substantial amount of lipid contained in adipose tissue. The present protocol describes an optimized procedure for isolating mature adipocytes that leverages heptane to separate lipids from the targets of interest (RNA/chromatin). The resulting RNA has high integrity and generates high-quality RNA-seq results. Likewise, the procedure improves nuclei yield rate and generates reproducible ChIP-seq results across samples. Therefore, the current study provides a reliable and universal murine adipocyte isolation protocol suitable for whole-genome transcriptome and epigenome studies.

The present protocol summarizes a universal method for isolating, purifying, and upstream processing of murine white adipocytes optimized for downstream total RNA sequencing, Nuclei Extraction by SONication (NEXSON), and ChIP-seq.

Obesity is a complex disease influenced by genetics, epigenetics, the environment, and their interactions. Mature adipocytes represent the major cell type ...

Genetics

Isolation, Expansion, and Adipogenic Induction of CD34+CD31+ Endothelial Cells from Human Omental and Subcutaneous Adipose Tissue

Obesity is accompanied by an extensive remodeling of adipose tissue primarily via adipocyte hypertrophy. Extreme adipocyte growth results in a poor response to insulin, local hypoxia, and inflammation. By stimulating the differentiation of functional white adipocytes from progenitors, radical hypertrophy of the adipocyte population can be prevented and, consequently, the metabolic health of adipose tissue can be improved along with a reduction of inflammation. Also, by stimulating a differentiation of beige/brown adipocytes, the total body energy expenditure can be increased, resulting in weight loss. This approach could prevent the development of obesity co-morbidities such as type 2 diabetes and cardiovascular disease.
This paper describes the isolation, expansion, and differentiation of white and beige adipocytes from a subset of human adipose tissue endothelial cells that co-express the CD31 and CD34 markers. The method is relatively cheap and is not labor-intensive. It requires access to human adipose tissue and the subcutaneous depot is suitable for sampling. For this protocol, fresh adipose tissue samples from morbidly obese subjects [body mass index (BMI) &#62;35] are collected during bariatric surgery procedures. Using a sequential immunoseparation from the stromal vascular fraction, enough cells are produced from as little as 2&#8211;3 g of fat. These cells can be expanded in culture over 10&#8211;14 days, can be cryopreserved, and retain their adipogenic properties with passaging up to passage 5&#8211;6. The cells are treated for 14 days with an adipogenic cocktail using a combination of human insulin and the PPAR&#947; agonist-rosiglitazone.
This methodology can be used for obtaining proof of concept experiments on molecular mechanisms that drive adipogenic responses in adipose endothelial cells, or for screening new drugs that can enhance the adipogenic response directed either towards white or beige/brown adipocyte differentiation. Using small subcutaneous biopsies, this methodology can be used to screen out non-responder subjects for clinical trials aimed to stimulate beige/brown and white adipocytes for the treatment of obesity and co-morbidities.

The differentiation of white and beige adipocytes from adipose tissue vascular progenitors bears potential for metabolic improvement in obesity. We describe protocols for a CD34+CD31+ endothelial cell isolation from human fat and for a subsequent in vitro expansion and differentiation into white and beige adipocytes. Several downstream applications are discussed.

Obesity is accompanied by an extensive remodeling of adipose tissue primarily via adipocyte hypertrophy. Extreme adipocyte growth results in a poor ...

Immunology and Infection

Isolation of Adipogenic and Fibro-Inflammatory Stromal Cell Subpopulations from Murine Intra-Abdominal Adipose Depots

The stromal-vascular fraction (SVF) of white adipose tissue (WAT) is remarkably heterogeneous and consists of numerous cell types that contribute functionally to the expansion and remodeling of WAT in adulthood. A tremendous barrier to studying the implications of this cellular heterogeneity is the inability to readily isolate functionally distinct cell subpopulations from WAT SVF for in vitro and in vivo analyses. Single-cell sequencing technology has recently identified functionally distinct fibro-inflammatory and adipogenic PDGFR&#946;+ perivascular cell subpopulations in intra-abdominal WAT depots of adult mice. Fibro-inflammatory progenitors (termed, &#8220;FIPs&#8221;) are non-adipogenic collagen producing cells that can exert a pro-inflammatory phenotype. PDGFR&#946;+ adipocyte precursor cells (APCs) are highly adipogenic both in vitro and in vivo upon cell transplantation. Here, we describe multiple methods for the isolation of these stromal cell subpopulations from murine intra-abdominal WAT depots. FIPs and APCs can be isolated by fluorescence-activated cell sorting (FACS) or by taking advantage of biotinylated antibody-based immunomagnetic bead technology. Isolated cells can be used for molecular and functional analysis. Studying the functional properties of stromal cell subpopulation in isolation will expand our current knowledge of adipose tissue remodeling under physiological or pathological conditions on the cellular level.

This protocol describes the technical approach to isolate adipogenic and fibro-inflammatory stromal cell subpopulations from murine intra-abdominal white adipose tissue (WAT) depots by fluorescence-activated cell sorting or immunomagnetic bead separation.

The stromal-vascular fraction (SVF) of white adipose tissue (WAT) is remarkably heterogeneous and consists of numerous cell types that contribute ...

Isolation and Differentiation of Primary White and Brown Preadipocytes from Newborn Mice

The understanding of the mechanisms underlying adipocyte differentiation and function has greatly benefited from the use of immortalized white preadipocyte cell lines. These cultured cell lines, however, have limitations. They do not fully capture the diverse functional spectrum of the heterogenous adipocyte populations that are now known to exist within white adipose depots. To provide a more physiologically relevant model to study the complexity of white adipose tissue, a protocol has been developed and optimized to enable simultaneous isolation of primary white and brown adipocyte progenitors from newborn mice, their rapid expansion in culture, and their differentiation in vitro into mature, fully functional adipocytes. The primary advantage of isolating primary cells from newborn, rather than adult mice, is that the adipose depots are actively developing and are, therefore, a rich source of proliferating preadipocytes. Primary preadipocytes isolated using this protocol differentiate rapidly upon reaching confluence and become fully mature in 4-5 days, a temporal window that accurately reflects the appearance of developed fat pads in newborn mice. Primary cultures prepared using this strategy can be expanded and studied with high reproducibility, making them suitable for genetic and phenotypic screens and enabling the study of the cell-autonomous adipocyte phenotypes of genetic mouse models. This protocol offers a simple, rapid, and inexpensive approach to study the complexity of adipose tissue in vitro.

This report describes a protocol for the simultaneous isolation of primary brown and white preadipocytes from newborn mice. Isolated cells can be grown in culture and induced to differentiate into fully mature white and brown adipocytes. The method enables genetic, molecular, and functional characterization of primary fat cells in culture.

The understanding of the mechanisms underlying adipocyte differentiation and function has greatly benefited from the use of immortalized white ...

Differentiated Mouse Adipocytes in Primary Culture: A Model of Insulin Resistance

Insulin resistance is a reduced effect of insulin on its target cells, usually derived from decreased insulin receptor signaling. Insulin resistance contributes to the development of type 2 diabetes (T2D) and other obesity-derived diseases of high prevalence worldwide. Therefore, understanding the mechanisms underlying insulin resistance is of great relevance. Several models have been used to study insulin resistance both in vivo and in vitro; primary adipocytes represent an attractive option to study the mechanisms of insulin resistance and identify molecules that counteract this condition and the molecular targets of insulin-sensitizing drugs. Here, we have established an insulin resistance model using primary adipocytes in culture treated with tumor necrosis factor-&#945; (TNF-&#945;).
Adipocyte precursor cells (APCs), isolated from collagenase-digested mouse subcutaneous adipose tissue by magnetic cell separation technology, are differentiated into primary adipocytes. Insulin resistance is then induced by treatment with TNF-&#945;, a proinflammatory cytokine that reduces the tyrosine phosphorylation/activation of members of the insulin signaling cascade. Decreased phosphorylation of insulin receptor (IR), insulin receptor substrate (IRS-1), and protein kinase B (AKT) are quantified by western blot. This method provides an excellent tool to study the mechanisms mediating insulin resistance in adipose tissue.

This protocol describes the isolation of mouse preadipocytes from subcutaneous fat, their differentiation into mature adipocytes, and the induction of insulin resistance. Insulin action is evaluated by the phosphorylation/activation of members of the insulin signaling pathway through western blot. This method allows direct determination of insulin resistance/sensitivity in primary adipocytes.

Insulin resistance is a reduced effect of insulin on its target cells, usually derived from decreased insulin receptor signaling. Insulin resistance ...

Culturing Preadipocytes Isolated from Murine Perivascular Adipose Tissue

Isolation, Culture, and Adipogenic Induction of Stromal Vascular Fraction-derived Preadipocytes from Mouse Periaortic Adipose Tissue

Perivascular adipose tissue (PVAT) is an adipose tissue depot that surrounds blood vessels and exhibits the phenotypes of white, beige, and brown adipocytes. Recent discoveries have shed light on the central role of PVAT in regulating vascular homeostasis and participating in the pathogenesis of cardiovascular diseases. A comprehensive understanding of PVAT properties and regulation is of great importance for the development of future therapies. Primary cultures of periaortic adipocytes are valuable for studying PVAT function and the crosstalk between periaortic adipocytes and vascular cells. This paper presents an economical and feasible protocol for the isolation, culture, and adipogenic induction of stromal vascular fraction-derived preadipocytes from mouse periaortic adipose tissue, which can be useful for modeling adipogenesis or lipogenesis in vitro. The protocol outlines tissue processing and cell differentiation for culturing periaortic adipocytes from young mice. This protocol will provide the technological cornerstone at the bench side for the investigation of PVAT function.

Author Spotlight: The Significance of Isolation, Culture, and Adipogenic Induction of SVF-Derived Preadipocytes from Mouse Perivascular Adipose Tissue 

Here, we describe the isolation, culture, and adipogenic induction of stromal vascular fraction-derived preadipocytes from mouse periaortic adipose tissue, allowing for the study of perivascular adipose tissue function and its relationship with vascular cells.

Perivascular adipose tissue (PVAT) is an adipose tissue depot that surrounds blood vessels and exhibits the phenotypes of white, beige, and brown ...

Primary Culture of Adipose Tissue Derived Stem Cells from Mouse Epididymis

Isolation, In Vitro Expansion, and Characterization of Mesenchymal Stem Cells from Mouse Epididymal Adipose Tissue

Mesenchymal stem cells (MSCs) have been extensively studied as a new therapeutic approach, mainly to stop exacerbated inflammation due to their potential to modulate the immune response. The MSCs are immune-privileged cells capable of surviving in immunologically incompatible allogeneic transplant recipients based on low expression of class I major histocompatibility complex (MHC) molecules and in the use of cell-based therapy for allogeneic transplant. These cells can be isolated from several tissues, the most commonly used being the bone marrow and adipose tissues. We provide an easy protocol to isolate, culture, and characterize MSCs from epididymal adipose tissue of mice. The epididymal adipose tissue is surgically excised, physically fragmented, and digested with 0.15% collagenase type II solution. Then, primary adipose tissue-derived stem (ADSCs) cells are cultured and expanded in vitro, and the phenotypic characterization is performed by flow cytometry. We also provide the steps to differentiate the ADSCs into osteogenic, adipogenic, and chondrogenic cells, followed by functional characterization of each cell lineage. The protocol provided here can be used for in vivo and ex vivo experiments, and as an alternative, the adipose-derived stem cells can be used to generate MSCs-like immortalized cells.

Author Spotlight: Advancing Treatment Approaches with Adipose-Derived Stem Cells

The adipose tissue is an excellent source of mesenchymal stem cells. Here, we bring the step-by-step extraction, cultivation, and characterization of adipose tissue-derived stem cells (ADSCs) from Swiss mice epididymal adipose tissue.

Mesenchymal stem cells (MSCs) have been extensively studied as a new therapeutic approach, mainly to stop exacerbated inflammation due to their potential ...

Culturing Murine Adipocytes and Explants for Functional and Imaging Studies

Isolation and Culturing of Primary Murine Adipocytes from Lean and Obese Mice

Adipose tissue is primarily composed of mature, lipid-laden adipocytes by volume. These postmitotic cells play a critical role in energy storage and mobilization, thermoregulation, and the secretion of endocrine factors. The expansion of white adipose tissue due to caloric imbalance results in both the enlargement of existing adipocytes and the generation of additional adipocytes from adipocyte progenitor cells. Obesity-driven changes to white adipose tissue, including those affecting adipocytes, are associated with numerous comorbidities, such as type 2 diabetes and 13 types of cancer. A significant barrier to studying how adipocytes contribute to disease is the inability to readily isolate and culture mature adipocytes. This article describes a protocol to isolate murine lean and obese adipocytes from the subcutaneous and visceral fat depots of male and female C57BL/6 mice. The protocol details how isolated primary adipocytes can be cultured in a membrane adipocyte aggregate system for up to 2 weeks, facilitating their functional analysis in co-culture experiments, lipolysis assays, or through the collection of conditioned media containing adipocyte-secreted factors. Additionally, the protocol outlines methods for culturing adipose tissue explants in basement membrane matrix domes and imaging primary isolated adipocytes. Importantly, this approach can be integrated with existing protocols for the isolation of adipose tissue-resident adipocyte&#160;progenitor cells using fluorescence-activated cell sorting (FACS). Together, these protocols provide researchers with tools to functionally study adipocytes, adipocyte progenitor cells, and whole adipose tissue from lean and obese, male and female mice.

The size and fragility of mature adipocytes have limited the techniques and tools available for their study and isolation. Here, a protocol is described for the isolation of mature murine adipocytes, which can be easily adapted for different adipose depots and mouse diets.

Adipose tissue is primarily composed of mature, lipid-laden adipocytes by volume. These postmitotic cells play a critical role in energy storage and ...