This study was supported from the Instituto Nacional de Perinatologia (grant numbers: 3300-11402-01-575-17 and 212250-3210-21002-06-15) and CONACyT, Fondo Sectorial de Investigacion en Salud y Seguridad Social (FOSISS) (grant number 2015-3-2-61661).

This protocol was approved by the IRB of the Instituto Nacional de Perinatologia (212250-3210-21002-06-15). Participation was voluntary, and all the enrolled women signed the informed consent form.
1. Visceral adipose tissue collection
<ol>
	<li>Obtain VAT biopsies through partial omentectomy during cesarean section from healthy adult women with singleton pregnancies at term without labor.</li>
	<li>After the uterine closure and hemostasis, proceed to identify greater omentum and extend it on a wet compress. The AT exposed is VAT.</li>
	<li>Locate the largest blood vessel and trace an imaginary line of 7 x 5 cm to the greater omentum base.</li>
	<li>Identify an avascular zone and use Kelly forceps to drill the outer side of VAT.</li>
	<li>Use Ochsner forceps to clamp the proximal and distal side in the zone where VAT was drilled and use Metzenbaum scissors to cut the tissue.</li>
	<li>Tie greater omentum with black silk number 1.</li>
	<li>Remove Ochsner forceps and evaluate the hemostasis.</li>
	<li>Place the VAT biopsy into a sterile container and transport it to the lab immediately.</li>
</ol>
2. Enzymatic digestion of visceral adipose tissue and isolation of mature adipocytes and stromal vascular fraction cells
<ol>
	<li>Weigh the VAT biopsy and rinse with 1x PBS pH 7.4.</li>
	<li>Cut 4 g of VAT and use scissors to mince the tissue into small pieces in a dissection tray.</li>
	<li>Transfer minced VAT to a sterile 50 mL centrifuge tube, add 20 mL of PBS, and shake gently to remove the excess of red blood cells.</li>
	<li>Discard PBS and repeat the procedure twice.</li>
	<li>Transfer VAT to a new sterile 50 mL centrifuge tube and add 25 mL of digestion solution (0.25% collagenase type II, 5 mM glucose, 1.5% albumin in PBS).</li>
	<li>Incubate at 37 &#176;C for 60 min in an orbital shaker at 125 rpm.</li>
	<li>Filter the digested tissue through three layers of gauze into a new sterile 50 mL centrifuge tube.</li>
	<li>Centrifuge at 200 x g for 5 min at 4 &#176;C.</li>
	<li>Two phases are obtained, an upper phase that corresponds to mature adipocytes, while SFV cells remain in the pellet. Gently transfer the mature adipocytes into a new sterile 50 mL centrifuge tube using a transfer pipette.</li>
	<li>Add 20 mL of cold PBS, shake gently, and centrifuge at 200 x g for 5 min at 4 &#176;C.</li>
	<li>Discard PBS and repeat the procedure twice.</li>
	<li>Use a transfer pipette to gently transfer the mature adipocytes into a 1.5 mL DNase-RNase free microcentrifuge tube.</li>
	<li>Centrifuge at 200 x g for 1 min at 4 &#176;C and remove the excess PBS using a P200 micropipette. Repeat this step if it is necessary.</li>
	<li>Gently transfer 300 &#956;L of mature adipocyte suspension into a 1.5 mL DNase-RNase free microcentrifuge tubes. Store mature adipocytes at -80 &#176;C until RNA extraction. 
	NOTE: Adipocytes do not form a pellet.</li>
	<li>Once adipocytes are separated (step 2.9), aspirate most of the digestion solution with a transfer pipette, keeping the SVF pellet at the bottom of the tube.</li>
	<li>Transfer the pellet with SVF cells into a new 50 mL centrifuge tube using a transfer pipette.</li>
	<li>Wash cell pellet gently, resuspending in 20 mL of cold 1x PBS by pipetting up and down.</li>
	<li>Centrifuge at 800 x g for 5 min at 4 &#176;C and rapidly discard the supernatant by decantation.</li>
	<li>Perform a second wash by repeating steps 2.17 and 2.18.</li>
	<li>Add 5 mL of red blood cell lysis buffer equilibrated to room temperature (RT) to the SVF pellet and suspend by repeated pipetting. Do not vortex.</li>
	<li>Incubate for 5 min at RT and centrifuge for 5 min at 800 x g. Carefully remove the supernatant using a transfer pipette and dispose of properly.</li>
	<li>To neutralize the lysis buffer, add 10 mL of cold 1x PBS and gently mix until the cell pellet disaggregates.</li>
	<li>Centrifuge at 800 x g for 5 min to obtain SVF pellet and discard PBS. A white pellet should be visible at the bottom of the tube.</li>
	<li>Resuspend cells in 5 mL of 1x PBS at RT by repeated pipetting and filtered through three layers of gauze into a new 50 mL conical tube. Subsequently, these cells will be used for macrophage subpopulation characterization by flow cytometry.</li>
</ol>
3. RNA extraction from mature adipocytes
<ol>
	<li>Prepare a clean area, using RNase decontamination spray to avoid RNA degradation. Use a set of pipettes reserved for RNA procedures. All tubes and tips employed should be RNase-free.</li>
	<li>Thaw the mature adipocyte suspension (section 2.14) at 4 &#176;C if it was stored to -80 &#176;C. 
	NOTE: Avoid multiple freeze-thaw cycles.</li>
	<li>Lyse cells by adding 1,000 &#956;L of acid-guanidinium-phenol based reagent, and mix thoroughly with a P1000 micropipette to homogenize.</li>
	<li>Incubate for 5 min at RT to boost dissociation of nucleoprotein complexes.</li>
	<li>Centrifuge cell lysate for 5 min at 12,000 x g at RT. Three phases will be obtained: an upper phase (yellow) corresponding to adipocyte lipids, a middle phase (pink) corresponding to nucleic acids, and a pellet (cellular debris).</li>
	<li>Carefully remove the lipid layer, using a P200 micropipette.</li>
	<li>Transfer the middle phase into a new 2 mL tube, avoiding lipid remnant and pellet disturbing (approximately 700 &#956;L).</li>
</ol>
4. Purification of total RNA, including microRNAs
NOTE: A column-based total RNA purification method is used to obtain high-quality total RNA.
<ol>
	<li>Add an equal volume of ethanol (95%&#8211;100%) to the sample from section 3.7, approximately 700 &#956;L, and mix by hand inverting the tube for 10 s.</li>
	<li>Transfer 700 &#956;L of the mixture into a column inserted in a collection tube, centrifuge and discard the flow-through.</li>
	<li>Reload the column and repeat step 4.2.</li>
	<li>Transfer the column into a new collection tube.</li>
	<li>Add 400 &#181;L of pre-wash buffer to the column and centrifuge. Discard the flow-through and repeat this step.</li>
	<li>Add 700 &#181;L of wash buffer to the column and centrifuge for 2 min.</li>
	<li>Transfer the column carefully into a nuclease-free tube.</li>
	<li>Add 50 &#181;L of nuclease-free water directly to the column matrix and elute the RNA by centrifugation. Prepare aliquots of 10 &#181;L using 200 &#181;L microfuge tubes.</li>
	<li>Immediately put aliquots on ice and use one of them to determine RNA concentration and purity.</li>
	<li>Prepare an aliquot of 5 &#181;L of total RNA adjusted to 100 ng/&#181;L to measure RNA integrity and microRNA concentration.</li>
	<li>Store at -80 &#176;C until use.</li>
</ol>
5. Determination of mature adipocyte RNA concentration, purity, and integrity; microRNA quantification assay
NOTE: RNA concentration and purity determinations are performed using a UV-Vis spectrophotometer; RNA integrity and miRNA quantification are performed using an RNA quality control analyzer.
<ol>
	<li>Wash the sample reader with molecular grade water and wipe.</li>
	<li>Load 2 &#181;L of elution water (blank), change the setting to RNA, and click on the Blank button.</li>
	<li>Load 2 &#181;L of sample and click on the Measure button.</li>
	<li>After the reading is complete, record the A260/A280 and A260/A230 ratios as well as the amount of RNA (ng/&#181;L) (Figure 1A). 
	NOTE: RNA with OD260/OD280 and OD260/OD230 ratio around 2.0 is considered pure.</li>
	<li>Measure the RNA integrity number (RIN) using an RNA integrity kit following the manufacturer&#180;s instructions (Figure 1B). 
	NOTE: A RIN =10 corresponds to intact RNA, whereas a RIN &#8804; 3.0 indicates a strongly degraded RNA. For expression microarrays or RT-qPCR, use RNA with RIN &#8805; 6.0.</li>
	<li>Use a small RNA kit to determine the concentration and percent of microRNAs, following the manufacturer&#180;s instructions (Figure 1C). 
	NOTE: To avoid the overestimation of small and micro RNAs, use RNA samples with RIN &#8805; 6.0.</li>
</ol>
6. Count and viability of stromal vascular fraction cells
<ol>
	<li>Dilute 10 &#956;L of SVF cell suspension (section 2.24) into 90 &#956;L of 0.4% Trypan Blue Solution (final dilution 1:10) and apply 10 &#956;L to a standard hemocytometer.</li>
	<li>Count the viable cells carefully, excluding the dead cells, in four squares at the corner of the counting chamber.</li>
	<li>Determine the cell concentration present in the original suspension: Cell concentration = Total cell count/4 x dilution factor (10) x 10,000 = Cells/mL</li>
	<li>To calculate the cellular yield (cells per gram of tissue) obtained, multiply the cellular concentration by the original total sample volume (in mL) and divide by the weight of tissue digested (in grams).</li>
	<li>Evaluate cell viability as the percentage of the living cells as follows: % Viability = (Number of viable cells / Total number of cells) x 100.</li>
</ol>
7. Characterization of macrophage subsets from stromal vascular fraction
<ol>
	<li>Transfer a total of 1 x 106 SVF cells/mL to a 5 mL round-bottom polypropylene test tube for flow cytometry and pellet cells by centrifugation at 800 x g for 5 min at 4 &#176;C.</li>
	<li>Vortex carefully to loosen the pellet and resuspend the cells in 100 &#956;L of 1x PBS at RT.</li>
	<li>Add pre-titrated optimal concentration of each fluorochrome-conjugated monoclonal antibody specific for a cell surface antigen; mix gently and incubate for 15 min in the dark at RT.</li>
	<li>Add an excess of cold 1x PBS (&#8776; 1 mL) and centrifuge the SVF at 400 x g for 5 min at 4 &#176;C.</li>
	<li>Discard supernatants rapidly by decantation. Be careful not to disturb the pellet.</li>
	<li>Add 500 &#956;L of 1x lysing solution and incubate 15 min at RT, protecting the tubes from direct light.</li>
	<li>Remove the solution after centrifuge at 400 x g for 5 min at 4 &#176;C, and store at 2&#8211;8 &#176;C in the dark until data acquisition.</li>
	<li>Vortex the cells thoroughly at low speed to reduce aggregation before acquiring.</li>
	<li>Resuspend the SVF pellet in 5 mL of sheath fluid at RT, and subsequently filter through three layers of gauze into a new 5 mL round-bottom polypropylene test tube before analysis by flow cytometry, to reduce clogging the cell sorter lines.</li>
	<li>Vortex each tube briefly before analysis.</li>
	<li>Acquire data from the samples of interest. For flow analysis, count a minimum of 10,000 events. 
	NOTE: If using a cell sorting flow cytometer, separate the macrophages for application in subsequent studies.</li>
</ol>
8. Gating strategy
<ol>
	<li>Plot the height or width against the area for Forward Scatter (FSC) to determine the singlet population (Figure 2A).</li>
	<li>Select cells plotting the area for Side Scatter (SSC) against FSC, discarding the cellular debris (Figure 2B).</li>
	<li>From selected cells, identify the populations expressing CD45 as hematopoietic cells (Figure 2C), and CD45/CD14 double positive cells as macrophages (Figure 2D).</li>
	<li>From CD45+/CD14+ macrophages, detect negative and positive HLA-DR cells (Figure 2E). 
	NOTE: Include the compensation controls for the antibody panel and adjust spectral overlap on a multicolor flow cytometer adequate for the panel. We perform flow cytometry analysis using a cytometer equipped with three lasers (405 nm violet laser, 488 nm blue laser, and 640 nm red laser), and detectors for the indicated fluorochromes.</li>
</ol>

The authors have no conflicts of interest to disclose.

VAT plays a crucial role in metabolic regulation and inflammation. Increasing interest in the role of adipocytes and immune cells in the chronic inflammation associated with obesity has led to the development of different techniques to separate the SVF and fat cells present in AT. However, most techniques do not allow to obtain these two different sets of cells viable for downstream applications from the same VAT biopsy in a single procedure, which could be crucial for studies regarding interactions between adipocytes an...

White adipose tissue is composed not only of fat cells or adipocytes, but also of a non-fat cell fraction known as stromal vascular fraction (SVF), which contains a heterogeneous cell population consisting in macrophages, other immune cells as regulatory T cells (Tregs), and eosinophils, preadipocytes, and fibroblasts, surrounded by vascular and connective tissue1,2. Adipose tissue (AT) is now considered an organ that regulates physiological processes related to metabolism and inflammation through adipokines, cytokines, and microRNAs produced and released by different cells into the tissue, with autocrine, paracrine, and endocrine effects3,4. In humans, white adipose tissue comprises the subcutaneous adipose tissue (SAT) and the visceral adipose tissue (VAT), with important anatomic, molecular, cellular, and physiological differences between them2,5. SAT represents up to 80% of human AT, while VAT is located within the abdominal cavity, mainly in the mesentery and omentum, being metabolically more active6. Moreover, VAT is an endocrine organ that secretes mediators with a substantial impact on body weight, insulin sensitivity, lipid metabolism, and inflammation. Consequently, VAT accumulation leads to abdominal obesity and obesity-related diseases such as type-2 diabetes, metabolic syndrome, hypertension, and cardiovascular disease risk, representing a better predictor of obesity-associated mortality6,7,8,9.
In homeostatic conditions, adipocytes, macrophages, and the other immune cells cooperate to maintain the VAT metabolism through the secretion of anti-inflammatory mediators10. However, excessive VAT expansion promotes the recruitment of activated T cells, NK cells, and macrophages. In fact, in lean VAT, the ratio of the macrophages is 5%, while this ratio rises up to 50% in obesity, with macrophage polarization from anti-inflammatory to pro-inflammatory phenotype, generating a chronic inflammatory environment10,11.
As a consequence of the obesity pandemic, an astonishing number of reports have arisen addressing different VAT research topics, including adipocyte biology, epigenetics, inflammation, endocrine properties, and emerging areas as extracellular vesicles, among others8,10,12,13. However, although the VAT environment is defined by crosstalk between adipocytes and the resident or arriving macrophages, most studies have focused on only one cell population, and there is scarce information about the interaction of these cells in VAT and their pathophysiological consequences11,14. Moreover, valuable studies addressing the adipocyte-macrophage interplay in AT were performed using cell lines, lacking the in vivo priming conditions11,14,15. A suitable strategy to dissect the interaction or the particular contribution of these cells in VAT requires the isolation of both cell types from the same fat biopsy to perform in vitro assays that mirror as similar as possible the in vivo properties that regulate VAT metabolism.
Although the non-enzymatic dissociation methods based on mechanical forces to break the AT ensure minimal manipulation, these methods cannot be used if the aim is to study SVF cells, as they have lower efficiency in cell recovery and low cell viability compared to enzymatic methods, and a larger volume of tissue is needed16,17. Enzymatic digestion using collagenase is a gentle method that allows adequate digestion of collagen and extracellular matrix proteins of fibrous tissues such as WAT18 and is frequently used when trypsin is ineffective or damaging19. The protocol provides fundamental troubleshooting guidelines for efficient isolation of viable mature adipocytes and SVF cells from human VAT biopsies in a single process, using a collagenase enzymatic digestion technique, giving information to ensure high yields (quantity, purity, and integrity) of total RNA from mature adipocytes, including microRNAs, for downstream expression applications. Simultaneously, the protocol is optimized to identify macrophage subsets from SVF cells through the staining of multiple membrane-bound markers for further analysis by flow cytometry20.

<table>
	<tbody>
		<tr>
			<td>0.2 mL PCR tubes</td>
			<td>Axygen</td>
			<td>PCR-02-C</td>
			<td>RNase, DNase free and nonpyrogenic</td>
		</tr>
		<tr>
			<td>1.5 mL microcentrifuge tubes</td>
			<td>Axygen</td>
			<td>MCT-150-C</td>
			<td>RNase, DNase free and nonpyrogenic</td>
		</tr>
		<tr>
			<td>10 mL serological pipettes</td>
			<td>Corning</td>
			<td>CLS4101-50EA</td>
			<td>Individually plastic wrapped</td>
		</tr>
		<tr>
			<td>10 &#181;L universal pipet tip</td>
			<td>Axygen</td>
			<td>T-300-L-R</td>
			<td>RNase, DNase free and nonpyrogenic</td>
		</tr>
		<tr>
			<td>10 &#181;L universal pipet tip</td>
			<td>Axygen</td>
			<td>T-300-R-S</td>
			<td>RNase, DNase free and nonpyrogenic</td>
		</tr>
		<tr>
			<td>1000 &#181;L universal pipet tip</td>
			<td>Axygen</td>
			<td>T-1000-B-R</td>
			<td>RNase, DNase free and nonpyrogenic</td>
		</tr>
		<tr>
			<td>2.0 mL microcentrifuge tube</td>
			<td>Axygen</td>
			<td>MCT-200-C</td>
			<td>RNase, DNase free and nonpyrogenic</td>
		</tr>
		<tr>
			<td>200 &#181;L universal pipet tip</td>
			<td>Axygen</td>
			<td>T-200-Y-R</td>
			<td>RNase, DNase free and nonpyrogenic</td>
		</tr>
		<tr>
			<td>2100 Bioanalyzer Instrument</td>
			<td>Agilent</td>
			<td>G2939BA</td>
			<td>-</td>
		</tr>
		<tr>
			<td>2101 Bioanalyzer PC</td>
			<td>Agilent</td>
			<td>G2953CA</td>
			<td>2100 Expert Software pre-installed in PC</td>
		</tr>
		<tr>
			<td>5 ml Round Bottom Polystyrene Test Tube</td>
			<td>Corning</td>
			<td>352003&#160;</td>
			<td>Snap cap, sterile</td>
		</tr>
		<tr>
			<td>50 mL centrifuge tubes</td>
			<td>Corning</td>
			<td>CLS430828-100EA</td>
			<td>Polipropilene, conical bottom and sterile</td>
		</tr>
		<tr>
			<td>Acid-guanidinium-phenol based reagent</td>
			<td>Zymo Research</td>
			<td>R2050-1-200</td>
			<td>TRI Reagent or similar</td>
		</tr>
		<tr>
			<td>Agilent RNA 6000 Nano Kit</td>
			<td>Agilent</td>
			<td>5067-1511</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Agilent Small RNA Kit</td>
			<td>Agilent</td>
			<td>5067-1548</td>
			<td>-</td>
		</tr>
		<tr>
			<td>APC/Cy7 anti-human CD14 Antibody</td>
			<td>BioLegend</td>
			<td>325620</td>
			<td>0.4 mg/106 cells, present on monocytes/macrophages, clone HCD14</td>
		</tr>
		<tr>
			<td>Baker</td>
			<td>-</td>
			<td>-</td>
			<td>250 ml, non sterile</td>
		</tr>
		<tr>
			<td>Bovine serum albumin</td>
			<td>Sigma-Aldrich</td>
			<td>A3912-100G</td>
			<td>Heat shock fraction, pH 5.2, &#8805;96%</td>
		</tr>
		<tr>
			<td>Chip priming station</td>
			<td>Agilent</td>
			<td>5065-9951</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Collagenase type II</td>
			<td>Gibco</td>
			<td>17101-015</td>
			<td>Powder</td>
		</tr>
		<tr>
			<td>D-(+)-Glucose</td>
			<td>Sigma-Aldrich</td>
			<td>G8270-100G</td>
			<td>Powder</td>
		</tr>
		<tr>
			<td>Direct-zol RNA Miniprep</td>
			<td>Zymo Research</td>
			<td>R2051</td>
			<td>Supplied with 50 mL TRI reagen</td>
		</tr>
		<tr>
			<td>Dissecting forceps</td>
			<td>-</td>
			<td>-</td>
			<td>Steel, serrated jaws and round ends</td>
		</tr>
		<tr>
			<td>Dissection tray</td>
			<td>-</td>
			<td>-</td>
			<td>Stainless steel</td>
		</tr>
		<tr>
			<td>Ethyl alcohol</td>
			<td>Sigma-Aldrich</td>
			<td>E7023-500ML</td>
			<td>200&#160;proof, for molecular biology</td>
		</tr>
		<tr>
			<td>FACS Flow Sheath Fluid</td>
			<td>BD Biosciences</td>
			<td>342003</td>
			<td>-</td>
		</tr>
		<tr>
			<td>FACS Lysing Solution</td>
			<td>BD Biosciences</td>
			<td>349202</td>
			<td>-</td>
		</tr>
		<tr>
			<td>FACSAria III Flow Cytometer/Cell Sorter</td>
			<td>BD Biosciences</td>
			<td>648282</td>
			<td>-</td>
		</tr>
		<tr>
			<td>FASCDiva Software</td>
			<td>BD Biosciences</td>
			<td>642868</td>
			<td>Software v6.0 pre-installed</td>
		</tr>
		<tr>
			<td>Hemacytometer</td>
			<td>Sigma</td>
			<td>Z359629-1EA</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Manual cell counter</td>
			<td>-</td>
			<td>-</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Mayo dissecting scisors</td>
			<td>-</td>
			<td>-</td>
			<td>Stainless steel</td>
		</tr>
		<tr>
			<td>Microcentrifuge</td>
			<td>-</td>
			<td>-</td>
			<td>Adjustable temperature</td>
		</tr>
		<tr>
			<td>Nanodrop spectrophotometer</td>
			<td>Thermo Scientific</td>
			<td>ND2000LAPTOP</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Orbital shaker</td>
			<td>-</td>
			<td>-</td>
			<td>Adjustable temperature and speed</td>
		</tr>
		<tr>
			<td>P10&#160;variable volume&#160;micropipette&#160;</td>
			<td>Thermo Scientific-Finnpipette</td>
			<td>4642040</td>
			<td>1 to 10 &#956;L</td>
		</tr>
		<tr>
			<td>P1000&#160;variable volume&#160;micropipette&#160;</td>
			<td>Thermo Scientific-Finnpipette</td>
			<td>4642090</td>
			<td>100 to 1000 &#956;L</td>
		</tr>
		<tr>
			<td>P2&#160;variable volume&#160;micropipette&#160;</td>
			<td>Thermo Scientific-Finnpipette</td>
			<td>4642010</td>
			<td>0.2 to 2 &#956;L</td>
		</tr>
		<tr>
			<td>P200&#160;variable volume&#160;micropipette&#160;</td>
			<td>Thermo Scientific-Finnpipette</td>
			<td>4642080</td>
			<td>20 to 200 &#956;L</td>
		</tr>
		<tr>
			<td>PCR tube storage rack</td>
			<td>Axygen</td>
			<td>R96PCRFSP</td>
			<td>-</td>
		</tr>
		<tr>
			<td>PE/Cy5 anti-human HLA-DR Antibody</td>
			<td>BioLegend</td>
			<td>307608</td>
			<td>0.0625 mg/106 cells, present on macrophages, clone L243</td>
		</tr>
		<tr>
			<td>PE/Cy7 anti-human CD45 Antibody</td>
			<td>BioLegend</td>
			<td>304016</td>
			<td>0.1 mg/106 cells, present on leukocytes, clone H130</td>
		</tr>
		<tr>
			<td>Phosphate buffered saline</td>
			<td>Sigma-Aldrich</td>
			<td>P3813-10PAK</td>
			<td>Powder, pH 7.4, for preparing 1 L solutions</td>
		</tr>
		<tr>
			<td>Pipette controller</td>
			<td>-</td>
			<td>-</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Red Blood Cells Lysis Buffer</td>
			<td>Roche</td>
			<td>11 814 389 001</td>
			<td>For preferential lysis of red blood cells from human whole blood</td>
		</tr>
		<tr>
			<td>Refrigerated centrifuge</td>
			<td>-</td>
			<td>-</td>
			<td>Whit adapter for 50 mL conical tubes</td>
		</tr>
		<tr>
			<td>Sterile Specimen container</td>
			<td>-</td>
			<td>-</td>
			<td>-</td>
		</tr>
		<tr>
			<td>Transfer pipette</td>
			<td>Thermo Scientific-Samco</td>
			<td>204-1S</td>
			<td>Sterile</td>
		</tr>
		<tr>
			<td>Trypan Blue</td>
			<td>Gibco</td>
			<td>15250-061</td>
			<td>0.4% Solution</td>
		</tr>
		<tr>
			<td>Tube racks</td>
			<td>-</td>
			<td>-</td>
			<td>For different tube sizes</td>
		</tr>
		<tr>
			<td>Vortex Mini Shaker</td>
			<td>Cientifica SENNA</td>
			<td>BV101</td>
			<td>-</td>
		</tr>
	</tbody>
</table>

isolation of viable adipocytes and stromal vascular fraction from human visceral adipose tissue suitable for rna analysis and macrophage phenotyping

Visceral adipose tissue (VAT) is an active metabolic organ composed mainly of mature adipocytes and stromal vascular fraction (SVF) cells, which release different bioactive molecules that control metabolic, hormonal, and immune processes; currently, it is unclear how these processes are regulated within the adipose tissue. Therefore, the development of methods evaluating the contribution of each cell population to the pathophysiology of adipose tissue is crucial. This protocol describes the isolation steps and provides the necessary troubleshooting guidelines for efficient isolation of viable mature adipocytes and SVF from human VAT biopsies in a single process, using a collagenase enzymatic digestion technique. Moreover, the protocol is also optimized to identify macrophage subsets and perform mature adipocyte RNA isolation for gene expression studies, which allows performing studies dissecting the interaction between these cell populations. Briefly, VAT biopsies are washed, minced mechanically, and digested to generate a single-cell suspension. After centrifugation, mature adipocytes are isolated by flotation from the SVF pellet. The RNA extraction protocol ensures a high yield of total RNA (including miRNAs) from adipocytes for downstream expression assays. Simultaneously, SVF cells are used to characterize macrophage subsets (pro- and anti-inflammatory phenotype) through flow cytometry analysis.

This protocol describes an enzymatic method using collagenase digestion followed by differential centrifugation to isolate, in a single process, viable mature adipocytes and SVF cells from VAT biopsies obtained from healthy pregnant women after partial omentectomy. In this case, we use the adipocytes for RNA extraction and the SVF for macrophage phenotyping.
The RNA extraction protocol enabled to obtain RNA with an adequate purity high integrity, and microRNAs from mature adipocytes (<strong c...

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Isolation of Viable Adipocytes and Stromal Vascular Fraction from Human Visceral Adipose Tissue Suitable for RNA Analysis and Macrophage Phenotyping

This protocol provides an efficient collagenase digestion method for isolation of viable adipocytes and stromal vascular fraction-SVF cells from human visceral fat in a single process, including methodology to obtain high-quality RNA from adipocytes and phenotypification of SVF-macrophages through staining of multiple membrane-bound markers for analysis by flow cytometry.

Visceral adipose tissue (VAT) is an active metabolic organ composed mainly of mature adipocytes and stromal vascular fraction (SVF) cells, which release ...

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3.5K Views.  Instituto Nacional de Perinatologia. This protocol provides an efficient collagenase digestion method for isolation of viable adipocytes and stromal vascular fraction-SVF cells from human visceral fat in a single process, including methodology to obtain high-quality RNA from adipocytes and phenotypification of SVF-macrophages through staining of multiple membrane-bound markers for analysis by flow cytometry.

Video: Isolation of Viable Adipocytes and Stromal Vascular Fraction from Human Visceral Adipose Tissue Suitable for RNA Analysis and Macrophage Phenotyping

Isolation of Human Islets from Partially Pancreatectomized Patients

Investigations into the pathogenesis of type 2 diabetes and islets of Langerhans malfunction 1 have been hampered by the limited availability of type 2 diabetic islets from organ donors2. Here we share our protocol for isolating islets from human pancreatic tissue obtained from type 2 diabetic and non-diabetic patients who have undergone partial pancreatectomy due to different pancreatic diseases (benign or malignant pancreatic tumors, chronic pancreatitis, and common bile duct or duodenal tumors). All patients involved gave their consent to this study, which had also been approved by the local ethics committee. The surgical specimens were immediately delivered to the pathologist who selected soft and healthy appearing pancreatic tissue for islet isolation, retaining the damaged tissue for diagnostic purposes. We found that to isolate more than 1,000 islets, we had to begin with at least 2 g of pancreatic tissue. Also essential to our protocol was to visibly distend the tissue when injecting the enzyme-containing media and subsequently mince it to aid digestion by increasing the surface area.
To extend the applicability of our protocol to include the occasional case in which a large amount (&gt;15g) of human pancreatic tissue is available , we used a Ricordi chamber (50 ml) to digest the tissue. During digestion, we manually shook the Ricordi chamber3 at an intensity that varied by specimen according to its level of tissue fibrosis. A discontinous Ficoll gradient was then used to separate the islets from acinar tissue. We noted that the tissue pellet should be small enough to be homogenously resuspended in Ficoll medium with a density of 1.125 g/ml. After isolation, we cultured the islets under stress free conditions (no shaking or rotation) with 5% CO2 at 37 &deg;C for at least 48 h in order to facilitate their functional recovery. Widespread application of our protocol and its future improvement could enable the timely harvesting of large quantities of human islets from diabetic and clinically matched non-diabetic subjects, greatly advancing type 2 diabetes research.

The supply of type 2 diabetic islets for research is insufficient. Here we share our protocol for isolating islets from patients undergoing partial pancreatectomy. This approach represents a unique venue for obtaining islets from type 2 diabetic and clinically matched non-diabetic subjects in adequate numbers for basic and clinical studies.

Investigations into the pathogenesis of type 2 diabetes and islets of Langerhans malfunction 1 have been hampered by the limited availability of type 2 ...

Experimental Generation of Carcinoma-Associated Fibroblasts (CAFs) from Human Mammary Fibroblasts

Carcinomas are complex tissues comprised of neoplastic cells and a non-cancerous compartment referred to as the 'stroma'. The stroma consists of extracellular matrix (ECM) and a variety of mesenchymal cells, including fibroblasts, myofibroblasts, endothelial cells, pericytes and leukocytes 1-3.
The tumour-associated stroma is responsive to substantial paracrine signals released by neighbouring carcinoma cells. During the disease process, the stroma often becomes populated by carcinoma-associated fibroblasts (CAFs) including large numbers of myofibroblasts. These cells have previously been extracted from many different types of human carcinomas for their in vitro culture. A subpopulation of CAFs is distinguishable through their up-regulation of &alpha;-smooth muscle actin (&alpha;-SMA) expression4,5. These cells are a hallmark of 'activated fibroblasts' that share similar properties with myofibroblasts commonly observed in injured and fibrotic tissues 6. The presence of this myofibroblastic CAF subset is highly related to high-grade malignancies and associated with poor prognoses in patients.
Many laboratories, including our own, have shown that CAFs, when injected with carcinoma cells into immunodeficient mice, are capable of substantially promoting tumourigenesis 7-10. CAFs prepared from carcinoma patients, however, frequently undergo senescence during propagation in culture limiting the extensiveness of their use throughout ongoing experimentation. To overcome this difficulty, we developed a novel technique to experimentally generate immortalised human mammary CAF cell lines (exp-CAFs) from human mammary fibroblasts, using a coimplantation breast tumour xenograft model.
In order to generate exp-CAFs, parental human mammary fibroblasts, obtained from the reduction mammoplasty tissue, were first immortalised with hTERT, the catalytic subunit of the telomerase holoenzyme, and engineered to express GFP and a puromycin resistance gene. These cells were coimplanted with MCF-7 human breast carcinoma cells expressing an activated ras oncogene (MCF-7-ras cells) into a mouse xenograft. After a period of incubation in vivo, the initially injected human mammary fibroblasts were extracted from the tumour xenografts on the basis of their puromycin resistance 11.
We observed that the resident human mammary fibroblasts have differentiated, adopting a myofibroblastic phenotype and acquired tumour-promoting properties during the course of tumour progression. Importantly, these cells, defined as exp-CAFs, closely mimic the tumour-promoting myofibroblastic phenotype of CAFs isolated from breast carcinomas dissected from patients. Our tumour xenograft-derived exp-CAFs therefore provide an effective model to study the biology of CAFs in human breast carcinomas. The described protocol may also be extended for generating and characterising various CAF populations derived from other types of human carcinomas.

Experimental Generation of Carcinoma-Associated Fibroblasts CAFs from Human Mammary Fibroblasts

Carcinoma-associated fibroblasts (CAFs) rich in myofibroblasts present within the tumour stroma, play a major role in driving tumour progression. We developed a coimplantation tumour xengraft model for experimentally generating CAFs from human mammary fibroblasts. The protocol describes how to establish CAF myofibroblasts that acquire an ability to promote tumourigenesis.

Carcinomas are complex tissues comprised of neoplastic cells and a non-cancerous compartment referred to as the 'stroma'. The stroma consists of ...

Encapsulation Thermogenic Preadipocytes for Transplantation into Adipose Tissue Depots

Cell encapsulation was developed to entrap viable cells within semi-permeable membranes. The engrafted encapsulated cells can exchange low molecular weight metabolites in tissues of the treated host to achieve long-term survival. The semipermeable membrane allows engrafted encapsulated cells to avoid rejection by the immune system. The encapsulation procedure was designed to enable a controlled release of bioactive compounds, such as insulin, other hormones, and cytokines. Here we describe a method for encapsulation of catabolic cells, which consume lipids for heat production and energy dissipation (thermogenesis) in the intra-abdominal adipose tissue of obese mice. Encapsulation of thermogenic catabolic cells may be potentially applicable to the prevention and treatment of obesity and type 2 diabetes. Another potential application of catabolic cells may include detoxification from alcohols or other toxic metabolites and environmental pollutants.

Here, we present a protocol for encapsulation of catabolic cells, which consume lipids for heat production in intra-abdominal adipose tissue and increase energy dissipation in obese mice.

Cell encapsulation was developed to entrap viable cells within semi-permeable membranes. The engrafted encapsulated cells can exchange low molecular ...

Stromal Vascular Fraction-enriched Fat Grafting for the Treatment of Symptomatic End-neuromata

The purpose of this study was to methodically illustrate and highlight the crucial steps of stromal vascular fraction (SVF)-enriched fat grafting as a novel treatment of symptomatic end-neuromata of peripheral sensory nerves, and in this study, specifically of the superficial branch of the radial nerve (SBRN). Despite a multitude of existing treatments, persistent postoperative pain and common pain relapse are still very common, independent of the procedure assessed. The neuroma is microsurgically excised accordingly to standardized protocol. Instead of the relocation of the regenerating nerve stump in neighboring anatomical structures, such as muscle or bone, a fat graft is applied perifocally and acts as a mechanical barrier. In order to reduce the fat resorption rate and boost the regenerative potential of the graft, the highly concentrated SVF is integrated in the grafting. The SVF is isolated from subcutaneous fat by enzymatic and mechanic separation of the lipoaspirate by a specific commercial isolation system. The SVF-enriched fat graft provides both a mechanical barrier and various biological effects at the cellular level, including improving angiogenesis, inflammation, and fibrosis. Both mechanical and biologic effects help to reduce the disorganized axonal outgrowth of the nerve stump during nerve regeneration and hence prevent the recurrence of painful end-neuromata.

The purpose of the study is to illustrate the technical procedure of stromal vascular fraction (SVF)-enriched fat grafting as a novel treatment of symptomatic end-neuromata. This technique provides advantages of both the mechanical barrier and the biological action at the cellular level by the processed and concentrated SVF.

The purpose of this study was to methodically illustrate and highlight the crucial steps of stromal vascular fraction (SVF)-enriched fat grafting as a ...

Assessment of Human Adipose Tissue Microvascular Function Using Videomicroscopy

While obesity is closely linked to the development of metabolic and cardiovascular disease, little is known about mechanisms that govern these processes. It is hypothesized that pro-atherogenic mediators released from fat tissues particularly in association with central/visceral adiposity may promote pathogenic vascular changes locally and systemically, and the notion that cardiovascular disease may be the consequence of adipose tissue dysfunction continues to evolve. Here, we describe a unique method of videomicroscopy that involves analysis of vasodilator and vasoconstrictor responses of intact small human arterioles removed from the adipose depot of living human subjects. Videomicroscopy is used to examine functional properties of isolated microvessels in response to pharmacological or physiological stimuli using a pressured system that mimics in vivo conditions. The technique is a useful approach to gain understanding of the pathophysiology and molecular mechanisms that contribute to vascular dysfunction locally within the adipose tissue milieu. Moreover, abnormalities in the adipose tissue microvasculature have also been linked with systemic diseases. We applied this technique to examine depot-specific vascular responses in obese subjects. We assessed endothelium-dependent vasodilation to both increased flow and acetylcholine in adipose arterioles (50 - 350 &#181;m internal diameter, 2 - 3 mm in length) isolated from two different adipose depots during bariatric surgery from the same individual. We demonstrated that arterioles from visceral fat exhibit impaired endothelium-dependent vasodilation compared to vessels isolated from the subcutaneous depot. The findings suggest that the visceral microenvironment is associated with vascular endothelial dysfunction which may be relevant to clinical observation linking increased visceral adiposity to systemic disease mechanisms. The videomicroscopy technique can be used to examine vascular phenotypes from different fat depots as well as compare findings across individuals with different degrees of obesity and metabolic dysfunction. The method can also be used to examine vascular responses longitudinally in response to clinical interventions.

Videomicroscopy systems are used to examine functional properties of isolated adipose tissue arterioles in response to physiological and pharmacological stimuli. This technique can be used to examine microvascular phenotypes in different adipose tissue domains in obese humans.

While obesity is closely linked to the development of metabolic and cardiovascular disease, little is known about mechanisms that govern these processes. ...

Clinical Protocol of Producing Adipose Tissue-Derived Stromal Vascular Fraction for Potential Cartilage Regeneration

Osteoarthritis (OA) is one of the most common debilitating disorders.&#160;Recently, numerous attempts have been made to improve the functions of the knees by using different forms of mesenchymal stem cells (MSCs). In Korea, bone marrow concentrates and cord blood-derived stem cells have been approved by the Korean Food and Drug Administration (KFDA) for cartilage regeneration. In addition, an adipose tissue-derived stromal vascular fraction (SVF) has been allowed by the KFDA for joint injections in human patients. Autologous adipose tissue-derived SVF contains extracellular matrix (ECM) in addition to mesenchymal stem cells. ECM excretes various cytokines that, along with hyaluronic acid (HA) and platelet-rich plasma (PRP) activated by calcium chloride, may help MSCs to regenerate cartilage and improve knee functions. In this article, we presented a protocol to improve knee functions by regenerating cartilage-like tissue in human patients with OA. The result of the protocol was first reported in 2011 followed by a few additional publications. The protocol involves liposuction to obtain autologous lipoaspirates that are mixed with collagenase. This lipoaspirates-collagenase mixture is then cut and homogenized to remove large fibrous tissue that may clog up the needle during the injection. Afterwards, the mixture is incubated to obtain adipose tissue-derived SVF. The resulting adipose tissue-derived SVF, containing both adipose tissue-derived MSCs and remnants of ECM, is injected into knees of patients, combined with HA and calcium chloride activated PRP. Included are three cases of patients who were treated with our protocol resulting in improvement of knee pain, swelling, and range of motion along with MRI evidence of hyaline cartilage-like tissue.

Here, we present a protocol to produce an adipose tissue-derived stromal vascular fraction and its application to improve knee functions by regenerating cartilage-like tissue in human patients with osteoarthritis.

Osteoarthritis (OA) is one of the most common debilitating disorders.&#160;Recently, numerous attempts have been made to improve the functions of the ...

Isolation of Adipose Derived Regenerative Cells for the Treatment of Erectile Dysfunction Following Radical Prostatectomy

Stem cells are used in many research areas within regenerative medicine in part because these treatments can be curative rather than symptomatic. Stem cells can be obtained from different tissues and several methods for isolation have been described. The presented method for the isolation of adipose-derived regenerative cells (ADRCs) can be used within many therapeutic areas because the method is a general procedure and, therefore, not limited to erectile dysfunction (ED) therapy. ED is a common and serious side effect to radical prostatectomy (RP) since ED often is not well treated with conventional therapy. Using ADRC&#8217;s as treatment for ED has attracted great interest due to the initial positive results after a single injection of cells into the corpora cavernosum. The method used for the isolation of ADRC&#8217;s is a simple, automated process, that is reproducible and ensures a uniform product. Furthermore, the sterility of the isolated product is ensured because the entire process takes place in a closed system. It is important to minimize the risk of contamination and infection since the stem cells are used for injection in humans. The whole procedure can be done within 2.5-3.5 hours and does not require a classified laboratory which eliminates the need for shipping tissue to an off-site. However, the procedure has some limitations since the minimum amount of drained lipoaspirate for the isolation device to function is 100 g.

Precise disclosure of methods and protocols is crucial for large scale uptake of stem cell therapies. Here, we present a protocol to isolate adipose-derived regenerative cells, used for a single intracavernous injection as treatment of erectile dysfunction (ED) following radical prostatectomy (RP).

Stem cells are used in many research areas within regenerative medicine in part because these treatments can be curative rather than symptomatic. Stem ...

Technique for Obtaining Mesenchymal Stem Cell from Adipose Tissue and Stromal Vascular Fraction Characterization in Long-Term Cryopreservation

Human mesenchymal stem cells derived from adipose tissue have become increasingly attractive as they show appropriate features and are an accessible source for regenerative clinical applications. Different protocols have been used to obtain adipose-derived stem cells. This article describes different steps of an improved time-saving protocol to obtain a more significant amount of ADSC, showing how to cryopreserve and thaw ADSC to obtain viable cells for culture expansion. One hundred milliliters of lipoaspirate were collected, using a 26 cm three-hole and 3 mm caliber syringe liposuction, from the abdominal area of nine patients who subsequently underwent elective abdominoplasty. The stem cells isolation was carried out with a series of washes with Dulbecco&#39;s Phosphate Buffered Saline (DPBS) solution supplemented with calcium and the use of collagenase. Stromal Vascular Fraction (SVF) cells were cryopreserved, and their viability was checked by immunophenotyping. The SVF cellular yield was 15.7 x 105 cells/mL, ranging between 6.1-26.2 cells/mL. Adherent SVF cells reached confluence after an average of 7.5 (&#177;4.5) days, with an average cellular yield of 12.3 (&#177; 5.7) x 105 cells/mL. The viability of thawed SVF after 8 months, 1 year, and 2 years ranged between 23.06%-72.34% with an average of 47.7% (&#177;24.64) with the lowest viability correlating with cases of two-year freezing. The use of DPBS solution supplemented with calcium and bag resting times for fat precipitation with a shorter time of collagenase digestion resulted in an increased stem cell final cellular yield. The detailed procedure for obtaining high yields of viable stem cells was more efficient regarding time and cellular yield than the techniques from previous studies. Even after a long period of cryopreservation, viable ADSC cells were found in the SVF.

The present protocol describes an improved methodology for ADSC isolation resulting in a tremendous cellular yield with time gain compared to the literature. This study also provides a straightforward method for obtaining a relatively large number of viable cells after long-term cryopreservation.

Human mesenchymal stem cells derived from adipose tissue have become increasingly attractive as they show appropriate features and are an accessible ...

Isolation and Culture of Human Adipose-Derived Stem Cells With an Innovative Xenogeneic-Free Method for Human Therapy

Considering the increasing impact of stem cell therapy, biosafety concerns have been raised regarding potential contamination or infection transmission due to the introduction of animal-derived products during in vitro manipulation. The xenogeneic components, such as collagenase or fetal bovine serum, commonly used during the cell isolation and expansion steps could be associated with the potential risks of immune reactivity or viral, bacterial, and prion infection in the receiving patients. Following good manufacturing practice guidelines, chemical tissue dissociation should be avoided, while fetal bovine serum (FBS) can be substituted with xenogeneic-free supplements. Moreover, to ensure the safety of cell products, the definition of more reliable and reproducible methods is important. We have developed an innovative, completely xenogeneic-free method for the isolation and in vitro expansion of human adipose-derived stem cells without altering their properties compared to collagenase FBS-cultured standard protocols. Here, human adipose-derived stem cells (hASCs) were isolated from abdominal adipose tissue. The sample was mechanically minced with scissors/a scalpel, micro-dissected and mechanically dispersed in a 10 cm Petri dish, and prepared with scalpel incisions to facilitate the attachment of the tissue fragments and the migration of hASCs. Following the washing steps, hASCs were selected due to their plastic adherence without enzymatic digestion. The isolated hASCs were cultured with medium supplemented with 5% heparin-free human platelet lysate and detached with an animal-free trypsin substitute. Following good manufacturing practice (GMP) directions on the production of cell products intended for human therapy, no antibiotics were used in any culture media.

Xenogeneic (chemical or animal-derived) products introduced in the cell therapy preparation/manipulation steps are associated with an increased risk of immune reactivity and pathogenic transmission in host patients. Here, a complete xenogeneic-free method for the isolation and in vitro expansion of human adipose-derived stem cells is described.

Considering the increasing impact of stem cell therapy, biosafety concerns have been raised regarding potential contamination or infection transmission ...

Isolation, Culture, and Characterization of Primary Dermal Fibroblasts from Human Keloid Tissue

Fibroblasts, the major cell type in keloid tissue, play an essential role in the formation and development&#160;of keloids. The isolation and culture of primary fibroblasts derived from keloid tissue are the basis for further studies of the biological function and molecular mechanisms of keloids, as well as new therapeutic strategies for treating them. The traditional method of obtaining primary fibroblasts has limitations, such as poor cellular state, mixing with other types of cells, and susceptibility to contamination. This paper describes an optimized and easily reproducible protocol that could reduce the occurrence of possible issues when obtaining fibroblasts. In this protocol, fibroblasts can be observed 5 days after isolation and reach nearly 80% confluency after 10 days of culture. Then, the fibroblasts are passaged and verified using PDGFR&#945; and vimentin antibodies for immunofluorescence assays and CD90 antibodies for flow cytometry. In conclusion, fibroblasts from keloid tissue can be easily acquired through this protocol, which can provide an abundant and stable source of cells in the laboratory for keloid research.

This study describes an optimized protocol for establishing primary fibroblasts from keloid tissues that can effectively and steadily provide pure and viable fibroblasts.

Fibroblasts, the major cell type in keloid tissue, play an essential role in the formation and development&#160;of keloids. The isolation and culture of ...