This work was supported by the National Key Research and Development Program of China (2017YFA0104604), the General Program of National Natural Science Foundation of China (NSFC, 81772093), the Science and Technology Development Program of Suzhou (ZXL2015128), the Natural Science Foundation of Jiangsu Province (BK20161241), and a Shandong Taishan Scholar Award (tshw201502065).

Human tissues used in this protocol have been handled according to the guidelines of the Institution&#39;s human research ethics committee (NO.2015120401, date: May 12, 2015).
1. Preparations
<ol>
	<li>Collect fresh adult abdominal skin tissues discarded from plastic surgery at the hospital in a 50-mL tube with 10 mL of ice-cold Dulbecco&#39;s modified Eagle medium (DMEM). The specimen can be kept at 4 &#176;C for up to 72 h without significantly affecting the cell viability.</li>
	<li>Prepare the reagents and culture medium as described below.
	<ol>
		<li>Add 1 mL of penicillin (100 U/mL) and streptomycin (100 mg/L) to 50 mL of phosphate-buffered solution (PBS) to prepare the washing solution.</li>
		<li>Prepare two sets of enzyme digestion solutions: (1) prepare 50 mL of dispase (2.5 mg/mL in DMEM) and 50 mL of type I collagenase (2.5 mg/mL in DMEM) separately for the conventional method; and (2) prepare 50 mL of a mixture of dispase and type I collagenase (dissolve 125 mg of dispase powder and 125 mg of type I collagenase powder in 50 mL of DMEM) for the new method. 
		NOTE: All enzyme solutions should be filtered with a 0.22-&#181;m strainer and kept at4 &#176;C.</li>
		<li>Prepare digestion solutions for both methods: 0.05% trypsin and 0.25% trypsin were commercially purchased. Prepare a 10 mg/mL DNase I solution by dissolving 50 mg of DNase I powder in 5 mL of PBS, filter it with a 0.22-&#181;m strainer, and store it at -20 &#176;C.</li>
		<li>Prepare 500 mL of medium to neutralize the enzymatic digestion: DMEM medium supplemented with 10% fetal bovine serum (FBS) and 1% penicillin/streptomycin.</li>
		<li>Prepare 500 mL of inoculation medium (growth-factor-containing medium, called G-medium): DMEM/F12 (3:1) medium containing 1% penicillin/streptomycin, 40 &#181;g/mL fungizone, 40 ng/mL fibroblast growth factor 2 (FGF2), 20 ng/mL epidermal growth factor (EGF), and 2% B27 supplement.</li>
		<li>Pretreat 100-mm cell culture dishes with 2 mL of coating matrix containing type I collagen for 30 min at room temperature.</li>
	</ol>
	</li>
</ol>
2. Conventional Method
<ol>
	<li>Skin tissue pretreatment
	<ol>
		<li>Take 1.5 cm2 of skin tissue and wash it 1x with 10 mL of PBS; then, rinse it with 10 mL of 70% ethanol for 30 s and incubate it 2x with 10 mL of washing solution (PBS containing 2% penicillin and streptomycin), 5 min each. 
		NOTE: All washes are performed in 100-mm cell culture dishes inside a laminar flow hood.</li>
		<li>Trim the tissue with sterile scissors to remove the subcutaneous fat layer in a 100-mm cell culture dish and, then, weigh the skin tissue (the weight is 1 g in this protocol). 
		NOTE: Sufficient trimming is very crucial for the efficient separation of the epidermis from the dermis. The yellowish fat layer can be easily distinguished visually.</li>
		<li>Transfer the tissue to another 100-mm sterile dish with the dermis side down and, then, cut the skin tissue into 3- to 4-mm-wide strips using a scalpel blade. 
		NOTE: The dermis side with the fat layer is easily recognized visually.</li>
		<li>Add 10 mL of 2.5 mg/mL dispase solution to the skin tissues in a 100-mm culture dish and, then, incubate the dish overnight at 4 &#176;C (no more than 20 h). 
		NOTE: The amount of dispase solution can be calculated by using 10 mL of dispase solution for the digestion of each gram of tissue.</li>
	</ol>
	</li>
	<li>Separation of the epidermis from the skin tissue
	<ol>
		<li>On the second day, peel off the epidermis from the dermis using fine tweezers. 
		NOTE: If it is difficult to peel off the epidermis, the dispase digestion was not sufficient, which is usually due to insufficient trimming of the tissue. In this case, the tissue needs a longer incubation time.</li>
		<li>Mince the peeled epidermis with 500 &#181;L of cell culture medium into a tissue slurry using scalpel blades; then, resuspend it with 10 mL of 0.25% trypsin in a 50-mL tube and incubate it 20 min in a water bath at 37 &#176;C, with shaking.</li>
	</ol>
	</li>
	<li>Collection and culturing of primary cells
	<ol>
		<li>Neutralize the trypsin activity by adding an equal volume of neutralization solution (10 mL in this protocol).</li>
		<li>Dissociate the epidermal cells by pipetting the solution up and down 20x with a 10-mL serological pipette and pass the cell solution through a 100-&#181;m cell strainer to remove any residual tissue debris.</li>
		<li>Centrifuge the cell solution at 200 x g for 5 min after filtration; resuspend the cell pellet in neutralization medium for washing and, then, centrifuge it again at 200 x g to obtain the cell pellet.</li>
		<li>Resuspend the cell pellet in 10 mL of low-calcium, serum-free keratinocyte medium (SFM). Take 10 &#181;L of this solution to count the total cell number and, then, plate about 2 x 106 cells with 10 mL of SFM into 100-mm cell culture dishes pretreated with coating matrix (containing type I collagen). 
		NOTE: Coating is a necessary step for the conventional method.</li>
		<li>Change the culture medium every 2 d. 
		NOTE: Check the cell adhesion under a microscope before and after changing the culture medium.</li>
		<li>Passage the cells when they reach about 80% confluence. 
		NOTE: All culture dishes are pretreated with the coating matrix.</li>
	</ol>
	</li>
</ol>
3. The New Method
<ol>
	<li>Skin tissue pretreatment
	<ol>
		<li>Collect the tissue as described above (step 2.1) for the conventional method.</li>
		<li>Wash the skin tissue 1x with 10 mL of PBS and, then, weigh it in a sterile plastic container by an electronic scale (the weight is around 1 g in this protocol). 
		NOTE: The minimum weight of tissue needed for this protocol is 0.1 g, since it is difficult to obtain a sufficient number of cells if the tissue specimen used is too small. There is no maximum weight of tissue for this protocol, which ultimately depends on the handling capacity of the operator.</li>
		<li>Use forceps to rinse the skin tissue with 10 mL of 70% ethanol for 30 s.</li>
		<li>Incubate the tissue 2x with 10 mL of washing solution (prepared in step 2.1.1), for 5 min each time. 
		NOTE: All the washing steps noted above are performed in 100-mm cell culture dishes inside a laminar flow hood (a tissue culture hood).</li>
		<li>Transfer the tissue to another 100-mm cell culture sterile dish.</li>
		<li>Using scalpel blades, mince the tissue thoroughly into a tissue slurry.</li>
		<li>Add 200 &#181;L of PBS every 5 min to keep the tissues wet. 
		NOTE: Take around 15 min for steps 3.1.5 - 3.1.7. All the above steps are performed at room temperature.</li>
	</ol>
	</li>
	<li>Digestion of skin tissue
	<ol>
		<li>Transfer the homogenized tissue solution into a 50-mL tube. Add 10 mL of enzyme mixture for every 1 g of skin tissue. Mix the enzymes thoroughly with the homogenized tissues.</li>
		<li>Incubate the mixture with shaking in a water bath at 37 &#176;C for 1 h.</li>
		<li>Add a 1/5 volume of 0.25% trypsin (2.5 mL in this protocol) to the digestion mixture for another 30 min in a water bath at 37 &#176;C.</li>
		<li>Add DNase I solution to the enzyme mixture at a 1:100 (v/v) ratio (250 &#181;L in this protocol) and incubate it for 5 min at room temperature.</li>
	</ol>
	</li>
	<li>Collection and culturing of primary cells
	<ol>
		<li>Stop the digestion process by adding 12.5 mL of neutralization medium in a 1:1 ratio. Pipette the solution up and down for about 20x, using a 10-mL serological pipette to dissociate the cells.</li>
		<li>Filter the dissociated cells through a 100-&#181;m cell strainer to remove the tissue debris. Centrifuge the supernatant at 200 x g for 5 min. Observe the pellet at the bottom of the tube.</li>
		<li>Discard the supernatant and wash the cell pellet with 10 mL of neutralization medium, and centrifuge again at 200 x g for 5 min to collect the cells.</li>
		<li>Resuspend the cell pellet in 10 mL of inoculation medium (G-medium from step 1.2.5) with 10 &#181;M of Y-27632.</li>
		<li>Take 10 &#181;L of the solution to count the total cell number and, then, plate about 2 x 106 cells with 10 mL of G-medium into a 100-mm cell culture dish. 
		NOTE: The precoating step is not necessary for the new method, and no removal of the dermal layer is required either.</li>
		<li>After 3 d, replace the inoculation medium with low-calcium SFM medium. Change the culture medium every 2 d. 
		NOTE: Check the cell adhesion before and after changing the medium.</li>
		<li>Passage the cells when they reach about 80% confluence. 
		NOTE: If necessary, pretreat the cells with 0.05% trypsin for 2 min and wash the cells with PBS to remove contaminating dermal cells before trypsinizing the epidermal cells.</li>
	</ol>
	</li>
</ol>
4. Cell Passaging
<ol>
	<li>Remove the medium, wash the cells with PBS, and, then, add 2 mL of 0.05% trypsin (per each 100-mm dish).</li>
	<li>Incubate the cells in an incubator (37 &#176;C with 5% CO2) for 5 min.</li>
	<li>Check the cells using a microscope to make sure that all cells have detached from the culture dish.</li>
	<li>Add 8 mL of DMEM with 10% FBS to neutralize the enzymatic reaction and, then, collect the cells in a 15-mL tube.</li>
	<li>Centrifuge at 200 x g for 5 min to obtain the cell pellet.</li>
	<li>Remove the supernatant slowly and, then, resuspend the cell pellet with 10 mL of SFM medium and count the number of cells.</li>
	<li>Plate 1 x 106 cells with 10 mL of SFM into each 100-mm cell dish.</li>
	<li>Change the medium every 2 d.</li>
</ol>

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P., Park, C. J., Choudhary, I., Vogel, J. 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The authors have nothing to disclose.

Cultured primary HKCs have been widely utilized to treat wounds in clinics for more than three decades and, since that time, it has been always important to efficiently obtain sufficient numbers of cells for clinical applications in a timely manner. Therefore, in practice, the conventional isolation method, which requires the separation of the epidermis from the dermis, makes it difficult to meet these demands, due to the low yield of cells and the low ability to passage adult cells. Here, we describe a new simple method...

The goal was to develop a simple and efficient protocol to isolate primary human keratinocytes (HKCs) from adult tissues, especially for clinical applications. Skin epidermal stem cells, localized in the basal layer of the skin, possess a high potential to proliferate and differentiate and provide keratinocytes to maintain the functions of the skin1,2,3,4. HKCs isolated from skin tissues are widely used for skin tissue engineering and regeneration purposes, especially in the repair of damaged skin and in gene therapy for clinical applications5,6. The key issue for HKC-based applications is to efficiently isolate and expand large numbers of HKCs with high potential in vitro7,8. Although various research groups have developed methods to produce cultures of stem-like HKCs, these methods are sometimes time-consuming and complicated to perform and have other limitations, such as low cell yields and being limited by the type of skin specimen used9. For instance, the traditional method to isolate HKCs from skin tissues involves a two-step enzymatic digestion with a separation of the epidermis from the dermis6. That method usually works well for neonatal tissues, but it becomes very difficult when used to isolate cells from adult tissues.
Y-27632, an inhibitor of Rho-associated protein kinase (ROCK), has been reported to significantly enhance the efficiency of epidermal stem cell isolation and colony growth10,11,12. In a previous study, we discovered that Y-27632 facilitates the clonal growth of epidermal cells but reduces the yield of dermal cells by differentially controlling the expression of adhesion molecules13. We also established a new conditioned inoculation medium, called G-medium, which supports the growth and yield of primary epidermal cells. By combining G-medium with Y-27632, this novel method can spontaneously separate epidermal and dermal cells after enzyme digestion, thus removing the step of epidermis-dermis separation13,14. Based on previous reports, we now describe the detailed procedure of this new method to isolate HKCs from adult skin tissue.

<table border="0" cellpadding="0" cellspacing="0" style="width:1344px;" width="1342">
	<tbody>
		<tr height="23">
			<td height="23" style="height:23px;width:263px;">Countess automated cell counter</td>
			<td style="width:291px;">Invitrogen Inc.&#160;</td>
			<td style="width:264px;">C10227</td>
			<td style="width:527px;">Automatic cell counting&#160;</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">CO2 Incubator</td>
			<td>Thermo Scientific</td>
			<td>51026333</td>
			<td>For cell incubating</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">Sorvall ST 16R Centrifuge</td>
			<td>Thermo Scientific</td>
			<td>75004380</td>
			<td>Cell centrifuge</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">Constant Temperature Shaker</td>
			<td>Shanghai Boxun</td>
			<td>150036</td>
			<td>For water bath</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">Electronic Scale</td>
			<td>Harbin Zhonghui</td>
			<td>1171193</td>
			<td>For tissue weighing</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">Cell Culture Dish</td>
			<td>Eppendorf</td>
			<td>30702115</td>
			<td>For cell culture</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">50ml Centrifuge Tube</td>
			<td>KIRGEN</td>
			<td>171003</td>
			<td>For cell centrifuge</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">Cell Strainer</td>
			<td>Corning incorporated</td>
			<td>431792</td>
			<td>Cell filtration</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">Phosphate buffered solution</td>
			<td>Solarbio Life Science&#160;</td>
			<td>P1020-500</td>
			<td>Washing solution</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">DMEM</td>
			<td>Thermo Scientific</td>
			<td>C11995500</td>
			<td>Component of neutralization medium</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">Defined K-SFM</td>
			<td>Life Technologies</td>
			<td>10785-012</td>
			<td>Epidermal cells culture medium</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">Penicillin Streptomycin</td>
			<td>Thermo Scientific</td>
			<td>15140-122</td>
			<td>Antibiotics</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">Fetal Bovine Serum</td>
			<td>Biological Industries</td>
			<td>04-001-1AC5</td>
			<td>Component of neutralization medium</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">0.05% Trypsin</td>
			<td>Life Technologies</td>
			<td>25300-062</td>
			<td>For HKC dissociation</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">0.25% Trypsin&#160;</td>
			<td>Beijing Solarbio Science &#38; Technology</td>
			<td>T1350-100</td>
			<td>For HKC dissociation</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">Coating Matrix Kit</td>
			<td>Life Technologies</td>
			<td>R-011-K</td>
			<td>For coating matrix</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">Dispase</td>
			<td>Gibco</td>
			<td>17105-041</td>
			<td>For HKC isolation</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">Collagenase Type I</td>
			<td>Life Technologies</td>
			<td>17100-017</td>
			<td>For HKC isolation</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">Deoxyribonuclease I</td>
			<td>Sigma</td>
			<td>9003-98-9</td>
			<td>For HKC isolation</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">F12 Nutrient Mix, Hams</td>
			<td>Life Technologies</td>
			<td>31765035</td>
			<td>Component of G-medium</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">B27 Supplement</td>
			<td>Life Technologies</td>
			<td>17504044</td>
			<td>Growth factor in G-medium</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">FGF-2 Millipore</td>
			<td>Merck Biosciences</td>
			<td>341595</td>
			<td>Growth factor in G-medium</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">Y-27632</td>
			<td>Sigma-Aldrich</td>
			<td>Y0503</td>
			<td>ROCK inhibitor</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">Fungizone</td>
			<td>Gibco</td>
			<td>15290026</td>
			<td>Preparation for G-medium</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">EGF Recombinant Human Protein</td>
			<td>Gibco</td>
			<td>PHG0311</td>
			<td>Growth factor in G-medium</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">Cell Counting Kit-8</td>
			<td>Thermo Scientific</td>
			<td>NC9864731</td>
			<td>cell proliferation and cytotoxicity assays</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">Mouse Anti-Human Cytokeratin5</td>
			<td>Hewlett-Packard Development Company</td>
			<td>MA-20142</td>
			<td>For immunofluorescence staining to check differentiation marker of HKCs</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">Rabbit Anti-Human Loricrin</td>
			<td>Covance</td>
			<td>PRB-145p</td>
			<td>For immunofluorescence staining to check differentiation marker of HKCs</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">Mouse anti-human Vimentin</td>
			<td>Cell Signaling Technology</td>
			<td>3390</td>
			<td>For immunofluorescence staining of dermal fibroblasts</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">Integrin &#945;6(GOH3)</td>
			<td>Santa Cruz&#160;</td>
			<td>SC-19622</td>
			<td>flow cytometry analysis of HKCs</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:263px;">Rat IgG2a FITC</td>
			<td>Santa Cruz&#160;</td>
			<td>SC-2831</td>
			<td>negative control antibody of &#945;6-integrin&#160; in flow cytometry analysis&#160;</td>
		</tr>
	</tbody>
</table>

a simplified and efficient method to isolate primary human keratinocytes from adult skin tissue

Primary human keratinocytes isolated from fresh skin tissues and their expansion in vitro have been widely used for laboratory research and for clinical applications. The conventional isolation method of human keratinocytes involves a two-step sequential enzymatic digestion procedure, which has been proven to be inefficient in generating primary cells from adult tissues due to the low cell recovery rate and reduced cell viability. We recently reported an advanced method to isolate human primary epidermal progenitor cells from skin tissues that utilizes the Rho kinase inhibitor Y-27632 in the medium. Compared with the traditional protocol, this new method is simpler, easier, and less time-consuming, and increases epithelial stem cell yield and enhances their stem cell characteristics. Moreover, the new methodology does not require the separation of the epidermis from the dermis, and, therefore, is suitable for isolating cells from different types of adult tissues. This new isolation method overcomes the major shortcomings of conventional methods and is more suitable for producing large numbers of epidermal cells with high potency both for laboratory and for clinical applications. Here, we describe the new method in detail.

Schematic diagrams of the new method (Figure 1A) and the conventional method (Figure 1B) are presented in Figure 1. The conventional method is a two-step digestion, which requires a 2-day procedure. By contrast, the new method is a one-step digestion, which takes around 3 hours to perform. Importantly, the one-step new method can obtain two populations (epidermal and dermal cells) at the same time, w...

Watch this Scientific Journal Video about A Simplified and Efficient Method to Isolate Primary Human Keratinocytes from Adult Skin Tissue at JoVE.com

A Simplified and Efficient Method to Isolate Primary Human Keratinocytes from Adult Skin Tissue

Here we present a protocol to efficiently isolate primary human keratinocytes from adult skin tissues. This method simplifies the conventional procedure by using the ROCK Inhibitor Y-27632 in the inoculation medium to spontaneously separate epidermal cells from dermal cells.

Primary human keratinocytes isolated from fresh skin tissues and their expansion in vitro have been widely used for laboratory research and for clinical ...

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JoVE Journal

Developmental Biology

10.0K Views.  Shandong University. Here we present a protocol to efficiently isolate primary human keratinocytes from adult skin tissues. This method simplifies the conventional procedure by using the ROCK Inhibitor Y-27632 in the inoculation medium to spontaneously separate epidermal cells from dermal cells.

Video: A Simplified and Efficient Method to Isolate Primary Human Keratinocytes from Adult Skin Tissue

Isolation and Quantitative Immunocytochemical Characterization of Primary Myogenic Cells and Fibroblasts from Human Skeletal Muscle

The repair and regeneration of skeletal muscle requires the action of satellite cells, which are the resident muscle stem cells. These can be isolated from human muscle biopsy samples using enzymatic digestion and their myogenic properties studied in culture. Quantitatively, the two main adherent cell types obtained from enzymatic digestion are: (i) the satellite cells (termed myogenic cells or muscle precursor cells), identified initially as CD56+ and later as CD56+/desmin+ cells and (ii) muscle-derived fibroblasts, identified as CD56&#8211; and TE-7+. Fibroblasts proliferate very efficiently in culture and in mixed cell populations these cells may overrun myogenic cells to dominate the culture. The isolation and purification of different cell types from human muscle is thus an important methodological consideration when trying to investigate the innate behavior of either cell type in culture. Here we describe a system of sorting based on the gentle enzymatic digestion of cells using collagenase and dispase followed by magnetic activated cell sorting (MACS) which gives both a high purity (&#62;95% myogenic cells) and good yield (~2.8 x 106 &#177; 8.87 x 105 cells/g tissue after 7 days in vitro) for experiments in culture. This approach is based on incubating the mixed muscle-derived cell population with magnetic microbeads beads conjugated to an antibody against CD56 and then passing cells though a magnetic field. CD56+ cells bound to microbeads are retained by the field whereas CD56&#8211; cells pass unimpeded through the column. Cell suspensions from any stage of the sorting process can be plated and cultured. Following a given intervention, cell morphology, and the expression and localization of proteins including nuclear transcription factors can be quantified using immunofluorescent labeling with specific antibodies and an image processing and analysis package.

The main adherent cell types derived from human muscle are myogenic cells and fibroblasts. Here, cell populations are enriched using magnetic-activated cell sorting based on the CD56 antigen. Subsequent immunolabelling with specific antibodies and use of image analysis techniques allows quantification of cytoplasmic and nuclear characteristics in individual cells.

The repair and regeneration of skeletal muscle requires the action of satellite cells, which are the resident muscle stem cells. These can be isolated ...

Transfection, Selection, and Colony-picking of Human Induced Pluripotent Stem Cells TALEN-targeted with a GFP Gene into the AAVS1 Safe Harbor

Targeted transgene addition can provide persistent gene expression while circumventing the gene silencing and insertional mutagenesis caused by viral vector mediated random integration. This protocol describes a universal and efficient transgene targeted addition platform in human iPSCs based on utilization of validated open-source TALENs and a gene-trap-like donor to deliver transgenes into a safe harbor locus. Importantly, effective gene editing is rate-limited by the delivery efficiency of gene editing vectors. Therefore, this protocol first focuses on preparation of iPSCs for transfection to achieve high nuclear delivery efficiency. When iPSCs are dissociated into single cells using a gentle-cell dissociation reagent and transfected using an optimized program, >50% cells can be induced to take up the large gene editing vectors. Because the AAVS1 locus is located in the intron of an active gene (PPP1R12C), a splicing acceptor (SA)-linked puromycin resistant gene (PAC) was used to select targeted iPSCs while excluding random integration-only and untransfected cells. This strategy greatly increases the chance of obtaining targeted clones, and can be used in other active gene targeting experiments as well. Two weeks after puromycin selection at the dose adjusted for the specific iPSC line, clones are ready to be picked by manual dissection of large, isolated colonies into smaller pieces that are transferred to fresh medium in a smaller well for further expansion and genetic and functional screening. One can follow this protocol to readily obtain multiple GFP reporter iPSC lines that are useful for in vivo and in vitro imaging and cell isolation.

TALEN-mediated gene editing at the safe harbor AAVS1 locus enables high-efficiency transgene addition in human iPSCs. This protocol describes the procedures for preparing iPSCs for TALEN and donor vector delivery, transfecting iPSCs, and selecting and isolating iPSC clones to achieve targeted integration of a GFP gene to generate reporter lines.

Targeted transgene addition can provide persistent gene expression while circumventing the gene silencing and insertional mutagenesis caused by viral ...

A Quick and Efficient Method for the Purification of Endoderm Cells Generated from Human Embryonic Stem Cells

The differentiation capabilities of pluripotent stem cells such as embryonic stem cells (ESCs) allow a potential therapeutic application for cell replacement therapies. Terminally differentiated cell types could be used for the treatment of various degenerative diseases. In vitro differentiation of these cells towards tissues of the lung, liver and pancreas requires as a first step the generation of definitive endodermal cells. This step is rate-limiting for further differentiation towards terminally matured cell types such as insulin-producing beta cells, hepatocytes or other endoderm-derived cell types. Cells that are committed towards the endoderm lineage highly express a multitude of transcription factors such as FOXA2, SOX17, HNF1B, members of the GATA family, and the surface receptor CXCR4. However, differentiation protocols are rarely 100% efficient. Here, we describe a method for the purification of a CXCR4+ cell population after differentiation into the DE by using magnetic microbeads. This purification additionally removes cells of unwanted lineages. The gentle purification method is quick and reliable and might be used to improve downstream applications and differentiations.

Here, we describe a method for the purification of differentiated human embryonic stem cells that are committed towards the definitive endoderm for the improvement of downstream applications and further differentiations.

The differentiation capabilities of pluripotent stem cells such as embryonic stem cells (ESCs) allow a potential therapeutic application for cell ...

Epigenetic Conversion as a Safe and Simple Method to Obtain Insulin-secreting Cells from Adult Skin Fibroblasts

Regenerative medicine requires new, fully functional cells that are delivered to patients in order to repair degenerated or damaged tissues. When such cells are not readily available, they can be obtained using different approaches that include, among the many, reprogramming and trans-differentiation, with advantages and limitations that are specific of the different techniques. Here a new strategy for the conversion of an adult mature fibroblast into an insulin-secreting cell, arbitrarily designated as epigenetic converted cells (EpiCC), is described. The method has been developed, based on the increasing understanding of the mechanisms controlling epigenetic regulation of cell fate and differentiation. In particular, the first step uses an epigenetic modifier, namely 5-aza-cytidine, to drive adult cells into a "highly permissive" state. It then takes advantage of this brief and reversible window of epigenetic plasticity, to re-address cells toward a different lineage. The approach is designated "epigenetic cell conversion". It is a simple and robust way to obtain an efficient, controlled and stable cellular inter-lineage switch. Since the protocol does not involve the use of any gene transfection, it is free of viral vectors and does not involve a stable pluripotent state, it is highly promising for translational medicine applications.

Here, a new method that allows the conversion of adult skin fibroblasts into insulin-secreting cells is presented. This technique is based on epigenetic conversion, does not involve the use of retroviral vectors nor the acquisition of a stable pluripotent state. It is therefore highly promising for translational medicine applications.

Regenerative medicine requires new, fully functional cells that are delivered to patients in order to repair degenerated or damaged tissues. When such ...

Isolating Hair Follicle Stem Cells and Epidermal Keratinocytes from Dorsal Mouse Skin

The hair follicle (HF) is an ideal system for studying the biology and regulation of adult stem cells (SCs). This dynamic mini organ is replenished by distinct pools of SCs, which are located in the permanent portion of the HF, a region known as the bulge. These multipotent bulge SCs were initially identified as slow cycling label retaining cells; however, their isolation has been made feasible after identification of specific cell markers, such as CD34 and keratin 15 (K15). Here, we describe a robust method for isolating bulge SCs and epidermal keratinocytes from mouse HFs utilizing fluorescence activated cell-sorting (FACS) technology. Isolated hair follicle SCs (HFSCs) can be utilized in various in vivo grafting models and are a valuable in vitro model for studying the mechanisms that govern multipotency, quiescence and activation.

An ideal model for studying adult stem cell biology is the mouse hair follicle. Here we present a protocol for isolating different populations of hair follicles stem cells and epidermal keratinocytes, employing enzymatic digestion of mouse dorsal skin followed by FACS analysis.

The hair follicle (HF) is an ideal system for studying the biology and regulation of adult stem cells (SCs). This dynamic mini organ is replenished by ...

An Efficient Method to Obtain Dedifferentiated Fat Cells

Tissue engineering and cell therapy hold great promise clinically. In this regard, multipotent cells, such as mesenchymal stem cells (MSCs), may be used therapeutically, in the near future, to restore function to damaged organs. Nevertheless, several technical issues, including the highly invasive procedure of isolating MSCs and the inefficiency surrounding their amplification, currently hamper the potential clinical use of these therapeutic modalities. Herein, we introduce a highly efficient method for the generation of dedifferentiated fat cells (DFAT), MSC-like cells. Interestingly, DFAT cells can be differentiated into several cell types including adipogenic, osteogenic, and chondrogenic cells. Although other groups have previously presented various methods for generating DFAT cells from mature adipose tissue, our method allows us to produce DFAT cells more efficiently. In this regard, we demonstrate that DFAT culture medium (DCM), supplemented with 20% FBS, is more effective in generating DFAT cells than DMEM, supplemented with 20% FBS. Additionally, the DFAT cells produced by our cell culture method can be redifferentiated into several tissue types. As such, a very interesting and useful model for the study of tissue dedifferentiation is presented.

We have modified the conditions for DFAT cell generation and provide herein information regarding the use of an improved growth medium for the production of these cells.

Tissue engineering and cell therapy hold great promise clinically. In this regard, multipotent cells, such as mesenchymal stem cells (MSCs), may be used ...

Isolation and Expansion of Mesenchymal Stem/Stromal Cells Derived from Human Placenta Tissue

Mesenchymal stem/stromal cells (MSC) are promising candidates for use in cell-based therapies. In most cases, therapeutic response appears to be cell-dose dependent. Human term placenta is rich in MSC and is a physically large tissue that is generally discarded following birth. Placenta is an ideal starting material for the large-scale manufacture of multiple cell doses of allogeneic MSC. The placenta is a fetomaternal organ from which either fetal or maternal tissue can be isolated. This article describes the placental anatomy and procedure to dissect apart the decidua (maternal), chorionic villi (fetal), and chorionic plate (fetal) tissue. The protocol then outlines how to isolate MSC from each dissected tissue region, and provides representative analysis of expanded MSC derived from the respective tissue types. These methods are intended for pre-clinical MSC isolation, but have also been adapted for clinical manufacture of placental MSC for human therapeutic use.

Herein we describe methods for the dissection of fetal and maternal tissues from human term placenta, followed by isolation and expansion of mesenchymal stem/stromal cells (MSC) from these tissues.

Mesenchymal stem/stromal cells (MSC) are promising candidates for use in cell-based therapies. In most cases, therapeutic response appears to be cell-dose ...

Generation and Culturing of Primary Human Keratinocytes from Adult Skin

The main function of keratinocytes is to provide the structural integrity of the epidermis, thereby maintaining a mechanical barrier to the outside world. In addition, keratinocytes play an essential role in the initiation, maintenance, and regulation of epidermal immune responses by being part of the innate immune system responding to antigenic stimuli in a fast, nonspecific manner. Here, we describe a protocol for isolation of primary human keratinocytes from adult skin, and demonstrate that these cells respond to calcium-induced terminal differentiation, as measured by an increased expression of the differentiation marker involucrin. In addition, we show that the isolated keratinocytes are responsive to IL-1&#946;-induced activation of intracellular signaling pathways as measured by the activation of the p38 MAPK pathway. Taken together, we describe a method for isolation and culturing of primary human keratinocytes from adult skin. Because the keratinocytes are the predominant cell type in the epidermis, this method is useful to study molecular mechanisms in cutaneous biology in vitro.

The human skin acts as a first line of defense against the external environment. We present a method for isolating primary human keratinocytes from adult skin. These isolated keratinocytes are useful in numerous experimental setups, and are a highly suitable model for studying molecular mechanisms in cutaneous biology in vitro.

The main function of keratinocytes is to provide the structural integrity of the epidermis, thereby maintaining a mechanical barrier to the outside world. ...

The Isolation and Culture of Primary Epicardial Cells Derived from Human Adult and Fetal Heart Specimens

The epicardium, an epithelial cell layer covering the myocardium, has an essential role during cardiac development, as well as in the repair response of the heart after ischemic injury. When activated, epicardial cells undergo a process known as epithelial to mesenchymal transition (EMT) to provide cells to the regenerating myocardium. Furthermore, the epicardium contributes via secretion of essential paracrine factors. To fully appreciate the regenerative potential of the epicardium, a human cell model is required. Here we outline a novel cell culture model to derive primary epicardial derived cells (EPDCs) from human adult and fetal cardiac tissue. To isolate EPDCs, the epicardium is dissected from the outside of the heart specimen and processed into a single cell suspension. Next, EPDCs are plated and cultured in EPDC medium containing the ALK 5-kinase inhibitor SB431542 to maintain their epithelial phenotype. EMT is induced by stimulation with TGF&#946;. This method enables, for the first time, the study of the process of human epicardial EMT in a controlled setting, and facilitates gaining more insight in the secretome of EPDCs that may aid heart regeneration. Furthermore, this uniform approach allows for direct comparison of human adult and fetal epicardial behavior.

The epicardium plays a crucial role in the development and repair of the heart by providing cells and growth factors to the myocardial wall. Here, we describe a method to culture human primary epicardial cells that enables the study and comparison of their developmental and adult characteristics.

The epicardium, an epithelial cell layer covering the myocardium, has an essential role during cardiac development, as well as in the repair response of ...

A Direct and Simple Method to Assess Drosophila melanogaster's Viability from Embryo to Adult

In Drosophila melanogaster, viability assays are used to determine the fitness of certain genetic backgrounds. Allelic variations can result in partial or complete loss of viability at different stages of development. Our lab has developed a method to assess viability in Drosophila from embryo to fully mature adult. The method relies on quantifying the number of progeny present at different stages during development, starting with hatched embryos. After embryos have been quantified, additional stages are counted, including L1/L2, pupae, and mature adults. After all stages have been examined, a statistical analysis such as the chi-square test is used to determine if there is a significant difference between the starting number of progeny (hatched embryos) and later stages culminating in the observed number of adults, thus rejecting or accepting the null hypothesis (that the number of hatched embryos will be equal to the number of larvae, pupae, and adults recorded throughout the stages of development). The primary advantage of this assay is its simplicity and accuracy, as it does not require an embryo rinse to transfer them to the food vial, avoiding losses from technical errors. Although the protocol described here does not directly examine L2/L3 larvae, additional steps can be added to account for these. Comparing the number of hatched embryos, L1, pupae, and adults can help determine if viability was compromised during the L2/L3 stages for further studies (the use of colored food helps with visual identification of larvae). Overall, this method can help Drosophila researchers and educators determine when viability is compromised during the fly life cycle. Routine assessment of stocks using this assay can prevent accumulation of secondary mutations that may affect the phenotype of the originally isolated mutant, especially if the original mutations affect fitness. For this reason, our lab maintains multiple copies of each of our Dm ime4 alleles and routinely checks the purity of each stock with this method in addition to other molecular analyses.&#160;

A Direct and Simple Method to Assess Drosophila melanogaster's Viability from Embryo to Adult

This protocol is designed to assess the viability of Drosophila at every developmental stage, from embryo to adult. The method can be used to determine and compare the viability of different genotypes or growth conditions.

In Drosophila melanogaster, viability assays are used to determine the fitness of certain genetic backgrounds. Allelic variations can result in partial or ...