Name: determining the toxicity of uv radiation and chemicals on primary and immortalized human corneal epithelial cells
Uploaded: 2021-07-22T13:00:00
Description: Watch this Scientific Journal Video about Determining the Toxicity of UV Radiation and Chemicals on Primary and Immortalized Human Corneal Epithelial Cells at JoVE.com

The authors received no funding for this work.

1. Culture of pHCECs and iHCECs
<ol>
	<li>Grow the pHCECs and iHCECs in human ocular epithelial medium (HOEM) with the following supplements: 6 mM L-glutamine, 0.002% cell media supplement O (Table of Materials), 1.0 &#181;M epinephrine, 0.4% cell media supplement P (Table of Materials), 5 &#181;g/mL rh insulin, 5 &#181;g/mL apo-transferrin, and 100 ng/mL hydrocortisone hemisuccinate in collagen-1 coated culture flasks (18 mL in a 75 cm2 culture flask).</li>
	<li>Change the ...

<ol>
	<li>McCanna, D. J., Harrington, K. L., Driot, J. Y., Ward, K. W., Tchao, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Use+of+a+human+corneal+epithelial+cell+line+for+screening+the+safety+of+contact+lens+care+solutions+in+vitro.">Use of a human corneal epithelial cell line for screening the safety of contact lens care solutions in vitro.</a> Eye &amp; Contact Lens. 34 (1), 6-12 (2008).</li><li>Xu, M., Sivak, J. G., McCanna, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+the+effects+of+ophthalmic+solutions+on+human+corneal+epithelial+cells+using+fluorescent+dyes.">Comparison of the effects of ophthalmic solutions on human corneal epithelial cells using fluorescent dyes.</a> Journal of Ocular Pharmacology and Therapeutics. 29 (9), 794-802 (2013).</li><li>Youn, H. Y., McCanna, D. J., Sivak, J. G., Jones, L. W. <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+ultraviolet-induced+damage+in+human+corneal,+lens,+and+retinal+pigment+epithelial+cells.">In vitro ultraviolet-induced damage in human corneal, lens, and retinal pigment epithelial cells.</a> Molecular Vision. 17, 237-246 (2011).</li><li>Hakkarainen, J. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acute+cytotoxic+effects+of+marketed+ophthalmic+formulations+on+human+corneal+epithelial+cells.">Acute cytotoxic effects of marketed ophthalmic formulations on human corneal epithelial cells.</a> International Journal of Pharmaceutics. 511 (1), 73-78 (2016).</li><li>Spurr, S. J., Gipson, I. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+of+corneal+epithelium+with+Dispase+II+or+EDTA.+Effects+on+the+basement+membrane+zone.">Isolation of corneal epithelium with Dispase II or EDTA. Effects on the basement membrane zone.</a> Investigative Ophthalmology &amp; Visual Science. 26 (6), 818-827 (1985).</li><li>Kahn, C. R., Young, E., Lee, I. H., Rhim, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+corneal+epithelial+primary+cultures+and+cell+lines+with+extended+life+span:+in+vitro+model+for+ocular+studies.">Human corneal epithelial primary cultures and cell lines with extended life span: in vitro model for ocular studies.</a> Investigative Ophthalmology &amp; Visual Science. 34 (12), 3429-3441 (1993).</li><li>Araki-Sasaki, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+SV40-immortalized+human+corneal+epithelial+cell+line+and+its+characterization.">An SV40-immortalized human corneal epithelial cell line and its characterization.</a> Investigative Ophthalmology &amp; Visual Science. 36 (3), 614-621 (1995).</li><li>Griffith, 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=Functional+human+corneal+equivalents+constructed+from+cell+lines.">Functional human corneal equivalents constructed from cell lines.</a> Science. 286 (5447), 2169-2172 (1999).</li><li>Toouli, C. 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A., Engelke, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+human+corneal+cell+cultures+in+cytotoxicity+testing.">Comparison of human corneal cell cultures in cytotoxicity testing.</a> Altex. 21 (3), 129-134 (2004).</li><li>Huhtala, 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=Comparison+of+an+immortalized+human+corneal+epithelial+cell+line+and+rabbit+corneal+epithelial+cell+culture+in+cytotoxicity+testing.">Comparison of an immortalized human corneal epithelial cell line and rabbit corneal epithelial cell culture in cytotoxicity testing.</a> Journal of Ocular Pharmacology and Therapeutics. 18 (2), 163-175 (2002).</li><li>Pisella, P. J., Fillacier, K., Elena, P. P., Debbasch, C., Baudouin, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+the+effects+of+preserved+and+unpreserved+formulations+of+timolol+on+the+ocular+surface+of+albino+rabbits.">Comparison of the effects of preserved and unpreserved formulations of timolol on the ocular surface of albino rabbits.</a> Ophthalmic Research. 32 (1), 3-8 (2000).</li><li>Youn, H. Y., Moran, K. L., Oriowo, O. M., Bols, N. C., Sivak, J. 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M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=SV40+large+T+antigen+targets+multiple+cellular+pathways+to+elicit+cellular+transformation.">SV40 large T antigen targets multiple cellular pathways to elicit cellular transformation.</a> Oncogene. 24 (52), 7729-7745 (2005).</li><li>Tong, 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=Pin1+inhibits+PP2A-mediated+Rb+dephosphorylation+in+regulation+of+cell+cycle+and+S-phase+DNA+damage.">Pin1 inhibits PP2A-mediated Rb dephosphorylation in regulation of cell cycle and S-phase DNA damage.</a> Cell Death &amp; Disease. 6, 1640 (2015).</li><li>Muller, P. A., Vousden, K. 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Q., Balagula, Y., Osterwalder, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Photoprotection:+a+review+of+the+current+and+future+technologies.">Photoprotection: a review of the current and future technologies.</a> Dermatologic Therapy. 23 (1), 31-47 (2010).</li><li>Svobodova, A. 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Potential differences in the use of two types of HCECs were assessed. Cells were placed in the same medium (HOEM) at identical concentrations of cells and then exposed to short and long periods of UV radiation and three ocular toxins. Doses of UV radiation and chemicals were selected based on their physiological effects, which were damaging enough to the cells to produce intermediate responses that could be compared. Exposure times of 5 and 20 min for UV radiation and 5 and 15 min for the selected doses of BAK (0.001%), ...

In vitro toxicology studies are performed to predict the toxic effects of chemicals and other agents that can cause damage to cells. In the assessment of toxicity to the cornea, human corneal epithelial cells (HCECs) have been used in models for evaluating these effects1,2,3,4. These models typically evaluate physiological effects such as changes to the cell&#39;s metabolic activity, cell proliferation, and other cell functions such as the production and release of inflammatory cytokines. For these toxicology studies, cells from various sources have been selected to assess the damaging effects of chemicals and UV radiation on HCECs2,3. pHCEC lines are available from companies that provide these cells from donor tissues of adults. Primary cells can be treated with dispase and gently scraped off the cornea for culture5. The cells are then tested for viruses and contamination and then shipped cryopreserved in 10% dimethyl sulfoxide.
The advantage of primary cell lines is that the cells are genetically identical to the cells of the donor. This is ideal, as an in vitro model should mimic the in vivo tissue as much as possible. The disadvantage of primary cell lines is that they have a limited number of cell divisions or passages6. The limited number of cells available restricts the number of experiments that can be conducted with a single primary culture, increasing the cost of the experiments.
Immortalized cell lines have also been used in cell culture toxicity models. However, unlike the primary cell line obtained from in vivo tissue, the immortalized cell line has been genetically altered. Immortalized cells are created by incorporating the genes of a virus into the DNA of primary cells6,7,8. Cells with successful viral gene incorporation are selected for the immortalized cell line. The advantage of immortalization is that it allows for indefinite rapid proliferation, providing an unlimited number of cells to perform multiple experiments using the same cell line. This allows for consistency between experiments and reduces the cost.
In addition to changes in the genes that limited cell proliferation, changes in the expression of genes of critical functionality could also occur9. Therefore, the disadvantage of using immortalized cells is that they may no longer represent the original in vivo cells in terms of their response to various external stimuli10. Comparisons have involved observing the toxic effects of chemicals on primary and immortalized human corneal keratocytes11, as well as immortalized HCECs and rabbit corneal epithelial primary cells12. The comparison between the effects of toxins on primary human keratocytes and immortalized keratocytes showed no significant differences11. Using the methods detailed in this article, the effectiveness of these assays to assess the toxicity of UV radiation and ocular toxins on pHCECs and iHCECs will be determined.
Three ocular toxins commonly used in in vitro assays were selected: BAK, H2O2, and SDS. BAK is a cationic preservative commonly used in ophthalmic solutions13,14, H2O2 is commonly used to disinfect contact lenses15, and SDS is an anionic surfactant found in detergents and shampoos14. Similar to ocular toxins, UV radiation can also cause significant damage to HCECs3. In addition, overexposure to UV can cause an ocular condition known as photokeratitis characterized by symptoms of tearing, light sensitivity, and a feeling of grittiness16.
There is an unlimited number of primary cell cultures that can be used and various immortalized cell lines that have been developed. Therefore, an investigation was undertaken to compare primary HCECs to an immortalized HCEC line to determine similarities and differences between models that incorporate these types of cells.
This investigation used microscopy to assess possible differences between pHCECs and iHCECs on cell physiological response to UV and toxins. The effects of UV radiation and chemicals on cell metabolic activity and inflammatory cytokine release for the two cell lines were also evaluated. The importance of determining the differences among the two cell lines is to understand the optimal use of these cell lines for evaluating: 1) the effect of UV radiation on cells, 2) the effects of toxins on cells, and 3) the resulting changes to metabolism, cell viability, and cell cytokine release for future studies.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>75 cm2 Vented Flask</td>
			<td>Corning</td>
			<td>354485</td>
			<td>This is the BioCoat brand, collagen-coated</td>
		</tr>
		<tr>
			<td>96 well plate</td>
			<td>costar</td>
			<td>3370</td>
			<td></td>
		</tr>
		<tr>
			<td>alamarBlue</td>
			<td>Fisher Scientific</td>
			<td>dal 1025</td>
			<td></td>
		</tr>
		<tr>
			<td>Annexin Staining buffer solution</td>
			<td>Invitrogen, Burlington, ON, Canada</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Annexin V</td>
			<td>Invitrogen, Burlington, ON, Canada</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Axiovert 100 microscope with a Zeiss confocal laser scanning microscope 510 system</td>
			<td>Carl Zeiss Inc., Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Corning 48 Well plates</td>
			<td>Corning</td>
			<td>354505</td>
			<td>This is the BioCoat brand, collagen-coated</td>
		</tr>
		<tr>
			<td>Cytation 5</td>
			<td>BioTek</td>
			<td>CYT5MPV</td>
			<td>Can read fluorescence from 280 - 700 nm (for assay 540/590)</td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum</td>
			<td>Hycone</td>
			<td>SH30396.03</td>
			<td></td>
		</tr>
		<tr>
			<td>glass bottom coverslips</td>
			<td>MatTek Corporation, Ashland, MA, USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Human Corneal Epithelial Cells</td>
			<td>University of Ottawa</td>
			<td>N/A</td>
			<td>SV40-immortalized human corneal epithelial cells from Dr. M. Griffith (Ottawa Eye Research Institute, Ottawa, Canada) and have been characterized Griffith M, Osborne R, Munger R, Xiong X, Doillon CJ, Laycock NL, Hakim M, Song Y, Watsky MA. Functional human corneal equivalents constructed from cell lines. Science. 1999;286:2169-72.</td>
		</tr>
		<tr>
			<td>Human Ocular Epithelia Media (HOEM) with the following supplements:</td>
			<td>Millipore, Billerica, MA, USA</td>
			<td>SCMC001</td>
			<td>Epigro base media supplemented with 6 mM L-Glutamine, 0.002% EpiFactor O (cell media supplement O in article) , 1.0 &#956;M Epinephrine, 0.4% EpiFactor P (cell media supplement P in article), 5 &#956;g/mL rh Insulin, 5 &#956;g/mL Apo- Transferrin, and 100 ng/mL Hydrocortisone Hemisuccinate in Collagen-1 coated culture flasks (BioCoat, Corning, Tewksbury, MA, USA).</td>
		</tr>
		<tr>
			<td>Live Dead calcien and ethidium homodimer</td>
			<td>Invitrogen, Burlington, ON, Canada</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>MesoScale Discovery (MSD) QuickPlex SQ 120 instrument</td>
			<td>Rockville, MD, USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>MSD Human Proinflammatory Panel II (4-Plex) V-Plex assay</td>
			<td>Rockville, MD, USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin Streptomycin</td>
			<td>Gibco</td>
			<td>15140-122</td>
			<td>100x concentration so add 1 mL to each 99 mL of media</td>
		</tr>
		<tr>
			<td>Primary Corneal Epithelial Cells</td>
			<td>Millipore, Billerica, MA, USA</td>
			<td>SCCE016</td>
			<td></td>
		</tr>
		<tr>
			<td>SpectraMax fluorescence multi-well plate reader</td>
			<td>Molecular Devices, Sunnyvale, CA, USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>TrypLE Express (cell disassociation solution)</td>
			<td>Fisher Scientific</td>
			<td>12605036</td>
			<td></td>
		</tr>
	</tbody>
</table>

determining the toxicity of uv radiation and chemicals on primary and immortalized human corneal epithelial cells

This article describes the methods of measuring the toxicity of ultraviolet (UV) radiation and ocular toxins on primary (pHCEC) and immortalized (iHCEC) human corneal epithelial cell cultures. Cells were exposed to UV radiation and toxic doses of benzalkonium chloride (BAK), hydrogen peroxide (H2O2), and sodium dodecyl sulfate (SDS). Metabolic activity was measured using a metabolic assay. The release of inflammatory cytokines was measured using a multi-plex interleukin (IL)-1&#946;, IL-6, IL-8, and tumor necrosis factor-alpha (TNF-&#945;) assay, and cells were evaluated for viability using fluorescent dyes. 
The damaging effects of UV on cell metabolic activity and cytokine release occurred at 5 min of UV exposure for iHCEC and 20 min for pHCEC. Similar percent drops in metabolic activity of the iHCEC and pHCEC occurred after exposure to BAK, H2O2, or SDS, and the most significant changes in cytokine release occurred for IL-6 and IL-8. Microscopy of fluorescently stained iHCEC and pHCEC BAK-exposed cells showed cell death at 0.005% BAK exposure, although the degree of ethidium staining was greater in the iHCECs than pHCECs. Utilizing multiple methods of assessing toxic effects using microscopy, assessments of metabolic activity, and cytokine production, the toxicity of UV radiation and chemical toxins could be determined for both primary and immortalized cell lines.

Cell size 
The primary and immortalized HCECs were visualized with three fluorescent dyes, which reflect three different stages of cell viability. Live cells are green (calcein-AM), dead cells are red (ethidium homodimer-1), and apoptotic cells are yellow (annexin V-computer-adjusted color for better visualization of the fluorescence signal). Live cells contain esterases in the cell cytoplasm and convert calcein-AM to calcein. Dead cells have cell membranes that are permeable to ethidium homodimer-1...

Watch this Scientific Journal Video about Determining the Toxicity of UV Radiation and Chemicals on Primary and Immortalized Human Corneal Epithelial Cells at JoVE.com

Determining the Toxicity of UV Radiation and Chemicals on Primary and Immortalized Human Corneal Epithelial Cells

This article describes the procedures used to evaluate the toxicity of UV radiation and chemical toxins on a primary and immortalized cell line.

This article describes the methods of measuring the toxicity of ultraviolet (UV) radiation and ocular toxins on primary (pHCEC) and immortalized (iHCEC) ...

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Epithelial  to mesenchymal transition (EMT) is essential for proper morphogenesis during  development. Misregulation of this  process has been implicated ...

Culturing of Human Nasal Epithelial Cells at the Air Liquid Interface

In vitro models using human primary  epithelial cells are essential in understanding key functions of the respiratory  epithelium in the context of ...

Quantitation of Endothelial Cell Adhesiveness In Vitro

Quantitation of Endothelial Cell Adhesiveness In Vitro

One of the cardinal processes of inflammation is the infiltration of immune cells from the lumen of the blood vessel to the surrounding tissue. This ...

Analysis of SCAP N-glycosylation and Trafficking in Human Cells

Analysis of SCAP N-glycosylation and Trafficking in Human Cells

Elevated lipogenesis is a common characteristic of cancer and metabolic diseases. Sterol regulatory element-binding proteins (SREBPs), a family of ...

Multicellular Human Alveolar Model Composed of Epithelial Cells and Primary Immune Cells for Hazard Assessment

A human alveolar cell coculture model is described here for simulation of the alveolar epithelial tissue barrier composed of alveolar epithelial type II ...