This work was supported by grants from the National Natural Science Foundation of China (grant numbers 81903189 and 82073418) and the Science and Technology Foundation of Guangzhou (grant number 202102020025).

This study was approved by the institutional review board of the Dermatology Hospital, Southern Medical University (2020081). Informed patient consent was obtained before tissues were collectedfrom the individuals.
1. Preparation
NOTE: The following procedures should be performed in a sterile environment under a biological safety cabinet.
<ol>
	<li>Prepare complete culture medium by adding 10% fetal bovine serum (FBS) and 1% penicillin-streptomycin-amphotericin B solution (PSA) to high-glucose Dulbecco&#39;s modified Eagle medium (DMEM).</li>
	<li>Prepare phosphate-buffered saline solution (PBS) with PSA by adding 1% PSA into 1x PBS. Prepare PBS with FBS by adding 1% FBS to 1x PBS.</li>
	<li>Prepare several sterilized scissors, forceps, and scalpels by autoclaving.</li>
</ol>
2. Obtaining removed tissues
<ol>
	<li>Obtain tissues from keloid patients through surgery. Collect the fresh keloid tissues in a sterile packing bag or sterile centrifuge tube, and transfer them to a biological safety cabinet in the laboratory as soon as possible. 
	&#8203;NOTE: In this protocol, the size of the acquired keloid tissue was approximately ~20 x 20 x 10 mm3, and the size may vary depending on the surgery.</li>
</ol>
3. Isolation
<ol>
	<li>Take out the keloid tissue using sterile tweezers, and place it in a 50 mL sterile centrifuge tube containing 10-25 mL of PBS with 1% PSA for 10 min. Then, prepare a 6-well plate, and add 4 mL of PBS supplemented with 1% PSA to each well. Take out the tissue using sterilized tweezers, and wash it twice with PBS supplemented with 1% PSA. Using sterile forceps, transfer the tissue sequentially from one well to the next.</li>
	<li>Remove the adipose andepidermis layers using surgical scissors or a surgical scalpel, and leave the dermis layer untouched. Trim and dissect the dermis layer into 3-5 mm2 pieces with scissors, transfer these pieces using sterile forceps to the next well, and wash them in PBS with 1% PSA solution again.</li>
</ol>
4. Culture
<ol>
	<li>Place the dermis tissue pieces in Petri dishes using sterilized forceps; ensure that the number of pieces is between 10 and 30 and the distance between each piece is &#62;5 mm. Put the Petri dishes upside down in a 5% CO2 incubator at 37 &#176;C for 30-60 min until the pieces of tissues dry a little and stick to the Petri dish. Then, add DMEM supplemented with 10% FBS and 1% PSA, and carefully place the Petri dishes into a 5% CO2 incubator at 37 &#176;C. 
	NOTE: Fibroblasts are a morphologically and functionally heterogeneous cell population. Considering this complexity, the isolation and culture steps should be performed with care; select the keloid dermal tissue pieces evenly, and mix these pieces well before placing them in the Petri dish.</li>
	<li>After 3 days, replace half of the supernatant with a complete culture medium. Change the culture medium every 2-3 days. Observe the fibroblasts under a microscope at 40x magnification every day. 
	NOTE: All the steps should be performed gently. Do not move the Petri dish for 2 days after isolating, as the tissue pieces take time to adhere to the Petri dishes.</li>
	<li>When the fibroblasts growing around the tissue pieces reach approximately 90% confluency, remove the tissue pieces and the culture medium. Wash the fibroblasts with sterile 1x PBS, and add 2 mL of sterile 1x trypsin-EDTA solution to the plates.Incubate the cells for approximately ~3-5 min at 37 &#176;C in a humidified 5% CO2 incubator.Gently tap the culture dish, and observe it under a microscope. When the majority of the cells detach from the plate, add 2 mL of complete medium to end the digestion process.</li>
	<li>Transfer the cell suspension to a 15 mL sterile centrifuge tube, and centrifuge the tube at 300 &#215; g for 3 min at room temperature. Discard the supernatant carefully, and resuspend the cell pellet in complete medium.Seed the fibroblasts into a 9 cm cell culture dish, and incubate at 37 &#176;C in a humidified 5% CO2 incubator.</li>
</ol>
5. Maintenance and preservation
<ol>
	<li>Approximately 3-4 days later, when the fibroblasts have grown to 80% confluency, repeat steps 4.2-4.4, and passage the fibroblasts at a ratio of 1:3. Use the passaged fibroblasts for further experiments. 
	&#8203;NOTE: The fibroblast culture should be stopped after 10 passages, because the cells may start to show changed characteristics compared to the original cells.</li>
	<li>Cryopreserve the passaged cells of P1-P3 in liquid nitrogen for further usage.
	<ol>
		<li>Repeat steps 4.2-4.3. Transfer the cell suspension to a 15 mL sterile centrifuge tube, and centrifuge the tube for 3 min at 300 &#215; g. Discard the supernatant carefully, resuspend the cell pellet in 1 mL of cell freezing medium containing 90% FBS and 10% DMSO, and transfer the suspension into cell cryotubes.</li>
		<li>Move the cells into a frozen box, and then put the frozen box in a &#8722;80 &#176;C freezer. After 1 day, transfer the cells to liquid nitrogen for long-term preservation.</li>
	</ol>
	</li>
</ol>
6. Identification of fibroblasts by immunofluorescence staining
<ol>
	<li>Place round coverslips in a 24-well plate, and culture the passaged fibroblasts at a concentration of 1 &#215; 104 cells/well. When the fibroblasts reach 60% confluency, remove the culture medium. Add 1 mL of 4% paraformaldehyde to fix the fibroblasts for 20 min at room temperature, and wash 3x with PBS for 1 min each time. 
	NOTE: Count the number of cells by using a hemocytometer slide under a microscope or an automatic cell counter.</li>
	<li>Remove the PBS, incubate with 0.5% Triton X-100 for 20 min for the permeabilization of cell membranes, and then wash 3x with PBS for 1 min each time. Add PBS with 0.5% bovine serum albumin, and soak for 30 min. Then, remove it, and add the PDGFR-&#945;/vimentin antibody diluted in antibody diluent at 1:1,000. Incubate overnight at 4 &#176;C.</li>
	<li>The next day, remove the primary antibody, wash the cells 3x with PBS for 3 min, and add the secondary antibody Alexa Fluor-555 goat anti-rabbit IgG diluted with antibody diluent at 1:200 to soak for 1 h.</li>
	<li>Remove the secondary antibody, and wash the cells 3x with PBS. Take out the round coverslips using forceps, put them on glass slides, and add 50 &#181;L of 5 &#181;g/mL 4&#39;,6-diamidino-2-phenylindole (DAPI) solution to stain the cellular nuclei. Keep the samples in a wet, dark box, and observe them under a laser confocal fluorescence microscope. 
	&#8203;NOTE: Add a negative control group without a primary antibody but with a secondary antibody to exclude nonspecific staining.</li>
</ol>
7. Identification of fibroblasts by flow cytometry
<ol>
	<li>Collect the cell pellet into a 1.5 mL sterile centrifuge tube, and resuspend with 50 &#181;L of PBS containing 1% FBS. Incubate with anti-CD90 for 30 min in the dark, and add an anti-IgG isotype control to the control group. Then, add 200 &#181;L of PBS containing 1% FBS, and centrifuge the tube for 10 min at 300 &#215; g at 4 &#176;C.</li>
	<li>Remove the supernatant, and add 200 &#181;L of PBS containing 1% FBS. Resuspend and filter the suspension through a cell strainer (70 mesh). Add a 5 &#181;g/mL stock solution of DAPI at 1:100 to the filtrate, and then acquire the results by flow cytometry. Set the forward scatter (FSC) as the abscissa and the side scatter (SSC) as the ordinate, and circle the main cell population. Select the cell population, and set the phycoerythrin as the abscissa and the count as the ordinate for analysis.</li>
</ol>

<ol>
	<li>Zhu, Y. Q., 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=Genome-wide+analysis+of+Chinese+keloid+patients+identifies+novel+causative+genes.">Genome-wide analysis of Chinese keloid patients identifies novel causative genes.</a> Annals Of Translational Medicine. 10 (16), 883 (2022).</li><li>Feng, F., 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=Biomechanical+regulatory+factors+and+therapeutic+targets+in+keloid+fibrosis.">Biomechanical regulatory factors and therapeutic targets in keloid fibrosis.</a> Frontiers in Pharmacology. 13, 906212 (2022).</li><li>Cohen, A. J., Nikbakht, N., Uitto, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Keloid+disorder:+Genetic+basis,+gene+expression+profiles,+and+immunological+modulation+of+the+fibrotic+processes+in+the+skin.">Keloid disorder: Genetic basis, gene expression profiles, and immunological modulation of the fibrotic processes in the skin.</a> Cold Spring Harbor Perspectives in Biology. , (2022).</li><li>Wang, W., 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=Current+advances+in+the+selection+of+adjuvant+radiotherapy+regimens+for+keloid.">Current advances in the selection of adjuvant radiotherapy regimens for keloid.</a> Frontiers in Medicine. 9, 1043840 (2022).</li><li>Ghadiri, S. J., Kloczko, E., Flohr, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Topical+treatments+in+the+management+of+keloids+and+hypertrophic+scars:+A+critically+appraised+topic.">Topical treatments in the management of keloids and hypertrophic scars: A critically appraised topic.</a> British Journal of Dermatology. 187 (6), 855-856 (2022).</li><li>Neves, L. M. G., Wilgus, T. A., Bayat, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vitro,+ex+vivo,+and+in+vivo+approaches+for+investigation+of+skin+scarring:+Human+and+animal+models.">In vitro, ex vivo, and in vivo approaches for investigation of skin scarring: Human and animal models.</a> Advances in Wound Care. 12 (2), 97-116 (2023).</li><li>Supp, D. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+models+for+studies+of+keloid+scarring.">Animal models for studies of keloid scarring.</a> Advances in Wound Care. 8 (2), 77-89 (2019).</li><li>K&#252;nzel, S. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrasonic-augmented+primary+adult+fibroblast+isolation.">Ultrasonic-augmented primary adult fibroblast isolation.</a> Journal of Visualized Experiments. (149), e59858 (2019).</li><li>He, 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=An+improved+explants+culture+method:+Sustainable+isolation+of+keloid+fibroblasts+with+primary+characteristics.">An improved explants culture method: Sustainable isolation of keloid fibroblasts with primary characteristics.</a> Journal of Cosmetic Dermatology. 21 (12), 7131-7139 (2022).</li><li>Philippeos, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spatial+and+single-cell+transcriptional+profiling+identifies+functionally+distinct+human+dermal+fibroblast+subpopulations.">Spatial and single-cell transcriptional profiling identifies functionally distinct human dermal fibroblast subpopulations.</a> Journal of Investigative Dermatology. 138 (4), 811-825 (2018).</li><li>Li, 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=Hydrogen+sulfide+suppresses+skin+fibroblast+proliferation+via+oxidative+stress+alleviation+and+necroptosis+inhibition.">Hydrogen sulfide suppresses skin fibroblast proliferation via oxidative stress alleviation and necroptosis inhibition.</a> Medicine and Cellular Longevity. 2022, 7434733 (2022).</li><li>Zhou, B. 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=Nintedanib+inhibits+keloid+fibroblast+functions+by+blocking+the+phosphorylation+of+multiple+kinases+and+enhancing+receptor+internalization.">Nintedanib inhibits keloid fibroblast functions by blocking the phosphorylation of multiple kinases and enhancing receptor internalization.</a> Acta Pharmacologica Sinica. 41 (9), 1234-1245 (2020).</li><li>Wang, X. M., Liu, X. M., Wang, Y., Chen, Z. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Activating+transcription+factor+3+(ATF3)+regulates+cell+growth,+apoptosis,+invasion+and+collagen+synthesis+in+keloid+fibroblast+through+transforming+growth+factor+beta+(TGF-beta)/SMAD+signaling+pathway.">Activating transcription factor 3 (ATF3) regulates cell growth, apoptosis, invasion and collagen synthesis in keloid fibroblast through transforming growth factor beta (TGF-beta)/SMAD signaling pathway.</a> Bioengineered. 12 (1), 117-126 (2021).</li><li>Sato, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Conditioned+medium+obtained+from+amnion-derived+mesenchymal+stem+cell+culture+prevents+activation+of+keloid+fibroblasts.">Conditioned medium obtained from amnion-derived mesenchymal stem cell culture prevents activation of keloid fibroblasts.</a> Plastic and Reconstructive Surgery. 141 (2), 390-398 (2018).</li><li>Li, 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=Long-term+explant+culture:+An+improved+method+for+consistently+harvesting+homogeneous+populations+of+keloid+fibroblasts.">Long-term explant culture: An improved method for consistently harvesting homogeneous populations of keloid fibroblasts.</a> Bioengineered. 13 (1), 1565-1574 (2022).</li><li>Wang, Q., 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=Altered+glucose+metabolism+and+cell+function+in+keloid+fibroblasts+under+hypoxia.">Altered glucose metabolism and cell function in keloid fibroblasts under hypoxia.</a> Redox Biology. 38, 101815 (2021).</li><li>Fan, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single-cell+transcriptome+integration+analysis+reveals+the+correlation+between+mesenchymal+stromal+cells+and+fibroblasts.">Single-cell transcriptome integration analysis reveals the correlation between mesenchymal stromal cells and fibroblasts.</a> Frontiers in Genetics. 13, 798331 (2022).</li><li>Yao, 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=Temporal+control+of+PDGFR&#945;+regulates+the+fibroblast-to-myofibroblast+transition+in+wound+healing.">Temporal control of PDGFR&#945; regulates the fibroblast-to-myofibroblast transition in wound healing.</a> Cell Reports. 40 (7), 111192 (2022).</li><li>Domdey, 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=Consecutive+dosing+of+UVB+irradiation+induces+loss+of+ABCB5+expression+and+activation+of+EMT+and+fibrosis+proteins+in+limbal+epithelial+cells+similar+to+pterygium+epithelium.">Consecutive dosing of UVB irradiation induces loss of ABCB5 expression and activation of EMT and fibrosis proteins in limbal epithelial cells similar to pterygium epithelium.</a> Stem Cell Research. 40, 102936 (2022).</li><li>Lin, Z., 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=Renal+tubular+epithelial+cell+necroptosis+promotes+tubulointerstitial+fibrosis+in+patients+with+chronic+kidney+disease.">Renal tubular epithelial cell necroptosis promotes tubulointerstitial fibrosis in patients with chronic kidney disease.</a> FASEB Journal. 36 (12), e22625 (2022).</li><li>Korosec, 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=Lineage+identity+and+location+within+the+dermis+determine+the+function+of+papillary+and+reticular+fibroblasts+in+human+skin.">Lineage identity and location within the dermis determine the function of papillary and reticular fibroblasts in human skin.</a> Journal of Investigative Dermatology. 139 (2), 342-351 (2019).</li></ol>

There are no conflicts of interest to declare.

Obtaining primary fibroblasts from keloid tissues is a critical basis for further research. Up until now, there have been two methods for acquiring primary fibroblasts: enzyme digestion and explant culture11,12,13,14. However, both traditional methods have limitations, such as susceptibility to contamination, mixing with other types of cells, a long culture period, and a low rate of success<sup...

Keloid, a fibroproliferative disease, manifests as the continuous growth of plaques that often invade the surrounding normal skin without self-limitation and cause various degrees of itching, pain, and cosmetic and psychological burdens for patients1. Fibroblasts, the primary cells involved in keloids, play an essential role in the formation and development of this disease through excessive proliferation, redundant extracellular matrix production, and disorganized collagens2,3. However, the underlying pathogenesis remains unclear, and an effective therapeutic method for keloid is still lacking; therefore, there is an urgent need for further research4,5.
As there is no ideal animal model for keloid research in vivo6,7,building an in vitro model by acquiring primary fibroblasts from keloid tissues can offer feasibility and reliability for keloid research2,6. Primary cells are those derived directly from living tissue, and it is generally recognized that these cells can more closely resemble the physiological state and genetic background of multiple individuals compared with cell lines8,9. Culturing primary cells provides a powerful means to study the growth and metabolism of cells, as well as other cell phenotypes.
At present, there are two methods for acquiring primary fibroblasts: enzyme digestion and explant culture. However, several obstacles have been identified to obtaining primary fibroblasts, such as the risk of contamination by various bacteria or fungi, mixing with other types of cells that are not easily removed, the long period of the culture cycle, the subsequent changes to the cell characteristics compared to the original cells, and so on9. Therefore, developing a feasible and effective process for obtaining primary fibroblasts is the foundation for further studies and applications.This study describes an optimized protocol for extracting primary fibroblasts from keloid tissues that can effectively and steadily provide pure and viable fibroblasts.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>1.5 mL sterile centrifuge tube</td>
			<td>JETBIOFIL</td>
			<td>CFT002015</td>
			<td></td>
		</tr>
		<tr>
			<td>15 mL sterile centrifuge tube</td>
			<td>JETBIOFIL</td>
			<td>8076</td>
			<td></td>
		</tr>
		<tr>
			<td>4% polyformaldehyde</td>
			<td>Beyotime Biotechnology</td>
			<td>P0099</td>
			<td>Cell fixation</td>
		</tr>
		<tr>
			<td>50 mL sterile centrifuge tube</td>
			<td>JETBIOFIL</td>
			<td>8081</td>
			<td>Put keloid tissue</td>
		</tr>
		<tr>
			<td>Alexa Fluor-555 goat anti-rabbit IgG&#160;</td>
			<td>Abcam</td>
			<td>Alexa&#160;Fluor&#160;555&#160;</td>
			<td>second antibody for immunofluorescence staining assay</td>
		</tr>
		<tr>
			<td>Anti human CD90</td>
			<td>BioLegend</td>
			<td>B301002</td>
			<td>Identify the purity of fibroblasts</td>
		</tr>
		<tr>
			<td>Antibody diluent</td>
			<td>Beyotime Biotechnology</td>
			<td>P0262</td>
			<td></td>
		</tr>
		<tr>
			<td>Biological safety cabinet&#160;</td>
			<td>Thermo Scientific</td>
			<td>1300 series A2</td>
			<td>Isolation and culture cells</td>
		</tr>
		<tr>
			<td>Bovine serum albumin</td>
			<td>aladdin</td>
			<td>B265993</td>
			<td>Blocking for immunofluorescence staining assay</td>
		</tr>
		<tr>
			<td>Carbon dioxide incubator</td>
			<td>ESCO</td>
			<td>CCL-170B-8</td>
			<td>Using for culturing cells</td>
		</tr>
		<tr>
			<td>Cell cryotubes</td>
			<td>Corning</td>
			<td>43513</td>
			<td>Store the cells in low temperature</td>
		</tr>
		<tr>
			<td>centrifugal machine</td>
			<td>Thermo Fisher</td>
			<td>ST 16R</td>
			<td>Discard supernatant&#160;</td>
		</tr>
		<tr>
			<td>DAPI</td>
			<td>Beyotime Biotechnology</td>
			<td>C1006</td>
			<td>Stain the cellular nucleus</td>
		</tr>
		<tr>
			<td>DMSO</td>
			<td>MP Biomedicals</td>
			<td>196055</td>
			<td>Using for preserving cells</td>
		</tr>
		<tr>
			<td>Dulbecco&#39;s modified eagle medium</td>
			<td>Gibco</td>
			<td>C11995500BT</td>
			<td>Culture medium solution</td>
		</tr>
		<tr>
			<td>Fetal bovine serum</td>
			<td>BI</td>
			<td>04-001-1A</td>
			<td></td>
		</tr>
		<tr>
			<td>Flow cytometer</td>
			<td>BD</td>
			<td>BD FACSCelesta</td>
			<td>Observing the identity of cells</td>
		</tr>
		<tr>
			<td>frozen box</td>
			<td>Thermo Scientific</td>
			<td>&#160;5100-0050</td>
			<td></td>
		</tr>
		<tr>
			<td>Inverted microscope</td>
			<td>Nikon</td>
			<td>ECLIPSE Ts2</td>
			<td></td>
		</tr>
		<tr>
			<td>Laser confocal microscope</td>
			<td>Nikon</td>
			<td>AIR-HD25</td>
			<td>Observing the immunofluorescence staining assay</td>
		</tr>
		<tr>
			<td>PDGFR-&#945; antibody</td>
			<td>CST</td>
			<td>3174T</td>
			<td>First antibody for immunofluorescence staining assay</td>
		</tr>
		<tr>
			<td>Penicillin-streptomycin-Am solution</td>
			<td>Solarbio</td>
			<td>P1410</td>
			<td>Add in culture medium solution to avoid contamination</td>
		</tr>
		<tr>
			<td>petri dish</td>
			<td>JETBIOFIL</td>
			<td>7556</td>
			<td>Culture fibroblasts</td>
		</tr>
		<tr>
			<td>Phosphate buffered saline solution</td>
			<td>Gibco</td>
			<td>C10010500BT</td>
			<td>Culture medium solution</td>
		</tr>
		<tr>
			<td>Rabbit (DAIE) mAB IgG XR (R) Isotuge Control (PE)</td>
			<td>Cell Signaling Technology</td>
			<td>5742S</td>
			<td>As a control for flow cytometry</td>
		</tr>
		<tr>
			<td>Round coverslip</td>
			<td>Biosharp</td>
			<td>801007</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Triton X 100</td>
			<td>Solarbio</td>
			<td>T8200</td>
			<td>Punch holes in the cell membrane</td>
		</tr>
		<tr>
			<td>Trypsin-EDTA</td>
			<td>Gibco</td>
			<td>25200072</td>
			<td>Used for passaging cells</td>
		</tr>
		<tr>
			<td>Vimentin antibody</td>
			<td>Abcam</td>
			<td>ab8978</td>
			<td>First antibody for immunofluorescence staining assay</td>
		</tr>
	</tbody>
</table>

isolation, culture, and characterization of primary dermal fibroblasts from human keloid tissue

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

The timeline of the protocol is summarized in Figure 1A. Some representative images of the isolation process are shown in Figure 2; the epidermis and adipose layers were carefully removed, and the dermis layer was separated into small fragments of 3-4 mm2, which were inoculated into the Petri dishes.
As shown in Figure 3A, several fibroblast outgrowths of the tissue pieces were observed und...

Watch this Scientific Journal Video about Isolation, Culture, and Characterization of Primary Dermal Fibroblasts from Human Keloid Tissue at JoVE.com

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

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

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

isolation-culture-characterization-primary-dermal-fibroblasts-from

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JoVE Journal

Medicine

2.0K Views.  Southern Medical University. This study describes an optimized protocol for establishing primary fibroblasts from keloid tissues that can effectively and steadily provide pure and viable fibroblasts.

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

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

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

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

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

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

Skin Punch Biopsy Explant Culture for Derivation of Primary Human Fibroblasts

Tissues and cell lines derived from an individual with disease are ideal sources to study disease-related cellular phenotypes. Patient-derived fibroblasts in this protocol have been successfully used in the derivation of induced pluripotent stem cells to model disease1. Early passages of these fibroblasts can also be used for cell-based functional assays to study specific disease pathways, mechanisms2 and subsequent drug screening approaches. The advantage of the presented protocol over enzymatic procedures are 1) the reproducibility of the technique from small amounts of tissue derived from older patients, e.g. patients affected with Parkinson's disease, 2) the technically simple approach over more challenging methodologies using enzymatic treatments, and 3) the time consideration: this protocol takes 15-20 min and can be performed immediately after biopsy arrival. Enzymatic treatments can take up to 4 hr and have the problems of overdigestion, reduction of cell viability and subsequent attachment of cells when not handled properly. This protocol describes the dissection and preparation of a 4-mm human skin biopsy for derivation of a fibroblast culture and has a very high success rate which is important when dealing with patient-derived tissue samples. In this culture, keratinocytes migrate out of the biopsy tissue within the first week after preparation. Fibroblasts appear 7-10 days after the first outgrowth of keratinocytes. DMEM high glucose media supplemented with 20% FBS favors the growth of fibroblasts over keratinocytes and fibroblasts will overgrow the keratinocytes. After 2 passages keratinocytes have been diluted out resulting in relatively homogenous fibroblast cultures which expresses the fibroblast marker SERPINH1 (HSP-47). Using this approach, 15-20 million fibroblasts can be derived in 4-8 weeks for cell banking. The skin dissection takes about 15-20 min, cells are then monitored once a day under the microscope, and media is changed every 2-3 days after attachment and outgrowth of cells.

The fibroblast explant culture protocol from human skin punch biopsies is a technically robust and simple way to derive skin cells within 4-8 weeks for banking of about 15-20 million cells at a low passage number.

Tissues and cell lines derived from an individual with disease are ideal sources to study disease-related cellular phenotypes. Patient-derived fibroblasts ...

Isolation of Cardiomyocyte Nuclei from Post-mortem Tissue

Identification of cardiomyocyte nuclei has been challenging in tissue sections as most strategies rely only on cytoplasmic marker proteins1. Rare events in cardiac myocytes such as proliferation and apoptosis require an accurate identification of cardiac myocyte nuclei to analyze cellular renewal in homeostasis and in pathological conditions2. Here, we provide a method to isolate cardiomyocyte nuclei from post mortem tissue by density sedimentation and immunolabeling with antibodies against pericentriolar material 1 (PCM-1) and subsequent flow cytometry sorting. This strategy allows a high throughput analysis and isolation with the advantage of working equally well on fresh tissue and frozen archival material. This makes it possible to study material already collected in biobanks. This technique is applicable and tested in a wide range of species and suitable for multiple downstream applications such as carbon-14 dating3, cell-cycle analysis4, visualization of thymidine analogues (e.g. BrdU and IdU)4, transcriptome and epigenetic analysis.

Cardiac nuclei are isolated via density sedimentation and immunolabeled with antibodies against pericentriolar material 1 (PCM-1) to identify and sort cardiomyocyte nuclei by flow cytometry.

Identification of cardiomyocyte nuclei has been challenging in tissue sections as most strategies rely only on cytoplasmic marker proteins1. Rare events ...

The Use of Primary Human Fibroblasts for Monitoring Mitochondrial Phenotypes in the Field of Parkinson's Disease

Parkinson's disease (PD) is the second most common movement disorder and affects 1% of people over the age of 60 1. Because ageing is the most important risk factor, cases of PD will increase during the next decades 2. Next to pathological protein folding and impaired protein degradation pathways, alterations of mitochondrial function and morphology were pointed out as further hallmark of neurodegeneration in PD 3-11.
After years of research in murine and human cancer cells as in vitro models to dissect molecular pathways of Parkinsonism, the use of human fibroblasts from patients and appropriate controls as ex vivo models has become a valuable research tool, if potential caveats are considered. Other than immortalized, rather artificial cell models, primary fibroblasts from patients carrying disease-associated mutations apparently reflect important pathological features of the human disease.
Here we delineate the procedure of taking skin biopsies, culturing human fibroblasts and using detailed protocols for essential microscopic techniques to define mitochondrial phenotypes. These were used to investigate different features associated with PD that are relevant to mitochondrial function and dynamics. Ex vivo, mitochondria can be analyzed in terms of their function, morphology, colocalization with lysosomes (the organelles degrading dysfunctional mitochondria) and degradation via the lysosomal pathway. These phenotypes are highly relevant for the identification of early signs of PD and may precede clinical motor symptoms in human disease-gene carriers. Hence, the assays presented here can be utilized as valuable tools to identify pathological features of neurodegeneration and help to define new therapeutic strategies in PD.

Fibroblasts from patients carrying mutations in Parkinson's disease-causing genes represent an easily accessible ex vivo model to study disease-associated phenotypes. Live cell imaging gives the opportunity to study morphological and functional parameters in living cells. Here we describe the preparation of human fibroblasts and subsequent monitoring of mitochondrial phenotypes.

Parkinson's disease (PD) is the second most  common movement disorder and affects 1% of people over the age of 60 1. Because ageing is  the most important ...

Isolation, Culture, and Imaging of Human Fetal Pancreatic Cell Clusters

For almost 30 years, scientists have demonstrated that human fetal ICCs transplanted under the kidney capsule of nude mice matured into functioning endocrine cells, as evidenced by a significant increase in circulating human C-peptide following glucose stimulation1-9. However in vitro, genesis of insulin producing cells from human fetal ICCs is low10; results reminiscent of recent experiments performed with human embryonic stem cells (hESC), a renewable source of cells that hold great promise as a potential therapeutic treatment for type 1 diabetes. Like ICCs, transplantation of partially differentiated hESC generate glucose responsive, insulin producing cells, but in vitro genesis of insulin producing cells from hESC is much less robust11-17. A complete understanding of the factors that influence the growth and differentiation of endocrine precursor cells will likely require data generated from both ICCs and hESC. While a number of protocols exist to generate insulin producing cells from hESC in vitro11-22, far fewer exist for ICCs10,23,24. Part of that discrepancy likely comes from the difficulty of working with human fetal pancreas. Towards that end, we have continued to build upon existing methods to isolate fetal islets from human pancreases with gestational ages ranging from 12 to 23 weeks, grow the cells as a monolayer or in suspension, and image for cell proliferation, pancreatic markers and human hormones including glucagon and C-peptide. ICCs generated by the protocol described below result in C-peptide release after transplantation under the kidney capsule of nude mice that are similar to C-peptide levels obtained by transplantation of fresh tissue6. Although the examples presented here focus upon the pancreatic endoderm proliferation and &#946;&#160;cell genesis, the protocol can be employed to study other aspects of pancreatic development, including exocrine, ductal, and other hormone producing cells.

A protocol to isolate, culture, and image islet cell clusters (ICCs) derived from human fetal pancreatic cells is described.&#160; The method details the steps necessary to generate ICCs from tissue, culture as monolayers or in suspension as aggregates, and image for markers of proliferation and pancreatic cell fate decisions.

For almost 30 years, scientists have demonstrated that human fetal ICCs transplanted under the kidney capsule of nude mice matured into functioning ...

A Three-dimensional Tissue Culture Model to Study Primary Human Bone Marrow and its Malignancies

Tissue culture has been an invaluable tool to study many aspects of cell function, from normal development to disease. Conventional cell culture methods rely on the ability of cells either to attach to a solid substratum of a tissue culture dish or to grow in suspension in liquid medium. Multiple immortal cell lines have been created and grown using such approaches, however, these methods frequently fail when primary cells need to be grown ex vivo. Such failure has been attributed to the absence of the appropriate extracellular matrix components of the tissue microenvironment from the standard systems where tissue culture plastic is used as a surface for cell growth. Extracellular matrix is an integral component of the tissue microenvironment and its presence is crucial for the maintenance of physiological functions such as cell polarization, survival, and proliferation. Here we present a 3-dimensional tissue culture method where primary bone marrow cells are grown in extracellular matrix formulated to recapitulate the microenvironment of the human bone (rBM system). Embedded in the extracellular matrix, cells are supplied with nutrients through the medium supplemented with human plasma, thus providing a comprehensive system where cell survival and proliferation can be sustained for up to 30 days while maintaining the cellular composition of the primary tissue. Using the rBM system we have successfully grown primary bone marrow cells from normal donors and patients with amyloidosis, and various hematological malignancies. The rBM system allows for direct, in-matrix real time visualization of the cell behavior and evaluation of preclinical efficacy of novel therapeutics. Moreover, cells can be isolated from the rBM and subsequently used for in vivo transplantation, cell sorting, flow cytometry, and nucleic acid and protein analysis. Taken together, the rBM method provides a reliable system for the growth of primary bone marrow cells under physiological conditions.

In standard culture methods cells are taken out of their physiological environment and grown on the plastic surface of a dish. To study the behavior of primary human bone marrow cells we created a 3-D culture system where cells are grown under conditions recapitulating the native microenvironment of the tissue.

Tissue culture has been an invaluable tool to study many aspects of cell function, from normal development to disease. Conventional cell culture methods ...

Primary Culture of Human Vestibular Schwannomas

Vestibular schwannomas (VSs) represent Schwann cell (SC) tumors of the vestibular nerve, compromising 10% of all intracranial neoplasms. VSs occur in either sporadic or familial (neurofibromatosis type 2, NF2) forms, both associated with inactivating defects in the NF2 tumor suppressor gene. Treatment for VSs is generally surgical resection or radiosurgery, however the morbidity of such procedures has driven investigations into less invasive treatments. Historically, lack of access to fresh tissue specimens and the fact that schwannoma cells are not immortalized have significantly hampered the use of primary cultures for investigation of schwannoma tumorigenesis. To overcome the limited supply of primary cultures, the immortalized HEI193 VS cell line was generated by transduction with HPV E6 and E7 oncogenes. This oncogenic transduction introduced significant molecular and phenotypic alterations to the cells, which limit their use as a model for human schwannoma tumors. We therefore illustrate a simplified, reproducible protocol for culture of primary human VS cells. This easily mastered technique allows for molecular and cellular investigations that more accurately recapitulate the complexity of VS disease.

Vestibular Schwannomas (VSs) are non-malignant tumors of Schwann cell (SC) origin, associated with mutations in the NF2 tumor suppressor gene. We report a reproducible, efficient protocol for primary human VS cell culture that allows for molecular and cellular experimental manipulation and analysis and recapitulates the heterogeneous nature of human disease.

Vestibular schwannomas (VSs) represent Schwann cell (SC) tumors of the vestibular nerve, compromising 10% of all intracranial neoplasms. VSs occur in ...

Isolation and Functional Characterization of Human Ventricular Cardiomyocytes from Fresh Surgical Samples

Cardiomyocytes from diseased hearts are subjected to complex remodeling processes involving changes in cell structure, excitation contraction coupling and membrane ion currents. Those changes are likely&#160;to be responsible for the increased arrhythmogenic risk and the contractile alterations leading to systolic and diastolic dysfunction in cardiac patients. However, most information on the alterations of myocyte function in cardiac diseases has come from animal models.
Here we describe and validate a protocol to isolate viable myocytes from small surgical samples of ventricular myocardium from patients undergoing cardiac surgery operations. The protocol is described in detail. Electrophysiological and intracellular calcium measurements are reported to demonstrate the feasibility of a number of single cell measurements in human ventricular cardiomyocytes obtained with this method.
The protocol reported here can be useful for future investigations of the cellular and molecular basis of functional alterations of the human heart in the presence of different cardiac diseases. Further, this method can be used to identify novel therapeutic targets at cellular level and to test the effectiveness of new compounds on human cardiomyocytes, with direct translational value.

Current knowledge on the cellular basis of cardiac diseases mostly relies on studies on animal models. Here we describe and validate a novel method to obtain single viable cardiomyocytes from small surgical samples of human ventricular myocardium. Human ventricular myocytes can be used for electrophysiological studies and drug testing.

Cardiomyocytes from diseased hearts are subjected to complex remodeling processes involving changes in cell structure, excitation contraction coupling and ...

Tissue Characterization after a New Disaggregation Method for Skin Micro-Grafts Generation

Several new methods have been developed in the field of biotechnology to obtain autologous cellular suspensions during surgery, in order to provide one step treatments for acute and chronic skin lesions. Moreover, the management of chronic but also acute wounds resulting from trauma, diabetes, infections and other causes, remains challenging. In this study we describe a new method to create autologous micro-grafts from cutaneous tissue of a single patient and their clinical application. Moreover, in vitro biological characterization of cutaneous tissue derived from skin, de-epidermized dermis (Ded) and dermis of multi-organ and/or multi-tissue donors was also performed. All tissues were disaggregated by this new protocol, allowing us to obtain viable micro-grafts. In particular, we reported that this innovative protocol is able to create bio-complexes composed by autologous micro-grafts and collagen sponges ready to be applied on skin lesions. The clinical application of autologous bio-complexes on a leg lesion was also reported, showing an improvement of both re-epitalization process and softness of the lesion. Additionally, our in vitro model showed that cell viability after mechanical disaggregation with this system is maintained over time for up to seven (7) days of culture. We also observed, by flow cytometry analysis, that the pool of cells obtained from disaggregation is composed of several cell types, including mesenchymal stem cells, that exert a key role in the processes of tissue regeneration and repair, for their high regenerative potential. Finally, we demonstrated in vitro that this procedure maintains the sterility of micro-grafts when cultured in Agar dishes. In summary, we conclude that this new regenerative approach can be a promising tool for clinicians to obtain in one step viable, sterile and ready to use micro-grafts that can be applied alone or in combination with most common biological scaffolds.

The protocol describes a new method to disaggregate human tissues and to create autologous micro-grafts that, combined with collagen sponges, give rise to human bio-complexes ready to use in the treatment of skin lesions. Further, this system preserves cell viability of micro-grafts at different times after mechanical disaggregation.

Several new methods have been developed in the field of biotechnology to obtain autologous cellular suspensions during surgery, in order to provide one ...

Isolation and Culture of Primary Endothelial Cells from Canine Arteries and Veins

Cardiovascular disease is studied in both human and veterinary medicine. Endothelial cells have been used extensively as an in vitro model to study vasculogenesis, (tumor) angiogenesis, and atherosclerosis. The current standard for in vitro research on human endothelial cells (ECs) is the use of Human Umbilical Vein Endothelial Cells (HUVECs) and Human Umbilical Artery Endothelial Cells (HUAECs). For canine endothelial research, only one cell line (CnAOEC) is available, which is derived from canine aortic endothelium. Although currently not completely understood, there is a difference between ECs originating from either arteries or veins. For a more direct approach to in vitro functionality studies on ECs, we describe a new method for isolating Canine Primary Endothelial Cells (CaPECs) from a variety of vessels. This technique reduces the chance of contamination with fast-growing cells such as fibroblasts and smooth muscle cells, a problem that is common in standard isolation methods such as flushing the vessel with enzymatic solutions or mincing the vessel prior to digestion of the tissue containing all cells. The technique we describe was optimized for the canine model, but can easily be utilized in other species such as human.

Novel isolation methods of primary endothelial cells from blood vessels are needed. This protocol describes a new technique that completely inverts blood vessels of interest, exposing only the endothelial side to enzymatic digestion. The resulting pure endothelial cell culture can be used to study cardiovascular diseases, disease modelling, and angiogenesis.

Cardiovascular disease is studied in both human and veterinary medicine. Endothelial cells have been used extensively as an in vitro model to study ...