Name: primary cell cultures from the mouse retinal pigment epithelium
Uploaded: 2018-03-16T13:30:00
Description: Watch this Scientific Journal Video about Primary Cell Cultures from the Mouse Retinal Pigment Epithelium at JoVE.com

This study was partly funded by The BrightFocus Foundation (to DS).

Procedures involving animal subjects have been approved by the Institutional Animal Care and Use Committee (IACUC) at&#160;University of Pittsburgh
1. Prepare solutions
<ol>
	<li>Prepare growth medium by supplementing Dulbecco Modified Eagle Medium (DMEM), high glucose with 10% fetal bovine serum (FBS), 1% penicillin/streptomycin, 2.5 mM L-glutamine, and 1x MEM nonessential amino acids. Pre-warm the media in 37 &#176;C incubator before use.</li>
	<li>Prepare 2% (wt/vol) dispase II working so...

<ol>
	<li>Mart&#237;nez-Morales, J. R., Rodrigo, I., Bovolenta, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Eye+development:+a+view+from+the+retina+pigmented+epithelium.">Eye development: a view from the retina pigmented epithelium.</a> Bioessays. 26, 766-777 (2004).</li><li>Lehmann, G. L., Benedicto, I., Philp, N. J., Rodriguez-Boulan, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plasma+membrane+protein+polarity+and+trafficking+in+RPE+cells:+past,+present+and+future.">Plasma membrane protein polarity and trafficking in RPE cells: past, present and future.</a> Exp Eye Res. 126, 5-15 (2014).</li><li>Fronk, A. H., Vargis, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methods+for+culturing+retinal+pigment+epithelial+cells:+a+review+of+current+protocols+and+future+recommendations.">Methods for culturing retinal pigment epithelial cells: a review of current protocols and future recommendations.</a> J Tissue Eng. 7, (2016).</li><li>Rizzolo, L. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Barrier+properties+of+cultured+retinal+pigment+epithelium.">Barrier properties of cultured retinal pigment epithelium.</a> Exp Eye Res. 126, 16-26 (2014).</li><li>Lu, F., Yan, D., Zhou, X., Hu, D. N., Qu, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Expression+of+melanin-related+genes+in+cultured+adult+human+retinal+pigment+epithelium+and+uveal+melanoma+cells.">Expression of melanin-related genes in cultured adult human retinal pigment epithelium and uveal melanoma cells.</a> Mol Vis. 13, 2066-2072 (2007).</li><li>Boulton, M. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Studying+melanin+and+lipofuscin+in+RPE+cell+culture+models.">Studying melanin and lipofuscin in RPE cell culture models.</a> Exp Eye Res. 126, 61-67 (2014).</li><li>Saini, J. S., Temple, S., Stern, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+Retinal+Pigment+Epithelium+Stem+Cell+(RPESC).">Human Retinal Pigment Epithelium Stem Cell (RPESC).</a> Adv Exp Med Biol. 854, 557-562 (2016).</li><li>Akrami, H., 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=Retinal+pigment+epithelium+culture;a+potential+source+of+retinal+stem+cells.">Retinal pigment epithelium culture;a potential source of retinal stem cells.</a> J Ophthalmic Vis Res. 4, 134-141 (2009).</li><li>Hu, J., Bok, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+use+of+cultured+human+fetal+retinal+pigment+epithelium+in+studies+of+the+classical+retinoid+visual+cycle+and+retinoid-based+disease+processes.">The use of cultured human fetal retinal pigment epithelium in studies of the classical retinoid visual cycle and retinoid-based disease processes.</a> Exp Eye Res. , 46-50 (2014).</li><li>Mazzoni, F., Safa, H., Finnemann, S. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Understanding+photoreceptor+outer+segment+phagocytosis:+use+and+utility+of+RPE+cells+in+culture.">Understanding photoreceptor outer segment phagocytosis: use and utility of RPE cells in culture.</a> Exp Eye Res. 126, 51-60 (2014).</li><li>Reichhart, N., Strauss, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ion+channels+and+transporters+of+the+retinal+pigment+epithelium.">Ion channels and transporters of the retinal pigment epithelium.</a> Exp Eye Res. 126, 27-37 (2014).</li><li>Valapala, 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=Lysosomal-mediated+waste+clearance+in+retinal+pigment+epithelial+cells+is+regulated+by+CRYBA1/&#946;A3/A1-crystallin+via+V-ATPase-MTORC1+signaling.">Lysosomal-mediated waste clearance in retinal pigment epithelial cells is regulated by CRYBA1/&#946;A3/A1-crystallin via V-ATPase-MTORC1 signaling.</a> Autophagy. 10, 480-496 (2014).</li><li>Shang, 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=The+amino+acid+transporter+SLC36A4+regulates+the+amino+acid+pool+in+retinal+pigmented+epithelial+cells+and+mediates+the+mechanistic+target+of+rapamycin,+complex+1+signaling.">The amino acid transporter SLC36A4 regulates the amino acid pool in retinal pigmented epithelial cells and mediates the mechanistic target of rapamycin, complex 1 signaling.</a> Aging Cell. , (2017).</li><li>Fernandez-Godino, R., Garland, D. L., Pierce, E. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation,+culture+and+characterization+of+primary+mouse+RPE+cells.">Isolation, culture and characterization of primary mouse RPE cells.</a> Nat Protoc. 11, 1206-1218 (2016).</li><li>Pfeffer, B. A., Philp, N. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+culture+of+retinal+pigment+epithelium:+Special+Issue.">Cell culture of retinal pigment epithelium: Special Issue.</a> Exp Eye Res. 126, 1-4 (2014).</li><li>Singh, S., Woerly, S., McLaughlin, B. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Natural+and+artificial+substrates+for+retinal+pigment+epithelial+monolayer+transplantation.">Natural and artificial substrates for retinal pigment epithelial monolayer transplantation.</a> Biomaterials. 22, 3337-3343 (2001).</li><li>Sonoda, S., 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=A+protocol+for+the+culture+and+differentiation+of+highly+polarized+human+retinal+pigment+epithelial+cells.">A protocol for the culture and differentiation of highly polarized human retinal pigment epithelial cells.</a> Nat Protoc. 4, 662-673 (2009).</li><li>Ho, T. C., Del Priore, L. V., Kaplan, H. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tissue+culture+of+retinal+pigment+epithelium+following+isolation+with+a+gelatin+matrix+technique.">Tissue culture of retinal pigment epithelium following isolation with a gelatin matrix technique.</a> Experimental eye research. 64, 133-139 (1997).</li><li>Toops, K. A., Tan, L. X., Lakkaraju, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+detailed+three-step+protocol+for+live+imaging+of+intracellular+traffic+in+polarized+primary+porcine+RPE+monolayers.">A detailed three-step protocol for live imaging of intracellular traffic in polarized primary porcine RPE monolayers.</a> Exp Eye Res. , 74-85 (2014).</li><li>Gibbs, D., Kitamoto, J., Williams, D. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Abnormal+phagocytosis+by+retinal+pigmented+epithelium+that+lacks+myosin+VIIa,+the+Usher+syndrome+1B+protein.">Abnormal phagocytosis by retinal pigmented epithelium that lacks myosin VIIa, the Usher syndrome 1B protein.</a> Proc Natl Acad Sci USA. 100, 6481-6486 (2003).</li><li>Gibbs, D., Williams, D. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+and+culture+of+primary+mouse+retinal+pigmented+epithelial+cells.">Isolation and culture of primary mouse retinal pigmented epithelial cells.</a> Adv Exp Med Biol. 533, 347-352 (2003).</li><li>Pitk&#228;nen, L., Ranta, V. P., Moilanen, H., Urtti, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Permeability+of+retinal+pigment+epithelium:+effects+of+permeant+molecular+weight+and+lipophilicity.">Permeability of retinal pigment epithelium: effects of permeant molecular weight and lipophilicity.</a> Invest Ophthalmol Vis Sci. 46, 641-646 (2005).</li><li>Mao, Y., Finnemann, S. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+photoreceptor+outer+segment+phagocytosis+by+RPE+cells+in+culture.">Analysis of photoreceptor outer segment phagocytosis by RPE cells in culture.</a> Methods Mol Biol. 935, 285-295 (2013).</li></ol>

The presented detailed protocol enables reliable establishment of mouse primary RPE cultures that reach confluency after 1 week and present the main RPE characteristics such as hexagonal shape and pigmentation after 2 weeks. The obtained RPE cells can be used for a number of downstream applications such as vitamin A metabolism9, phagocytosis of the photoreceptor outer segments10 and ion transport11, epithelial cell polarity2, ...

The retinal pigment epithelium (RPE) is a single layer of polarized epithelial cells that is located between the neural retina and the choroid of the eye. The functionality of the RPE cells and the integrity of the RPE monolayer are critical for vision because the RPE plays a major role in multiple processes such as maintaining the outer blood-retinal barrier, transport of water and ions between the retina and the choroid, light absorption, protection from oxidative stress, control of retinoid metabolism, and phagocytosis of the outer segments of the photoreceptors1,2. The location of the RPE at the back of the eye, as well as its barrier function preventing drugs administered systemically from passing from the blood to the vitreous humor, make it difficult to study the complexity of the RPE function in vivo. Thus, there is a great need for the establishment of RPE cell cultures to study the RPE cells in a flexible, controlled environment3,4.
A number of established RPE cell lines exist, providing an easy and convenient way of obtaining and storing the cells; however, passaged cells have some disadvantages compared to primary cells2,3,4. First, they are often characterized by changes in cell morphology. For example, none of the existing cell lines were found to be suitable for a reliable study of the RPE barrier properties due to the loss of cell polarity phenotype and partial disappearance of tight junctions4. In addition to the loss of polarity and proper cell-to-cell connections, the RPE cell lines quickly lose their pigmentation due to the absence of the key melanogenesis enzymes in the adult RPE5. The pigmentation can be restored, but the comprehensive analysis of the mechanism of re-pigmentation which would include a combination of transmission electron microscopy, gene expression analysis and chemical assays to confirm the presence of melanin has never been performed6. One more limitation is that the RPE cell lines have extended cell life (sometimes - immortality) and under certain conditions can transform into self-renewing multipotent stem cells that detach from the substrate and form floating colonies7,8. This limitation makes it impossible to use the cell lines for transplantation experiments3.
Considering the disadvantages of the established RPE cell lines, primary RPE cell cultures obtained from fresh tissues might serve as a more biologically relevant model to study the RPE. Primary RPE cells have been used not only to study RPE-specific functions such as vitamin A metabolism9, phagocytosis of the photoreceptor outer segments10 and ion transport11, but also to study basic cell biology such as epithelial cell polarity2 , lysosomal homeostasis, and autophagy12,13.
In the last couple of years there have been a number of publications on establishing primary RPE cultures, indicating a growing interest in this area of research3,14,15. Numerous protocols for human RPE cells and non-human RPE cells such as bovine and porcine RPE cells were published16,17,18,19. However, it is more difficult to handle mouse RPE cells because of their much smaller size. Even though quite a number of publications have described protocols to isolate RPE cells from the mouse14,20,21, there are still many researchers struggling to isolate RPE cells without contamination of choroid cells or cells from neural retina debris. Here we present the protocol for establishing primary mouse RPE cell culture, including obtaining the eyes from the mouse, dissection of the eyes and isolation of the RPE sheets to yield the cells for culturing. This video protocol would be especially useful for researchers who are starting to work with mouse primary RPE cultures and need guidance on the dissection techniques.

<table border="0" cellpadding="0" cellspacing="0" width="980">
	<tbody>
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			<td height="20" style="height:20px;width:347px;">animals</td>
			<td style="width:123px;"></td>
			<td style="width:123px;"></td>
			<td style="width:388px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:347px;">2~3-week old wildtype mice</td>
			<td style="width:123px;"></td>
			<td style="width:123px;"></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:347px;">Name</td>
			<td style="width:123px;">Company</td>
			<td style="width:123px;">Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:347px;">reagents</td>
			<td style="width:123px;"></td>
			<td style="width:123px;"></td>
			<td></td>
		</tr>
		<tr height="35">
			<td height="35" style="height:35px;width:347px;">Dulbecco&#39;s Modified Eagle&#39;s Medium (DMEM), high glucose</td>
			<td style="width:123px;">GIBCO</td>
			<td style="width:123px;">11965092</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:347px;">Dispase II</td>
			<td style="width:123px;">Sigma</td>
			<td style="width:123px;">D4693</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:347px;">Fetal Bovine Serum (FBS)</td>
			<td style="width:123px;">Sigma</td>
			<td style="width:123px;">F4135</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:347px;">Penicillin-Streptomycin (10,000 U/mL)</td>
			<td style="width:123px;">GIBCO</td>
			<td style="width:123px;">15140122</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:347px;">MEM Non-Essential Amino Acids Solution (100X)</td>
			<td style="width:123px;">GIBCO</td>
			<td style="width:123px;">11140050</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:347px;">Phosphate-buffered saline (PBS), 1X, pH 7.4</td>
			<td style="width:123px;">GIBCO</td>
			<td style="width:123px;">10010023</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:347px;">HEPES</td>
			<td style="width:123px;">Cellgro</td>
			<td style="width:123px;">61-034</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">KOH</td>
			<td style="width:123px;">Sigma-Aldrich</td>
			<td style="width:123px;">1310-58-3</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">NaCl</td>
			<td style="width:123px;">Ambion</td>
			<td style="width:123px;">AM9759</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">L-Glutamine (200 mM)</td>
			<td style="width:123px;">GIBCO</td>
			<td style="width:123px;">25030-081</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Ethyl Alcohol</td>
			<td style="width:123px;">Fisher Scientific</td>
			<td style="width:123px;">111000200</td>
			<td></td>
		</tr>
		<tr height="37">
			<td height="37" style="height:38px;width:347px;">RPE65 antibody</td>
			<td style="width:123px;">A gift from Dr. Michael Redmond</td>
			<td style="width:123px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Fluorescein Phalloidin&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;</td>
			<td style="width:123px;">Invitrogen</td>
			<td style="width:123px;">F432</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Goat anti-Rabbit IgG (H+L), Alexa Flour 568&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;</td>
			<td style="width:123px;">Invitrogen</td>
			<td style="width:123px;">A11011&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Goat serum</td>
			<td style="width:123px;">Sigma-Aldrich</td>
			<td style="width:123px;">G9023</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">DAPI</td>
			<td style="width:123px;">Invitrogen</td>
			<td style="width:123px;">D1306</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Paraformaldehyde (PFA)</td>
			<td style="width:123px;">Polysciences, Inc</td>
			<td style="width:123px;">00380</td>
			<td></td>
		</tr>
		<tr height="37">
			<td height="37" style="height:38px;width:347px;">ZO-1 Polyclonal Antibody</td>
			<td style="width:123px;">ThermoFisher Scientific</td>
			<td style="width:123px;">40-2200</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:347px;">Name</td>
			<td style="width:123px;">Company</td>
			<td style="width:123px;">Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">instruments and equipments</td>
			<td style="width:123px;"></td>
			<td style="width:123px;"></td>
			<td></td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;width:347px;">Laminar flow cabinet</td>
			<td style="width:123px;">Baker</td>
			<td style="width:123px;">SterilGARD SG403A</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:347px;">Dissecting microscope (Zoom stereomicroscope)</td>
			<td style="width:123px;">Nikon</td>
			<td style="width:123px;">SMZ1500</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:347px;">CO2 incubator with hot air sterilization</td>
			<td style="width:123px;">Binder</td>
			<td style="width:123px;">C150</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:347px;">Centrifuge</td>
			<td style="width:123px;">Eppendorf</td>
			<td style="width:123px;">5702</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:347px;">Petri dishes</td>
			<td style="width:123px;">Fisher Scientific</td>
			<td style="width:123px;">0875712</td>
			<td></td>
		</tr>
		<tr height="35">
			<td height="35" style="height:35px;width:347px;">12 mm Polyester Membrane Inserts Pre-Loaded in 12-Well Culture Plates, Pore Size: 0.4 &#181;m, Sterile</td>
			<td style="width:123px;">Corning Incorporated</td>
			<td style="width:123px;">COR-3460</td>
			<td></td>
		</tr>
		<tr height="35">
			<td height="35" style="height:35px;width:347px;">Westcott tenotomy scissors, std blades, sharp</td>
			<td style="width:123px;">STEPHENS instruments</td>
			<td style="width:123px;">S7-1320</td>
			<td></td>
		</tr>
		<tr height="35">
			<td height="35" style="height:35px;width:347px;">Castroviejo suturing forceps 0.12mm</td>
			<td style="width:123px;">Stroz Ophthalmic Instruments</td>
			<td style="width:123px;">E1796</td>
			<td></td>
		</tr>
		<tr height="35">
			<td height="35" style="height:35px;width:347px;">Crescent straight knife</td>
			<td style="width:123px;">Beaver-Visitec International</td>
			<td style="width:123px;">373808</td>
			<td></td>
		</tr>
		<tr height="35">
			<td height="35" style="height:35px;width:347px;">Dumont Tweezers #5, 11 cm, Straight, 0.1x0.06 mm Tips, Dumostar</td>
			<td style="width:123px;">World Precision Instruments</td>
			<td style="width:123px;">500233</td>
			<td></td>
		</tr>
		<tr height="35">
			<td height="35" style="height:35px;width:347px;">Vannas Scissors, 8 cm, 45&#176; Angle, Standard</td>
			<td style="width:123px;">World Precision Instruments</td>
			<td style="width:123px;">500260</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:347px;">Millex-GS Syringe Filter Unit, 0.22 &#181;m</td>
			<td style="width:123px;">Millipore</td>
			<td style="width:123px;">SLGL0250S</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:347px;">Syringe, 5 mL</td>
			<td style="width:123px;">BD</td>
			<td style="width:123px;">309632</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:347px;">Inverted Laboratory Microscope&#160;Leica DM IL LED</td>
			<td style="width:123px;">&#160;Leica&#160;</td>
			<td style="width:123px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Pipette</td>
			<td style="width:123px;">Gilson</td>
			<td style="width:123px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Barrier and non-filtered pipette tips</td>
			<td style="width:123px;">Thermo Scientific</td>
			<td style="width:123px;"></td>
			<td></td>
		</tr>
	</tbody>
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primary cell cultures from the mouse retinal pigment epithelium

The retinal pigment epithelium (RPE) is a highly polarized multi-functional epithelium that is located between the neural retina and the choroid of the eye. It is a single sheet of pigmented cells that are hexagonally packed and connected by tight junctions. The main functions of the RPE include absorption of light, phagocytosis of the shed photoreceptor outer segments, spatial buffering of ions, transport of nutrients, ions and water as well as active involvement in the visual cycle. With such important and diverse functions, it is critically important to study the biology of RPE cells. A number of RPE cell lines have been established; however, passaged and immortalized cells are known to quickly lose some of the morphological and physiological characteristics of natural RPE cells. Thus, primary cells are more suitable for studying different aspects of RPE cell biology and function. Mouse primary RPE cell culture is very useful to researchers since mouse models are widely used in biological studies, however collecting RPE cells from mouse is also very challenging due to their small size. Here, we present a protocol for establishing primary mouse RPE cell cultures which includes enucleation and dissection of the eyes and isolation of the RPE sheets to yield the cells for culturing. This method enables efficient cell recovery. The RPE cells obtained from two mice&#160;can reach confluency on one 12 mm polyester membrane insert pre-loaded in culture plate after one week of culture and display some of the original properties of bona fide RPE cells such as hexagonal shape and pigmentation after two weeks of culture.

The mouse primary RPE culture established from 2 mice in 12 mm polyester membrane insert reaches 90 - 95% confluency after 1 week in culture. After 2 weeks of culture, the cells reached 100% confluency and started to form a mosaic of hexagonal, pigmented, and bi-nucleated cells. By 3 weeks of culture, the cells continued to form the shape and pigmentation, however, after 4 weeks a portion of cells got hyperpigmented (Figure 2).
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Watch this Scientific Journal Video about Primary Cell Cultures from the Mouse Retinal Pigment Epithelium at JoVE.com

Primary Cell Cultures from the Mouse Retinal Pigment Epithelium

The retinal pigment epithelium (RPE) is a multi-functional epithelium of the eye. Here we present a protocol to establish primary cell cultures derived from the murine RPE.

The retinal pigment epithelium (RPE) is a highly polarized multi-functional epithelium that is located between the neural retina and the choroid of the ...

The overall goal of this procedure is to demonstrate a feasible way to obtain retinal pigment epithelium cells from mouse eyes, and to culture them in vitro while retaining their original properties. This method will help RPE researchers to obtain dissection skills that are required for establishing of mouse RPE cell cultures, and to demonstrate how to do that in an easy way. The main advantage of this procedure is that it is simple and feasible.The only thing required is practice, and the visual demonstration of RPE isolation and the microscopy literally demonstrates how to obtain the required skills. To isolate the mouse eyeballs, first euthanize two mice using any approved method, and wearing gloves place it on an absorbent pad. Position a thumb and index finger around the eye and gently push the skin to bulge out the eyeball.Once the eyeball is protruded, tuck the tip of a pair of angled scissors between the skin and the eyeball and carefully cut the tissue around the eye until it is released. Then, briefly dip the isolated eye in the 70%ethanol and submerge it in PBS in a Petri dish. After collecting both eyes from each of the mice, proceed with the dissection.Under the dissecting microscope, carefully remove the majority of connective tissue from around the eye. It is not necessary to keep the eye submerged during this step. To do so, use suturing forceps to lift the connective tissues from the eyeball, and cut them out using Vannas scissors.Do not cut the sclera because it is practically impossible to obtain the intact posterior eye cups if the sclera gets cut. After cleaning off the connective tissue, submerge the eyeballs in PBS, and switch to working in a laminar flow cabinet under sterile conditions. Now, use forceps to transfer the eyes into a dish of warm DMEM containing a high concentration of glucose.After 20 to 30 seconds, replace the wash solution using aspiration for a second wash. Transfer eyeballs to warmed 2%Dispase II working solution in 15 mL tubes and let the eyes incubate at 37 degrees celsius for 45 minutes to dissociate. After the incubation, the eyeballs should be soft.Next, wash the eyes two times in the same vessel with warmed growth medium. After the second wash, replace the growth medium with fresh medium, and transfer the eyeballs and the medium to a new dish to continue the dissection. Continue working in a clean bench with the help of a dissection microscope.Start the dissection by securing the eye with forceps and make an incision around the ora serrata using Vannas scissors. Keeping the eyeball in the solution, carefully remove the anterior cornea by extending the cut around the ora serrata circumference. After completing the cut, pull off the anterior cornea.Next, remove the lens capsule and associated iris pigmented epithelium by gently pulling it out of the eye cup using toothed forceps. Then, repeat the dissection on the remaining eyes and incubate the posterior eye cups in growth medium for 20 minutes at 37 degrees celsius to facilitate separation of the neural retina from the RPE. After 20 minutes, cut the posterior eye cups into four petals.Make the cuts long enough to flatten the eye cup, but short enough to keep the petals connected. Next, flatten the eye cup to remove the neural retina. Secure the remaining RPE choroid sclera complex with the non-dominant hand and very gently tug away the retina from the edges.Once the neural retina is removed, transfer the quartered RPE choroid sclera complex into a new sterile culture dish filled with warm growth medium. In the Petri dish, secure one petal of the quartered RPE choroid sclera complex with super fine forceps, and using a microsurgical crescent knife, gently peel off the intact sheets of RPE from the underlying basement membrane. The brownish RPE should be clearly distinguishable from the dark, sticky, fluffy choroid.Then, wet a p200 micropipette tip with growth medium and use the tip to transfer the RPE sheets into the new dish containing warmed growth medium. Now, wash the RPE sheets three times in warmed growth medium. After each wash step, carefully collect the RPE sheets while avoiding other tissues, such as the debris from the retina or choroid.After the last wash, transfer the RPE sheets to a 1.5 mL tube, and allow them to sediment by gravity. Then, in the laminar flow cabinet remove the extra growth medium and re-suspend the cells in freshly made warm growth medium. Now, gently triturate the tissue using a p200 micropipette without making bubbles.Triturate between 40 and 50 times, just enough to make a single cell suspension. Be careful as too much trituration can be lethal. Now, plate the RPE cells collected from both mice in one 12 mL polyester membrane insert in the well of a 12 well culture plate.A high cell density is desired so that the RPE cells retain their hexagonal shape and pigmentation. A mouse primary RPE culture established from two mice in a 12 mm polyester membrane insert reached 90 to 95%confluency after one week in culture. After two weeks in culture, the cells were 100%confluent and started to form a mosaic of hexagonal pigmented and bi-nucleated cells.By week three, the cells continued to change in shape and pigmentation. However, after four weeks a portion of the cells became hyperpigmented. The purity of the primary RPE cell culture was assessed using the RPE65 antibody, which labels retinoid isomerohydrolase, an enzyme critical to the vertebrate visual cycle.The integrity of the cell to cell junctions and hexagonal cell shape was demonstrated by staining with phalloidin. Tight junctions were visualized by analysis of ZO-1 protein expression, which could be visualized using an amino stain and validated by western blotting. Overall, the cultures are able to proliferate, retain pigmentation and their hexagonal shape while forming tight junctions and expressing functional markers, such as RPE65.After watching this video, you should have a good understanding of how to isolate RPE cells from the mouse eyes and culture them properly in vitro. Once mastered, this technique can be done in three hours if it is performed properly. While attempting this procedure, it is important to remember to always keep the eyes wet and try to operate as fast as you can.

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