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>
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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. 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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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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 ...

The overall goal of this procedure is to enhance extracellular matrix deposition and improve on current 2D and 3D skin models using macromolecular crowding. Crowding improves the generation of cell-derived matrices, and mature organotypic cultures in a condensed time frame. This method can answer key questions in the field of tissue engineering because it offers improved ways of generating cell-derived extracellular matrices for the bioengineering of skin and other tissues.The main advantage of this technique is that cell-derived matrices and organotypic skin constructs can be generated in a significantly condensed time frame when applying macromolecular crowding to these cultures. The technique of interference reflection microscopy allows you to visualize the total extracellular matrix deposition without the need of antibody staining. Applications of these techniques will extend from studies of extracellular matrix deposition by skin cells to improved wound therapies, especially with the generation of better skin equivalents and tissue culture for grafting.To begin, seed 50, 000 primary fibroblasts, primary keratinocytes, or a co-culture of both, in one milliliter of medium pro well, into the wells of a 24-well plate. Allow the cells to adhere in a 37 degree Celsius, 5%carbon dioxide incubator overnight. Then, discard the old medium and replace it with one milliliter of fresh medium containing macromolecular crowders and 100-micromolar ascorbic acid.Incubate the cultures for six days, changing the medium every two days. Carry out immunofluorescence and Western blotting according to the text protocol. To make and use a cell-derived matrix, after culturing the cells for six days with molecular crowders and ascorbic acid as just demonstrated, decellularize the cell layers to obtain a cell-derived matrix by first using 1X PBS to wash the cell layers twice.Aspirate the PBS, and then add 250 microliter of 0.5%sodium deoxycholate and incubate on ice for 10 minutes. Aspirate the cell lysate, then add an additional 250 microliter of 0.5%sodium deoxycholate and repeat the 10-minute incubation and aspiration two more times. Use distilled water to wash the cell-derived matrix twice.Aspirate the water, and then add 1X PBS. Store the matrix at four degrees Celsius for up to one week. To prepare a secondary cell suspension, aspirate the PBS from the matrix, and seed 50, 000 keratinocytes on top of the F mat for example.Allow the cells to adhere overnight. To carry out interference reflection microscopy, or RIM, on a cell-derived matrix, perform image acquisition using a con-focal microscope according to the text protocol. To cast a collagen gel with fibroblasts encapsulated in a cell culture insert, aliquot 10 milliliters of rat tail collagen type one into a cold beaker.Add one milliliter of cold DMEM and 0.5 milliliters of one molar sodium hydroxide to neutralize the acidic collagen. Then add 0.5 milliliters of fibroblast suspension. Using a cold pipette, evenly divide the 12 milliliters of solution into cell culture inserts in a six-well culture plate.Incubate the gel at 37 degrees Celsius and 5%carbon dioxide for one hour. Once the gel has solidified, submerge it in fibroblast medium or FM.Then after incubating it for 24 hours, aspirate the FM.Use four milliliters of fresh medium containing macromolecular crowders to replace the old FM by adding two milliliters to the interior of the cell culture insert and two milliliters to the outside of the cell culture insert. Following a 24-hour incubation, use 0.125%trypsin cheating agent to trysonize the keratinocytes.Tap the sides of the flask gently to dislodge the cells and add serum-containing medium to neutralize the trypsin. After counting the cells, prepare a keratinocyte suspension. Next, aspirate the medium from the cell culture inserts, and add the keratinocytes to the top of the gel.Incubate the gel for one hour. After the keratinocytes have attached to the gel surface, use two milliliters of KSFM, or CTN-57 serum-free medium to submerge the cell inside the gel culture insert and add two milliliters of FM to the outside of the cell culture insert. Following a 24-hour incubation, discard the old medium and replace it with fresh medium containing macromolecular crowders.After seven days in the submerged culture, to raise the culture to an air-liquid interface, transfer the culture insert to a deep-well plate. Add 10 milliliters of stratification medium to the outside of the cell culture insert, keeping the interior of the insert dry. Finally, incubate the cultures and change the medium every three days for 14 days.Harvest and process them according to the text protocol. As shown here, macromolecular crowding allowed fibroblasts to deposit more extracellular matrix or ECM as compared to control cultures. Upon secularization, it was evident that fibroblasts were the main depositors of collagen one, collagen four, and fibronectin.This figure demonstrates that is was fibroblasts rather than keratinocytes that were the main depositors of collagen seven, and this is the first report of successful collagen seven deposition in vitro. Using RIM, the full extent of the cell-derived matrix was captured. An overlay of the RIM image with antibody staining shows the relative quantity of that ECM component in relation to the total amount of ECM.In a 3D in vitro skin model, macromolecular crowding or MMC, shortened the culture time from five weeks to three, to obtain a mature organotypic skin co-culture. As seen here, by H and E staining, at three weeks, the culture with MMC consisted of a pleuristratified epidermis and a stromol ridge dermis. In addition, intense and continuous collagen seven immnunostaining was detected at the dermalepidermal junction of crowded cell cultures as compared to a weak and spotty collagen seven immunostaining in control cultures.Transmission electron microscopy also show the presence of anchoring fibrils in organotypic cultures generated with MMC, showing functional collagen seven. Cell-derived matrices could be used for secondary cell seeding purposes as an alternative scaffold as the complexity of the extracellular matrix is maintained, and it is produced by cells themselves. Organotypic skin cultures, which are generated under macromolecular crowding, could be used as an improved 3D skin model as it contain a stromal ridge dermis, a major dermalepidermal junction, and a pleuristratifed epidermis.Organotypic, or skin equivalent cultures generated with macromolecular crowders can also be used for skin grafting because they have a better developed dermalepidermal junction, which is likely to improve graft success. In addition to enhanced extracellular matrix deposition, macromolecular crowding can be applied to other in vitro systems to enhance reactions with are rate limited, without having to increase the amount of reagents. For example, polymerase chain reactions.

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Research

JoVE Journal

Bioengineering

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 ...

Electric Field-controlled Directed Migration of Neural Progenitor Cells in 2D and 3D Environments

Endogenous electric fields (EFs) occur naturally in vivo and play a critical role during tissue/organ development and regeneration, including that of the central nervous system1,2. These endogenous EFs are generated by cellular regulation of ionic transport combined with the electrical resistance of cells and tissues. It has been reported that applied EF treatment can promote functional repair of spinal cord injuries in animals and humans3,4. In particular, EF-directed cell migration has been demonstrated in a wide variety of cell types5,6, including neural progenitor cells (NPCs)7,8. Application of direct current (DC) EFs is not a commonly available technique in most laboratories. We have described detailed protocols for the application of DC EFs to cell and tissue cultures previously5,11. Here we present a video demonstration of standard methods based on a calculated field strength to set up 2D and 3D environments for NPCs, and to investigate cellular responses to EF stimulation in both single cell growth conditions in 2D, and the organotypic spinal cord slice in 3D. The spinal cordslice is an ideal recipient tissue for studying NPC ex vivo behaviours, post-transplantation, because the cytoarchitectonic tissue organization is well preserved within these cultures9,10. Additionally, this ex vivo model also allows procedures that are not technically feasible to track cells in vivo using time-lapse recording at the single cell level. It is critically essential to evaluate cell behaviours in not only a 2D environment, but also in a 3D organotypic condition which mimicks the in vivo environment. This system will allow high-resolution imaging using cover glass-based dishes in tissue or organ culture with 3D tracking of single cell migration in vitro and ex vivo and can be an intermediate step before moving onto in vivo paradigms.

This protocol demonstrates methods used to establish 2D and 3D environments in custom-designed electrotactic chambers, which can track cells in vivo/ex vivo using time-lapse recording at the single cell level, in order to investigate galvanotaxis/electrotaxis and other cellular responses to direct current (DC) electric fields (EFs).

Endogenous electric fields (EFs) occur naturally in vivo and play a critical role during tissue/organ development and regeneration, including that of the ...

Longitudinal Measurement of Extracellular Matrix Rigidity in 3D Tumor Models Using Particle-tracking Microrheology

The mechanical microenvironment has been shown to act as a crucial regulator of tumor growth behavior and signaling, which is itself remodeled and modified as part of a set of complex, two-way mechanosensitive interactions. While the development of biologically-relevant 3D tumor models have facilitated mechanistic studies on the impact of matrix rheology on tumor growth, the inverse problem of mapping changes in the mechanical environment induced by tumors remains challenging. Here, we describe the implementation of particle-tracking microrheology (PTM) in conjunction with 3D models of pancreatic cancer as part of a robust and viable approach for longitudinally monitoring physical changes in the tumor microenvironment, in situ. The methodology described here integrates a system of preparing in vitro 3D models embedded in a model extracellular matrix (ECM) scaffold of Type I collagen with fluorescently labeled probes uniformly distributed for position- and time-dependent microrheology measurements throughout the specimen. In vitro tumors are plated and probed in parallel conditions using multiwell imaging plates. Drawing on established methods, videos of tracer probe movements are transformed via the Generalized Stokes Einstein Relation (GSER) to report the complex frequency-dependent viscoelastic shear modulus, G*(&#969;). Because this approach is imaging-based, mechanical characterization is also mapped onto large transmitted-light spatial fields to simultaneously report qualitative changes in 3D tumor size and phenotype. Representative results showing contrasting mechanical response in sub-regions associated with localized invasion-induced matrix degradation as well as system calibration, validation data are presented. Undesirable outcomes from common experimental errors and troubleshooting of these issues are also presented. The 96-well 3D culture plating format implemented in this protocol is conducive to correlation of microrheology measurements with therapeutic screening assays or molecular imaging to gain new insights into impact of treatments or biochemical stimuli on the mechanical microenvironment.

Particle-tracking microrheology can be used to non-destructively quantify and spatially map changes in extracellular matrix mechanical properties in 3D tumor models.

The mechanical microenvironment has been shown to act as a crucial regulator of tumor growth behavior and signaling, which is itself remodeled and ...

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 ...

2D and 3D Matrices to Study Linear Invadosome Formation and Activity

Cell adhesion, migration, and invasion are involved in many physiological and pathological processes. For example, during metastasis formation, tumor cells have to cross anatomical barriers to invade and migrate through the surrounding tissue in order to reach blood or lymphatic vessels. This requires the interaction between cells and the extracellular matrix (ECM). At the cellular level, many cells, including the majority of cancer cells, are able to form invadosomes, which are F-actin-based structures capable of degrading ECM. Invadosomes are protrusive actin structures that recruit and activate matrix metalloproteinases (MMPs). The molecular composition, density, organization, and stiffness of the ECM are crucial in regulating invadosome formation and activation. In vitro, a gelatin assay is the standard assay used to observe and quantify invadosome degradation activity. However, gelatin, which is denatured collagen I, is not a physiological matrix element. A novel assay using type I collagen fibrils was developed and used to demonstrate that this physiological matrix is a potent inducer of invadosomes. Invadosomes that form along the collagen fibrils are known as linear invadosomes due to their linear organization on the fibers. Moreover, molecular analysis of linear invadosomes showed that the discoidin domain receptor 1 (DDR1) is the receptor involved in their formation. These data clearly demonstrate the importance of using a physiologically relevant matrix in order to understand the complex interactions between cells and the ECM.

This protocol describes how to prepare a 2D mixed matrix, consisting of gelatin and collagen I, and a 3D collagen I plug to study linear invadosomes. These protocols allow for the study of linear invadosome formation, matrix degradation activity, and the invasion capabilities of primary cells and cancer cell lines.

Cell adhesion, migration, and invasion are involved in many physiological and pathological processes. For example, during metastasis formation, tumor ...

Bioprinting of Cartilage and Skin Tissue Analogs Utilizing a Novel Passive Mixing Unit Technique for Bioink Precellularization

Bioprinting is a powerful technique for the rapid and reproducible fabrication of constructs for tissue engineering applications. In this study, both cartilage and skin analogs were fabricated after bioink pre-cellularization utilizing a novel passive mixing unit technique. This technique was developed with the aim to simplify the steps involved in the mixing of a cell suspension into a highly viscous bioink. The resolution of filaments deposited through bioprinting necessitates the assurance of uniformity in cell distribution prior to printing to avoid the deposition of regions without cells or retention of large cell clumps that can clog the needle. We demonstrate the ability to rapidly blend a cell suspension with a bioink prior to bioprinting of both cartilage and skin analogs. Both tissue analogs could be cultured for up to 4 weeks. Histological analysis demonstrated both cell viability and deposition of tissue specific extracellular matrix (ECM) markers such as glycosaminoglycans (GAGs) and collagen I respectively.

Cartilage and skin analogs were bioprinted using a nanocellulose-alginate based bioink. The bioinks were cellularized prior to printing via a single step passive mixing unit. The constructs were demonstrated to be uniformly cellularized, have high viability, and exhibit favorable markers of differentiation.

Bioprinting is a powerful technique for the rapid and reproducible fabrication of constructs for tissue engineering applications. In this study, both ...

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.

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 ...

Advanced 3D Liver Models for In vitro Genotoxicity Testing Following Long-Term Nanomaterial Exposure

Due to the rapid development and implementation of a diverse array of engineered nanomaterials (ENM), exposure to ENM is inevitable and the development of robust, predictive in vitro test systems is essential. Hepatic toxicology is key when considering ENM exposure, as the liver serves a vital role in metabolic homeostasis and detoxification as well as being a major site of ENM accumulation post exposure. Based upon this and the accepted understanding that 2D hepatocyte models do not accurately mimic the complexities of intricate multi-cellular interactions and metabolic activity observed in vivo, there is a greater focus on the development of physiologically relevant 3D liver models tailored for ENM hazard assessment purposes in vitro. In line with the principles of the 3Rs to replace, reduce and refine animal experimentation, a 3D HepG2 cell-line based liver model has been developed, which is a user friendly, cost effective system that can support both extended and repeated ENM exposure regimes (&#8804;14 days). These spheroid models (&#8805;500 &#181;m in diameter) retain their proliferative capacity (i.e., dividing cell models) allowing them to be coupled with the &#8216;gold standard&#8217; micronucleus assay to effectively assess genotoxicity in vitro. Their ability to report on a range of toxicological endpoints (e.g., liver function, (pro-)inflammatory response, cytotoxicity and genotoxicity) has been characterized using several ENMs across both acute (24 h) and long-term (120 h) exposure regimes. This 3D in vitro hepatic model has the capacity to be utilized for evaluating more realistic ENM exposures, thereby providing a future in vitro approach to better support ENM hazard assessment in a routine and easily accessible manner.

This procedure was established to be used for developing advanced 3D hepatic cultures in vitro, which can provide a more physiologically relevant assessment of the genotoxic hazards associated with nanomaterial exposures over both an acute or long-term, repeated dose regimes.

Due to the rapid development and implementation of a diverse array of engineered nanomaterials (ENM), exposure to ENM is inevitable and the development of ...

Evaluating Regional Pulmonary Deposition using Patient-Specific 3D Printed Lung Models

Development of targeted therapies for pulmonary diseases is limited by the availability of preclinical testing methods with the ability to predict regional aerosol delivery. Leveraging 3D printing to generate patient-specific lung models, we outline the design of a high-throughput, in vitro experimental setup for quantifying lobular pulmonary deposition. This system is made with a combination of commercially available and 3D printed components and allows the flow rate through each lobe of the lung to be independently controlled. Delivery of fluorescent aerosols to each lobe is measured using fluorescence microscopy. This protocol has the potential to promote the growth of personalized medicine for respiratory diseases through its ability to model a wide range of patient demographics and disease states. Both the geometry of the 3D printed lung model and the air flow profile setting can be easily modulated to reflect clinical data for patients with varying age, race, and gender. Clinically relevant drug delivery devices, such as the endotracheal tube shown here, can be incorporated into the testing setup to more accurately predict a device&#8217;s capacity to target therapeutic delivery to a diseased region of the lung. The versatility of this experimental setup allows it to be customized to reflect a multitude of inhalation conditions, enhancing the rigor of preclinical therapeutic testing.

We present a high-throughput, in vitro method for quantifying regional pulmonary deposition at the lobe level using CT scan-derived, 3D printed lung models with tunable air flow profiles.

Development of targeted therapies for pulmonary diseases is limited by the availability of preclinical testing methods with the ability to predict ...

In Vitro 3D Cell-Cultured Arterial Models for Studying Vascular Drug Targeting Under Flow

The use of three-dimensional (3D) models of human arteries, which are designed with the correct dimensions and anatomy, enables the proper modeling of various important processes in the cardiovascular system. Recently, although several biological studies have been performed using such 3D models of human arteries, they have not been applied to study vascular targeting. This paper presents a new method to fabricate real-sized, reconstructed human arterial models using a 3D printing technique, line them with human endothelial cells (ECs), and study particle targeting under physiological flow. These models have the advantage of replicating the physiological size and conditions of blood vessels in the human body using low-cost components. This technique may serve as a new platform for studying and understanding drug targeting in the cardiovascular system and may improve the design of new injectable nanomedicines. Moreover, the presented approach may provide significant tools for the study of targeted delivery of different agents for cardiovascular diseases under patient-specific flow and physiological conditions.

In Vitro 3D Cell-Cultured Arterial Models for Studying Vascular Drug Targeting Under Flow

Here, we present a new protocol to study and map the targeted deposition of drug carriers to endothelial cells in fabricated, real-sized, three-dimensional human artery models under physiological flow. The presented method may serve as a new platform for targeting drug carriers within the vascular system.

The use of three-dimensional (3D) models of human arteries, which are designed with the correct dimensions and anatomy, enables the proper modeling of ...