This work was supported by funding from Singapore&#39;s Agency for Science, Technology and Research &#8220;SPF 2013/004: Skin Biology Basic Research&#8221; and the &#8220;Wound Care Innovation for the Tropics&#8221; IAF-PP/2017 (HBMS) H17/01/a0/009. The authors gratefully acknowledge advice and assistance from Dr. Paula Benny and Dr. Michael Raghunath.

1. Cell culture
<ol>
	<li>Maintain hHSFs and normal dermal fibroblasts derived from non-pathological tissue (hNSFs) in Dulbecco&#39;s modified Eagle&#39;s medium (DMEM) containing 10% fetal calf serum (FCS) and 1% v/v penicillin/streptomycin solution (P/S) at 37&#176;C in an incubator with 5% CO2/95% air.</li>
	<li>Purchase Ficoll 70, Ficoll 400, and ascorbic acid from the appropriate companies.</li>
</ol>
2. Construction of MMC hypertrophic scar model
<ol>
	<li>Seed the hHSFs or hNSFs (50,000/well) into a 24 well plate containing 1 mL of media in each well.</li>
	<li>Place in a 37&#176;C incubator at 5% CO2 and leave overnight.</li>
	<li>Prepare the MMC media. Based on the total volume required for the experiment, produce 10% FCS/DMEM media by mixing Ficoll 70 (18.75 mg/mL), Ficoll 400 (12.5 mg/mL), and ascorbic acid (100 &#956;M).</li>
	<li>Place the mixture into a 37&#176;C water bath for 1 h to disperse the crowders into the solution, then sterilize the MMC media using a 0.2 &#956;m filter.</li>
	<li>Aspirate the spent media and replace with the freshly made MMC media.</li>
	<li>Incubate the cells for 6 days at 37&#176;C and 5% CO2, changing the media every 3 days.</li>
</ol>
3. Expression of the total amount of collagen
<ol>
	<li>Prepare Sirius red solution (0.1% w/v). Dissolve 0.2 g of Direct Red 80 powder in 200 mL of distilled deionized water (ddH2O) with 1 mL of acetic acid.</li>
	<li>Aspirate the MMC media and add 300 &#956;L of Sirius Red solution into each well. Incubate at 37 &#176;C for 90 min.</li>
	<li>Gently rinse the Sirius Red solution with tap water and allow the plate to air-dry overnight.</li>
	<li>Extract the Sirius Red stain by adding 200 &#956;L of sodium hydroxide (0.1 M) into each well. Place the plate onto an orbital shaker for 5&#8211;10 min to fully extract the Sirius Red stain.</li>
	<li>Transfer 100 &#956;L of the extracted Sirius Red stain into a 96 well transparent plate and measure the absorbance at 620 nm using a microplate reader.</li>
</ol>
4. Expression of collagen I (immunostaining)
<ol>
	<li>Wash the wells using 200 &#956;L of phosphate-buffered saline (PBS, pH = 7.35).</li>
	<li>Fix the cells using methanol (500 &#956;L/well) at 4 &#176;C for 10 min.</li>
	<li>Block nonspecific interactions with 3% bovine serum albumin for 30 min at room temperature (RT).</li>
	<li>Aspirate the blocking solution and incubate with 200 &#956;L of anti-collagen I antibody (10 &#956;g/mL) for 90 min at RT.</li>
	<li>Aspirate the primary antibody and wash 3x with PBS for 5 min each.</li>
	<li>Incubate with 200 &#956;L of Goat anti-Rabbit-FITC secondary antibody (1:400 dilution) and 4&#8217;,6-diamidino-2-phenylindole (DAPI; 1: 2000 dilution) for 30 min at RT. Cover the plate with aluminum foil.</li>
	<li>Discard both the secondary antibody and DAPI and wash 3x with PBS for 5 min each.</li>
	<li>Visualize the fluorescence staining directly under a microscope.</li>
</ol>
5. Western blotting
<ol>
	<li>Wash the cells 2x with PBS.</li>
	<li>Add 40 &#956;L of lysis buffer into each well and scrape the cell layer with a pipette tip. The lysis buffer contains RIPA buffer, protease inhibitor cocktail (PIC), 2 mM sodium vanadate, and 10 mM sodium fluoride.</li>
	<li>Transfer the protein lysate into microcentrifuge tubes and measure the protein concentration using a protein assay as per the manufacturer&#39;s instructions16.</li>
	<li>Load 10 &#956;g of protein of each group into the wells of 4%&#8211;12% Bis-Tris protein gels. Perform sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) at 200 V for 30 min.</li>
	<li>Transfer the protein to nitrocellulose membrane by running a western blot at 90 V for 90 min. Avoid formation of air bubbles between the gel and nitrocellulose membrane.</li>
	<li>Block the membrane with 10 mL of blocking buffer.</li>
	<li>Incubate with primary antibodies at 4&#176;C overnight. Primary antibodies are: anti-collagen I, anti-collagen III, anti-collagen IV, anti-&#945;SMA, anti-MMP-1, anti-MMP-2, anti-MMP-9, anti-MMP-13, and anti-glyceraldehyde 3-phosphate dehydrogenase (GAPDH).</li>
	<li>Wash the membrane with 0.1% TBS-Tween 20 (5x for 5 min each). TBS/Tween 20 (1 L) contains the following: 50 mL of 1 M Tris (pH = 7.4), 30 mL of 5 M sodium chloride, 1 mL of Tween 20, and 920 mL of ddH2O.</li>
	<li>Incubate with a species appropriate secondary antibody at RT for 1 h.</li>
	<li>Repeat step 5.8 and visualize fluorescence using an imaging system.</li>
</ol>
6. RT-PCR
<ol>
	<li>Collect the total RNA using the lysis buffer mixed with 2-mercaptoethanol included in the RNA extraction assay kit.</li>
	<li>Purify the RNA as per the manufacturer&#39;s instructions17.</li>
	<li>Measure the RNA concentration using a microvolume spectrophotometer.</li>
	<li>Perform first strand cDNA synthesis using a cDNA synthesis kit as per the manufacturer&#39;s instructions.</li>
	<li>RT-PCR oligonucleotide primers are provided (precoated) in custom 96 well plates. Mix 100 ng of the cDNA samples with 10 &#956;L of SYBR green supermix into the customized plate.</li>
	<li>Increase the total volume to 20 &#956;L/well using ddH2O.</li>
	<li>Run RT-PCR using a thermal cycler following the manufacturer&#39;s instructions: 40 cycles of denaturing at 98&#176;C for 15 s and annealing/extension at 60 &#176;C for 60 s. The genes tested in RT-PCR include: COL1A1, COL3A1, ACTA2, SMAD2, SMAD3, SMAD4, SMAD7, IL1A, IL1B, IL6, IL8, MMP1, MMP2, MMP3, TGFB1, and VEGF.</li>
</ol>

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C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Matrix+remodeling+by+MMPs+during+wound+repair.">Matrix remodeling by MMPs during wound repair.</a> Matrix Biology. 44-46, 113-121 (2015).</li><li>Ulrich, D., Ulrich, F., Unglaub, F., Piatkowski, A., Pallua, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Matrix+metalloproteinases+and+tissue+inhibitors+of+metalloproteinases+in+patients+with+different+types+of+scars+and+keloids.">Matrix metalloproteinases and tissue inhibitors of metalloproteinases in patients with different types of scars and keloids.</a> Journal of Plastic, Reconstructive &amp; Aesthetic Surgery. 63 (6), 1015-1021 (2010).</li><li>Ghazizadeh, M., Tosa, M., Shimizu, H., Hyakusoku, H., Kawanami, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+Implications+of+the+IL-6+Signaling+Pathway+in+Keloid+Pathogenesis.">Functional Implications of the IL-6 Signaling Pathway in Keloid Pathogenesis.</a> Journal of Investigative Dermatology. 127 (1), 98-105 (2007).</li><li>Wilgus, T. 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The authors have no conflicts of interest.

This protocol aims to optimize and authenticate an improved :scar-in-a-jar&#8221; in vitro model for human cutaneous scar tissue. Previous studies have reported the application of MMC technique to human lung fibroblasts12, human bone marrow mesenchymal stem cells23, and human dermal fibroblasts23 using dextran12, Ficoll12, and PVP23 as crowders. In the study reported here, the pr...

Scar tissue represents the endpoint of tissue repair. However, in many individuals, especially those suffering from burns or trauma1, scarring can be excessive and impose undesirable effects on the morphology and functioning of healed skin. Although the exact mechanisms of pathological (hypertrophic scars and keloids) scar formation are not fully understood, excessive deposition of collagen during wound healing has been demonstrated to be an essential contribution2.
It is well-established that transforming growth factor beta 1 (TGF-&#946;1) and alpha smooth muscle actin (&#945;SMA) play key roles in the formation of hypertrophic scars. Evidence suggests that elevated TGF-&#946;1 directly stimulates excessive deposition of collagen via regulating the SMAD signaling pathway3. In addition, &#945;SMA has been found to contribute to hypertrophic scar formation by regulating cell contraction and reepithelialization in the wound healing process4. The lack of suitable in vitro and in vivo models is a major impediment towards developing and evaluating interventions and therapies for scar remediation. The aim of this study is to utilize the existing MMC technique to construct an &#8220;in vivo-like&#8221; hypertrophic scar model that is suitable for evaluating novel and emerging scar-related interventions.
Reproducing living tissue outside of the body has been a goal for years in the scientific community. The development of in vitro techniques in the early twentieth century partly achieved this goal. Current in vitro techniques have slightly evolved from Roux&#39;s original demonstration that embryonic cells can survive ex vivo for several days in warm saline5. However, in vitro methodologies are mostly limited to single cell types cultivated in 2-D and do not accurately recapitulate tissues in vivo. While useful for examining cell biochemistry, physiology, and genetics, native tissues are 3-D and incorporate multiple cell types. Simple 2-D in vitro systems subject mammalian cells to highly artificial environments in which native tissue-specific architecture is lost6. In turn, this affects intracellular and extracellular events, resulting in abnormal cell morphology, physiology, and behaviour7.
The interest behind this protocol lies in the development and clinical management of hypertrophic scars and keloids. While it is well-established that dermal fibroblasts are largely responsible for the abundant production of collagens present in scar tissue, cultivating dermal fibroblasts using 2-D in vitro systems fails to reproduce the turnover of collagen observed in vivo8. Contemporary in vitro methods still essentially use &#8220;warm saline&#8221;, an environment completely different from that in living tissues. Tissues in vivo are extremely crowded, with proteins, nucleic acids, ribonucleoproteins, and polysaccharides, occupying 5%&#8211;40% of the total volume. As no two molecules can occupy the same space at the same time, there is little free space available and an almost complete absence of free water9.
The MMC technique imposes constraints affecting the thermodynamic properties of cytosol and interstitial fluids. Molecular interactions, receptor-ligand signaling complexes, enzymes, and organelles are confined and restricted from interacting freely9. Interactions within the pericellular environment (i.e., interstitium) are also constrained. Recent evidence confirms that high concentrations of inert macromolecules in crowded solutions perturb diffusion, physical association, viscosity and hydrodynamic properties10.
Interestingly, several popular crowding agents (i.e., Ficoll, dextran, polyvinylpyrrolidone [PVP], and sodium 4-styrenesulfonate [PSS]) are not equivalent when applied to different cell types and in different settings. In one previous study, Ficoll was reported to be less cytotoxic for mesenchymal stem cells compared to PVP. These results were interpreted to be the consequence of its neutral charge and relatively small hydrodynamic radius11. In contrast, a second study found that dextran is more effective in stimulating collagen I deposition by human lung fibroblasts compared to Ficoll12. Data from our own study suggests that Ficoll enhances collagen deposition by hypertrophic scar-derived fibroblasts, whereas PVP is toxic to these cells13.
It has been demonstrated that the conversion of procollagen to collagen is faster in a highly crowded in vivo environment14, while the rate of biological reactions is delayed in a diluted 2-D culture system15. We have optimized the in vitro protocol here, incorporating MMC to show the cultivation of dermal fibroblasts serving as a more &#8220;in vivo-like&#8221; model for dermal fibrosis and scar formation. In contrast to the common 2-D culture system, cultivating hHSFs with MMC stimulates the biosynthesis and deposition of collagen significantly13. Notably, other characteristics of fibrosis (i.e., increased expression of matrix metalloproteinases [MMPs] and proinflammatory cytokines) are also evident under this optimized MMC protocol13. When cultivated using this method, it is shown that dermal cells recapitulate the physiological, biochemical, and functional parameters measured in vivo.
The optimized MMC in vitro protocol has been used to evaluate the expression of collagen and other ECM proteins by dermal fibroblasts isolated from hypertrophic scar dermis and uninvolved adjacent dermis. When cultivated in MMC environments in vitro, it has been observed that hHSFs express certain characteristics (i.e., mRNA, biochemistry, physiology, and phenotype) similar to dermal hypertrophic scar tissue in vivo. The evidence indicates that physical and chemical properties are important considerations when selecting crowders and optimizing MMC conditions for cultivation in vitro.
For proof-of-principle, the MMC protocol is applied here to qualitatively and quantitatively evaluate the ability of Shikonin and its analogues to induce apoptosis. This allows evaluation of the potential applications of these naturally-derived Traditional Chinese Medicine (TCM) compounds for managing dermal scarring13. Notwithstanding, the simplicity, cost-effectiveness, and timeliness of this in vitro MMC protocol also satisfies recent regulations to eliminate experimentation in mammals by the EU Directive 2010/63/EU and U.S. Environmental Protection Agency (EPA).

<table border="0" cellpadding="0" cellspacing="0" style="width:1337px;" width="1336">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">0.2 &#956;m filter</td>
			<td style="width:195px;">Sartorius</td>
			<td style="width:119px;">16534</td>
			<td style="width:537px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">2-Mercaptoethanol</td>
			<td style="width:195px;">Sigma-Aldrich</td>
			<td style="width:119px;">M6250</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">4&#8217;,6-diamidino-2-phenylindole (DAPI)</td>
			<td style="width:195px;">Thermo Fisher Scientific</td>
			<td style="width:119px;">P36962</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">Alexa Fluor 680</td>
			<td style="width:195px;">Thermo Fisher Scientific</td>
			<td style="width:119px;">A-21076</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">Alexa Fluor 800</td>
			<td style="width:195px;">Thermo Fisher Scientific</td>
			<td style="width:119px;">A-11371</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">alpha smooth muscle actin (&#945;SMA) primary antibody</td>
			<td style="width:195px;">Abcam</td>
			<td style="width:119px;">ab5694</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">Applied Biosystems 7500 Fast Real-Time PCR System (thermal cycler )</td>
			<td style="width:195px;">Thermo Fisher Scientific</td>
			<td style="width:119px;">4351106</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">Ascorbic acid</td>
			<td style="width:195px;">Wako</td>
			<td style="width:119px;">#013-12061</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">Bovine serum albumin</td>
			<td style="width:195px;">Sigma-Aldrich</td>
			<td style="width:119px;">#A2153</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">Bradford protein assay</td>
			<td style="width:195px;">Bio-Rad</td>
			<td style="width:119px;">500-0006</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">Collagen I primary antibody (for immunostaining)</td>
			<td style="width:195px;">Abcam</td>
			<td style="width:119px;">6308</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">Collagen I primary antibody (for western blot)</td>
			<td style="width:195px;">Abcam</td>
			<td style="width:119px;">ab21286</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">Collagen III primary antibody</td>
			<td style="width:195px;">Abcam</td>
			<td style="width:119px;">ab7778</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">Collagen IV primary antibody</td>
			<td style="width:195px;">Abcam</td>
			<td style="width:119px;">ab6586</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">Direct Red 80</td>
			<td style="width:195px;">Sigma-Aldrich</td>
			<td>2610108</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">Dulbecco&#39;s Modified Eagle&#39;s Medium (DMEM)</td>
			<td style="width:195px;">Life Technologies</td>
			<td style="width:119px;">11996-065</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">Fetal calf serum (FCS)</td>
			<td style="width:195px;">Life Technologies</td>
			<td style="width:119px;">6000-044</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">Ficoll 400</td>
			<td style="width:195px;">GE HealthCare</td>
			<td style="width:119px;">#17-0300-10</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">Ficoll 70</td>
			<td style="width:195px;">GE HealthCare</td>
			<td style="width:119px;">#17-0310-10</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">GAPDH primary antibody</td>
			<td style="width:195px;">Sigma-Aldrich</td>
			<td style="width:119px;">G8795</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">Goat Anti-Rabbit secondary antibody</td>
			<td style="width:195px;">Abcam</td>
			<td style="width:119px;">ab97050</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">Human hypertrophic scar/normal fibroblasts (hHSF/hNSF)</td>
			<td style="width:195px;">Cell Research Corporation</td>
			<td style="width:119px;">106, 107, 108</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">iScript cDNA Synthesis Kit</td>
			<td style="width:195px;">Bio-Rad</td>
			<td style="width:119px;">#1708890</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">MMP-1 primary antibody</td>
			<td style="width:195px;">Abcam</td>
			<td style="width:119px;">ab38929</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">MMP-13 primary antibody</td>
			<td style="width:195px;">Abcam</td>
			<td style="width:119px;">ab39012</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">MMP-2 primary antibody</td>
			<td style="width:195px;">Abcam</td>
			<td style="width:119px;">ab37150</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">MMP-9 primary antibody</td>
			<td style="width:195px;">Abcam</td>
			<td style="width:119px;">ab38898</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">NanoDrop Microvolume Spectrophotometers</td>
			<td style="width:195px;">Thermo Fisher Scientific</td>
			<td style="width:119px;">N/A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">Nitrocellulose membrane</td>
			<td style="width:195px;">Bio-Rad</td>
			<td style="width:119px;">10484060</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">NuPAGE 4-12% Bis-Tris Protein Gels</td>
			<td style="width:195px;">Thermo Fisher Scientific</td>
			<td style="width:119px;">NP0321BOX</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">Odyssey blocking buffer</td>
			<td style="width:195px;">LI-COR Biosciences</td>
			<td style="width:119px;">927&#8211;40000</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">Odyssey Fc Imaging System</td>
			<td style="width:195px;">LI-COR Biosciences</td>
			<td style="width:119px;">N/A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">Olympus IX-81 HCS microscope (for immunostaining)</td>
			<td style="width:195px;">Olympus</td>
			<td style="width:119px;">N/A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">Penicillin/streptomycin solution (P/S)</td>
			<td style="width:195px;">Life Technologies</td>
			<td style="width:119px;">15140-122</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">PrimePCR Assays</td>
			<td style="width:195px;">Bio-Rad</td>
			<td style="width:119px;"></td>
			<td>Customized primers pre-coated in 96-well plates based on requirement</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">Protease inhibitor cocktail (PIC)</td>
			<td style="width:195px;">Sigma-Aldrich</td>
			<td style="width:119px;">11697498001</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">PVP 360</td>
			<td style="width:195px;">Sigma</td>
			<td style="width:119px;">#PVP360</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">PVP 40</td>
			<td style="width:195px;">Sigma</td>
			<td style="width:119px;">#PVP40</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">RIPA buffer</td>
			<td style="width:195px;">Merck</td>
			<td style="width:119px;">R0278</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">RNeasy Plus Mini Kit</td>
			<td style="width:195px;">QIAGEN</td>
			<td style="width:119px;">#74134</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">Sodium vanadate</td>
			<td style="width:195px;">Sigma-Aldrich</td>
			<td style="width:119px;">450022</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">Sodium vanadate</td>
			<td style="width:195px;">Sigma-Aldrich</td>
			<td style="width:119px;">450243</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">SpectraMax M5 Multi-Mode microplate reader</td>
			<td style="width:195px;">Molecular Devices</td>
			<td style="width:119px;">N/A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">SsoAdvanced universal SYBR green supermix</td>
			<td style="width:195px;">Bio-Rad</td>
			<td style="width:119px;">#172-5270</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:487px;">Tween 20</td>
			<td style="width:195px;">Sigma-Aldrich</td>
			<td style="width:119px;">P9416</td>
			<td></td>
		</tr>
	</tbody>
</table>

in vitro model of human cutaneous hypertrophic scarring using macromolecular crowding

It has been shown that in vivo tissues are highly crowded by proteins, nucleic acids, ribonucleoproteins, polysaccharides, etc. The following protocol applies a macromolecular crowding (MMC) technique to mimic this physiological crowding through the addition of neutral polymers (crowders) to cell cultures in vitro. Previous studies using Ficoll or dextran as crowders demonstrate that the expression of collagen I and fibronectin in WI38 and WS-1 cell lines are significantly enhanced using the MMC technique. However, this technique has not been validated in primary hypertrophic scar-derived human skin fibroblasts (hHSFs). As hypertrophic scarring arises from the excessive deposition of collagen, this protocol aims to construct a collagen-rich in vitro hypertrophic scar model by applying the MMC technique with hHSFs. This optimized MMC model has been shown to possess more similarities with in vivo scar tissue compared to traditional 2-dimensional (2-D) cell culture systems. In addition, it is cost-effective, time-efficient, and ethically desirable compared to animal models. Therefore, the optimized model reported here offers an advanced &#8220;in vivo-like&#8221; model for hypertrophic scar-related studies.

Triplicate samples were performed in each experiment, and each experiment was repeated 3x using cells from three individual patients. Data are expressed as percentages of the control group. One-way ANOVA and Tukey&#39;s post-hoc test were applied to analyze statistical differences (*p &#706; 0.05).
MMC using Ficoll at 9% FVO (fractional volume occupancy) enhances the total amount of collagen and collagen I deposition in hHSF13. As illustrated in <strong class="...

Watch this Scientific Journal Video about In Vitro Model of Human Cutaneous Hypertrophic Scarring using Macromolecular Crowding at JoVE.com

In Vitro Model of Human Cutaneous Hypertrophic Scarring using Macromolecular Crowding

This protocol describes the use of macromolecular crowding to create an in vitro human hypertrophic scar tissue model that resembles in vivo conditions. When cultivated in a crowded macromolecular environment, human skin fibroblasts exhibit phenotypes, biochemistry, physiology, and functional characteristics resembling scar tissue.

It has been shown that in vivo tissues are highly crowded by proteins, nucleic acids, ribonucleoproteins, polysaccharides, etc. The following protocol ...

in-vitro-model-human-cutaneous-hypertrophic-scarring-using

Research

JoVE Journal

Bioengineering

6.6K Views.  Agency for Science, Technology and Research (A*STAR). This protocol describes the use of macromolecular crowding to create an in vitro human hypertrophic scar tissue model that resembles in vivo conditions. When cultivated in a crowded macromolecular environment, human skin fibroblasts exhibit phenotypes, biochemistry, physiology, and functional characteristics resembling scar tissue.

Video: In Vitro Model of Human Cutaneous Hypertrophic Scarring using Macromolecular Crowding

Visualizing Proteins and Macromolecular Complexes by Negative Stain EM: from Grid Preparation to Image Acquisition

Single particle electron microscopy (EM), of both negative stained or frozen hydrated biological samples, has become a versatile tool in structural biology 1. In recent years, this method has achieved great success in studying structures of proteins and macromolecular complexes 2, 3. Compared with electron cryomicroscopy (cryoEM), in which frozen hydrated protein samples are embedded in a thin layer of vitreous ice 4, negative staining is a simpler sample preparation method in which protein samples are embedded in a thin layer of dried heavy metal salt to increase specimen contrast 5. The enhanced contrast of negative stain EM allows examination of relatively small biological samples. In addition to determining three-dimensional (3D) structure of purified proteins or protein complexes 6, this method can be used for much broader purposes. For example, negative stain EM can be easily used to visualize purified protein samples, obtaining information such as homogeneity/heterogeneity of the sample, formation of protein complexes or large assemblies, or simply to evaluate the quality of a protein preparation.
In this video article, we present a complete protocol for using an EM to observe negatively stained protein sample, from preparing carbon coated grids for negative stain EM to acquiring images of negatively stained sample in an electron microscope operated at 120kV accelerating voltage. These protocols have been used in our laboratory routinely and can be easily followed by novice users.

Visualizing protein samples by negative stain electron microscopy (EM) has become a popular structural analysis method. It is useful for quantitative structural analysis, such as calculating a 3D reconstruction of the molecules being studied, and also for qualitative examination of the quality of protein preparations. In this article we present detailed protocols for preparing the EM grids, staining the sample and visualizing the sample in an electron microscope. Novice users can follow these protocols easily and to utilize negative stain EM as a routine assay, in addition to other biochemical assays, for evaluating their protein samples.

Single particle electron microscopy (EM), of both negative stained or frozen hydrated biological samples, has become a versatile tool in structural ...

Anatomical Reconstructions of the Human Cardiac Venous System using Contrast-computed Tomography of Perfusion-fixed Specimens

A detailed understanding of the complexity and relative variability within the human cardiac venous system is crucial for the development of cardiac devices that require access to these vessels. For example, cardiac venous anatomy is known to be one of the key limitations for the proper delivery of cardiac resynchronization therapy (CRT)1 Therefore, the development of a database of anatomical parameters for human cardiac venous systems can aid in the design of CRT delivery devices to overcome such a limitation. In this research project, the anatomical parameters were obtained from 3D reconstructions of the venous system using contrast-computed tomography (CT) imaging and modeling software (Materialise, Leuven, Belgium). The following parameters were assessed for each vein: arc length, tortuousity, branching angle, distance to the coronary sinus ostium, and vessel diameter.
	CRT is a potential treatment for patients with electromechanical dyssynchrony. Approximately 10-20% of heart failure patients may benefit from CRT2. Electromechanical dyssynchrony implies that parts of the myocardium activate and contract earlier or later than the normal conduction pathway of the heart. In CRT, dyssynchronous areas of the myocardium are treated with electrical stimulation. CRT pacing typically involves pacing leads that stimulate the right atrium (RA), right ventricle (RV), and left ventricle (LV) to produce more resynchronized rhythms. The LV lead is typically implanted within a cardiac vein, with the aim to overlay it within the site of latest myocardial activation. 
	We believe that the models obtained and the analyses thereof will promote the anatomical education for patients, students, clinicians, and medical device designers. The methodologies employed here can also be utilized to study other anatomical features of our human heart specimens, such as the coronary arteries. To further encourage the educational value of this research, we have shared the venous models on our free access website: <a href="http://www.vhlab.umn.edu/atlas" target="_blank">www.vhlab.umn.edu/atlas</a>.

The objective of this research is to recreate and then access the anatomy of the human cardiac venous system using 3D reconstructions generated from contrast-computed tomography scans.

A detailed  understanding of the complexity and relative variability within the human  cardiac venous system is crucial for the development of cardiac ...

Cell Co-culture Patterning Using Aqueous Two-phase Systems

Cell patterning technologies that are fast, easy to use and affordable will be required for the future development of high throughput cell assays, platforms for studying cell-cell interactions and tissue engineered systems. This detailed protocol describes a method for generating co-cultures of cells using biocompatible solutions of dextran (DEX) and polyethylene glycol (PEG) that phase-separate when combined above threshold concentrations. Cells can be patterned in a variety of configurations using this method. Cell exclusion patterning can be performed by printing droplets of DEX on a substrate and covering them with a solution of PEG containing cells. The interfacial tension formed between the two polymer solutions causes cells to fall around the outside of the DEX droplet and form a circular clearing that can be used for migration assays. Cell islands can be patterned by dispensing a cell-rich DEX phase into a PEG solution or by covering the DEX droplet with a solution of PEG. Co-cultures can be formed directly by combining cell exclusion with DEX island patterning. These methods are compatible with a variety of liquid handling approaches, including manual micropipetting, and can be used with virtually any adherent cell type.

Aqueous two-phase systems were used to simultaneously pattern multiple populations of cells. This fast and easy method for cell patterning takes advantage of the phase separation of aqueous solutions of dextran and polyethylene glycol and the interfacial tension that exists between the two polymer solutions.

Cell patterning  technologies that are fast, easy to use and affordable will be required for the  future development of high throughput cell assays, ...

Tissue Engineering of a Human 3D in vitro Tumor Test System

Cancer is one of the leading causes of death worldwide. Current therapeutic strategies are predominantly developed in 2D culture systems, which inadequately reflect physiological conditions in vivo. Biological 3D matrices provide cells an environment in which cells can self-organize, allowing the study of tissue organization and cell differentiation. Such scaffolds can be seeded with a mixture of different cell types to study direct 3D cell-cell-interactions. To mimic the 3D complexity of cancer tumors, our group has developed a 3D in vitro tumor test system.	
	Our 3D tissue test system models the in vivo situation of malignant peripheral nerve sheath tumors (MPNSTs), which we established with our decellularized porcine jejunal segment derived biological vascularized scaffold (BioVaSc). In our model, we reseeded a modified BioVaSc matrix with primary fibroblasts, microvascular endothelial cells (mvECs) and the S462 tumor cell line. For static culture, the vascular structure of the BioVaSc is removed and the remaining scaffold is cut open on one side (Small Intestinal Submucosa SIS-Muc). The resulting matrix is then fixed between two metal rings (cell crowns).	
	Another option is to culture the cell-seeded SIS-Muc in a flow bioreactor system that exposes the cells to shear stress. Here, the bioreactor is connected to a peristaltic pump in a self-constructed incubator. A computer regulates the arterial oxygen and nutrient supply via parameters such as blood pressure, temperature, and flow rate. This setup allows for a dynamic culture with either pressure-regulated pulsatile or constant flow.	
	In this study, we could successfully establish both a static and dynamic 3D culture system for MPNSTs. The ability to model cancer tumors in a more natural 3D environment will enable the discovery, testing, and validation of future pharmaceuticals in a human-like model.

Tissue Engineering of a Human 3D in vitro Tumor Test System

Methods to create human 3D tumor tissues as test systems are described. These technologies are based on a decellularized Biological Vascularized Scaffold (BioVaSc), primary human cells and a tumor cell line, which can be cultured under static as well as under dynamic conditions in a flow bioreactor.

Cancer is one of the leading causes of death worldwide.  Current therapeutic strategies are predominantly developed in 2D culture  systems, which ...

In vitro Cell Culture Model for Toxic Inhaled Chemical Testing

Cell cultures are indispensable to develop and study efficacy of therapeutic agents, prior to their use in animal models. We have the unique ability to model well differentiated human airway epithelium and heart muscle cells. This could be an invaluable tool to study the deleterious effects of toxic inhaled chemicals, such as chlorine, that can normally interact with the cell surfaces, and form various byproducts upon reacting with water, and limiting their effects in submerged cultures. Our model using well differentiated human airway epithelial cell cultures at air-liqiuid interface circumvents this limitation as well as provides an opportunity to evaluate critical mechanisms of toxicity of potential poisonous inhaled chemicals. We describe enhanced loss of membrane integrity, caspase release and death upon toxic inhaled chemical such as chlorine exposure. In this article, we propose methods to model chlorine exposure in mammalian heart and airway epithelial cells in culture and simple tests to evaluate its effect on these cell types.

In vitro Cell Culture Model for Toxic Inhaled Chemical Testing

This protocol is designed to demonstrate exposure method of cell cultures to inhaled toxic chemicals. Exposure of differentiated air-liquid&#160;interface (ALI) cultures of airway epithelial cells provides a unique model of airway exposure to toxic gases such as chlorine. In this manuscript we describe effect of chlorine exposure on air-liquid&#160;interface cultures of epithelial cells and submerged culture of cardiomyocytes. In vitro exposure systems allow important mechanistic studies to evaluate pathways that could then be utilized to develop novel therapeutic agents.

Cell cultures are indispensable to develop and study efficacy of therapeutic agents, prior to their use in animal models. We have the unique ability to ...

Production, Characterization and Potential Uses of a 3D Tissue-engineered Human Esophageal Mucosal Model

The incidence of both esophageal adenocarcinoma and its precursor, Barrett&#8217;s Metaplasia, are rising rapidly in the western world. Furthermore esophageal adenocarcinoma generally has a poor prognosis, with little improvement in survival rates in recent years. These are difficult conditions to study and there has been a lack of suitable experimental platforms to investigate disorders of the esophageal mucosa.
A model of the human esophageal mucosa has been developed in the MacNeil laboratory which, unlike conventional 2D cell culture systems, recapitulates the cell-cell and cell-matrix interactions present in vivo and produces a mature, stratified epithelium similar to that of the normal human esophagus. Briefly, the model utilizes non-transformed normal primary human esophageal fibroblasts and epithelial cells grown within a porcine-derived acellular esophageal scaffold. Immunohistochemical characterization of this model by CK4, CK14, Ki67 and involucrin staining demonstrates appropriate recapitulation of the histology of the normal human esophageal mucosa.
This model provides a robust, biologically relevant experimental model of the human esophageal mucosa. It can easily be manipulated to investigate a number of research questions including the effectiveness of pharmacological agents and the impact of exposure to environmental factors such as alcohol, toxins, high temperature or gastro-esophageal refluxate components. The model also facilitates extended culture periods not achievable with conventional 2D cell culture, enabling, inter alia, the study of the impact of repeated exposure of a mature epithelium to the agent of interest for up to 20 days. Furthermore, a variety of cell lines, such as those derived from esophageal tumors or Barrett&#8217;s Metaplasia, can be incorporated into the model to investigate processes such as tumor invasion and drug responsiveness in a more biologically relevant environment.

This manuscript describes the production, characterization and potential uses of a tissue engineered 3D esophageal construct prepared from normal primary human esophageal fibroblast and squamous epithelial cells seeded within a de-cellularized porcine scaffold. The results demonstrate the formation of a mature stratified epithelium similar to the normal human esophagus.

The incidence of both esophageal adenocarcinoma and its precursor, Barrett&#8217;s Metaplasia, are rising rapidly in the western world. Furthermore ...

Eye Irritation Test (EIT) for Hazard Identification of Eye Irritating Chemicals using Reconstructed Human Cornea-like Epithelial (RhCE) Tissue Model

To comply with the Seventh Amendment to the EU Cosmetics Directive and EU REACH legislation, validated non-animal alternative methods for reliable and accurate assessment of ocular toxicity in man are needed. To address this need, we have developed an eye irritation test (EIT) which utilizes a three dimensional reconstructed human cornea-like epithelial (RhCE) tissue model that is based on normal human cells. The EIT is able to separate ocular&#160;irritants and corrosives (GHS Categories 1 and 2 combined) and those that do not require labeling (GHS No Category). The test utilizes two separate protocols, one designed for liquid chemicals and a second, similar protocol for solid test articles. The EIT prediction model uses a single exposure period (30 min for liquids, 6 hr for solids) and a single tissue viability cut-off (60.0% as determined by the MTT assay). Based on the results for 83 chemicals (44 liquids and 39 solids) EIT achieved 95.5/68.2/ and 81.8% sensitivity/specificity and accuracy (SS&#38;A) for liquids, 100.0/68.4/ and 84.6% SS&#38;A for solids, and 97.6/68.3/ and 83.1% for overall SS&#38;A. The EIT will contribute significantly to classifying the ocular irritation potential of a wide range of liquid and solid chemicals without the use of animals to meet regulatory testing requirements. The EpiOcular EIT method was implemented in 2015 into the OECD Test Guidelines as TG 492.

Eye Irritation Test EIT for Hazard Identification of Eye Irritating Chemicals using Reconstructed Human Cornea-like Epithelial RhCE Tissue Model

We have developed an eye irritation test which utilizes a three dimensional reconstructed human cornea-like epithelial (RhCE) tissue model. The test is able to discriminate between ocular irritant and corrosive materials (GHS Categories 1 and 2 combined) and those that do not require labeling (GHS No Category).

To comply with the Seventh Amendment to the EU Cosmetics Directive and EU REACH legislation, validated non-animal alternative methods for reliable and ...

Improving 2D and 3D Skin In Vitro Models Using Macromolecular Crowding

The glycoprotein family of collagens represents the main structural proteins in the human body, and are key components of biomaterials used in modern tissue engineering. A technical bottleneck is the deposition of collagen in vitro, as it is notoriously slow, resulting in sub-optimal formation of connective tissue and subsequent tissue cohesion, particularly in skin models. Here, we describe a method which involves the addition of differentially-sized sucrose co-polymers to skin cultures to generate macromolecular crowding (MMC), which results in a dramatic enhancement of collagen deposition. Particularly, dermal fibroblasts deposited a significant amount of collagen I/IV/VII and fibronectin under MMC in comparison to controls.
The protocol also describes a method to decellularize crowded cell layers, exposing significant amounts of extracellular matrix (ECM) which were retained on the culture surface as evidenced by immunocytochemistry. Total matrix mass and distribution pattern was studied using interference reflection microscopy. Interestingly, fibroblasts, keratinocytes and co-cultures produced cell-derived matrices (CDM) of varying composition and morphology. CDM could be used as &#34;bio-scaffolds&#34; for secondary cell seeding, where the current use of coatings or scaffolds, typically from xenogenic animal sources, can be avoided, thus moving towards more clinically relevant applications.
In addition, this protocol describes the application of MMC during the submerged phase of a 3D-organotypic skin co-culture model which was sufficient to enhance ECM deposition in the dermo-epidermal junction (DEJ), in particular, collagen VII, the major component of anchoring fibrils. Electron microscopy confirmed the presence of anchoring fibrils in cultures developed with MMC, as compared to controls. This is significant as anchoring fibrils tether the dermis to the epidermis, hence, having a pre-formed mature DEJ may benefit skin graft recipients in terms of graft stability and overall wound healing. Furthermore, culture time was condensed from 5 weeks to 3 weeks to obtain a mature construct, when using MMC, reducing costs.

Improving 2D and 3D Skin In Vitro Models Using Macromolecular Crowding

We present a protocol to obtain cell-derived matrices rich in extracellular matrix proteins, using macromolecular crowders (MMC). In addition, we present a protocol which incorporates MMC in 3D organotypic skin co-culture generation, which reduces culture time while maintaining maturity of construct.

The glycoprotein family of collagens represents the main structural proteins in the human body, and are key components of biomaterials used in modern ...

Microfluidic Flow Chambers Using Reconstituted Blood to Model Hemostasis and Platelet Transfusion In Vitro

Blood platelets prepared for transfusion gradually lose hemostatic function during storage. Platelet function can be investigated using a variety of (indirect) in vitro experiments, but none of these is as comprehensive as microfluidic flow chambers. In this protocol, the reconstitution of thrombocytopenic fresh blood with stored blood bank platelets is used to simulate platelet transfusion. Next, the reconstituted sample is perfused in microfluidic flow chambers which mimic hemostasis on exposed subendothelial matrix proteins. Effects of blood donation, transport, component separation, storage and pathogen inactivation can be measured in paired experimental designs. This allows reliable comparison of the impact every manipulation in blood component preparation has on hemostasis. Our results demonstrate the impact of temperature cycling, shear rates, platelet concentration and storage duration on platelet function. In conclusion, this protocol analyzes the function of blood bank platelets and this ultimately aids in optimization of the processing chain including phlebotomy, transport, component preparation, storage and transfusion.

Microfluidic Flow Chambers Using Reconstituted Blood to Model Hemostasis and Platelet Transfusion In Vitro

Platelet transfusion and hemostasis was modeled using blood reconstitution and microfluidic flow chambers to investigate the function of blood banking platelets. The data demonstrate the consequences of platelet storage lesion on hemostasis, in vitro.

Blood platelets prepared for transfusion gradually lose hemostatic function during storage. Platelet function can be investigated using a variety of ...

An In Vitro Organ Culture Model of the Murine Intervertebral Disc

Intervertebral disc (IVD) degeneration is a significant contributor to low back pain. The IVD is a fibrocartilaginous joint that serves to transmit and dampen loads in the spine. The IVD consists of a proteoglycan-rich nucleus pulposus (NP) and a collagen-rich annulus fibrosis (AF) sandwiched by cartilaginous end-plates. Together with the adjacent vertebrae, the vertebrae-IVD structure forms a functional spine unit (FSU). These microstructures contain unique cell types as well as unique extracellular matrices. Whole organ culture of the FSU preserves the native extracellular matrix, cell differentiation phenotypes, and cellular-matrix interactions. Thus, organ culture techniques are particularly useful for investigating the complex biological mechanisms of the IVD. Here, we describe a high-throughput approach for culturing whole lumbar mouse FSUs that provides an ideal platform for studying disease mechanisms and therapies for the IVD. Furthermore, we describe several applications that utilize this organ culture method to conduct further studies including contrast-enhanced microCT imaging and three-dimensional high-resolution finite element modeling of the IVD.

An In Vitro Organ Culture Model of the Murine Intervertebral Disc

Whole organ culture of the intervertebral disc (IVD) preserves the native extracellular matrix, cell phenotypes, and cellular-matrix interactions. Here we describe an IVD culture system using mouse lumbar and caudal IVDs in their functional spinal units and several applications utilizing this system.

Intervertebral disc (IVD) degeneration is a significant contributor to low back pain. The IVD is a fibrocartilaginous joint that serves to transmit and ...