The authors have no acknowledgements.

NOTE: All animal procedures were performed with the approval of the Institutional Animal Care and Use Committee (IACUC) of the University of Cincinnati and in accordance with the Guide for the Care and Use of Laboratory Animals from the National Institutes of Health (NIH Publication No. 85-23, Revised 1996).
1. Euthanize and Sterilize the Mouse
<ol>
	<li>Place the mouse in a dropbox containing a supratheraputic dose of isoflurane and allow to inhale to effect. Once the mouse is euthanized, remove from the box.</li>
	<li>Cervically dislocate as a second means of euthanasia.</li>
	<li>Sterilize the external surface of the mouse by cleansing the animal with 70% ethanol.</li>
</ol>
2. Identification and Isolation of Three Different Adipose Depots
<ol>
	<li>Brown Adipose Tissue (BAT) Isolation:
	<ol>
		<li>Make sure the fur is wet from the alcohol cleansing to aid in cutting through the epidermal and dermal layers.</li>
		<li>Position the mouse in a supine position with its back against the table.</li>
		<li>Grab the skin just below the diaphragm with forceps, lift and incise with scissors.</li>
		<li>Cut transversely around the circumference of the mouse to expose the peritoneum.</li>
		<li>Reveal the butterfly-shaped BAT depot by degloving the top half of the mouse. Hold the lower appendages and abdomen in one hand and pulling the skin up towards the head.</li>
		<li>Orient the mouse, so that it is positioned prone on the table. Be careful not to contaminate the exposed depot with hair.</li>
		<li>Clean surgical instruments and change to a fresh pair of gloves.</li>
		<li>Locate the scapulae and corresponding depot. Carefully remove any superficial white adipose atop the butterfly and then dissect the butterfly of interscapular brown fat. Be careful to avoid the muscle closely associated with the brown fat. 
		NOTE: The use of a dissection microscope is recommended for removal of the white adipose, as well as in the separation of the brown adipose from the scapulae.</li>
		<li>Remove fat depot and transfer to a 2 ml microcentrifuge tube.</li>
		<li>If RNA or protein is to be extracted, freeze the tissue by immersion in liquid nitrogen and store at -80 &#176;C. Freeze the sample at once to prevent degradation. If culturing, cover the tissue in DMEF-12 and set on ice till all samples are collected for culture (supplemental info).</li>
	</ol>
	</li>
	<li>Isolation of Subcutaneous Adipose Tissue (SQ), a White Adipose Tissue Depot (WAT):
	<ol>
		<li>Put on a fresh pair of gloves as to not cross-contaminate between fat depots.</li>
		<li>Reveal the inguinal, triangular SQ depots by de-gloving the bottom half of the mouse. Hold the upper appendages and thorax in one hand and pulling the skin down towards the feet with the other hand.</li>
		<li>Orient the mouse in a supine position while being careful not to contaminate the exposed depot with hair.</li>
		<li>Clean surgical instruments and change to a fresh pair of gloves.</li>
		<li>Carefully dissect the triangles of SQ fat. Be careful not to contaminate the sample with muscle, neighboring fat, mammary glands or by cutting any vessels and contaminate the sample with blood. 
		NOTE: The use of a dissection microscope is recommended if borders are not clearly defined.</li>
		<li>Remove fat depots and transfer to 2 ml microcentrifuge tubes.</li>
		<li>If RNA or protein is to be extracted, freeze the tissue by immersion in liquid nitrogen and store at -80 &#176;C. Freeze the sample at once to prevent degradation.</li>
		<li>For staining, fix or embed in OCT. If culturing, cover the tissue in DMEF-12 and set on ice till all samples are collected for culture (supplemental info).</li>
	</ol>
	</li>
	<li>Isolation of Gonadal Fat a Visceral Adipose Tissue (VAT) and White Adipose Tissue (WAT) Depot:
	<ol>
		<li>Put on a fresh pair of gloves as to not cross-contaminate between fat depots.</li>
		<li>With scissors, cut the peritoneum transversely, directly below the diaphragm. Cut the peritoneum from the diaphragm to the rectum mid coronally to expose abdominal organs.</li>
		<li>Locate the testes or ovaries and identify the attached white adipose tissue, known as the epididymal adipose in males or gonadal adipose in females.</li>
		<li>Clean surgical instruments and change to a fresh pair of gloves</li>
		<li>Carefully dissect both epididymal fat depots from the testes, epididymides, and vasa deferentia. Or if female, carefully dissect both gonadal fat pads from the ovaries.</li>
		<li>Remove fat depots and transfer them to 2 ml microcentrifuge tubes.</li>
		<li>If RNA or protein is to be extracted, freeze the tissue by immersion in liquid nitrogen and store at -80 &#176;C. Freeze the sample at once to prevent degradation.</li>
		<li>For staining, fix or embed in OCT. If culturing, cover the tissue in DMEF-12 and set on ice till all samples are collected for culture (supplemental info).</li>
	</ol>
	</li>
</ol>
3. Isolation of Perivascular Adipose Tissue (PVAT)
<ol>
	<li>Isolation of the Heart:
	<ol>
		<li>Lay the mouse out in a supine position with upper and lower appendages extended outward.</li>
		<li>Secure appendages using surgical tape.</li>
		<li>After positioning the mouse as listed above, create tension by lifting up on the xiphoid process with forceps. Cut horizontally through the diaphragm, exposing the lower portion of the thoracic cavity.</li>
		<li>While maintaining tension, by lifting up on the xiphoid process, cut through the ribcage superiorly towards the head, just to the side of the sternum.</li>
		<li>Pick up the rib cage just inferior to the clavicle, and cut along the inferior length of the clavicle out toward the axilla in both directions. The thoracic cavity and its contents (heart, lungs, etc.) should now be clearly visible.</li>
		<li>Clean the thoracic cavity of extraneous blood and fluid by using sterile gauze to absorb the fluid. If collecting organs or vessels be sure to profuse (supplemental info).</li>
		<li>Once the area is cleared of fluid, cut the bronchi and attaching vessels to remove the lungs, allowing better exposure of the heart.</li>
	</ol>
	</li>
	<li>Localization and Excision of Aortic Perivascular Adipose Tissue (PVAT):
	<ol>
		<li>Remove the following organs as to better identify the inferior portions of the aorta: liver, stomach, spleen, pancreas, intestines, and colon.</li>
		<li>First start with identification of the stomach and the esophagus. Cut the esophagus at the gastro-esophageal junction to free the stomach from the body.</li>
		<li>Next, identify the intestines and the surrounding mesentery. Cut superficially through mesentery, as it lies very closely to the renal portion of the aorta, then &#8220;run the bowel.&#8221;</li>
		<li>Cut the colon free as close to the rectum as possible. Thus, freeing the stomach, intestine and colon from the mouse.</li>
		<li>Remove the stomach, intestine, colon, pancreas and spleen by cutting through the attaching mesentery and vessels. The pancreas and spleen should come free with the stomach, intestine and colon.</li>
		<li>Remove the liver by cutting through the hepatic veins and attaching mesentery, remove all lobes.</li>
		<li>Cut away the visceral layer and fat surround the kidneys. Leave the kidneys attached to the aorta in vivo to serve as geographic markers for different segments of the aorta.</li>
		<li>Rinse the area with sterile 1x PBS and remove all fluid by absorption with a sterile gauze.</li>
		<li>Using micro-scissors and micro-forceps, separate the aorta from its dorsal attachment to the spine and its ventral attachment to the esophagus.</li>
		<li>Isolate the aorta by following and detaching the aorta the length of the descending aorta from the origin in the heart to the bifurcation in the iliac region.</li>
		<li>Identify and isolate the subclavian vessels. Isolate these vessels from the neck to the aortic root to better expose the aortic junction and root in the heart.</li>
		<li>Remove the thymus then cut the brachiocephalic artery, the left common carotid artery, and the left subclavian artery, allowing movement of the heart.</li>
		<li>With the assistance of a dissection microscope, view the perivascular adipose tissue (PVAT) layer surrounding the aorta.</li>
		<li>Taking great care to not pinch or squeeze the PVAT, gently pull the PVAT way from the aorta with micro-forceps. Gently cut the attachment of the PVAT to the aorta with micro-scissors starting at the thoracic region just superior to where the diaphragm is located. 
		NOTE: A dissection microscope is recommended.</li>
		<li>Repeat this process the entire length of the aorta, finishing at the infrarenal aortic region, which is located just superior to the iliac bifurcation of the aortic vessel.</li>
		<li>If aortic arch PVAT is desired, used the same method to remove the PVAT from the lesser curvature of the arch.</li>
		<li>Place PVAT samples into 2 ml microcentrifuge tube(s).</li>
		<li>If RNA or protein is to be extracted, freeze the tissue by immersion in liquid nitrogen and store at -80 &#176;C. Freeze the sample at once to prevent degradation. If culturing, cover the tissue in DMEF-12 and set on ice till all samples are collected for culture (supplemental info). 
		NOTE: Additional adipose depots to consider if interested in a comprehensive adipose depot analysis include: retroperitoneal, mesenteric, omental, pericardial and popliteal.</li>
	</ol>
	</li>
</ol>

<ol>
	<li>Ogden, C. L., Carroll, M. D., Kit, B. K., Flegal, K. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prevalence+of+obesity+in+the+United+States,+2009-2010.">Prevalence of obesity in the United States, 2009-2010.</a> NCHS Data Brief. 82, 1-8 (2012).</li><li>Flegal, K. M., Carroll, M. D., Kit, B. K., Ogden, C. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prevalence+of+obesity+and+trends+in+the+distribution+of+body+mass+index+among+US+adults,+1999-2010.">Prevalence of obesity and trends in the distribution of body mass index among US adults, 1999-2010.</a> 307 (5), 491-497 (2012).</li><li>Cawley, J., Meyerhoefer, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+medical+care+costs+of+obesity:+an+instrumental+variables+approach.">The medical care costs of obesity: an instrumental variables approach.</a> Journal of Health Economics. 31 (1), 219-230 (2012).</li><li>Marder, W., Chang, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Childhood+Obesity:+Costs,+Treatment+Patterns,+Disparities+in+Care,+and+Prevalent+Medical+Conditions.">Childhood Obesity: Costs, Treatment Patterns, Disparities in Care, and Prevalent Medical Conditions.</a> Thomson Medstat Research Brief. , (2006).</li><li>Cortez, M., Carmo, L. S., Rogero, M. M., Borelli, P., Fock, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+high-fat+diet+increases+IL-1,+IL-6,+and+TNF-&#945;+production+by+increasing+NF-&#954;B+and+attenuating+PPAR-&#947;+expression+in+bone+marrow+mesenchymal+stem+cells.">A high-fat diet increases IL-1, IL-6, and TNF-&#945; production by increasing NF-&#954;B and attenuating PPAR-&#947; expression in bone marrow mesenchymal stem cells.</a> Inflammation. 36 (2), 379-386 (2013).</li><li>Sanchez-Gurmaches, J., Hung, C. M., Sparks, C. A., Tang, Y., Li, H., Guertin, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=PTEN+loss+in+the+Myf5+lineage+redistributes+body+fat+and+reveals+subsets+of+white+adipocytes+that+arise+from+Myf5+precursors.">PTEN loss in the Myf5 lineage redistributes body fat and reveals subsets of white adipocytes that arise from Myf5 precursors.</a> Cell Metab. 16 (3), 348-362 (2012).</li><li>Sethi, J. K., Vidal-Puig, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thematic+review+series:+adipocyte+biology.+Adipose+tissue+function+and+plasticity+orchestrate+nutritional+adaptation.">Thematic review series: adipocyte biology. Adipose tissue function and plasticity orchestrate nutritional adaptation.</a> J Lipid Res. 48 (6), 1253-1262 (2007).</li><li>Aarsland, A., Chinkes, D., Wolfe, R. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hepatic+and+whole-body+fat+synthesis+in+humans+during+carbohydrate+overfeeding.">Hepatic and whole-body fat synthesis in humans during carbohydrate overfeeding.</a> Am J Clin Nutr. 65 (6), 1774-1782 (1997).</li><li>Park, A., Kim, W. K., Bae, K. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Distinction+of+white,+beige+and+brown+adipocytes+derived+from+mesenchymal+stem+cells.">Distinction of white, beige and brown adipocytes derived from mesenchymal stem cells.</a> World J. Stem Cells. 6 (1), 33-42 (2014).</li><li>Wu, J., 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=Beige+adipocytes+are+a+distinct+type+of+thermogenic+fat+cell+in+mouse+and.">Beige adipocytes are a distinct type of thermogenic fat cell in mouse and.</a> 150 (2), 366-376 (2012).</li><li>Giralt, M., Villarroya, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=White,+brown,+beige/brite:+different+adipose+cells+for+different+functions.">White, brown, beige/brite: different adipose cells for different functions.</a> Endocrinology. 154 (9), 2992-3000 (2013).</li><li>Casteilla, L., P&#233;nicaud, L., Cousin, B., Calise, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Choosing+an+adipose+tissue+depot+for+sampling:+factors+in+selection+and+depot+specificity.">Choosing an adipose tissue depot for sampling: factors in selection and depot specificity.</a> Methods Mol. Biol. 456, 23-38 (2008).</li><li>Grant, R., Youm, Y. H., Ravussin, A., Dixit, V. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantification+of+adipose+tissue+leukocytosis+in+obesity.">Quantification of adipose tissue leukocytosis in obesity.</a> Methods Mol. Biol. 1040, 195-209 (2013).</li></ol>

The authors declare that they have no competing financial interests or other conflicts of interest.

Obesity can lead to a large host of morbidities and the full understanding of the role that adipose plays is not fully understood; therefore continued research in the field of adipose is necessary. Animal models, specifically murine models are ideal for initial research in the progression of diseases and testing of potential pharmaceutical treatments. In using these models, precise isolation and excision of adipose depots is an extremely important and necessary tool in the study of pathology of adipose affected diseases....

Adipose made a notable appearance in the media spotlight, due to obesity&#8217;s dramatic increase during the last few decades of the 20th century. Obesity currently affects more than one-third of adults and 17% of children and adolescents in the United States (US)1. Spanning all ethnic groups, statistical research surrounding the obesity epidemic has shown that non-Hispanic blacks have the highest age-adjusted rate of obesity (49.5%) compared with Mexican Americans (40.4%), all Hispanics (39.1%), and non-Hispanic whites (34.3%)2. The economic effect of obesity is also a growing concern for the healthcare system. In 2012, it was estimated that the annual medical cost of care for obesity in the US in 2005 was $190.2 billion, nearly 21% of the overall medical spending budget. Sadly, childhood obesity was estimated to be responsible for $14 billion in direct medical costs alone. Statistically, it was determined that the average medical cost of individuals with obesity was $2,741 higher a year than those without this morbidity3-5.
Obesity is a major risk factor for a variety of conditions such as: type 2 diabetes, dyslipidemia, cardiovascular disease, cancer, muscular skeletal disorders and chronic inflammation. Obesity is deeply tied to the pathogenesis of metabolic syndrome and other chronic diseases6-8. With such drastic and negative connections between obesity and other comorbidities, scientific research has focused attention to better understand the current epidemic and the diverse and pivotal roles played by adipose.
Historically, adipose tissue was considered inconsequential and was viewed merely as a simple filling tissue. Currently, adipose has been shown to play many essential roles in the body&#8217;s function in: metabolism, hormone regulation, inflammation, protection and insulation9. Adipose tissue is composed primarily of adipocytes but also contains pericytes, endothelial cells, monocytes, macrophages and pluripotent stem cells8. Adipose tissue is distributed throughout the body in distinct depots. The principal depots can be found subdermally, subcutaneously, intramuscularly, and viscerally10. Adipose depots have been shown to have depot specific metabolic profiles, which have shown a depot specific susceptibility to obesity and related disorders8.
Traditionally, adipose tissue has been classified into two major types: white adipose tissue (WAT) and brown adipose tissue (BAT); although recent literature indicates the presences of a third group christened brite or beige adipose11. Adipose tissue has been shown to have different colors, morphologies, metabolic functions, biochemical features and genetic patterns of expression10. Adipocytes in WAT have a single, large lipid droplet and variable amounts of mitochondria. WAT is dominantly found in subcutaneous and visceral localities of the body. WAT functions primarily as a site of energy storage and organ protection. Adipocytes in BAT have a multilocular morphology and abundant mitochondria. BAT is located primarily in the neck and large blood vessels of the thorax, as well as the scapulae12. BAT primarily functions in energy-expending behaviors that regulate thermogenesis7. Brite or beige adipose has been shown to share an analogous morphology and expression to BAT but has been found to be originated from white adipocytes11.
The described surgical method in this manuscript provides researchers with the capacity to analyze different effects that factors such as: environment, pharmaceuticals, and genetics, have on adipose; as well as the beneficial or detrimental role adipose plays in disease and overall health. Also, providing a way to identify and isolate different types of adipose tissue to allow for better understand of the biochemical relationships and differences between depots. This can aid in determining the relationship between location, function, and types of fat within the body. This described method accomplishes this by providing the means for gross visualization, gene expression analysis, protein expression analysis, histological examination, and isolation of primary cell lines for in vitro studies. Currently there are many articles that provide insight into the metabolic behavior of different adipose depots, as well as their anatomic locations; but do not provide an in-depth method on how to specifically localize, identify, and isolate these depots. This surgical method provides a precise technique that allows for isolation of multiple depots with a minimal quantity of dissection and contamination compared to others methods designed for the isolate of one or two depots13-14.
The goal of this protocol is to provide a precise method for the identification and isolation of different types of fat depots from multiple anatomic locations.

<table><tbody><tr><td>Isoflurane</td><td>Med-Vet International</td><td>#RXISO-250</td><td></td></tr><tr><td>70% Ethanol</td><td>Fisher</td><td>07-678-001</td><td></td></tr><tr><td>DMEF-12</td><td>Sigma Aldrich</td><td>D-6421</td><td>Warm in waterbath before putting on tissue.</td></tr><tr><td>2 ml Microcentrifuge tubes</td><td>Midsci</td><td>MCT-200-C-S</td><td></td></tr><tr><td>Phosphate buffered saline</td><td>Sigma Aldrich</td><td>P5368-10PAK</td><td></td></tr></tbody></table>

localization, identification, and excision of murine adipose depots

Obesity has increased dramatically in the last few decades and affects over one third of the adult US population. The economic effect of obesity in 2005 reached a staggering sum of $190.2 billion in direct medical costs alone. Obesity is a major risk factor for a wide host of diseases. Historically, little was known regarding adipose and its major and essential functions in the body. Brown and white adipose are the two main types of adipose but current literature has identified a new type of fat called brite or beige adipose. Research has shown that adipose depots have specific metabolic profiles and certain depots allow for a propensity for obesity and other related disorders. The goal of this protocol is to provide researchers the capacity to identify and excise adipose depots that will allow for the analysis of different factorial effects on adipose; as well as the beneficial or detrimental role adipose plays in disease and overall health. Isolation and excision of adipose depots allows investigators to look at gross morphological changes as well as histological changes. The adipose isolated can also be used for molecular studies to evaluate transcriptional and translational change or for in vitro experimentation to discover targets of interest and mechanisms of action. This technique is superior to other published techniques due to the design allowing for isolation of multiple depots with simplicity and minimal contamination.

Identification, and localization of inguinal subcutaneous adipose, interscapular brown adipose, visceral epididymal adipose (Figure 1), as well as the aortic arch perivascular adipose, thoracic aortic adipose, suprarenal aortic adipose and the infrarenal aortic adipose (Figure 2) was achieved successfully using the described surgical method. Histological examination and differentiation between BAT and WAT samples were positively evaluated using Hematoxylin and Eosin (H&#38;E) staining (<...

Watch this Scientific Journal Video about Localization, Identification, and Excision of Murine Adipose Depots at JoVE.com

Localization, Identification, and Excision of Murine Adipose Depots

Due to the drastic and negative connection between obesity and other comorbidities, research on the role adipose plays in disease and overall health is warranted. We present a protocol for the isolation and excision of adipose depots allowing for the study of adipose using in situ and in vitro methods.

Obesity has increased dramatically in the last few decades and affects over one third of the adult US population. The economic effect of obesity in 2005 ...

localization-identification-and-excision-of-murine-adipose-depots

Research

JoVE Journal

Medicine

40.9K Views.  University of Cincinnati College of Medicine. Due to the drastic and negative connection between obesity and other comorbidities, research on the role adipose plays in disease and overall health is warranted. We present a protocol for the isolation and excision of adipose depots allowing for the study of adipose using in situ and in vitro methods.

Video: Localization, Identification, and Excision of Murine Adipose Depots

Immunomagnetic Separation of Fat Depot-specific Sca1high Adipose-derived Stem Cells (ASCs)

The isolation of adipose-derived stem cells (ASCs) is an important method in the field of adipose tissue biology, adipogenesis, and extracellular matrix (ECM) remodeling. In vivo, ECM-rich environment consisting of fibrillar collagens provides a structural support to adipose tissues during the progression and regression of obesity. Physiological ECM remodeling mediated by matrix metalloproteinases (MMPs) plays a major role in regulating adipose tissue size and function1,2. The loss of physiological collagenolytic ECM remodeling may lead to excessive collagen accumulation (tissue fibrosis), macrophage infiltration, and ultimately, a loss of metabolic homeostasis including insulin resistance3,4. When a phenotypic change of the adipose tissue is observed in gene-targeted mouse models, isolating primary ASCs from fat depots for in vitro studies is an effective approach to define the role of the specific gene in regulating the function of ASCs. In the following, we define an immunomagnetic separation of Sca1high ASCs.

Immunomagnetic Separation of Fat Depot-specific Sca1high Adipose-derived Stem Cells ASCs

We present the techniques required to isolate the stromal vascular fraction (SVF) from mouse inguinal (subcutaneous) and perigonadal (visceral) adipose tissue depots to assess their gene expression and collagenolytic activity. This method includes the enrichment of Sca1high adipose-derived stem cells (ASCs) using immunomagnetic cell separation.

The isolation of adipose-derived stem cells (ASCs) is an important method in the field of adipose tissue biology, adipogenesis, and extracellular matrix ...

Developmental Biology

Preparation, Administration, and Assessment of In Vivo Tissue-Specific Cellular Uptake of Fluorescent Dye-Labeled Liposomes

There is a growing interest in using liposomes to deliver compounds in vivo particularly for targeted treatment approaches. Depending on the liposome formulation, liposomes may be preferentially taken up by different cell types in the body. This may influence the efficacy of the therapeutic particle as progression of different diseases is tissue- and cell-type-specific. In this protocol, we present one method for synthesizing and fluorescently labeling liposomes using DSPC, cholesterol, and PEG-2000 DSPE and the lipid dye DiD as a fluorescent label. This protocol also presents an approach for delivering liposomes in vivo and assessing cell-specific uptake of liposomes using flow cytometry. This approach can be used to determine the types of cells that take up liposomes and quantify the distribution and proportion of liposome-uptake across cell types and tissues. While not mentioned in this protocol, additional assays such as immunofluorescence and single-cell fluorescence imaging on a cytometer will strengthen any findings or conclusions made as they permit assessment of intracellular staining. Protocols may also need to be adapted depending on the tissue(s) of interest.

The goal of this protocol is to synthesize fluorescently-labeled liposomes and use flow cytometry to identify in vivo localization of liposomes at a cellular level.

There is a growing interest in using liposomes to deliver compounds in vivo particularly for targeted treatment approaches. Depending on the liposome ...

Bioengineering

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 ...

Immunology and Infection

Lymphatic and Blood Network Analysis During Obesity

Lymphatic collecting vessels and lymph nodes are inevitably embedded in adipose tissue. The physiological significance of this observation remains still not elucidated. However, obesity is characterized by impaired lymphatic function and increased vessel permeability. Inversely, lymphatic dysfunction induces obesity in mice, suggesting a significant interplay between lymphatic vessels and the adipose tissue. Therefore, understanding factors leading to lymphatic dysfunction might open new therapeutic windows to prevent obesity and associated comorbidities. The first step in this process requires a precise and detailed visualization of the lymphatic network in healthy and inflamed adipose tissue. Here, we describe a rapid, inexpensive, and efficient method that allows to label and analyze lymphatic and blood vessels. This approach takes advantage of the skin-draining brachial lymph node localization within the subcutaneous adipose tissue. The lymphatic arborization of this tissue can be revealed by injecting fluorochrome-conjugated lectins subcutaneously. Moreover, the in vivo labeling approach provides a way to evaluate lymphatic vessel density and functions. Coupled to blood vessel, adipocyte and immune cell staining, the protocol allows for high-resolution mapping of the subcutaneous adipose tissue by 3D imaging.

Obesity is a growing global public health issue. It has been previously associated with lymphatic dysfunction, suggesting a vital crosstalk between the adipose tissue and the lymphatic system. Here, we propose an accessible methodology allowing the distinct labeling of blood and lymphatic vasculatures within the subcutaneous adipose tissue.

Lymphatic collecting vessels and lymph nodes are inevitably embedded in adipose tissue. The physiological significance of this observation remains still ...

Identification and Dissection of Diverse Mouse Adipose Depots

Adipose tissues are complex organs with a wide array of functions, including storage and mobilization of energy in response to local and global needs, uncoupling of metabolism to generate heat, and secretion of adipokines to regulate whole-body homeostasis and immune responses. Emerging research is identifying important regional differences in the developmental, molecular, and functional profiles of adipocytes located in discrete depots throughout the body. Different properties of the depots are medically relevant since metabolic diseases often demonstrate depot-specific effects. This protocol will provide investigators with a detailed anatomic atlas and dissection guide for the reproducible and accurate identification and excision of diverse mouse adipose tissues. Standardized dissection of discrete adipose depots will allow detailed comparisons of their molecular and metabolic characteristics and contributions to local and systemic pathologic states under various nutritional and environmental conditions.

Adipocytes exist in discrete depots and have diverse roles within their unique microenvironments. As regional differences in adipocyte character and function are uncovered, standardized identification and isolation of depots is crucial for advancement of the field. Herein, we present a detailed protocol for the excision of various mouse adipose depots.

Adipose tissues are complex organs with a wide array of functions, including storage and mobilization of energy in response to local and global needs, ...

Biology

Isolation and Identification of Vascular Endothelial Cells from Distinct Adipose Depots for Downstream Applications

Vascular endothelial cells lining the wall of the vascular system play important roles in a variety of physiological processes, including vascular tone regulation, barrier functions, and angiogenesis. Endothelial cell dysfunction is a hallmark predictor and major driver for the progression of severe cardiovascular diseases, yet the underlying mechanisms remain poorly understood. The ability to isolate and perform analyses on endothelial cells from various vascular beds in their native form will give insight into the processes of cardiovascular disease. This protocol presents the procedure for the dissection of mouse subcutaneous and mesenteric adipose tissues, followed by isolation of their respective arterial vasculature. The isolated arteries are then digested using a specific cocktail of digestive enzymes focused on liberating functionally viable endothelial cells. The digested tissue is assessed by flow cytometry analysis using CD31+/CD45&#8722; cells as markers for positive endothelial cell identification. Cells can be sorted for immediate downstream functional assays or used to generate primary cell lines. The technique of isolating and digesting arteries from different vascular beds will provide options for researchers to evaluate freshly isolated vascular cells&#160;from arteries of interest and allow them to perform a wide range of functional tests on specific cell types.

This protocol details a method for the dissection of mouse adipose depots and the isolation and digestion of respective arteries to liberate and then identify the endothelial cell population. Freshly isolated cells used in downstream applications will advance the understanding of vascular cell biology and the mechanisms of vascular dysfunction.

Vascular endothelial cells lining the wall of the vascular system play important roles in a variety of physiological processes, including vascular tone ...

Semi-Automated Isolation of Murine White Adipose Tissue

Semi-Automated Isolation of the Stromal Vascular Fraction from Murine White Adipose Tissue Using a Tissue Dissociator

The in vitro study of white, brown, and beige adipocyte differentiation enables the investigation of cell-autonomous functions of adipocytes and their mechanisms. Immortalized white preadipocyte cell lines are publicly available and widely used. However, the emergence of beige adipocytes in white adipose tissue in response to external cues is difficult to recapitulate to the full extent using publicly available white adipocyte cell lines. Isolation of the stromal vascular fraction (SVF) from murine adipose tissue is commonly executed to obtain primary preadipocytes and perform adipocyte differentiation. However, mincing and collagenase digestion of adipose tissue by hand can result in experimental variation and is prone to contamination. Here, we present a modified semi-automated protocol that utilizes a tissue dissociator for collagenase digestion to achieve easier isolation of the SVF, with the aim of reducing experimental variation, reducing contamination, and increasing reproducibility. The obtained preadipocytes and differentiated adipocytes can be used for functional and mechanistic analyses.

Author Spotlight: Semi-Automated Isolation of the Stromal Vascular Fraction from Murine White Adipose Tissue Using a Tissue Dissociator  

This protocol describes the semi-automated isolation of the stromal vascular fraction (SVF) from murine adipose tissue to obtain preadipocytes and achieve adipocyte differentiation in vitro. Using a tissue dissociator for collagenase digestion reduces experimental variation and increases reproducibility.

The in vitro study of white, brown, and beige adipocyte differentiation enables the investigation of cell-autonomous functions of adipocytes and their ...

Morphological and Molecular Characterization of the scBAT in Mice

Dissection, Histological Processing, and Gene Expression Analysis of Murine Supraclavicular Brown Adipose Tissue

Brown adipose tissue (BAT)-mediated thermogenesis plays an important role in the regulation of metabolism, and its morphology and function can be greatly impacted by environmental stimuli in mice and humans. Currently, murine interscapular BAT (iBAT), which is located between two scapulae in the upper dorsal flank of mice, is the main BAT depot used by research laboratories to study BAT function. Recently, a few previously unknown BAT depots were identified in mice, including one analogous to human supraclavicular brown adipose tissue. Unlike iBAT, murine supraclavicular brown adipose tissue (scBAT) is situated in the intermediate layer of the neck and thus cannot be accessed as readily.
To facilitate the study of newly identified mouse scBAT, presented herein is a protocol detailing the steps to dissect intact scBAT from postnatal and adult mice. Due to scBAT&#39;s small size relative to other adipose depots, procedures have been modified and optimized specifically for processing scBAT. Among these modifications is the use of a dissecting microscope during tissue collection to increase the precision and homogenization of frozen scBAT samples to raise the efficiency of subsequent qPCR analysis. With these optimizations, the identification of, morphological appearance of, and molecular characterization of the scBAT can be determined in mice.

Author Spotlight: Optimizing Supraclavicular Brown Adipose Tissue Extraction for Genetic Analysis

Here, we provide a practical procedure for dissecting and performing histological and gene expression analyses of murine supraclavicular brown adipose tissue.

Brown adipose tissue (BAT)-mediated thermogenesis plays an important role in the regulation of metabolism, and its morphology and function can be greatly ...

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 ...

Harvesting Peritoneal Fat Depots: A Technique to Study Ovarian Cancer Colonization of Peritoneal Adipose Tissues in Mouse Models

Source: Krishnan, V. et al. <a href="https://www.jove.com/t/52721">In Vivo</a><a href="https://www.jove.com/t/52721">&#160;and&#160;Ex Vivo&#160;Approaches to Study Ovarian Cancer Metastatic Colonization of Milky Spot Structures in Peritoneal Adipose.</a> J. Vis. Exp. (2015)
In this video, we use a euthanized female mouse model bearing ovarian cancer. We then describe a protocol to identify and extract fat depots or adipose tissues associated with the five primary peritoneal organs to study metastatic cancer cell colonization.

Source: Krishnan, V. et al. In Vivo&#160;and&#160;Ex Vivo&#160;Approaches to Study Ovarian Cancer Metastatic Colonization of Milky Spot Structures in ...