Name: induction and analysis of oxidative stress in sleeping beauty transposon-transfected human retinal pigment epithelial cells
Uploaded: 2020-12-11T13:00:00
Description: Watch this Scientific Journal Video about Induction and Analysis of Oxidative Stress in Sleeping Beauty Transposon-Transfected Human Retinal Pigment Epithelial Cells at JoVE.com

The authors would like to thank Gregg Sealy and Alain Conti for excellent technical assistance and Prof. Zsuzsanna Izsv&#225;k from the Max-Delbr&#252;ck Center in Berlin for kindly providing the pSB100X&#160;and pT2-CAGGS-Venus&#160;plasmids. This work was supported by the Swiss National Sciences Foundation and the European Commission in the context of the Seventh Framework Programme. Z.I was funded by European Research Council, ERC Advanced [ERC-2011-ADG 294742].

Procedures for the collection and use of human eyes were approved by the Cantonal Ethical Commission for Research (no. 2016-01726).
1. Cell isolation and culture conditions
<ol>
	<li>Human ARPE-19 cell line
	<ol>
		<li>Culture 5 x 105 ARPE-19 cells, a human RPE cell line, in Dulbecco&#39;s Modified Eagle&#39;s Medium/Nutrient Mixture F-12 Ham (DMEM/Ham&#180;s F-12) supplemented with 10% fetal bovine serum (FBS), 80 U/mL penicillin, 80 &#181;g/mL streptomycin, and 2.5 &#181;g/mL am...

<ol>
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The protocol presented here offers an approach to analyze the anti-oxidative and protective function of PEDF and GM-CSF produced by transfected cells, which can be applied to cells transfected with any putative beneficial gene. In gene therapeutic strategies that have the objective to deliver proteins to tissue by transplanting genetically modified cells, it is critical to obtain information as to the level of protein expression, the longevity of expression, and the effectiveness of the expressed protein in a model of th...

The model described here, offers a useful approach to evaluate the efficiency ofbiopharmaceutical agents for reducing oxidative stress in cells. We have used the model to investigate the protective effects of PEDF and GM-CSF on the H2O2-mediated oxidative stress on retinal pigment epithelial cells, which are exposed to high levels of O2, and visible light, and the phagocytosis of photoreceptor outer segment membranes, generating significant levels of reactive oxygen species (ROS)1,2. They are considered a major contributor to the pathogenesis of avascular age-related macular degeneration (aAMD)3,4,5,6,7,8. Besides, there is a decrease in RPE-synthesized neuroprotective factors, specifically the pigment epithelium-derived factor (PEDF), insulin-like growth factors (IGFs), and granulocyte macrophage-colony-stimulating factor (GM-CSF) leading to the dysfunction and loss of RPE cells, followed by photoreceptor and retinal ganglion cell (RGC) death3,4,5. AMD is a complex disease that results from the interaction between metabolic, functional, genetic, and environmental factors4. The lack of treatments for aAMD is the major cause of blindness in patients older than 60 years of age in industrialized countries9,10. The reconstitution of the neuroprotective and neurogenic retinal environment by the subretinal transplantation of genetically modified RPE cells overexpressing PEDF and GM-CSF has the potential to prevent retinal degeneration by mitigating the effects of oxidative stress, inhibiting inflammation and supporting cell survival11,12,13,14,15,16. Even though there are several methodologies to deliver genes to cells, we have chosen the non-viral hyperactive Sleeping Beauty transposon system to deliver the PEDF and GM-CSF genes to RPE cells because of its safety profile, the integration of the genes into the host cells&#39; genome, and its propensity to integrate the delivered genes in non-transcriptionally active sites as we have shown previously17,18,19.
Cellular oxidative stress can be induced in cells cultured in vitro by several oxidative agents, including hydrogen peroxide (H2O2), 4-hydroynonenal (HNE), tertbutylhydroperoxide (tBH), high oxygen tensions, and visible light (full spectrum or UV irradiation)20,21. High oxygen tensions and light require special equipment and conditions, which limits transferability to other systems. Agents such as H2O2, HNE, and tBH induce overlapping oxidative stress molecular and cellular changes. We chose H2O2 to test the antioxidant activity of PEDF and GM-CSF because it is convenient and biologically relevant since it is produced by RPE cells as a reactive oxygen intermediate during photoreceptor outer segment phagocytosis22 and it is found in ocular tissues in vivo23. Since the oxidation of glutathione may be partially responsible for the production of H2O2 in the eye, we have analyzed the levels of GSH/glutathione in our studies, which are linked to H2O2-induced oxidative stress and the regenerative capacity of cells21,22. The analysis of glutathione levels is especially relevant since it participates in the anti-oxidative protective mechanisms in the eye24. Exposure to H2O2 is used frequently as a model to examine the oxidative stress susceptibility and antioxidant activity of RPE cells1,25,26,27,28,29,30, and, additionally, it shows similarities to light-induced oxidative stress damage, a &#34;physiological&#34; source of oxidative stress21.
To evaluate the functionality and the effectiveness of neuroprotective factors, we have developed an in vitro model that allows for the analysis to quantify the anti-oxidative effect of growth factors expressed by cells genetically modified to overexpress PEDF and GM-CSF. Here, we show that RPE cells transfected with the genes for PEDF and GM-CSF are more resistant to the harmful effects of H2O2 than are non-transfected control cells, as evidenced by cell morphology, density, viability, intracellular level of glutathione, and expression of UCP2 gene, which codes for the mitochondrial uncoupling protein 2 that has been shown to reduce reactive oxygen species (ROS)31.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>24-well plates</td>
			<td>Corning</td>
			<td>353047</td>
			<td></td>
		</tr>
		<tr>
			<td>6-well plates</td>
			<td>Greiner</td>
			<td>7657160</td>
			<td></td>
		</tr>
		<tr>
			<td>96-well culture plate white with clear flat bottom&#160;</td>
			<td>Costar</td>
			<td>3610</td>
			<td>Allows to check the cells before measuring the luminescence (GSH-Glo Assay)</td>
		</tr>
		<tr>
			<td>96-well plates</td>
			<td>Corning&#160;</td>
			<td>353072</td>
			<td></td>
		</tr>
		<tr>
			<td>Acrylamid 40%</td>
			<td>Biorad</td>
			<td>161-0144</td>
			<td></td>
		</tr>
		<tr>
			<td>Amphotericin B</td>
			<td>AMIMED</td>
			<td>4-05F00-H</td>
			<td></td>
		</tr>
		<tr>
			<td>Antibody anti-GMCSF</td>
			<td>ThermoFisher Scientific</td>
			<td>PA5-24184</td>
			<td></td>
		</tr>
		<tr>
			<td>Antibody anti-mouse IgG/IgA/IgM&#160;</td>
			<td>Agilent</td>
			<td>P0260</td>
			<td></td>
		</tr>
		<tr>
			<td>Antibody anti-PEDF&#160;</td>
			<td>Santa Cruz Biotechnology Inc</td>
			<td>sc-390172</td>
			<td></td>
		</tr>
		<tr>
			<td>Antibody anti-penta-His&#160;</td>
			<td>Qiagen</td>
			<td>34660</td>
			<td></td>
		</tr>
		<tr>
			<td>Antibody anti-phospho-Akt</td>
			<td>Cell Signaling Technology</td>
			<td>9271</td>
			<td></td>
		</tr>
		<tr>
			<td>Antibody anti-rabbit IgG H&#38;L-HRP</td>
			<td>Abcam</td>
			<td>ab6721</td>
			<td></td>
		</tr>
		<tr>
			<td>Antibody donkey anti-rabbit Alexa Fluor 594&#160;</td>
			<td>ThermoFisher Scientific&#160;</td>
			<td>A11034</td>
			<td></td>
		</tr>
		<tr>
			<td>Antibody goat anti-mouse Alexa 488</td>
			<td>ThermoFisher Scientific</td>
			<td>A-11029</td>
			<td></td>
		</tr>
		<tr>
			<td>ARPE-19 cell line</td>
			<td>ATCC</td>
			<td>CRL-2302</td>
			<td></td>
		</tr>
		<tr>
			<td>BSA&#160;</td>
			<td>Sigma-Aldrich</td>
			<td>A9418-500G</td>
			<td></td>
		</tr>
		<tr>
			<td>chamber culture glass slides</td>
			<td>Corning</td>
			<td>354118</td>
			<td></td>
		</tr>
		<tr>
			<td>CytoTox-Glo Cytotoxicity Assay&#160;</td>
			<td>Promega</td>
			<td>G9291</td>
			<td></td>
		</tr>
		<tr>
			<td>DAPI</td>
			<td>Sigma-Aldrich</td>
			<td>D9542-5MG</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM/Ham`s F12&#160;</td>
			<td>Sigma-Aldrich</td>
			<td>D8062</td>
			<td></td>
		</tr>
		<tr>
			<td>Duo Set ELISA kit</td>
			<td>R&#38;D Systems&#160;</td>
			<td>DY215-05</td>
			<td></td>
		</tr>
		<tr>
			<td>EDTA</td>
			<td>ThermoFisher Scientific</td>
			<td>78440</td>
			<td></td>
		</tr>
		<tr>
			<td>ELISAquant kit</td>
			<td>BioProducts MD</td>
			<td>PED613-10-Human</td>
			<td></td>
		</tr>
		<tr>
			<td>Eyes (human)</td>
			<td>Lions Gift of Sight Eye Bank (Saint Paul, MN)</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>FBS&#160;</td>
			<td>Brunschwig</td>
			<td>P40-37500</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluoromount Aqueous Mounting Medium</td>
			<td>Sigma-Aldrich</td>
			<td>F4680-25ML</td>
			<td></td>
		</tr>
		<tr>
			<td>FLUOstar Omega plate reader&#160;</td>
			<td>BMG Labtech</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>GraphPad Prism software (version 8.0)</td>
			<td>GraphPad Software, Inc.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>GSH-Glo Glutathione Assay</td>
			<td>Promega</td>
			<td>V6912</td>
			<td></td>
		</tr>
		<tr>
			<td>hydrogen peroxide (H2O2)</td>
			<td>Merck</td>
			<td>107209</td>
			<td></td>
		</tr>
		<tr>
			<td>ImageJ software (image processing program)</td>
			<td>W.S. Rasband, NIH, Bethesda, MD, USA; https://imagej.nih.gov/ij/; 1997&#8211;2014</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Imidazol&#160;</td>
			<td>Axonlab</td>
			<td>A1378.0010</td>
			<td></td>
		</tr>
		<tr>
			<td>Leica DMI4000B microscope&#160;</td>
			<td>Leica Microsystems</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>LightCycler 480 Instrument II&#160;</td>
			<td>Roche Molecular Systems</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>LightCycler 480 SW1.5.1 software</td>
			<td>Roche Molecular Systems</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Sigma-Aldrich</td>
			<td>71376-1000</td>
			<td></td>
		</tr>
		<tr>
			<td>NaH2PO4</td>
			<td>Axonlab</td>
			<td>3468.1000</td>
			<td></td>
		</tr>
		<tr>
			<td>Neon Transfection System&#160;</td>
			<td>ThermoFisher Scientific</td>
			<td>MPK5000</td>
			<td></td>
		</tr>
		<tr>
			<td>Neon Transfection System 10 &#181;L Kit</td>
			<td>ThermoFisher Scientific</td>
			<td>MPK1096</td>
			<td></td>
		</tr>
		<tr>
			<td>Neubauer chamber</td>
			<td>Marienfeld-superior</td>
			<td>640010</td>
			<td></td>
		</tr>
		<tr>
			<td>Ni-NTA superflow&#160;</td>
			<td>Qiagen</td>
			<td>30410</td>
			<td></td>
		</tr>
		<tr>
			<td>Nitrocellulose&#160;</td>
			<td>VWR</td>
			<td>732-3197</td>
			<td></td>
		</tr>
		<tr>
			<td>Omega Lum G Gel Imaging System</td>
			<td>Aplegen Life Science</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>PBS 1X</td>
			<td>Sigma-Aldrich</td>
			<td>D8537</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin/Streptomycin</td>
			<td>Sigma-Aldrich</td>
			<td>P0781-100</td>
			<td></td>
		</tr>
		<tr>
			<td>PerfeCTa SYBR Green FastMix</td>
			<td>Quantabio</td>
			<td>95072-012</td>
			<td></td>
		</tr>
		<tr>
			<td>PFA&#160;</td>
			<td>Sigma-Aldrich</td>
			<td>158127-100G</td>
			<td></td>
		</tr>
		<tr>
			<td>Pierce BCA Protein Assay Kit&#160;</td>
			<td>ThermoFisher Scientific</td>
			<td>23227</td>
			<td></td>
		</tr>
		<tr>
			<td>Primers&#160;</td>
			<td>Invitrogen&#160;</td>
			<td></td>
			<td>See Table 1 in Supplementary Materials</td>
		</tr>
		<tr>
			<td>pSB100X (250 ng/&#181;L)</td>
			<td></td>
			<td></td>
			<td>M&#225;t&#233;s et al., 2009. Provide by Prof. Zsuzsanna Izsvak</td>
		</tr>
		<tr>
			<td>pT2-CMV-GMCSF-His plasmid DNA (250 ng/&#181;L)</td>
			<td></td>
			<td></td>
			<td>Constructed using the existing pT2-CMV-PEDF-EGFP plasmid reported in Johnen, S. et al. (2012) IOVS, 53 (8), 4787-4796.</td>
		</tr>
		<tr>
			<td>pT2-CMV-PEDF-His plasmid DNA (250 ng/&#181;L)</td>
			<td></td>
			<td></td>
			<td>Constructed using the existing pT2-CMV-PEDF-EGFP plasmid reported in Johnen, S. et al. (2012) IOVS, 53 (8), 4787-4796.</td>
		</tr>
		<tr>
			<td>QIAamp DNA Mini Kit</td>
			<td>QIAGEN</td>
			<td>51304</td>
			<td></td>
		</tr>
		<tr>
			<td>recombinant hGM-CSF&#160;</td>
			<td>Peprotech</td>
			<td>100-11</td>
			<td></td>
		</tr>
		<tr>
			<td>recombinant hPEDF&#160;&#160;</td>
			<td>BioProductsMD</td>
			<td>004-096</td>
			<td></td>
		</tr>
		<tr>
			<td>ReliaPrep RNA Cell Miniprep System</td>
			<td>Promega</td>
			<td>Z6011</td>
			<td></td>
		</tr>
		<tr>
			<td>RIPA buffer</td>
			<td>ThermoFisher Scientific</td>
			<td>89901</td>
			<td></td>
		</tr>
		<tr>
			<td>RNase-free DNase Set</td>
			<td>QIAGEN</td>
			<td>79254</td>
			<td></td>
		</tr>
		<tr>
			<td>RNeasy Mini Kit</td>
			<td>QIAGEN</td>
			<td>74204</td>
			<td></td>
		</tr>
		<tr>
			<td>SDS</td>
			<td>Applichem</td>
			<td>A2572</td>
			<td></td>
		</tr>
		<tr>
			<td>Semi-dry transfer system for WB&#160;</td>
			<td>Bio-Rad</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>SuperMix qScript</td>
			<td>Quantabio</td>
			<td>95048-025</td>
			<td></td>
		</tr>
		<tr>
			<td>Tris-buffered saline (TBS)&#160;</td>
			<td>ThermoFisher Scientific</td>
			<td>15504020</td>
			<td></td>
		</tr>
		<tr>
			<td>Triton X-100</td>
			<td>AppliChem</td>
			<td>A4975</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypsin/EDTA</td>
			<td>Sigma-Aldrich</td>
			<td>T4174</td>
			<td></td>
		</tr>
		<tr>
			<td>Tween</td>
			<td>AppliChem&#160;</td>
			<td>A1390</td>
			<td></td>
		</tr>
		<tr>
			<td>Urea</td>
			<td>ThermoFisher Scientific</td>
			<td>29700</td>
			<td></td>
		</tr>
		<tr>
			<td>WesternBright ECL HRP substrate</td>
			<td>Advansta</td>
			<td>K-12045-D50</td>
			<td></td>
		</tr>
		<tr>
			<td>Whatman nitrocellulose membrane</td>
			<td>Chemie Brunschwig</td>
			<td>MNSC04530301</td>
			<td></td>
		</tr>
	</tbody>
</table>

induction and analysis of oxidative stress in sleeping beauty transposon-transfected human retinal pigment epithelial cells

Oxidative stress plays a critical role in several degenerative diseases, including age-related macular degeneration (AMD), a pathology that affects ~30 million patients worldwide. It leads to a decrease in retinal pigment epithelium (RPE)-synthesized neuroprotective factors, e.g., pigment epithelium-derived factor (PEDF) and granulocyte-macrophage colony-stimulating factor (GM-CSF), followed by the loss of RPE cells, and eventually photoreceptor and retinal ganglion cell (RGC) death. We hypothesize that the reconstitution of the neuroprotective and neurogenic retinal environment by the subretinal transplantation of transfected RPE cells overexpressing PEDF and GM-CSF has the potential to prevent retinal degeneration by mitigating the effects of oxidative stress, inhibiting inflammation, and supporting cell survival. Using the Sleeping Beauty transposon system (SB100X) human RPE cells have been transfected with the PEDF and GM-CSF genes and shown stable gene integration, long-term gene expression, and protein secretion using qPCR, western blot, ELISA, and immunofluorescence. To confirm the functionality and the potency of the PEDF and GM-CSF secreted by the transfected RPE cells, we have developed an in vitro assay to quantify the reduction of H2O2-induced oxidative stress on RPE cells in culture. Cell protection was evaluated by analyzing cell morphology, density, intracellular level of glutathione, UCP2 gene expression, and cell viability. Both, transfected RPE cells overexpressing PEDF and/or GM-CSF and cells non-transfected but pretreated with PEDF and/or GM-CSF (commercially available or purified from transfected cells) showed significant antioxidant cell protection compared to non-treated controls. The present H2O2-model is a simple and effective approach to evaluate the antioxidant effect of factors that may be effective to treat AMD or similar neurodegenerative diseases.

Induction of oxidative stress in human Retinal Pigment Epithelial cells 
ARPE-19 and primary hRPE cells were treated with varying concentrations of H2O2 for 24 h and the intracellular level of the antioxidant glutathione was quantified (Figure 2A,B). H2O2 at 50 &#181;M and 100 &#181;M did not affect glutathione production, whereas at 350 &#181;M there was a significant decrease...

Watch this Scientific Journal Video about Induction and Analysis of Oxidative Stress in Sleeping Beauty Transposon-Transfected Human Retinal Pigment Epithelial Cells at JoVE.com

Induction and Analysis of Oxidative Stress in Sleeping Beauty Transposon-Transfected Human Retinal Pigment Epithelial Cells

We present a protocol for the development and use ofan oxidative stress-model by treating retinal pigment epithelial cells with H2O2, analyzing cell morphology, viability, density, glutathione, and UCP-2 level. It is a useful model to investigate the antioxidant effect of proteins secreted by transposon-transfected cells to treat neuroretinal degeneration.

Induction and Analysis of Oxidative Stress in Sleeping Beauty Transposon-Transfected Human Retinal Pigment Epithelial Cells

Oxidative stress plays a critical role in several degenerative diseases, including age-related macular degeneration (AMD), a pathology that affects ~30 ...

The hydrogen peroxide model is a simple and effective approach for evaluating the antioxidant effects of factors that may be useful in treating age-related macular degeneration or similar neurodegenerative diseases. The oxidant agent, hydrogen peroxide, is delivered in one single pulse, making it faster and simpler to perform than models in which the hydrogen peroxide treatment must be repeated for several days. Because the number of cells seeded influences the oxidative effect of the treatment, it is important to count the cells carefully before their culture.Demonstrating the procedure will be Thais Bascuas, a post-doctorate from Gabriele Thumann's laboratory. For conditioned medium preparation, 28 days after transfection with PEDF, GM-CSF, or both, seed the human ARPE-19 cell line T-75 flasks out of 500, 000 cells per milliliter of complete medium concentration. When the cells reach approximately 80%confluency, replace the supernatant with fresh complete medium and collect the new supernatant after 24 hours.To purify the histidine-tagged GM-CSF and PEDF proteins, centrifuge the supernatant to eliminate potential remaining cells, and set the sample aside. Next, add 30 microliters of nickel NTA solution to a 1.5 milliliter tube. After centrifuging, discard the nickel NTA flow-through and wash the pellet two times with 200 microliters of 1X incubation buffer per wash.After the second wash, re-suspend the pellet in 40 microliters of 4X incubation buffer and 900 microliters of the centrifuged, conditioned medium. Incubate the conditioned medium solution for one hour at room temperature and 70 rotations per minute. At the end of the incubation, centrifuge the sample and wash the pellet two times with 175 microliters of 1X incubation per wash.After the second wash, add 20 microliters of elution buffer for a 20-minute incubation at 70 revolutions per minute at room temperature. At the end of the incubation, centrifuge the sample. Set aside the supernatant and quantify the total protein eluted by the BCA protein assay according to standard protocols.For the treatment of non-transfected retinal pigment epithelial cells with conditioned medium and hydrogen peroxide, seed 3000 cells in 200 microliters of complete medium to each well of a 96-well plate for 24-hour incubation in the cell culture incubator. The next morning replace the supernatants with 200 microliters of conditioned medium per well and return the cells to the cell culture incubators for 10 days. On day 11 of culture, treat the cells with 350-micromolar hydrogen peroxide in complete medium for 24 hours.For the treatment of non-transfected RPE cells with purified or commercial PEDF and/or GM-CSF, seed 3000 cells in 200 microliters of complete medium supplemented with 500 nanograms per milliliter of recombinant PEDF and/or 50 nanograms per milliliter of recombinant to GM-CSF per well for a 48-hour incubation in the cell culture incubator. At the end of the incubation, replace the supernatants with complete medium containing 350 micromolar hydrogen peroxide and 500 nanograms per milliliter of PEDF and/or 50 nanograms per milliliter of GM-CSF per well for 24 hours. For hydrogen peroxide treatment of transfected RPE cells, culture 5, 000 transfected cells in 200 microliters of complete medium per well for 24 hours in the cell culture incubator before treating the cells with 350 micromolar hydrogen peroxide as demonstrated.To measure the glutathione levels produced in transfected cells over-expressing PEDF and/or GM-CSF, or non-transfected cells pretreated with growth factor after hydrogen peroxide treatment, replace the supernatant in each well with 100 microliters of freshly-prepared 1X reagent mix per well and mix the cells with a reagent mix for 14 seconds at 500 revolutions per minute on an orbital shaker. After shaking, incubate the plate at room temperature for 30 minutes before adding 100 microliters of reconstituted luciferin detection reagent to each well. Mix the solution for 15 seconds on the shaker, followed by a 15-minute incubation at room temperature.At the end of the incubation, load the plate onto a plate reader and select Change Layout. Under the Basic Parameters tab, 96-well plate and Top optic should be selected and the positioning delay should be set to 0.1, the Measurement start time to zero, the Measurement interval time to one, and the Time to normalize results to zero. Define the blanks, standards, and samples, and click Start measurement.Then export the data as a spreadsheet file and calculate the concentration of glutathione in each sample by interpolation of the standard curve. To measure the cell viability, replace the supernatant in each well with 100 microliters of complete medium supplemented with 1%FBS per well, and place the cells in the cell culture incubator until the analysis. After collecting untreated ARPE-19 cells from culture, re-suspend the cells at a 100, 000 cells per milliliter in DMEM Hams F-12 medium supplemented with 1%FBS concentration.Next, prepare seven serial 1:1 dilutions in 200 microliters of medium supplemented with 1%FBS, and transfer 100 microliters of each standard to the appropriate wells of a 96-well plate in duplicate. Add 50 microliters of freshly-prepared reagent mix to all of the well and mix the cells with the mix for 15 seconds on the shaker before incubating the plate for 15 minutes at room temperature. At the end of the incubation, measure the luminescence as demonstrated.After obtaining the measurement, add 50 microliters of lysis reagent to each well for a 15-minute incubation at room temperature, then measure the luminescence again and use the formula to calculate the percentage of viable cells. 24 hours of treatment with 50-and 100-micromolar hydrogen peroxide does not impact intracellular glutathione production, whereas a significant decrease of glutathione is observed when the cells are treated with a 350-500-or 700-micromolar hydrogen peroxide concentration. Morphologically, hydrogen peroxide-treated cells appear less spread out and more rounded with increasing concentrations of the compound.This effect was less prominent for PEDF and GM-CSF-transfected cells treated with hydrogen peroxide. It is important to note that cell number influences hydrogen peroxide-mediated oxidative stress, as the level of glutathione was statistically significantly decreased after hydrogen peroxide treatment in wells seeded with 5, 000 cells only. Cells treated with or transfected to express PEDF and/or GM-CSF produce significantly more glutathione compared to untreated control cells under oxidative conditions.In addition, the level of UCP2 gene expression in PEDF and GM-CSF-transfected cells is increased after hydrogen peroxide, although the increase is not statistically significant. Western blot analysis of phosphorylated AKT from a lysate of GM-CSF-transfected cells exposed to hydrogen peroxide shows only a small decrease in phosphorylization compared to the untreated control cells, indicating that GM-CSF can protect the cells from oxidative stress damage. It is important to seed the cells at the correct densities, to use fresh hydrogen peroxide solution, and to add fresh proteins to the medium.Once the antioxidant effect of the growth factors has been corroborated using the hydrogen peroxide model, the factors can be tested in an oxidative stress-related ocular disease model. The current hydrogen peroxide oxidative stress model allows assessment of the antioxidant effects that different factors can have, and therefore, supports the development of new gene therapies.

induction-analysis-oxidative-stress-sleeping-beauty-transposon

Research

JoVE Journal

Medicine

Identification of Sleeping Beauty Transposon Insertions in Solid Tumors using Linker-mediated PCR

Genomic, proteomic, transcriptomic, and epigenomic analyses of human tumors indicate that there are thousands of anomalies within each cancer genome compared to matched normal tissue. Based on these analyses it is evident that there are many undiscovered genetic drivers of cancer1. Unfortunately these drivers are hidden within a much larger number of passenger anomalies in the genome that do not directly contribute to tumor formation. Another aspect of the cancer genome is that there is considerable genetic heterogeneity within similar tumor types. Each tumor can harbor different mutations that provide a selective advantage for tumor formation2. Performing an unbiased forward genetic screen in mice provides the tools to generate tumors and analyze their genetic composition, while reducing the background of passenger mutations. The Sleeping Beauty (SB) transposon system is one such method3. The SB system utilizes mobile vectors (transposons) that can be inserted throughout the genome by the transposase enzyme. Mutations are limited to a specific cell type through the use of a conditional transposase allele that is activated by Cre Recombinase. Many mouse lines exist that express Cre Recombinase in specific tissues. By crossing one of these lines to the conditional transposase allele (e.g. Lox-stop-Lox-SB11), the SB system is activated only in cells that express Cre Recombinase. The Cre Recombinase will excise a stop cassette that blocks expression of the transposase allele, thereby activating transposon mutagenesis within the designated cell type. An SB screen is initiated by breeding three strains of transgenic mice so that the experimental mice carry a conditional transposase allele, a concatamer of transposons, and a tissue-specific Cre Recombinase allele. These mice are allowed to age until tumors form and they become moribund. The mice are then necropsied and genomic DNA is isolated from the tumors. Next, the genomic DNA is subjected to linker-mediated-PCR (LM-PCR) that results in amplification of genomic loci containing an SB transposon. LM-PCR performed on a single tumor will result in hundreds of distinct amplicons representing the hundreds of genomic loci containing transposon insertions in a single tumor4. The transposon insertions in all tumors are analyzed and common insertion sites (CISs) are identified using an appropriate statistical method5. Genes within the CIS are highly likely to be oncogenes or tumor suppressor genes, and are considered candidate cancer genes. The advantages of using the SB system to identify candidate cancer genes are: 1) the transposon can easily be located in the genome because its sequence is known, 2) transposition can be directed to almost any cell type and 3) the transposon is capable of introducing both gain- and loss-of-function mutations6. The following protocol describes how to devise and execute a forward genetic screen using the SB transposon system to identify candidate cancer genes (Figure 1).

Identification of Sleeping Beauty Transposon Insertions in Solid Tumors using Linker-mediated PCR

A method of identifying unknown drivers of carcinogenesis using an unbiased approach is described. The method uses the Sleeping Beauty transposon as a random mutagen directed to specific tissues. Genomic mapping of transposon insertions that drive tumor formation identifies novel oncogenes and tumor suppressor genes

Genomic, proteomic, transcriptomic, and epigenomic analyses of human tumors indicate that there are thousands of anomalies within each cancer genome ...

Transcriptomic Analysis of Human Retinal Surgical Specimens Using jouRNAl

Retinal detachment (RD) describes a separation of the neurosensory retina from the retinal pigmented epithelium (RPE). The RPE is essential for normal function of the light sensitive neurons, the photoreceptors. Detachment of the retina from the RPE creates a physical gap that is filled with extracellular fluid. RD initiates cellular and molecular adverse events that affect both the neurosensory retina and the RPE since the physiological exchange of ions and metabolites is severely perturbed. The consequence for vision is related to the duration of the detachment since a rapid reapposition of the two tissues results in the restoration of vision 1. The treatment of RD is exclusively surgical. Removal of vitreous gel (vitrectomy) is followed by the removal non essential part of the retina around the detached area to favor retinal detachment. The removed retinal specimens are res nullius (nothing) and consequently normally discarded. To recover RNA from these surgical specimens, we developed the procedure jouRNAl that allows RNA conservation during the transfer from the surgical block to the laboratory. We also standardized a protocol to purify RNA by cesium chloride ultracentrifugation to assure that the purified RNAs are suitable for global gene expression analysis. The quality of the RNA was validated both by RT-PCR and microarray analysis. Analysis of the data shows a simultaneous involvement of inflammation and photoreceptor degeneration during RD.

We used retinal samples from retinectomy for a transcriptomic analysis of retinal detachment. We developed a procedure that allows RNA conservation between the surgical blocks and the laboratory. We standardized a protocol to purify RNA by cesium chloride ultracentrifugation to assure that the purified RNAs are suitable for microarray analysis.

Retinal detachment (RD) describes a separation of the neurosensory retina  from the retinal pigmented epithelium (RPE). The RPE is essential for normal  ...

Performing Subretinal Injections in Rodents to Deliver Retinal Pigment Epithelium Cells in Suspension

The conversion of light into electrical impulses occurs in the outer retina and is accomplished largely by rod and cone photoreceptors and retinal pigment epithelium (RPE) cells. RPE provide critical support for photoreceptors and death or dysfunction of RPE cells is characteristic of age-related macular degeneration (AMD), the leading cause of permanent vision loss in people age 55 and older. While no cure for AMD has been identified, implantation of healthy RPE in diseased eyes may prove to be an effective treatment, and large numbers of RPE cells can be readily generated from pluripotent stem cells. Several interesting questions regarding the safety and efficacy of RPE cell delivery can still be examined in animal models, and well-accepted protocols used to inject RPE have been developed. The technique described here has been used by multiple groups in various studies and involves first creating a hole in the eye with a sharp needle. Then a syringe with a blunt needle loaded with cells is inserted through the hole and passed through the vitreous until it gently touches the RPE. Using this injection method, which is relatively simple and requires minimal equipment, we achieve consistent and efficient integration of stem cell-derived RPE cells in between the host RPE that prevents significant amount of photoreceptor degeneration in animal models. While not part of the actual protocol, we also describe how to determine the extent of the trauma induced by the injection, and how to verify that the cells were injected into the subretinal space using in vivo imaging modalities. Finally, the use of this protocol is not limited to RPE cells; it may be used to inject any compound or cell into the subretinal space.

Here we present a community accepted protocol in multimedia format for subretinally injecting a bolus of RPE cells in rats and mice. This approach can be used for determining rescue potentials, safety profiles, and survival capacities of grafted RPE cells upon implantation in animal models of retinal degeneration.

The conversion of light into electrical impulses occurs in the outer retina and is accomplished largely by rod and cone photoreceptors and retinal pigment ...

A Step by Step Protocol for Subretinal Surgery in Rabbits

Age related macular degeneration (AMD), retinitis pigmentosa, and other RPE related diseases are the most common causes for irreversible loss of vision in adults in industrially developed countries. RPE transplantation appears to be a promising therapy, as it may replace dysfunctional RPE, restore its function, and thereby vision.
Here we describe a method for transplanting a cultured RPE monolayer on a scaffold into the subretinal space (SRS) of rabbits. After vitrectomy xenotransplants were delivered into the SRS using a custom made shooter consisting of a 20-gauge metallic nozzle with a polytetrafluoroethylene (PTFE) coated plunger. The current technique evolved in over 150 rabbit surgeries over 6 years. Post-operative follow-up can be obtained using non-invasive and repetitive in vivo imaging such as spectral domain optical coherence tomography (SD-OCT) followed by perfusion-fixed histology.
The method has well-defined steps for easy learning and high success rate. Rabbits are considered a large eye animal model useful in preclinical studies for clinical translation. In this context rabbits are a cost-efficient and perhaps convenient alternative to other large eye animal models.

Retinal pigment epithelium (RPE) replacement strategies and gene-based therapy are considered for several retinal degenerative conditions. For clinical translation, large eye animal models are required to study surgical techniques applicable in patients. Here we present a rabbit model for subretinal surgery geared towards RPE transplantation, which is versatile and cost-efficient.

Age related macular degeneration (AMD), retinitis pigmentosa, and other RPE related diseases are the most common causes for irreversible loss of vision in ...

Depletion of Mouse Cells from Human Tumor Xenografts Significantly Improves Downstream Analysis of Target Cells

The use of in vitro cell line models for cancer research has been a useful tool. However, it has been shown that these models fail to reliably mimic patient tumors in different assays1. Human tumor xenografts represent the gold standard with respect to tumor biology, drug discovery, and metastasis research 2-4. Tumor xenografts can be derived from different types of material like tumor cell lines, tumor tissue from primary patient tumors4 or serially transplanted tumors. When propagated in vivo, xenografted tissue is infiltrated and vascularized by cells of mouse origin. Multiple factors such as the tumor entity, the origin of xenografted material, growth rate and region of transplantation influence the composition and the amount of mouse cells present in tumor xenografts. However, even when these factors are kept constant, the degree of mouse cell contamination is highly variable.
Contaminating mouse cells significantly impair downstream analyses of human tumor xenografts. As mouse fibroblasts show high plating efficacies and proliferation rates, they tend to overgrow cultures of human tumor cells, especially slowly proliferating subpopulations. Mouse cell derived DNA, mRNA, and protein components can bias downstream gene expression analysis, next-generation sequencing, as well as proteome analysis 5. To overcome these limitations, we have developed a fast and easy method to isolate untouched human tumor cells from xenografted tumor tissue. This procedure is based on the comprehensive depletion of cells of mouse origin by combining automated tissue dissociation with the benchtop tissue dissociator and magnetic cell sorting. Here, we demonstrate that human target cells can be can be obtained with purities higher than 96% within less than 20 min independent of the tumor type.

Human tumor xenografts are vascularized and infiltrated by cells of mouse origin during the growth phase in vivo. To circumvent the bias caused by these contaminating cells during downstream analysis, we developed a method allowing for comprehensive depletion of all mouse cells by magnetic cell sorting.

The use of in vitro cell line models for cancer research has been a useful tool. However, it has been shown that these models fail to reliably mimic ...

Induction of Accelerated Atherosclerosis in Mice: The "Wire-Injury" Model

Atherosclerosis is a proliferative fibro-inflammatory disease developing in the arterial wall, inducing a deficient blood flow or a lack of blood flow. Moreover, by rupture of the defective vascular wall, atherosclerosis induces occlusive thrombus formation, which represents the main cause of myocardial infarction or stroke and the most frequent cause of death. Despite the advances in the cardiovascular field, many questions remain unanswered, and additional basic research is essential to improve our understanding of the molecular mechanisms during atherosclerosis and its effects. Due to limited clinical studies, there is a need for representative animal models recreating atherosclerotic conditions such as neointima formation after stent implantation, balloon angioplasty, or endarterectomy. Since the mouse presents many advantages and is the most frequently used model for studying molecular processes, the current study proposes an invasive procedure of endothelial denudation, also known as the wire-injury model, which is representative of the human condition of neointima formation in arteries after revascularization procedures.

This study describes an invasive procedure for the induction of accelerated atherosclerosis in mice. In comparison to other methods using electric- or cryo-induced injury, mechanical-induced injury mimics the human condition of restenosis after revascularization therapies and is ideal for the study of the molecular mechanisms involved.

Atherosclerosis is a proliferative fibro-inflammatory disease developing in the arterial wall, inducing a deficient blood flow or a lack of blood flow. ...

Electroporation-Based Genetic Modification of Primary Human Pigment Epithelial Cells Using the Sleeping Beauty Transposon System

Our increasingly aging society leads to a growing incidence of neurodegenerative diseases. So far, the pathological mechanisms are inadequately understood, thus impeding the establishment of defined treatments. Cell-based additive gene therapies for the increased expression of a protective factor are considered as a promising option to medicate neurodegenerative diseases, such as age-related macular degeneration (AMD). We have developed a method for the stable expression of the gene encoding pigment epithelium-derived factor (PEDF), which is characterized as a neuroprotective and anti-angiogenic protein in the nervous system, into the genome of primary human pigment epithelial (PE) cells using the Sleeping Beauty (SB) transposon system. Primary PE cells were isolated from human donor eyes and maintained in culture. After reaching confluence, 1 x 104 cells were suspended in 11 &#181;L of resuspension buffer and combined with 2 &#181;L of a purified solution containing 30 ng of hyperactive SB (SB100X) transposase plasmid and 470 ng of PEDF transposon plasmid. Genetic modification was carried out with a capillary electroporation system using the following parameters: two pulses with a voltage of 1,100 V and a width of 20 ms. Transfected cells were transferred into culture plates containing medium supplemented with fetal bovine serum; antibiotics and antimycotics were added with the first medium exchange. Successful transfection was demonstrated in independently performed experiments. Quantitative polymerase chain reaction (qPCR) showed the increased expression of the PEDF transgene. PEDF secretion was significantly elevated and remained stable, as evaluated by immunoblotting, and quantified by enzyme-linked immunosorbent assay (ELISA). SB100X-mediated transfer allowed for a stable PEDF gene integration into the genome of PE cells and ensured the continuous secretion of PEDF, which is critical for the development of a cell-based gene addition therapy to treat AMD or other retinal degenerative diseases. Moreover, analysis of the integration profile of the PEDF transposon into human PE cells indicated an almost random genomic distribution.

We have developed a protocol to transfect primary human pigment epithelial cells by electroporation with the gene encoding pigment epithelium-derived factor (PEDF) using the Sleeping Beauty (SB) transposon system. Successful transfection was demonstrated by quantitative polymerase chain reaction (qPCR), immunoblotting, and enzyme-linked immunosorbent assay (ELISA).

Our increasingly aging society leads to a growing incidence of neurodegenerative diseases. So far, the pathological mechanisms are inadequately ...

Directed Induction of Retinal Organoids from Human Pluripotent Stem Cells

Retinal cell transplantation is a promising therapeutic approach, which could restore the retinal architecture and stabilize or even improve the visual capabilities to the degenerated retina. Nevertheless, progress in cell replacement therapy presently faces the challenges of requiring an off-the-shelf source of high quality and standardized human retinas. Therefore, an easy and stable protocol is needed for the experiments. Here, we develop an optimized protocol, based on a self-organizing method with the use of exogenous molecules and reagent A as well as manual excision to generate the three-dimensional human retina organoids (RO). The human Pluripotent Stem Cells (PSCs)-derived RO expresses specific markers for photoreceptors. With the addition of COCO, a multifunctional antagonist, the differentiation efficiency of photoreceptor precursors and cones is significantly increased. The efficient use of this system, which has the benefits of cell lines and primary cells, and without the sourcing issues associated with the latter, could produce confluent retinal cells, especially photoreceptors. Thus, the differentiation of PSCs to RO provides an optimal and biorelevant platform for disease modelling, drug screening and cell transplantation.

Using a self-organizing method, we develop a protocol with the addition of COCO that could significantly increase the generation of photoreceptors.

Retinal cell transplantation is a promising therapeutic approach, which could restore the retinal architecture and stabilize or even improve the visual ...

Retinal Organoid Induction System for Derivation of 3D Retinal Tissues from Human Pluripotent Stem Cells

Retinal degenerative diseases are the main causes of irreversible blindness without effective treatment. Pluripotent stem cells that have the potential to differentiate into all types of retinal cells, even mini-retinal tissues, hold huge promises for patients with these diseases and many opportunities in disease modeling and drug screening. However, the induction process from hPSCs to retinal cells is complicated and time-consuming. Here, we describe an optimized retinal induction protocol to generate retinal tissues with high reproducibility and efficiency, suitable for various human pluripotent stem cells. This protocol is performed without the addition of retinoic acid, which benefits the enrichment of cone photoreceptors. The advantage of this protocol is the quantification of EB size and plating density to significantly enhance the efficiency and repeatability of retinal induction. With this method, all major retinal cells sequentially appear and recapitulate the main steps of retinal development. It will facilitate downstream applications, such as disease modeling and cell therapy.

Here we describe an optimized retinal organoid induction system, which is suitable for various human pluripotent stem cell lines to generate retinal tissues with high reproducibility and efficiency.

Retinal degenerative diseases are the main causes of irreversible blindness without effective treatment. Pluripotent stem cells that have the potential to ...

Retinal Pigment Epithelium Transplantation in a Non-human Primate Model for Degenerative Retinal Diseases

Retinal pigment epithelial (RPE) transplantation holds great promise for the treatment of inherited and acquired retinal degenerative diseases. These conditions include retinitis pigmentosa (RP) and advanced forms of age-related macular degeneration (AMD), such as geographic atrophy (GA). Together, these disorders represent a significant proportion of currently untreatable blindness globally. These unmet medical needs have generated heightened academic interest in developing methods of RPE replacement. Among the animal models commonly utilized for preclinical testing of therapeutics, the non-human primate (NHP) is the only animal model that has a macula. As it shares this anatomical similarity with the human eye, the NHP eye is an important and appropriate preclinical animal model for the development of advanced therapy medicinal products (ATMPs) such as RPE cell therapy.
This manuscript describes a method for the submacular transplantation of an RPE monolayer, cultured on a polyethylene terephthalate (PET) cell carrier, underneath the macula onto a surgically created RPE wound in immunosuppressed NHPs. The fovea-the central avascular portion of the macula-is the site of the greatest mechanical weakness during the transplantation. Foveal trauma will occur if the initial subretinal fluid injection generates an excessive force on the retina. Hence, slow injection under perfluorocarbon liquid (PFCL) vitreous tamponade is recommended with a dual-bore subretinal injection cannula at low intraocular pressure (IOP) settings to create a retinal bleb. 
Pretreatment with an intravitreal plasminogen injection to release parafoveal RPE-photoreceptor adhesions is also advised. These combined strategies can reduce the likelihood of foveal tears when compared to conventional techniques. The NHP is a key animal model in the preclinical phase of RPE cell therapy development. This protocol addresses the technical challenges associated with the delivery of RPE cellular therapy in the NHP eye.

The non-human primate (NHP) is an ideal model for studying human retinal cellular therapeutics due to the anatomical and genetic similarities. This manuscript describes a method for submacular transplantation of retinal pigment epithelial cells in the NHP eye and strategies to prevent intraoperative complications associated with macular manipulation.

Retinal pigment epithelial (RPE) transplantation holds great promise for the treatment of inherited and acquired retinal degenerative diseases. These ...