This work was supported by NIH Grants R01-DC010146 and R01-DC010397. Its content is solely the responsibility of the authors and does not necessarily represent the official view of the National Institutes of Health.

1. Cell Culture
Note: All cell culturing protocols must be performed using proper cell culture techniques (for reference see the first 3 Chapters of Cell Biology: A Laboratory Handbook, Volume I 10). HEI-OC1 cells do not require any additional coating or treatment of the cell culture dishes for proper adherence and growth. Very important: do not use glassware dishes for cell culture purposes; the phenotype and biological response of the cells to pharmacological drugs will change (G Ka...

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Neurootol. 8, 177-189 (2003).</li><li>Devarajan, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cisplatin-induced+apoptosis+in+auditory+cells:+role+of+death+receptor+and+mitochondrial+pathways.">Cisplatin-induced apoptosis in auditory cells: role of death receptor and mitochondrial pathways.</a> Hear Res. 174, 45-54 (2002).</li><li>Chen, F. Q., Hill, K., Guan, Y. J., Schacht, J., Sha, S. 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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=Autophagy+through+4EBP1+and+AMPK+regulates+oxidative+stress-induced+premature+senescence+in+auditory+cells.">Autophagy through 4EBP1 and AMPK regulates oxidative stress-induced premature senescence in auditory cells.</a> Oncotarget. 6, 3644-3655 (2015).</li><li>Youn, C. K., Kim, J., Park, J. H., Do, N. Y., Cho, S. 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The authors declare no existing or potential conflict of interest.

In this report we describe how to culture HEI-OC1 cells and use them to evaluate mechanisms of drug-induced cytotoxicity and to investigate functional properties of prestin, the molecular motor of cochlear OHCs. The technical procedures, however, are general enough to be easily adapted to different studies.
All the protocols described here require the correct use of well-established cell culture techniques 10. Just like with any other cell line, working with HEI-OC1 cells requires a...

House Ear Institute-Organ of Corti 1 (HEI-OC1) cells are derived from the auditory organ of a transgenic mouse 1,2. Incubation of any cell from this transgenic mouse at 33 &#176;C/10% CO2 (permissive conditions) induces expression of an immortalizing gene that triggers de-differentiation and accelerated proliferation; moving the cells to 39 &#176;C/5% CO2 (non-permissive conditions) lead to decreased proliferation, differentiation and, at least in the case of HEI-OC1, cell death 2,3.
HEI-OC1 cells were cloned and characterized in our laboratory over a decade ago, and initial studies indicated that they express specific markers of cochlear hair cells, such as prestin, myosin 7a, Atoh1, BDNF, calbindin and calmodulin, but also markers of supporting cells like connexin 26 and fibroblast growth factor receptor (FGF-R) 2. Therefore, it was suggested that HEI-OC1 could represent a common progenitor for sensory and supporting cells of the organ of Corti 2. Parallel studies provided strong evidence that archetypal ototoxic drugs like cisplatin, gentamicin and streptomycin induced caspase-3 activation in these cells, while drugs considered non-ototoxic, like penicillin, did not 2,3. Therefore, this cell line was proposed as an in vitro system to investigate the cellular and molecular mechanisms involved in ototoxicity and for screening of the potential ototoxicity or otoprotective properties of new pharmacological drugs. It is estimated that HEI-OC1 cells have been used in more than one hundred and fifty studies published in the last ten years.
Whereas looking at the potential pro-apoptotic effect of different drugs was the major goal of most of the studies involving this cell line, other important cell processes like autophagy and senescence have just started to be investigated in HEI-OC1 cells4-7. In a recent study from our laboratory 8, we used HEI-OC1 cells to collect a comprehensive set of data about cell death, survival, proliferation, senescence and autophagy induced by different pharmacological drugs frequently used in the clinic. We also compared some of the responses of HEI-OC1 cells with those from HEK-293 (human embryonic kidney cells) and HeLa (human epithelial cells) receiving identical treatment. Our results indicated that HEI-OC1 cells respond to the each drug in a characteristic way, with a distinctive dose- and time-dependent sensitivity to at least one of the mechanisms under study. We also emphasized in that study that a correct interpretation of the experimental results will require performing parallel studies with more than one technique 8.
In a different study we investigated the use of HEI-OC1 cells to evaluate the functional response of prestin, the motor protein of cochlear outer hair cells (OHCs) 9. We reported flow cytometry and confocal laser scanning microscopy studies on the pattern of prestin expression, as well as nonlinear capacitance (NLC) and whole cell-patch clamping studies in HEI-OC1 cells cultured at permissive (P-HEI-OC1) and non-permissive (NP-HEI-OC1) conditions. Our results indicated that both total prestin expression and plasma membrane localization increase in a time-dependent manner in NP-HEI-OC1 cells. Interestingly, we also found that the increase in prestin localization at the plasma membrane of NP-HEI-OC1 cells correlated with a decrease in Na+K+ATPase, which translocated from the plasma membrane to the cytoplasm without significant changes in total cell expression. In addition, we demonstrated that P-HEI-OC1 cells have a robust NLC associated to prestin motor function, which decreased when the density of prestin molecules present at the plasma membrane increased. Altogether, these results strongly support the usefulness of HEI-OC1 cells to investigate auditory proteins.
In this video article we describe how to culture HEI-OC1 cells, why it is convenient to use cells growing at permissive conditions (P-HEI-OC1) for cytotoxicity studies, how to evaluate the mechanism/s of drug-induced cytotoxicity and how to perform electrophysiological studies (e.g., patch-clamp, non-linear capacitance (NLC)) to investigate functional properties of prestin, the molecular motor of cochlear OHCs.

<table border="0" cellpadding="0" cellspacing="0" width="1447">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:905px;">HEI-OC1 cells</td>
			<td style="width:143px;"></td>
			<td style="width:139px;"></td>
			<td style="width:260px;">ALL THE ASSAY KITS, EQUIPMENTS&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Class II Biological Safety cabinet</td>
			<td>The Baker Company</td>
			<td>Sterilgard III</td>
			<td>AND COMPANIES INDICATED IN THE</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Refrigerated centrifuge</td>
			<td>Eppendorf</td>
			<td>5810R</td>
			<td>PREVIOUS 2 COLUMNS ARE ONLY</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Inverted microscope</td>
			<td>Zeiss</td>
			<td>Axiovert 25</td>
			<td>EXAMPLES, AND ANY OTHER SIMILAR</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Waterbath</td>
			<td>Stovall</td>
			<td>HWB115</td>
			<td>PRODUCT COULD BE USED.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cell counter</td>
			<td>Nexcelom</td>
			<td>Cellometer Auto T4</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Two (2) Cell incubators, one at 33&#176;C/10% CO2 and other at 39&#176;C/5% CO2</td>
			<td>Forma Scientific</td>
			<td>3110</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cell culture dishes, PS, 100 x 20 mm with vents</td>
			<td>Greinier Bio-One</td>
			<td>664-160</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cell culture dishes , PS,&#160; 60 x 15 mm with vents&#160;</td>
			<td>Greiner Bio-One</td>
			<td>628160</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cellstar tissue culture flasks&#160; 250 mL</td>
			<td>Greiner Bio-One</td>
			<td>658-175</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cellstar tissue cultur&#160; flasks 550 mL</td>
			<td>Greiner Bio-One</td>
			<td>660-175</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">&#160;6 well cell culture plate, with lid-Cellstar</td>
			<td>Greiner Bio-One</td>
			<td>657-160</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Microtest Tissue culture plate, 96 well,flat bottom with lid</td>
			<td>Becton Dickinson</td>
			<td>353072</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Micro-Assay-Plate, Chimmey, 96-well white,clear botton</td>
			<td>Greiner Bio-One</td>
			<td>655098</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">50 ml Polypropylene conical tube with cap Cellstars</td>
			<td>Becton Dickinson&#160;</td>
			<td>352070</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">15 ml Polypropylene conical tubes with cap-Cellstars</td>
			<td>Greiner Bio-One</td>
			<td>188-271</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">PBS pH 7.4 (1X)&#160;</td>
			<td>Life Technologies</td>
			<td>10010-023</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Dulbecco&#8217;s Modified Eagle&#8217;s Medium (DMEM)</td>
			<td>Life Technologies</td>
			<td>11965-084</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Fetal bovine serum (FBS)&#160;</td>
			<td>Hyclone</td>
			<td>SH10073.1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Leibovitz&#39;s L-15 Medium, no phenol red</td>
			<td>Gibco/Invitrogen</td>
			<td>21083-027</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Trypsin, 0.25%&#160;</td>
			<td>Life Technologies</td>
			<td>25200-056</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">TACS MTT Cell Proliferation Assay Kit</td>
			<td>Trevigen</td>
			<td>4890-25-K</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Caspase-Glo 3/7 Assay&#160; kit</td>
			<td>Promega</td>
			<td style="width:139px;">&#160; G8091&#160;</td>
			<td style="width:260px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">BrdU Cell Proliferation Assay Kit&#160;</td>
			<td>Cell Signaling</td>
			<td>6813</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Non-enzymatic cell dissociation solution&#160;</td>
			<td>Sigma-Aldrich</td>
			<td>C5789</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cell-Tox Green Cytotoxicity Assay Kit</td>
			<td>Promega</td>
			<td style="width:139px;">&#160; G8741&#160;</td>
			<td style="width:260px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">FACSAriaIII instrument&#160;</td>
			<td>BD Biosciences</td>
			<td>&#160;FACSAriaIII</td>
			<td>With 488 nm excitation (blue laser)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Digital Blot Scanner</td>
			<td>LI-COR</td>
			<td>C-DiGit</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Electrophoresis and Blotting Unit</td>
			<td>Hoefer</td>
			<td>SE300 miniVE</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Spectra Max 5 Plate Reader with Soft Max Pro 5.2 Software</td>
			<td>Molecular Devices</td>
			<td>SpectraMax 5</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Patch-clamp amplifier</td>
			<td>HEKA</td>
			<td>EPC-10</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Puller for preparing patch electrodes</td>
			<td>Sutter Instruments</td>
			<td>P-97</td>
			<td></td>
		</tr>
	</tbody>
</table>

working with auditory hei-oc1 cells

HEI-OC1 is one of the few mouse auditory cell lines available for research purposes. Originally proposed as an in vitro system for screening of ototoxic drugs, these cells have been used to investigate drug-activated apoptotic pathways, autophagy, senescence, mechanism of cell protection, inflammatory responses, cell differentiation, genetic and epigenetic effects of pharmacological drugs, effects of hypoxia, oxidative and endoplasmic reticulum stress, and expression of molecular channels and receptors. Among other several important markers of cochlear hair cells, HEI-OC1 cells endogenously express prestin, the paradigmatic motor protein of outer hair cells. Thus, they can be very useful to elucidate novel functional aspects of this important auditory protein. HEI-OC1 cells are very robust, and their culture usually does not present big complications. However, they require some special conditions such as avoiding the use of common anti-bacterial cocktails containing streptomycin or other antibiotics as well as incubation at 33 &#176;C to stimulate cell proliferation and incubation at 39 &#176;C to trigger cell differentiation. Here, we describe how to culture HEI-OC1 cells and how to use them in some typical assays, such as cell proliferation, viability, death, autophagy and senescence, as well as how to perform patch-clamp and non-linear capacitance measurements.

In a couple of recent publications we reported a comprehensive set of studies aimed at evaluating the response of HEI-OC1 cells to several commonly used pharmacological drugs as well as investigating prestin function 8,9. In these studies we made use of all the protocols described in the previous sections.
One of the results of these previous studies was that HEI-OC1 cells cultured at non-permissive conditions (39 &#1...

Watch this Scientific Journal Video about Working with Auditory HEI-OC1 Cells at JoVE.com

Working with Auditory HEI-OC1 Cells

House Ear Institute-Organ of Corti 1 (HEI-OC1) is one of the few mouse auditory cell lines currently available for research purposes. This protocol describes how to work with HEI-OC1 cells to investigate the cytotoxic effects of pharmacological drugs as well as functional properties of inner ear proteins.

HEI-OC1 is one of the few mouse auditory cell lines available for research purposes. Originally proposed as an in vitro system for screening of ototoxic ...

The overall goal of this protocol is to describe the basic procedures to work with HEI-OC1 cells, which can be used to study the effects of pharmacological drugs on auditory cells, and assist in the functional characterization of the motor protein prestin. HEI-OC1 cells are used by many researchers around the world in different experiments with different goals and using different techniques. Hopefully, the procedures described here will provide a common base to make these studies comparable.Of course, these experimental procedures may be further improved. But the differences with those described here could be key to understand and explain possibly contradictory results. In this demonstration we will describe how to work with HEI-OC1 cells starting from a frozen aliquot to having samples ready to perform different studies with widely available techniques.To begin this procedure remove a vial of cryopreserved HEI-OC1 cells from liquid nitrogen and place it in a water bath at 37 degrees Celsius. Submerge only the lower half of the vial and allow it to thaw until only a small amount of ice remains in the vial. In a biological safety cabinet, wipe the outside of the vial with 70%alcohol.Then, pipette the cells from the vial and deliver the entire volume drop by drop, slowly, into a 15 milliliter conical tube containing 10 milliliters of prewarmed growth medium such as DMEM supplemented with 10%FBS. Next, remove the DMSO by centrifuging the tube for five minutes. After five minutes, discard the supernatant and resuspend the cells in nine milliliters of fresh growth medium.Disaggregate the clumps or sheets of cells by fluxing and refluxing the suspended cells between the pipette and the medium three to four times with the tip of the pipette touching the bottom of the tube. Then, place the total volume of cells suspended in growth medium in a 100 millimeter diameter untreated plastic cell culture dish. Incubate the cells at 33 degrees Celsius with 10%CO2.In this step, remove the old medium and wash the cells with two milliliters of PBS. Then, cover the cell monolayer with 0.25%trypsin. Examine the cells using an inverted microscope when 40%of them have been detached.If necessary, gently rock the culture dish to release any remaining attached cells Resuspend the cells and remove the trypsin by centrifuging the tube for five minutes. Afterward, discard the supernatant and resuspend the cells in nine milliliters of fresh growth medium. Next, disaggregate the clumps or sheets of cells by fluxing and refluxing the suspended cells between the pipette and the medium, three to four times with the tip of the pipette touching the bottom of the tube.Proceed to seed the cells in 100 millimeter diameter cell culture dishes. Incubate them at 33 degrees Celsius with 10%CO2 and divide them as many times as necessary for the planned experiments, or for generating a new stock. For differentiation, incubate HEI-OC1 cells at the permissive conditions until they reach about 80%confluence.Then, incubate the cells at 39 degrees Celsius with 5%CO2 for two to three weeks and change the medium every other day to remove dead cells. Begin this procedure by counting the cells using either an automatic cell counter or a hemocytometer and adjust the cell concentration to the required value. Next, seed the cells in a 96 well clear flat bottom plate, a white walled 96 well plate, or a six well plate.If required by the particular assay, incubate the cells overnight for substrate attachment before treating them with the drugs of interest. Then, measure the outcome of the treatment by flow cytometry or another adequate technique. To harvest the cells, wash them twice with 10 milliliters of calcium-and magnesium-free PBS.Add two milliliters of the enzyme-free detacher solution and incubate the cells for three minutes at 37 degrees Celsius with 5%CO2. Use an inverted microscope to check the detachment of the cells. If necessary, move the cell culture dish gently to detach more cells, and be careful not to shake it.Next, add 10 milliliters of DMEM plus 10%FBS and pipette the cells up and down, gently, five times. After that, look at the cells under a microscope. If more than 80%of the cells are already separated, no further pipetting is needed.If the cells are still in clusters, continue gently pipetting until more than 80%of the cells are no longer in clusters. An optical control of the cells should show many single round cells with smooth membrane edges. Afterwards, proceed with patch-clamp and NLC measurements, as described in the text protocol.HEI-OC1 cells cultured at nonpermissive conditions showed a highly significant decrease in cell viability, and an equally significant increase in cell death in respect to cells cultures at permissive conditions. Since drug effects on cells already dying or with a decreased viability could be different than the effects of the same drug on healthy cells, considerable efforts should be dedicated to discriminate drug effects from the effects of culture conditions in any cytotoxicity study performed on NP-HEI-OC1 cells. Therefore, we recommend using HEI-OC1 cells cultured at permissive conditions for experiments that do not specifically require differentiated cells.The confocal images shown here confirm the expression of the auditory motor protein prestin in HEI-OC1 cells cultured at 33 degrees Celsius and 39 degrees Celsius. Note that prestin immunolocalizes mostly at the cytoplasm of HEI-OC1 cells growing in the permissive conditions, and it is more concentrated at the plasma membrane in the more differentiated cells. Flow cytometry studies showed a clear increase in prestin expression in both conditions, suggesting that translocation was accompanied by synthesis of more prestin molecules.On the other hand, the electrophysiological studies showed a robust NLC in HEI-OC1 cells growing at 33 degrees Celsius, with a peak value that decreased and a voltage at peak capacitance that shifted to the more depolarized values as the cells were moved to the nonpermissive conditions for one and two weeks. Intriguingly, these results suggest that motor function could be compromised if the density of prestin molecules in the plasma membrane is too high. It is important to remember that the protocols described here require the correct use of well-established cell culture techniques.Also, remember to avoid the use of antibiotics. In addition, remember that the phenotype and response of HEI-OC1 cells will strongly depend on the culture parameters.

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14.8K vistas.  University of California, Los Angeles. The overall goal of this protocol is to describe the basic procedures to work with HEI-OC1 cells, which can be used to study the effects of pharmacological drugs on auditory cells, and assist in the functional characterization of the motor protein prestin. HEI-OC1 cells are used by many researchers around the world in different experiments with different goals and using different techniques. Hopefully, the procedures described here will provide a common base to make these studies comparable.