This study was supported by Natural Sciences and Engineering Research Council of Canada Discovery Grant (371697-2011, AT). The authors want to acknowledge the help of bariatric surgeons Drs S. Biron, F-S. Hould, S. Lebel, O. Lescelleur, P. Marceau as well as Christine Racine and Caroline Gagnon from the IUCPQ Tissue Bank. We thank Mr Jacques Cadorette from the IUCPQ&#8217;s audiovisual services for video shooting and editing.

Ethics statement: The project has been approved by IUCPQ&#8217;s Research Ethics Committee prior to patient recruitment. For the purpose of this article/video, we obtained tissues from 2 patients: 1) a 62 year-old male patient with a BMI of 50.7 kg/m2 and 2) a 35 year-old female patient with a BMI of 57 kg/m2. Experiments can be done with both fat compartments, but have been limited to one fat compartment for the purpose of this video. Technical aspects of the video were performed with patient 1 and FABP4 immunofluorescence was performed with dedifferentiated cells from patient 2.
1. Sample Processing
<ol>
	<li>Ask surgeons to collect adipose tissue from the omental and subcutaneous fat compartments at the time of laparoscopic bariatric surgery.</li>
	<li>Quickly bring adipose samples to the laboratory at RT and process immediately.</li>
	<li>Perform digestion in the laboratory, in a non-sterile atmosphere. The cells will eventually be transferred to the culture room and cultivated under sterile conditions. To avoid contamination, prepare KRH buffer with distilled and filtrated water and follow by a filtration (0.22&#181;M filter) prior to digestion. Thoroughly clean tubes with ethanol prior transfer in the cell culture hood for flask and plate preparation.</li>
	<li>Place adipose tissue on a pre-weighted dish and record weight. Fix a small piece of each tissue sample (less than 1 cm2) in 10% formalin buffer at RT for at least 24 hr before paraffin embedding. Use this embedded sample for immunohistochemistry experiments (technique not shown).</li>
	<li>Place another piece in a 50-ml tube and flash-freeze in liquid nitrogen before storing at -80 &#176;C for further studies on whole adipose tissues (e.g.,&#160;gene expression - technique not shown).</li>
</ol>
2. Collagenase Digestion
<ol>
	<li>Place the remaining adipose tissue piece in a 50 ml tube for digestion.</li>
	<li>Add 4 ml of KRH-WB supplemented with collagenase (350 U/ml) per gram of sample in the digestion tube.</li>
	<li>Mince adipose tissue with scissors.</li>
	<li>Place minced adipose tissue suspension in a shaker, 37 &#176;C, 90 rpm maximum, for a 45-minute incubation (maximum 1 hr).</li>
</ol>
3. Purification of Adipocytes and Preadipocytes
<ol>
	<li>Pour the translucent solution with few chunks of fat through a 400 &#181;M nylon mesh into a plastic beaker.</li>
	<li>With tweezers, rub the cell preparation on the nylon mesh and wash with 5 ml of KRH-WB.</li>
	<li>Delicately transfer the filtrated cell suspension into a 50 ml tube with the plastic tubing in it and a 60cc syringe attached at the tubing extremity.</li>
	<li>Let the suspension with mature adipocytes stand for approximately 10 min, allowing the cells to reach the top of the buffer by floatation.</li>
	<li>Slowly aspirate the buffer at the bottom of the tube using 60cc syringe suction.</li>
	<li>Add 20 ml of KRH-WB to wash. Repeat from step 3.4 for 2 additional washes.</li>
	<li>Collect the buffer to bring the adipocyte suspension to a final volume of 5 or 10 ml, depending on cell quantity. Pursue with steps in section 5.</li>
	<li>Recover the stromal-vascular fraction from the buffer collected with the 60cc syringe by centrifugation (3,000 rpm, RT, 5 min) for further primary cell culture if desired (technique not shown).</li>
</ol>
4. Mature Adipocyte Cell Count
<ol>
	<li>Load 10 &#181;l of gently shaken adipocyte suspension in a counting chamber (haemocytometer). Perform cell count in quadruplicate.</li>
	<li>Calculate number of isolated mature cells.</li>
</ol>
5. Mature Adipocyte Dedifferentiation into T-25 Flask
<ol>
	<li>Fill a 25 cm2 tissue culture flask to &#190; of the volume with DMEM/F12-20% calf serum.</li>
	<li>According to cell count, pour 500,000 mature cells into the flask.</li>
	<li>Fill the flask completely using a 50ml tube with medium and remove as many bubbles as possible.</li>
	<li>Screw the unvented cap on the flask.</li>
	<li>Clean the flask with ethanol prior to incubation to avoid contamination.</li>
	<li>Incubate the flask upside down for a week without touching it to avoid movement in the culture that may disrupt cellular adherence.</li>
	<li>Prior to reversing the flask at 7 days of inverted culture, gently manipulate the flask and remove all medium in the flask by aspiration, avoiding abrupt movements.</li>
	<li>Add 12 ml of DMEM-F12-20% calf serum and cultivate cells with standard techniques. A filtered, vented cap may be added to the flask.</li>
</ol>
6. Mature Adipocyte Dedifferentiation into a 6-well Plate
<ol>
	<li>Place a coverslip on the bottom of each well of a 6-well plate</li>
	<li>Add a &#189;&#8221; plastic bushing on top of each coverslip.</li>
	<li>Fill wells with 8 ml of 20% calf serum-DMEM medium.</li>
	<li>Put a coverslip on each plastic bushing.</li>
	<li>Insert pipet tip between the slide and the tube to inject cells under the slide (50,000 cells per well).</li>
	<li>Incubate plates in a standard cell culture incubator at 37 &#176;C with 5% CO2 for a week.</li>
	<li>Reverse coverslip with attached cells into each well containing 2 ml of media supplemented with 20% calf serum and pursue culture.</li>
	<li>Use coverslip with cells undergoing dedifferentiation for several purposes including immunofluorescence (technique not shown).</li>
</ol>

<ol>
	<li>Zhang, H. H., Kumar, S., Barnett, A. H., Eggo, M. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ceiling+culture+of+mature+human+adipocytes:+use+in+studies+of+adipocyte+functions.">Ceiling culture of mature human adipocytes: use in studies of adipocyte functions.</a> J Endocrinol. 164 (2), 119-128 (2000).</li><li>Matsumoto, T., 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=Mature+adipocyte-derived+dedifferentiated+fat+cells+exhibit+multilineage+potential.">Mature adipocyte-derived dedifferentiated fat cells exhibit multilineage potential.</a> J Cell Physiol. 215 (1), 210-222 (2008).</li><li>Poloni, 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=Human+dedifferentiated+adipocytes+show+similar+properties+to+bone+marrow-derived+mesenchymal+stem+cells.">Human dedifferentiated adipocytes show similar properties to bone marrow-derived mesenchymal stem cells.</a> Stem Cells. 30 (5), 965-974 (2012).</li><li>Perrini, S., 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=Differences+in+gene+expression+and+cytokine+release+profiles+highlight+the+heterogeneity+of+distinct+subsets+of+adipose+tissue-derived+stem+cells+in+the+subcutaneous+and+visceral+adipose+tissue+in+humans.">Differences in gene expression and cytokine release profiles highlight the heterogeneity of distinct subsets of adipose tissue-derived stem cells in the subcutaneous and visceral adipose tissue in humans.</a> PLoS One. 8 (3), e57892 (2013).</li><li>Kishimoto, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+osteoblastic+differentiation+ability+of+human+dedifferentiated+fat+cells+is+higher+than+that+of+adipose+stem+cells+from+the+buccal+fat+pad.">The osteoblastic differentiation ability of human dedifferentiated fat cells is higher than that of adipose stem cells from the buccal fat pad.</a> Clin Oral Investig. , (2013).</li><li>Kou, L., 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=The+phenotype+and+tissue-specific+nature+of+multipotent+cells+derived+from+human+mature+adipocytes.">The phenotype and tissue-specific nature of multipotent cells derived from human mature adipocytes.</a> Biochem Biophys Res Commun. 444 (4), 543-548 (2014).</li><li>Jumabay, M., 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=Pluripotent+stem+cells+derived+from+mouse+and+human+white+mature+adipocytes.">Pluripotent stem cells derived from mouse and human white mature adipocytes.</a> Stem Cells Transl Med. 3 (2), 161-171 (2014).</li><li>Sugawara, A., Sato, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Application+of+dedifferentiated+fat+cells+for+periodontal+tissue+regeneration.">Application of dedifferentiated fat cells for periodontal tissue regeneration.</a> Hum Cell. 27 (1), 12-21 (2014).</li><li>Kikuta, S., 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=Osteogenic+effects+of+dedifferentiated+fat+cell+transplantation+in+rabbit+models+of+bone+defect+and+ovariectomy-induced+osteoporosis.">Osteogenic effects of dedifferentiated fat cell transplantation in rabbit models of bone defect and ovariectomy-induced osteoporosis.</a> Tissue Eng Part A. 19 (15-16), 1792-1802 (2013).</li><li>Obinata, 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=Transplantation+of+mature+adipocyte-derived+dedifferentiated+fat+(DFAT)+cells+improves+urethral+sphincter+contractility+in+a+rat+model.">Transplantation of mature adipocyte-derived dedifferentiated fat (DFAT) cells improves urethral sphincter contractility in a rat model.</a> Int J Urol. 18 (12), 827-834 (2011).</li><li>Jumabay, M., 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=Dedifferentiated+fat+cells+convert+to+cardiomyocyte+phenotype+and+repair+infarcted+cardiac+tissue+in+rats.">Dedifferentiated fat cells convert to cardiomyocyte phenotype and repair infarcted cardiac tissue in rats.</a> J Mol Cell Cardiol. 47 (5), 565-575 (2009).</li><li>Ohta, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mature+adipocyte-derived+cells,+dedifferentiated+fat+cells+(DFAT),+promoted+functional+recovery+from+spinal+cord+injury-induced+motor+dysfunction+in+rats.">Mature adipocyte-derived cells, dedifferentiated fat cells (DFAT), promoted functional recovery from spinal cord injury-induced motor dysfunction in rats.</a> Cell Transplant. 17 (8), 877-886 (2008).</li><li>Moreno-Navarrete, J. M. F. -. r., Symonds, M. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ch.+2.">Ch. 2.</a> Adipose Tissue Biology. , 17-38 (2012).</li><li>Poulos, S. P., Dodson, M. V., Hausman, G. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+line+models+for+differentiation:+preadipocytes+and+adipocytes.">Cell line models for differentiation: preadipocytes and adipocytes.</a> Exp Biol Med (Maywood. 235 (10), 1185-1193 (2010).</li><li>Casteilla, L., Penicaud, 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>Tchernof, A., Despres, J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pathophysiology+of+human+visceral+obesity:+an+update.">Pathophysiology of human visceral obesity: an update.</a> Physiol Rev. 93 (1), 359-404 (2013).</li><li>Rodbell, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Metabolism+of+Isolated+Fat+Cells.+I.+Effects+of+Hormones+on+Glucose+Metabolism+and+Lipolysis.">Metabolism of Isolated Fat Cells. I. Effects of Hormones on Glucose Metabolism and Lipolysis.</a> J Biol Chem. 239, 375-380 (1964).</li><li>Watson, J. E., 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=Comparison+of+Markers+and+Functional+Attributes+of+Human+Adipose-Derived+Stem+Cells+and+Dedifferentiated+Adipocyte+Cells+from+Subcutaneous+Fat+of+an+Obese+Diabetic+Donor.">Comparison of Markers and Functional Attributes of Human Adipose-Derived Stem Cells and Dedifferentiated Adipocyte Cells from Subcutaneous Fat of an Obese Diabetic Donor.</a> Adv Wound Care. 3 (3), 219-228 (2014).</li></ol>

The authors declare no conflict of interest.

Dedifferentiation of mature adipocytes with the ceiling culture technique is a new approach to obtain adipose stem cells from a small sample of native adipose tissue. Based on our experience and that of others2, one gram of tissue is sufficient to plate a 25-cm2 flask and to obtain a population of DFAT cells for which homogeneity has been demonstrated by Poloni and collaborators3. Adipocyte dedifferentiation seems possible with cells from any donor, independently of their age, sex and oth...

In vitro dedifferentiation of mature adipocytes is achieved through a technique called ceiling culture1. Because of their natural tendency to float in aqueous solutions, isolated mature adipocytes adhere to the surface of an inverted flask fully filled with culture medium. Over a few days, cells modify their spherical morphology and become fibroblast-like cells. The resulting cells, called dedifferentiated fat (DFAT) cells, are multipotent2. Research articles on adipocyte dedifferentiation, especially on human cells, are limited. However, they have already provided interesting information regarding multipotency, cell phenotype and replicative capacity of DFAT cells2. Mature adipocytes originating from various fat compartments have been successfully dedifferentiated including those originating from human visceral and subcutaneous adipose tissues2-4. In addition to these depots, Kishimoto and collaborators sampled adipose tissue from the buccal fat pads and dedifferentiated adipocytes into DFAT cells5. Matsumoto and collaborators successfully generated subcutaneous DFAT cells from patients covering a wide range of ages, and the majority of cells had a high proliferative rate and less than 6% of senescence even after 10 passages in culture2.
DFAT cells have been successfully re-differentiated into several lineages, including adipogenic, osteogenic, chondrogenic and neurogenic lineages2,3,6. These cells express several embryonic stem cell markers such as Nanog and the four identified pluripotent factors Oct4, c-myc, Klf4 and Sox23. They also express markers specific to each of the three germ layers7. In addition, DFAT cells are similar to Bone Marrow-derived Mesenchymal Stem Cells (BM-derived MSC) based on their epigenetic signature3. Exploiting the stem cell capacity of DFAT cells, many groups have investigated their potential to treat or improve various diseases8,9. Improvements of pathologic conditions, such as infracted cardiac tissue, spinal cord injury and urethral sphincter dysfunction, have been observed with DFAT cell injections in rat models of disease10-12. 
In addition to the stem cell properties of DFAT cells, they may represent a new cellular model for adipocyte physiology studies. The 3T3-L1 cell line is often used for this purpose as these cells differentiate into adherent, lipid-storing adipocytes under adipogenic stimulation13. However, these cells originate from mouse embryo tissue13. Also, depot-specificity cannot be investigated with this model and it may not fully reflect human adipocyte physiology14. Other laboratories work with isolated adipose cells from murine fat depots, but fat distribution is not dimorphic in mice and anatomical configuration of the rodent's abdominal cavity prevents from extrapolating directly to humans15. In order to study adipocytes in the context of the physiopathology of human obesity, consideration of body fat distribution and fat depot-specific differences has become essential16. Some limitations of primary preadipocyte cultures, including cell quantities obtained from adipose tissue biopsy samples and their senescence after a few passages in culture, created the need for alternate models. Perrini and collaborators investigated depot-specificity in gene expression of DFAT cells originating from visceral and subcutaneous fat and compared them to adipose-derived stem cells (ASC) from the same fat depot. They demonstrated that differences in gene expression and function where mainly found between depots than between cell types, suggesting that DFAT cells are physiologically close to ASC from the same depot. DFAT cells may represent an interesting alternative to available models for studies on fat distribution in the pathophysiology of human obesity. Moreover, ceiling culture is a promising method to obtain adult stem cells for tissue engineering purposes. 
Here, we describe collagenase digestion, a widely-used technique to isolate mature adipocytes from the subcutaneous and/or visceral fat samples17, and the subsequent steps to perform ceiling culture and dedifferentiate these cells into multipotent, fibroblast-like cells.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>Bovine serum albumine</td>
			<td>Sigma</td>
			<td>A7906</td>
			<td></td>
		</tr>
		<tr>
			<td>Adenosine</td>
			<td>Sigma</td>
			<td>A4036</td>
			<td></td>
		</tr>
		<tr>
			<td>Ascorbic acid</td>
			<td>Sigma</td>
			<td>A0278</td>
			<td></td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td></td>
			<td></td>
			<td>Any brand can be used</td>
		</tr>
		<tr>
			<td>KCl</td>
			<td></td>
			<td></td>
			<td>Any brand can be used</td>
		</tr>
		<tr>
			<td>CaCl2</td>
			<td></td>
			<td></td>
			<td>Any brand can be used</td>
		</tr>
		<tr>
			<td>MgCl2</td>
			<td></td>
			<td></td>
			<td>Any brand can be used</td>
		</tr>
		<tr>
			<td>KH2PO4</td>
			<td></td>
			<td></td>
			<td>Any brand can be used</td>
		</tr>
		<tr>
			<td>HEPES</td>
			<td></td>
			<td></td>
			<td>Any brand can be used</td>
		</tr>
		<tr>
			<td>Glucose</td>
			<td></td>
			<td></td>
			<td>Any brand can be used</td>
		</tr>
		<tr>
			<td>Type I collagenase</td>
			<td>Worthington Biochemical Corp</td>
			<td>LS-004196</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM/F-12, HEPES, no phenol red</td>
			<td>Gibco-Life Technologies</td>
			<td>11039-021</td>
			<td>Add to medium : 20% calf serum, gentamicin (50&#181;g/ml) and fungizone (2.5&#181;g/ml)</td>
		</tr>
		<tr>
			<td>Calf Serum, iron supplemented, from formula-fed calves</td>
			<td>Sigma</td>
			<td>C8056-500ml</td>
			<td></td>
		</tr>
		<tr>
			<td>1/2 In plastic bushing</td>
			<td>Iberville</td>
			<td>2704-CP</td>
			<td>SKU:1000120918 (Home Depot)</td>
		</tr>
		<tr>
			<td>Liquid nitrogen</td>
			<td>Linde</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Formalin soluton, neutral buffered, 10%</td>
			<td>SIGMA</td>
			<td>HT501128</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile tweezers</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile scissors</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>60cc syringes</td>
			<td>BD Syringe</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Plastic tubing</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Krebs-Ringer-Henseleit stock buffer (KRH)</td>
			<td></td>
			<td></td>
			<td>Prepare stock buffer as following: 25mM HEPES pH7.6, 125mM NaCl, 3.73mM KCl, 5mM CaCl2.2H2O, 2.5mM MgCl2.6H2O, 1mM K2HPO4. Adjust pH to 7.4.</td>
		</tr>
		<tr>
			<td>Krebs-Ringer-Henseleit-Working Buffer (KRH-WB)</td>
			<td></td>
			<td></td>
			<td>Add the following components freshly to KRH buffer: 4% bovine serum albumin, 5mM glucose, 0.1&#181;M adenosine, 560 &#181;M ascorbic acid</td>
		</tr>
		<tr>
			<td>KRH-WB supplemented with Type I collagenase</td>
			<td></td>
			<td></td>
			<td>Add 350U/ml of Type I collagenase</td>
		</tr>
		<tr>
			<td>T25 unvented cap tissue culture flask</td>
			<td>Sarsted or other brand</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>6-well tissue culture plate</td>
			<td>BD Falcon or other brand</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope cover glass 22x22</td>
			<td>Fisherbrand</td>
			<td>12-542-B</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile beakers</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

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.

Major morphological changes occur to mature adipocytes during dedifferentiation (Figure 1). As shown in Figure 2, cells undergoing dedifferentiation were stained with an anti-FABP4 antibody for fluorescence analysis. Cells with a round morphology expressed the FABP4 protein whereas the majority of the fibroblast-like cells did not. After dedifferentiation, DFAT cells can be cultivated with standard procedures for several passages. We have been able to reach more than 15 passages for huma...

Watch this Scientific Journal Video about Generation of Human Adipose Stem Cells through Dedifferentiation of Mature Adipocytes in Ceiling Cultures at JoVE.com

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

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 ...

generation-human-adipose-stem-cells-through-dedifferentiation-mature

Research

JoVE Journal

Developmental Biology

11.7K Views.  IUCPQ Research Center. 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.

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

Isolation and Enrichment of Human Adipose-derived Stromal Cells for Enhanced Osteogenesis

Bone marrow-derived mesenchymal stromal cells (BM-MSCs) are considered the gold standard for stem cell-based tissue engineering applications. However, the process by which they must be harvested can be associated with significant donor site morbidity. In contrast, adipose-derived stromal cells (ASCs) are more readily abundant and more easily harvested, making them an appealing alternative to BM-MSCs. Like BM-MSCs, ASCs can differentiate into osteogenic lineage cells and can be used in tissue engineering applications, such as seeding onto scaffolds for use in craniofacial skeletal defects. ASCs are obtained from the stromal vascular fraction (SVF) of digested adipose tissue, which is a heterogeneous mixture of ASCs, vascular endothelial and mural cells, smooth muscle cells, pericytes, fibroblasts, and circulating cells. Flow cytometric analysis has shown that the surface marker profile for ASCs is similar to that for BM-MSCs. Despite several published reports establishing markers for the ASC phenotype, there is still a lack of consensus over profiles identifying osteoprogenitor cells in this heterogeneous population. This protocol describes how to isolate and use a subpopulation of ASCs with enhanced osteogenic capacity to repair critical-sized calvarial defects.

The transcriptional heterogeneity within human adipose-derived stromal cells can be defined on the single cell level using cell surface markers and osteogenic genes. We describe a protocol utilizing flow cytometry for the isolation of cell subpopulations with increased osteogenic potential, which may be used to enhance craniofacial skeletal reconstruction.

Bone marrow-derived mesenchymal stromal cells (BM-MSCs) are considered the gold standard for stem cell-based tissue engineering applications. However, the ...

Generation of Integration-free Human Induced Pluripotent Stem Cells Using Hair-derived Keratinocytes

Recent advances in reprogramming allow us to turn somatic cells into human induced pluripotent stem cells (hiPSCs). Disease modeling using patient-specific hiPSCs allows the study of the underlying mechanism for pathogenesis, also providing a platform for the development of in vitro drug screening and gene therapy to improve treatment options. The promising potential of hiPSCs for regenerative medicine is also evident from the increasing number of publications (>7000) on iPSCs in recent years. Various cell types from distinct lineages have been successfully used for hiPSC generation, including skin fibroblasts, hematopoietic cells and epidermal keratinocytes. While skin biopsies and blood collection are routinely performed in many labs as a source of somatic cells for the generation of hiPSCs, the collection and subsequent derivation of hair keratinocytes are less commonly used. Hair-derived keratinocytes represent a non-invasive approach to obtain cell samples from patients. Here we outline a simple non-invasive method for the derivation of keratinocytes from plucked hair. We also provide instructions for maintenance of keratinocytes and subsequent reprogramming to generate integration-free hiPSC using episomal vectors.

This manuscript provides a step-by-step procedure for the derivation and maintenance of human keratinocytes from plucked hair and subsequent generation of integration-free human induced pluripotent stem cells (hiPSCs) by episomal vectors.

Recent advances in reprogramming allow us to turn somatic cells into human induced pluripotent stem cells (hiPSCs). Disease modeling using ...

Generation of Genetically Modified Organotypic Skin Cultures Using Devitalized Human Dermis

Organotypic cultures allow the reconstitution of a 3D environment critical for cell-cell contact and cell-matrix interactions which mimics the function and physiology of their in vivo tissue counterparts. This is exemplified by organotypic skin cultures which faithfully recapitulates the epidermal differentiation and stratification program. Primary human epidermal keratinocytes are genetically manipulable through retroviruses where genes can be easily overexpressed or knocked down. These genetically modified keratinocytes can then be used to regenerate human epidermis in organotypic skin cultures providing a powerful model to study genetic pathways impacting epidermal growth, differentiation, and disease progression. The protocols presented here describe methods to prepare devitalized human dermis as well as to genetically manipulate primary human keratinocytes in order to generate organotypic skin cultures. Regenerated human skin can be used in downstream applications such as gene expression profiling, immunostaining, and chromatin immunoprecipitations followed by high throughput sequencing. Thus, generation of these genetically modified organotypic skin cultures will allow the determination of genes that are critical for maintaining skin homeostasis.

The goal of this paper is to provide a comprehensive and detailed protocol on how to generate genetically modified human organotypic skin from epidermal keratinocytes and devitalized human dermis.

Organotypic cultures allow the reconstitution of a 3D environment critical for cell-cell contact and cell-matrix interactions which mimics the function ...

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. ...

Generation of Induced Pluripotent Stem Cells from Human Melanoma Tumor-infiltrating Lymphocytes

Adoptive transfer of ex vivo expanded autologous tumor-infiltrating lymphocytes (TILs) can mediate durable and complete responses in significant subsets of patients with metastatic melanoma. Major obstacles of this approach are the reduced viability of transferred T cells, caused by telomere shortening, and the limited number of TILs obtained from patients. Less-differentiated T cells with long telomeres would be an ideal T cell subset for adoptive T cell therapy;however, generating large numbers of these less-differentiated T cells is problematic. This limitation of adoptive T cell therapy can be theoretically overcome by using induced pluripotent stem cells (iPSCs) that self-renew, maintain pluripotency, have elongated telomeres, and provide an unlimited source of autologous T cells for immunotherapy. Here, we present a protocol to generate iPSCs using Sendai virus vectors for the transduction of reprogramming factors into TILs. This protocol generates fully reprogrammed, vector-free clones. These TIL-derived iPSCs might be able to generate less-differentiated patient- and tumor-specific T cells for adoptive T cell therapy.

The goal of this protocol is to show the protocol for reprogramming melanoma tumor-infiltrating lymphocytes into induced pluripotent stem cells.

Adoptive transfer of ex vivo expanded autologous tumor-infiltrating lymphocytes (TILs) can mediate durable and complete responses in significant subsets ...

Generation of Integration-free Induced Pluripotent Stem Cells from Human Peripheral Blood Mononuclear Cells Using Episomal Vectors

Induced Pluripotent Stem Cells (iPSCs) hold great promise for disease modeling and regenerative therapies. We previously reported the use of Episomal Vectors (EV) to generate integration-free iPSCs from peripheral blood mononuclear cells (PB MNCs). The episomal vectors used are DNA plasmids incorporated with oriP and EBNA1 elements from the Epstein-Barr (EB) virus, which&#160;allow for replication and long-term retainment of plasmids in mammalian cells, respectively. With further optimization, thousands of iPSC colonies can be obtained from 1 mL of peripheral blood. Two critical factors for achieving high reprogramming efficiencies&#160;are: 1) the use of a 2A &#34;self-cleavage&#34; peptide to link OCT4 and SOX2, thus achieving equimolar expression of the two factors; 2) the use of two vectors to express MYC and KLF4 individually. Here we describe a step-by-step protocol for generating integration-free iPSCs from adult peripheral blood samples. The generated iPSCs are integration-free as residual episomal plasmids are undetectable after five passages. Although the reprogramming efficiency is comparable to that of Sendai Virus (SV) vectors, EV plasmids are considerably more economical than the commercially available SV vectors. This affordable EV reprogramming system holds potential for clinical applications in regenerative medicine and provides an approach for the direct reprogramming of PB MNCs to integration-free mesenchymal stem cells, neural stem cells, etc.

This protocol describes a detailed method for efficient generation of integration-free iPSCs from human adult peripheral blood cells. With the use of four oriP/EBNA-based episomal vectors to express the reprogramming factors, KLF4, MYC, BCL-XL, or OCT4 and SOX2, thousands of iPSC colonies can be obtained from 1 mL of peripheral blood.

Induced Pluripotent Stem Cells (iPSCs) hold great promise for disease modeling and regenerative therapies. We previously reported the use of Episomal ...

Directed Differentiation of Primitive and Definitive Hematopoietic Progenitors from Human Pluripotent Stem Cells

One of the major goals for regenerative medicine is the generation and maintenance of hematopoietic stem cells (HSCs) derived from human pluripotent stem cells (hPSCs). Until recently, efforts to differentiate hPSCs into HSCs have predominantly generated hematopoietic progenitors that lack HSC potential, and instead resemble yolk sac hematopoiesis.&#160;These resulting hematopoietic progenitors may have limited utility for in vitro disease modeling of various adult hematopoietic disorders, particularly those of the lymphoid lineages. However, we have recently described methods to generate erythro-myelo-lymphoid multilineage definitive hematopoietic progenitors from hPSCs using a stage-specific directed differentiation protocol, which we outline here. Through enzymatic dissociation of hPSCs on basement membrane matrix-coated plasticware, embryoid bodies (EBs) are formed. EBs are differentiated to mesoderm by recombinant BMP4, which is subsequently specified to the definitive hematopoietic program by the GSK3&#946; inhibitor, CHIR99021. Alternatively, primitive hematopoiesis is specified by the PORCN inhibitor, IWP2. Hematopoiesis is further driven through the addition of recombinant VEGF and supportive hematopoietic cytokines. The resulting hematopoietic progenitors generated using this method have the potential to be used for disease and developmental modeling, in vitro.

Here, we present human pluripotent stem cell (hPSC) culture protocols, used to differentiate hPSCs into CD34+ hematopoietic progenitors. This method uses stage-specific manipulation of canonical WNT signaling to specify cells exclusively to either the definitive or primitive hematopoietic program.

One of the major goals for regenerative medicine is the generation and maintenance of hematopoietic stem cells (HSCs) derived from human pluripotent stem ...

Defined and Scalable Generation of Hepatocyte-like Cells from Human Pluripotent Stem Cells

Human pluripotent stem cells (hPSCs) possess great value for biomedical research. hPSCs can be scaled and differentiated to all cell types found in the human body. The differentiation of hPSCs to human hepatocyte-like cells (HLCs) has been extensively studied, and efficient differentiation protocols have been established. The combination of extracellular matrix and biological stimuli, including growth factors, cytokines, and small molecules, have made it possible to generate HLCs that resemble primary human hepatocytes. However, the majority of procedures still employ undefined components, giving rise to batch-to-batch variation. This serves as a significant barrier to the application of the technology. To tackle this issue, we developed a defined system for hepatocyte differentiation using human recombinant laminins as extracellular matrices in combination with a serum-free differentiation process. Highly efficient hepatocyte specification was achieved, with demonstrated improvements in both HLC function and phenotype. Importantly, this system is easy to scale up using research and GMP-grade hPSC lines&#160;promising advances in cell-based modelling and therapies.

The method presented here describes a scalable and good manufacturing practice (GMP)-ready differentiation system to generate human hepatocyte-like cells from pluripotent stem cells. It serves as a cost-effective and standardized system to generate human hepatocyte-like cells for basic and applied human liver research.

Human pluripotent stem cells (hPSCs) possess great value for biomedical research. hPSCs can be scaled and differentiated to all cell types found in the ...

Hypoxic Preconditioning of Marrow-derived Progenitor Cells As a Source for the Generation of Mature Schwann Cells

This manuscript describes a means to enrich for neural progenitors from the marrow stromal cell (MSC) population and thereafter to direct them to the mature Schwann cell fate. We subjected rat and human MSCs to transient hypoxic conditions (1% oxygen for 16 h) followed by expansion as neurospheres upon low-attachment substratum with epidermal growth factor (EGF)/basic fibroblast growth factor (bFGF) supplementation. Neurospheres were seeded onto poly-D-lysine/laminin-coated tissue culture plastic and cultured in a gliogenic cocktail containing &#946;-Heregulin, bFGF, and platelet-derived growth factor (PDGF) to generate Schwann cell-like cells (SCLCs). SCLCs were directed to fate commitment via coculture for 2 weeks with purified dorsal root ganglia (DRG) neurons obtained from E14-15 pregnant Sprague Dawley rats. Mature Schwann cells demonstrate persistence in S100&#946;/p75 expression and can form myelin segments. Cells generated in this manner have potential applications in autologous cell transplantation following spinal cord injury, as well as in disease modeling.

Marrow stromal cells (MSCs) with neural potential exist within the bone marrow. Our protocol enriches this population of cells via hypoxic preconditioning and thereafter directs them to become mature Schwann cells.

This manuscript describes a means to enrich for neural progenitors from the marrow stromal cell (MSC) population and thereafter to direct them to the ...

Single-cell Photoconversion in Living Intact Zebrafish

Animal and plant tissue is composed of distinct populations of cells. These cells interact over time to build and maintain the tissue and can cause disease when disrupted. Scientists have developed clever techniques to investigate characteristics and natural dynamics of these cells within intact tissue by expressing fluorescent proteins in subsets of cells. However, at times, experiments require more selected visualization of cells within the tissue, sometimes at the single-cell or population-of-cells manner. To achieve this and visualize single cells within a population of cells, scientists have utilized single-cell photoconversion of fluorescent proteins. To demonstrate this technique, we show here how to direct UV light to an Eos-expressing cell of interest in an intact, living zebrafish. We then image those photoconverted Eos+ cells 24 h later to determine how they changed in the tissue. We describe two techniques: single cell photoconversion and photoconversions of populations of cell. These techniques can be used to visualize cell-cell interactions, cell-fate and differentiation, and cell migrations, making it a technique that is applicable in numerous biological questions.

Here, we present a protocol to show how cell photoconversion is achieved through UV exposure to specific areas expressing the fluorescent protein, Eos, in living animals.

Animal and plant tissue is composed of distinct populations of cells. These cells interact over time to build and maintain the tissue and can cause ...