Name: improving 2d and 3d skin in vitro models using macromolecular crowding
Uploaded: 2016-08-22T13:00:00
Description: Watch this Scientific Journal Video about Improving 2D and 3D Skin In Vitro Models Using Macromolecular Crowding at JoVE.com

This work was supported by the Biomedical Research Council, Singapore through core support to the Institute of Medical Biology and grant SPF2013/005. M.R. was supported by a NUS Faculty Research Committee Grant (Engineering in Medicine) (M.R.) R-397-000-081-112, and the NUS Tissue Engineering Program (NUSTEP). The authors would like to thank Professor Irene Leigh for providing the collagen VII antibody. Electron microscopy work was carried out at the National University of Singapore Electron Microscopy Unit.

1. Macromolecular Crowding in 2D Skin Cell Cultures
<ol>
	<li>Seed 50,000 cells (primary fibroblasts or primary keratinocytes or co-culture of primary fibroblasts and keratinocytes) per well of a 24-well plate. Seed cells in 1 ml of the corresponding cell type growth media.</li>
	<li>Allow cells to adhere overnight, in a 37 &#176;C incubator at 5% CO2.</li>
	<li>Discard old media and replace with 1 ml fresh media containing macromolecular crowders and 100 &#181;M ascorbic acid. Use a crowder cocktail consist...

<ol>
	<li>Breitkreutz, D., Mirancea, N., Nischt, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Basement+membranes+in+skin:+unique+structures+with+diverse+functions.">Basement membranes in skin: unique structures with diverse functions.</a> Histochem Cell Biol. 132 (1), 1-10 (2009).</li><li>Lane, E. B., 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=mutation+in+the+conserved+helix+termination+peptide+of+keratin+5+in+hereditary+skin+blistering.">mutation in the conserved helix termination peptide of keratin 5 in hereditary skin blistering.</a> Nature. 356 (6366), 244-246 (1992).</li><li>Fuchs, E., Raghavan, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Getting+under+the+skin+of+epidermal+morphogenesis.">Getting under the skin of epidermal morphogenesis.</a> Nat Rev Genet. 3 (3), 199-209 (2002).</li><li>Niessen, C. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tight+junctions/adherens+junctions:+basic+structure+and+function.">Tight junctions/adherens junctions: basic structure and function.</a> J Invest Dermatol. 127 (11), 2525-2532 (2007).</li><li>Jarvelainen, H., Sainio, A., Koulu, M., Wight, T. N., Penttinen, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extracellular+matrix+molecules:+potential+targets+in+pharmacotherapy.">Extracellular matrix molecules: potential targets in pharmacotherapy.</a> Pharmacol Rev. 61 (2), 198-223 (2009).</li><li>Schaefer, L., Schaefer, R. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Proteoglycans:+from+structural+compounds+to+signaling+molecules.">Proteoglycans: from structural compounds to signaling molecules.</a> Cell Tissue Res. 339 (1), 237-246 (2010).</li><li>Frantz, C., Stewart, K. M., Weaver, V. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+extracellular+matrix+at+a+glance.">The extracellular matrix at a glance.</a> J Cell Sci. 123 (Pt 24), 4195-4200 (2010).</li><li>Ghalbzouri, A., Jonkman, M., Dijkman, R., Ponec, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Basement+membrane+reconstruction+in+human+skin+equivalents+is+regulated+by+fibroblasts+and/or+exogenously+activated+keratinocytes.">Basement membrane reconstruction in human skin equivalents is regulated by fibroblasts and/or exogenously activated keratinocytes.</a> J Invest Dermatol. 124 (1), 79-86 (2005).</li><li>Lareu, R. R., Arsianti, I., Harve, K. S., Peng, Y. X., Raghunath, M. <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+Enhancement+of+Collagen+Matrix+Formation+and+Crosslinking+for+Applications+in+Tissue+Engineering--a+Preliminary+Study.">In Vitro Enhancement of Collagen Matrix Formation and Crosslinking for Applications in Tissue Engineering--a Preliminary Study.</a> Tiss Eng. 13 (2), 385-391 (2007).</li><li>Lareu, R. 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=Collagen+matrix+deposition+is+dramatically+enhanced+in+vitro+when+crowded+with+charged+macromolecules:+the+biological+relevance+of+the+excluded+volume+effect.">Collagen matrix deposition is dramatically enhanced in vitro when crowded with charged macromolecules: the biological relevance of the excluded volume effect.</a> FEBS Lett. 581 (14), 2709-2714 (2007).</li><li>Lareu, R. R., Harve, K. S., Raghunath, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Emulating+a+crowded+intracellular+environment+in+vitro.+dramatically+improves+RT-PCR+performance.">Emulating a crowded intracellular environment in vitro. dramatically improves RT-PCR performance.</a> Biophys Biochem Res Comm. 363 (1), 171-177 (2007).</li><li>Harve, K. S., Ramakrishnan, V., Rajagopalan, R., Raghunath, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Macromolecular+crowding+in+vitro+as+means+of+emulating+cellular+interiors:+when+less+might+be+more.">Macromolecular crowding in vitro as means of emulating cellular interiors: when less might be more.</a> Proc Natl Acad USA Sci. 105 (51), E119 (2008).</li><li>Chen, 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=The+Scar-in-a-Jar:+Studying+antifibrotic+lead+compounds+from+the+epigenetic+to+extracellular+level+in+a+single+well.">The Scar-in-a-Jar: Studying antifibrotic lead compounds from the epigenetic to extracellular level in a single well.</a> Br J Pharmacol. 158 (5), 1196-1209 (2009).</li><li>Harve, K. S., Lareu, R., Rajagopalan, R., Raghunath, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Understanding+how+the+crowded+interior+of+cells+stabilizes+DNA/DNA+and+DNA/RNA+hybrids-in+silico+predictions+and+in+vitro+evidence.">Understanding how the crowded interior of cells stabilizes DNA/DNA and DNA/RNA hybrids-in silico predictions and in vitro evidence.</a> Nucleic Acids Res. 38 (1), 172-181 (2009).</li><li>Satyam, 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=Macromolecular+crowding+meets+tissue+engineering+by+self-assembly:+A+paradigm+shift+in+regenerative+medicine.">Macromolecular crowding meets tissue engineering by self-assembly: A paradigm shift in regenerative medicine.</a> Adv Mat. 26 (19), 3024-3034 (2014).</li><li>Chen, C. Z. C., Loe, F., Blocki, A., Peng, Y., Raghunath, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Applying+macromolecular+crowding+to+enhance+extracellular+matrix+deposition+and+its+remodeling+in+vitro+for+tissue+engineering+and+cell-based+therapies.">Applying macromolecular crowding to enhance extracellular matrix deposition and its remodeling in vitro for tissue engineering and cell-based therapies.</a> Adv Drug Deliv Rev. 63 (4-5), 277-290 (2011).</li><li>Rashid, 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=Novel+use+for+Polyvinylpyrrolidone+as+a+Macromolecular+Crowder+for+Enhanced+Extracellular+Matrix+Deposition+and+Cell+Proliferation.">Novel use for Polyvinylpyrrolidone as a Macromolecular Crowder for Enhanced Extracellular Matrix Deposition and Cell Proliferation.</a> Tiss Eng C. , (2014).</li><li>Dewavrin, J. Y., Hamzavi, N., Shim, V. P. W., Raghunath, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tuning+the+Architecture+of+3D+Collagen+Hydrogels+by+Physiological+Macromolecular+Crowding.">Tuning the Architecture of 3D Collagen Hydrogels by Physiological Macromolecular Crowding.</a> Acta Biomaterialia. 10 (10), 4351-4359 (2014).</li><li>Dewavrin, J. 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=Synergistic+Rate+Boosting+of+Collagen+Fibrillogenesis+in+Heterogeneous+Mixtures+of+Crowding+Agents.">Synergistic Rate Boosting of Collagen Fibrillogenesis in Heterogeneous Mixtures of Crowding Agents.</a> J Phys Chem B. 119 (12), 4350-4358 (2015).</li><li>Auger, F. A., Berthod, F., Moulin, V., Pouliot, R., Germain, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tissue+engineered+skin+substitutes:+from+in+vitro+constructs+to+in+vivo+applications.">Tissue engineered skin substitutes: from in vitro constructs to in vivo applications.</a> Biotechnol Appl Biochem. 39, 263 (2004).</li><li>Chen, B., 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=Macromolecular+crowding+effect+on+cartilaginous+matrix+production:+a+comparison+of+two-dimensional+and+three-dimensional+models.">Macromolecular crowding effect on cartilaginous matrix production: a comparison of two-dimensional and three-dimensional models.</a> Tiss Eng Part C Methods. 19 (8), 586-595 (2013).</li><li>Zeiger, A. S., Loe, F. C., Li, R., Raghunath, M., van Vliet, K. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Macromolecular+crowding+directs+extracellular+matrix+organization+and+mesenchymal+stem+cell+behavior.">Macromolecular crowding directs extracellular matrix organization and mesenchymal stem cell behavior.</a> PLOS One. 7 (5), e37904 (2012).</li><li>Kumar, P., 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=Macromolecularly+crowded+in+vitro+microenvironments+accelerate+the+production+of+extracellular+matrix-rich+supramolecular+assemblies.">Macromolecularly crowded in vitro microenvironments accelerate the production of extracellular matrix-rich supramolecular assemblies.</a> Scientific Reports. 5, 8729 (2015).</li><li>Ang, X. 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=Macromolecular+crowding+amplifies+adipogenesis+of+human+bone+marrow-derived+MSCs+by+enhancing+the+pro-adipogenic+microenvironment.">Macromolecular crowding amplifies adipogenesis of human bone marrow-derived MSCs by enhancing the pro-adipogenic microenvironment.</a> Tiss Eng Part A. 20 (5-6), 966-981 (2014).</li><li>Peng, Y. X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+Fibroblast+Matrices+Bioassembled+Under+Macromolecular+Crowding+Support+Stable+Propagation+Of+Human+Embryonic+Stem+Cells.">Human Fibroblast Matrices Bioassembled Under Macromolecular Crowding Support Stable Propagation Of Human Embryonic Stem Cells.</a> J Tiss Eng Regen Med. 6 (10), e74-e84 (2012).</li><li>Benny, P., Badowski, C., Lane, E. B., Raghunath, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Making+More+Matrix:+Enhancing+the+deposition+of+dermal-epidermal+junction+components+in+vitro+and+accelerating+organotypic+skin+culture+development,+using+macromolecular+crowding.">Making More Matrix: Enhancing the deposition of dermal-epidermal junction components in vitro and accelerating organotypic skin culture development, using macromolecular crowding.</a> Tiss Eng A. 21 (1-2), 182-192 (2015).</li></ol>

Enhanced extracellular matrix is obtained upon introduction of macromolecular crowders to cell culture, owing to the excluded volume effect which increases the propeptide cleavage by proteinases. This results in extracellular matrix, in particular collagen, to be processed faster and deposited on the culture surface. While other groups have obtained thick fibroblast cell layers, it involved a culture time of several weeks20. In contrast, MMC described in this Protocol, dramatically shortens the culture time wh...

The skin forms a protective barrier by preventing water loss and pathogen entry. It is made up of three major components; the stromal rich dermis1, a stratified epidermis2,3,4 on top of it, and the dermo-epidermal junction in between5,6. The dermis is composed largely of collagen and elastic fibers and is sparsely populated with fibroblasts7. In contrast, the cell-rich epidermis is composed of multiple layers of keratinocytes. The keratinocytes of the inner-most layer are proliferative and provide new basal cells which renew and replace terminally differentiating keratinocytes that constantly move to the outer-most layer of the skin and have lost their nuclei and cytoplasmic material, resulting in a cornified layer which undergoes desquamation.
The dermal-epidermal junction, a specific type of basement membrane, is a complex structure composed of interconnecting matrix molecules, which tethers the epidermis to the dermis. Collagen I fibers of the dermis interlace with collagen VII anchoring fibrils which are anchored to the collagen IV rich lamina densa. Anchoring filaments (laminin 5, collagen XVII and integrins) in turn connect the lamina densa with hemidesmosomes of basal keratinocytes. Basal keratinocytes (stratum basale) have the capacity to proliferate and renew, as well as differentiate and stratify to form the suprabasal layers; stratum spinosum, stratum granulosum, and finally the stratum corneum, which represents the contact surface of the skin with the environment. En route from the basal layer to the cornified layer, keratinocytes switch expression patterns of cytokeratins and finally undergo apoptosis and encase themselves in cornified envelopes, hulls of specific proteins that are covalently crosslinked by transglutaminase activity.
Recreating skin and its layers in vitro, including the complex structures of the dermal-epidermal junction and dermal extracellular matrix, and to emulate the cornification process, has long intrigued scientists and bioengineers as a challenging task. There have been significant advances in skin tissue engineering, for example, the successful extraction of skin cells from patient biopsies and the generation of skin organotypic cultures using patient-derived skin cells8. However, unsolved problems remain pertaining to poor secretion of extracellular matrix proteins by the skin cells themselves and resulting in sub-optimal skin models. Furthermore, the time required to generate 3D organotypic skin co-culture using current protocols varies between four to eight weeks, a timeframe which could potentially be shortened with the incorporation of macromolecular crowders. Reducing culture time saves reagent cost, reduces the incidence of cell senescence and reduces the waiting time of the patient should the product be used in the clinic.
Macromolecular crowding (MMC) involves introducing specific macromolecules to the culture medium to generate excluded volume effects. These affect enzymatic reaction rates including the proteolytic cleavage of procollagen which is tardy under standard aqueous culture conditions9-13. Under MMC, enzymatic reactions are hastened without increasing the amount of reagents14,15 resulting in, in the case of procollagen cleavage, an increased amount of collagen I molecules in crowded cultures as compared to uncrowded controls10. As the conversion of procollagen to collagen allows the formation of collagen assemblies, fibroblasts cultured with MMC for 48 hours yielded significantly more collagen I as compared to uncrowded fibroblast cultures monitored for up to four weeks11,16,17. Besides effects on enzymatic activities that affect the formation, stabilization and remodeling of ECM, MMC also has been shown to directly enhance and modulate collagen fiber formation18,19.
We present here a method to enhance the extracellular matrix (ECM) production by skin cells, in particular, dermal fibroblasts and epidermal keratinocytes. In addition, we show that the enriched ECM produced under MMC in monolayer cultures can be decellularized and used as pure cell-derived matrix (CDM).
We use a non-conventional approach to visualize and fully appreciate the ECM deposited by skin cells cultured with MMC. Interference reflection microscopy is typically used for studying cell-matrix interactions or cell-to-glass contact points. This technique was utilized in our system to view the total amount of matrix deposited on the glass surface. Interference reflection microscopy was coupled with fluorescent immunostaining to obtain the most amount of information in terms of extracellular matrix composition and pattern, in the presence and absence of MMC.
Organotypic skin co-cultures is a classical method to model the skin in vitro in a three-dimensional context. While two-dimensional co-cultures may provide significant information, it is limited when translating this data and applying it back to an in vivo environment, which is inherently a three-dimensional structure. Skin keratinocytes, in particular, are polarized and contain apical and basal segments which are essential for homeostasis and cell adherence. In addition, the expression of typical suprabasal proteins in keratinocytes above the basal layer, such as keratin 1, keratin 10 and filaggrin is only present in the course of stratification and terminal differentiation of keratinocytes. As terminal differentiation is hardly present in typical monolayer cultures, suprabasal protein expression is normally not achieved in this culture system. Therefore, organotypic cultures start submerged in culture medium, but are then lifted to an air-liquid interface to drive keratinocyte differentiation. This results in the expression of stratification markers, even cornification and a generally better reflection of epidermal physiology. While other groups have previously generated organotypic skin co-cultures successfully, the establishment of a functional dermo-epidermal junction zone has been an issue. Here, we present a new method for culturing organotypic skin co-cultures with an enhanced basement membrane, in a condensed time frame and without compromising the maturity of these constructs. This would provide skin mimetics for in vitro modeling, the study of skin biology and an assortment of screening assays.

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		<tr height="21">
			<td height="21" style="height:21px;width:299px;">Ascorbic acid</td>
			<td style="width:181px;">Wako</td>
			<td style="width:175px;">013-12061</td>
			<td style="width:499px;">Cell culture media additive</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cell culture inserts&#160; (6-well format)</td>
			<td style="width:181px;">Greiner Bio-One</td>
			<td style="width:175px;">657610</td>
			<td>Organotypic cultures</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Citrate solution</td>
			<td style="width:181px;">Dako</td>
			<td style="width:175px;">S2369</td>
			<td style="width:499px;">DakoCytomation Target Retrieval Solution Citrate, pH 6 (x10)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">Collagen (rat tail)</td>
			<td style="width:181px;">Corning</td>
			<td style="width:175px;">354236</td>
			<td>Organotypic cultures</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">CnT-57&#160;</td>
			<td style="width:181px;">CELLnTEC</td>
			<td style="width:175px;">CnT-57</td>
			<td>Cell culture media</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">DAB Substrate + chromogen kit</td>
			<td style="width:181px;">Dako</td>
			<td style="width:175px;">K3468</td>
			<td>Histology</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">Deep-well plate (6-well format)</td>
			<td style="width:181px;">Corning</td>
			<td style="width:175px;">355467</td>
			<td>Organotypic cultures</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:299px;">ECL detection reagent</td>
			<td style="width:181px;">GE Healthcare Life Sciences</td>
			<td style="width:175px;">RPN2106</td>
			<td>Amersham ECL Western Blotting Detection Reagent</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">Electron microscope (TEM)</td>
			<td>&#160;JEOL&#160;</td>
			<td>&#160;JEM-1010 (100kV)</td>
			<td>Transmission electron microscopy</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">Fibroblast media (FM)</td>
			<td></td>
			<td></td>
			<td>High Glucose-DMEM + 10% Fetal Bovine Serum + 1% Penicillin Streptomycin</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:299px;">Ficoll PM70</td>
			<td style="width:181px;">GE Healthcare Life Sciences</td>
			<td style="width:175px;">17-0310-05</td>
			<td>Macromolecular crowder</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:299px;">Ficoll PM400</td>
			<td style="width:181px;">GE Healthcare Life Sciences</td>
			<td style="width:175px;">17-0300-05</td>
			<td>Macromolecular crowder</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">Keratinocyte serum-free media (KSFM)</td>
			<td style="width:181px;">Life Technologies</td>
			<td style="width:175px;">17005-042</td>
			<td>Cell culture media</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:299px;">Lysis buffer</td>
			<td style="width:181px;">ThermoFisher Scientific</td>
			<td style="width:175px;">89900</td>
			<td style="width:499px;">Lysis buffer for protein extraction. A protease inhibitor (Roche, #11836170001) was added to this lysis buffer.&#160;</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:299px;">Microscope</td>
			<td style="width:181px;">Zeiss</td>
			<td style="width:175px;">LSM510</td>
			<td style="width:499px;">Red, green and blue channels to visualize AF594, AF488 and DAPI fluorescent immunostainings (40X mag).</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">Mounting media (Hydromount)</td>
			<td style="width:181px;">National Diagnostics</td>
			<td style="width:175px;">HS-106</td>
			<td>Fluorescent staining</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">Mounting media (Cytoseal)</td>
			<td style="width:181px;">ThermoFisher Scientific</td>
			<td style="width:175px;">8310-16</td>
			<td>Histology (HRP)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">OCT compound (Tissue Tek)</td>
			<td style="width:181px;">Sakura</td>
			<td style="width:175px;">4583</td>
			<td>Embedding for cryotomy</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">Penicillin-streptomycin antibiotics</td>
			<td style="width:181px;">Sigma Aldrich</td>
			<td style="width:175px;">A5955</td>
			<td>Cell culture media additive</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">Primary antibodies</td>
			<td style="width:181px;"></td>
			<td style="width:175px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">Anti-Collagen I antibody</td>
			<td style="width:181px;">Abcam</td>
			<td style="width:175px;">#ab6308</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">Anti-Collagen Type IV</td>
			<td style="width:181px;">Novocastra</td>
			<td style="width:175px;">#NCL-COLL-IV</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">Anti-collagen VII</td>
			<td style="width:181px;"></td>
			<td style="width:175px;"></td>
			<td>LH7.2 (in house)&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">Anti-Fibronectin antibody</td>
			<td style="width:181px;">Abcam</td>
			<td style="width:175px;">#ab2413</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">Reducing agent&#160;</td>
			<td style="width:181px;">ThermoFisher Scientific</td>
			<td style="width:175px;">NP0009</td>
			<td>Western blot</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">Sample buffer</td>
			<td style="width:181px;">ThermoFisher Scientific</td>
			<td style="width:175px;">NP0008</td>
			<td>Western blot</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">Secondary antibodies (Immunostaining)</td>
			<td style="width:181px;"></td>
			<td style="width:175px;"></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:299px;">4&#8242;,6-Diamidino-2-phenylindole dihydrochloride (DAPI)</td>
			<td style="width:181px;">Sigma Aldrich</td>
			<td style="width:175px;">#D9542</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">AlexaFluor 594 goat-anti-rabbit</td>
			<td style="width:181px;">ThermoFisher Scientific</td>
			<td style="width:175px;">#A-11037&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">AlexaFluor 594 goat-anti-mouse</td>
			<td style="width:181px;">ThermoFisher Scientific</td>
			<td style="width:175px;">&#160;#A-11005</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">AlexaFluor 488 chicken-anti-rabbit</td>
			<td style="width:181px;">ThermoFisher Scientific</td>
			<td style="width:175px;">#A-21441</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">AlexaFluor 488 goat-anti-mouse</td>
			<td style="width:181px;">ThermoFisher Scientific</td>
			<td style="width:175px;">#A-11001</td>
			<td></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:299px;">Secondary antibodies (HRP)</td>
			<td style="width:181px;">Dako</td>
			<td style="width:175px;">Envision + System - HRP Labelled Polymer Anti-Rabbit and Anti-Mouse</td>
			<td>undiluted</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:299px;">Sodium deoxycholate</td>
			<td style="width:181px;">Prodotti Chimicie Alimentari</td>
			<td style="width:175px;"></td>
			<td>Decellularization</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">Stratification media</td>
			<td style="width:181px;"></td>
			<td style="width:175px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">Dulbecco&#39;s Modified Eagle&#39;s Medium&#160;</td>
			<td style="width:181px;"></td>
			<td style="width:175px;"></td>
			<td>Used during the air-liquid interface of organotypic cultures. This media is added to the outside of the cell-culture insert.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">Ham&#8217;s F12&#160;&#160;&#160;</td>
			<td style="width:181px;"></td>
			<td style="width:175px;"></td>
			<td>Used during the air-liquid interface of organotypic cultures. This media is added to the outside of the cell-culture insert.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">10% fetal bovine serum&#160;</td>
			<td style="width:181px;"></td>
			<td style="width:175px;"></td>
			<td>Used during the air-liquid interface of organotypic cultures. This media is added to the outside of the cell-culture insert.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:299px;">100U/mL penicillin and 100U/mL streptomycin&#160;&#160;</td>
			<td style="width:181px;"></td>
			<td style="width:175px;"></td>
			<td>Used during the air-liquid interface of organotypic cultures. This media is added to the outside of the cell-culture insert.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">0.4mg/mL hydrocortisone&#160;&#160;&#160;</td>
			<td style="width:181px;"></td>
			<td style="width:175px;"></td>
			<td>Used during the air-liquid interface of organotypic cultures. This media is added to the outside of the cell-culture insert.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">5mg/mL insulin</td>
			<td style="width:181px;"></td>
			<td style="width:175px;"></td>
			<td>Used during the air-liquid interface of organotypic cultures. This media is added to the outside of the cell-culture insert.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">1.8&#183;10-4 M adenine&#160;&#160;</td>
			<td style="width:181px;"></td>
			<td style="width:175px;"></td>
			<td>Used during the air-liquid interface of organotypic cultures. This media is added to the outside of the cell-culture insert.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">5mg/mL transferrin&#160;</td>
			<td style="width:181px;"></td>
			<td style="width:175px;"></td>
			<td>Used during the air-liquid interface of organotypic cultures. This media is added to the outside of the cell-culture insert.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:299px;">2&#183;10- 11 M triiodothyronine&#160;</td>
			<td style="width:181px;"></td>
			<td style="width:175px;"></td>
			<td>Used during the air-liquid interface of organotypic cultures. This media is added to the outside of the cell-culture insert.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:299px;">Trypsin</td>
			<td style="width:181px;">Biopolis Shared Facilities</td>
			<td style="width:175px;">0.125% Trypsin/Versene&#160;&#160; pH 7.0 + 0.3&#160;</td>
			<td>Used to trypsinize cells</td>
		</tr>
	</tbody>
</table>

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.

Macromolecular crowding was able to enhance ECM deposition, in particular, fibroblasts deposited more collagen I, IV and fibronectin as compared to control cultures (Figure 1, Cell layer; 1A, collagen I; 1B, collagen IV; 1C, fibronectin). Upon decellularization, it was evident that fibroblasts were the main depositors of collagen I, IV and fibronectin as compared to keratinocytes (Figure 1, Matrix).
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Watch this Scientific Journal Video about Improving 2D and 3D Skin In Vitro Models Using Macromolecular Crowding at JoVE.com

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.

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 ...

Research

JoVE Journal

Bioengineering

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