This work was supported by the National Eye Institute (NEI), and National Eye Institute (NEI) fund R01 EY029751-04. We would like to thank Dr. Pamela Martin for her help in our initial stages of RPE isolation.

Animals were used as per the guidelines of Oakland university IACUC animal protocol number 21063 and the guidelines of the ARVO Statement for the Use of Animals in Ophthalmic and Vision Research.
1. Solution preparation
<ol>
	<li>Prepare the complete RPE cell culture media by supplementing Dulbecco&#39;s Modified Eagle Medium/Nutrient Mixture F-12 (DMEM/F12) with 25% Fetal Bovine Serum (FBS), 1.5% penicillin/streptomycin, and 0.02% gentamicin.</li>
	<li>Prepare Enzyme A by s...

<ol>
	<li>Young, R. W., Droz, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+renewal+of+protein+in+retinal+rods+and+cones.">The renewal of protein in retinal rods and cones.</a> The Journal of Cell Biology. 39 (1), 169-184 (1968).</li><li>Sparrow, J. R., Hicks, D., Hamel, C. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+retinal+pigment+epithelium+in+health+and+disease.">The retinal pigment epithelium in health and disease.</a> Current Molecular Medicine. 10 (9), 802-823 (2010).</li><li>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=The+retinal+pigment+epithelium+in+visual+function.">The retinal pigment epithelium in visual function.</a> Physiological Reviews. 85 (3), 845-881 (2005).</li><li>Marlhens, F., 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=Autosomal+recessive+retinal+dystrophy+associated+with+two+novel+mutations+in+the+RPE65+gene.">Autosomal recessive retinal dystrophy associated with two novel mutations in the RPE65 gene.</a> European Journal of Human Genetics. 6 (5), 527-531 (1998).</li><li>Morimura, 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=Mutations+in+the+RPE65+gene+in+patients+with+autosomal+recessive+retinitis+pigmentosa+or+leber+congenital+amaurosis.">Mutations in the RPE65 gene in patients with autosomal recessive retinitis pigmentosa or leber congenital amaurosis.</a> Proceedings of the National Academy of Sciences. 95 (6), 3088-3093 (1998).</li><li>Weiter, J. J., Delori, F. C., Wing, G. L., Fitch, K. A. <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+epithelial+lipofuscin+and+melanin+and+choroidal+melanin+in+human+eyes.">Retinal pigment epithelial lipofuscin and melanin and choroidal melanin in human eyes.</a> Investigative Ophthalmology &amp; Visual Science. 27 (2), 145-152 (1986).</li><li>Feeney-Burns, L., Hilderbrand, E. S., Eldridge, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aging+human+RPE:+morphometric+analysis+of+macular,+equatorial,+and+peripheral+cells.">Aging human RPE: morphometric analysis of macular, equatorial, and peripheral cells.</a> Investigative Ophthalmology &amp; Visual Science. 25 (2), 195-200 (1984).</li><li>Ibrahim, A. 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=Hyperhomocysteinemia+disrupts+retinal+pigment+epithelial+structure+and+function+with+features+of+age-related+macular+degeneration.">Hyperhomocysteinemia disrupts retinal pigment epithelial structure and function with features of age-related macular degeneration.</a> Oncotarget. 7 (8), 8532-8545 (2016).</li><li>Zarbin, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Age-related+macular+degeneration:+review+of+pathogenesis.">Age-related macular degeneration: review of pathogenesis.</a> European Journal of Ophthalmology. 8 (4), 199-206 (1998).</li><li>Dunn, K. C., Aotaki-Keen, A. E., Putkey, F. R., Hjelmeland, L. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ARPE-19,+a+human+retinal+pigment+epithelial+cell+line+with+differentiated+properties.">ARPE-19, a human retinal pigment epithelial cell line with differentiated properties.</a> Experimental Eye Research. 62 (2), 155-170 (1996).</li><li>Flannery, J. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transgenic+animal+models+for+the+study+of+inherited+retinal+dystrophies.">Transgenic animal models for the study of inherited retinal dystrophies.</a> ILAR Journal. 40 (2), 51-58 (1999).</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> Advances in Experimental Medicine and Biology. 533, 347-352 (2003).</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> Nature Protocols. 11 (7), 1206-1218 (2016).</li><li>Samra, Y. 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=Implication+of+N-Methyl-d-Aspartate+receptor+in+homocysteine-induced+age-related+macular+degeneration.">Implication of N-Methyl-d-Aspartate receptor in homocysteine-induced age-related macular degeneration.</a> International Journal of Molecular Sciences. 22 (17), 9356 (2021).</li><li>van Marum, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Update+on+the+use+of+memantine+in+Alzheimer's+disease.">Update on the use of memantine in Alzheimer's disease.</a> Neuropsychiatric Disease and Treatment. 5, 237-247 (2009).</li><li>Elsherbiny, N. 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=Homocysteine+induces+inflammation+in+retina+and+brain.">Homocysteine induces inflammation in retina and brain.</a> Biomolecules. 10 (3), 393 (2020).</li><li>Tawfik, A., Elsherbiny, N. M., Zaidi, Y., Rajpurohit, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Homocysteine+and+age-related+central+nervous+system+diseases:+role+of+inflammation.">Homocysteine and age-related central nervous system diseases: role of inflammation.</a> International Journal of Molecular Sciences. 22 (12), 6259 (2021).</li><li>Shang, P., Stepicheva, N. A., Hose, S., Zigler Jr, J. S., Sinha, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Primary+cell+cultures+from+the+mouse+retinal+pigment+epithelium.">Primary cell cultures from the mouse retinal pigment epithelium.</a> Journal of Visualized Experiments. (133), e56997 (2018).</li><li>Chen, 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=Characterization+of+a+spontaneous+mouse+retinal+pigment+epithelial+cell+line+B6-RPE07.">Characterization of a spontaneous mouse retinal pigment epithelial cell line B6-RPE07.</a> Investigative Ophthalmology &amp; Visual Science. 49 (8), 3699-3706 (2008).</li><li>AVMA Guidelines for the Euthanasia of Animals: 2020 Edition. Available from: <a target="_blank" href="https://www.avma.org/KB/Policies/Documents/euthanasia.pdf">https://www.avma.org/KB/Policies/Documents/euthanasia.pdf</a> (2020)</li><li>Cai, X., Conley, S. M., Naash, M. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=RPE65:+role+in+the+visual+cycle,+human+retinal+disease,+and+gene+therapy.">RPE65: role in the visual cycle, human retinal disease, and gene therapy.</a> Ophthalmic Genetics. 30 (2), 57-62 (2009).</li><li>P&#233;rez-&#193;lvarez, M. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vimentin+isoform+expression+in+the+human+retina+characterized+with+the+monoclonal+antibody+3CB2.">Vimentin isoform expression in the human retina characterized with the monoclonal antibody 3CB2.</a> Journal of Neuroscience Research. 86 (8), 1871-1883 (2008).</li><li>Tawfik, A., Samra, Y. A., Elsherbiny, N. M., Al-Shabrawey, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Implication+of+hyperhomocysteinemia+in+blood+retinal+barrier+(BRB)+dysfunction.">Implication of hyperhomocysteinemia in blood retinal barrier (BRB) dysfunction.</a> Biomolecules. 10 (8), 1119 (2020).</li><li>Promsote, W., Makala, L., Li, B., Smith, S. B., Singh, N., Ganapathy, V., Pace, B. S., Martin, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monomethylfumarate+induces+&#947;-globin+expression+and+fetal+hemoglobin+production+in+cultured+human+retinal+pigment+epithelial+(RPE)+and+erythroid+cells,+and+in+intact+retina.">Monomethylfumarate induces &#947;-globin expression and fetal hemoglobin production in cultured human retinal pigment epithelial (RPE) and erythroid cells, and in intact retina.</a> Invest Ophthalmol Vis Sci. 55 (8), 5382-5393 (2014).</li></ol>

The current protocol is a reported, modified, and simplified detailed procedure for RPE isolation from mouse eyes. The protocol includes enucleation, dissection, collection, seeding, culture, and characterization of RPE cells isolated from mouse eyes.
There are some limitations and critical steps that must be fulfilled for successful RPE isolation, such as mice age, the number of eyes dissected, the size of the tissue culture plate or dish, and cautions after seeding, storage, and passaging. T...

An erratum was issued for:&#160;<a href="https://www.jove.com/t/63543">Isolation of Primary Mouse Retinal Pigmented Epithelium Cells</a>. The Discussion and References sections were updated.
The third paragraph of the Discussion&#160;section was updated from:
This protocol is different from other valuable and reliable published protocols for primary mouse RPE isolation13,19,20 in that it is simplified with a few steps that are easy to follow. RPE cells are able to be identified by their morphology, pigmentation, and specific RPE markers such as RPE654,5,21. Validation of the purity and contamination of M&#252;ller cells was achieved by staining isolated cells with a specific cell marker for M&#252;ller cells (vimentin)22. Many techniques have been used to evaluate the integrity of the blood-retinal barrier (BRB) in vitro, such as electron microscope (EM) examination, assessment of tight junction proteins (TJPs), FITIC dextran leakage assay, and transepithelial electrical resistance (TER) measurement that evaluates the physiological function of RPE as a monolayer8,23. RPE cells play an important role in maintaining the outer BRB, and to validate this function, we evaluated tight junction proteins (TJPs) such as Zona ocludin-1 (ZO-1) and cytoskeletal proteins like F-actin as previously published8. TJPs evaluation is a more convenient method for the evaluation of BRB integrity and barrier function which doesn&#39;t require expensive equipment that may not be available in all research labs, as opposed to EM evaluation or TER.
to:
This protocol is different from other valuable and reliable published protocols for primary mouse RPE isolation13,19,20,24 in that it is simplified with a few steps that are easy to follow. RPE cells are able to be identified by their morphology, pigmentation, and specific RPE markers such as RPE654,5,21. Validation of the purity and contamination of M&#252;ller cells was achieved by staining isolated cells with a specific cell marker for M&#252;ller cells (vimentin)22. Many techniques have been used to evaluate the integrity of the blood-retinal barrier (BRB) in vitro, such as electron microscope (EM) examination, assessment of tight junction proteins (TJPs), FITIC dextran leakage assay, and transepithelial electrical resistance (TER) measurement that evaluates the physiological function of RPE as a monolayer8,23. RPE cells play an important role in maintaining the outer BRB, and to validate this function, we evaluated tight junction proteins (TJPs) such as Zona ocludin-1 (ZO-1) and cytoskeletal proteins like F-actin as previously published8. TJPs evaluation is a more convenient method for the evaluation of BRB integrity and barrier function which doesn&#39;t require expensive equipment that may not be available in all research labs, as opposed to EM evaluation or TER.
In the References section, a 24th reference was added:
<ol start="24">
	<li>Promsote, W., Makala, L., Li, B., Smith, SB., Singh, N., Ganapathy, V., Pace, B.S., Martin, P. Monomethylfumarate induces &#947;-globin expression and fetal hemoglobin production in cultured human retinal pigment epithelial (RPE) and erythroid cells, and in intact retina. Invest Ophthalmol Vis Sci. 55(8):5382-93 (2014).</li>
</ol>

An erratum was issued for:&#160;<a href="https://www.jove.com/t/63543">Isolation of Primary Mouse Retinal Pigmented Epithelium Cells</a>. The Discussion and References sections were updated.

Erratum: Isolation of Primary Mouse Retinal Pigmented Epithelium Cells

Retinal pigmented epithelium (RPE) cells are located between the choroid and the neural retina, forming a simple monolayer of cuboidal cells that lies behind the photoreceptor (PR) cells1. The RPE plays a critical role in maintaining a healthy environment for PR cells, mainly by reducing the excessive accumulation of reactive oxygen species (ROS) and consequent oxidative damage1.&#160;RPE cells oversee many functions, such as the conversion and storage of retinoids, the absorption of scattered light, fluid and ion transport, and phagocytosis of the shed PR outer segment membrane2,3. Alterations in the RPE (morphology/function) can impair their function leading to retinopathy and this is a common feature shared by many ocular disorders4. Many ocular diseases are associated with alterations in the morphology and function of RPE cells, including some genetic diseases such as retinitis pigmentosa, Leber congenital amaurosis, and albinism4,5,6, as well as age-related ocular disorders such as diabetic retinopathy (DR) and age-related macular degeneration (AMD)7,8. Human cells are the most desirable, thus it would be ideal to study RPE disorders in primary human RPE cells for forming RPE monolayers. However, ethical matters and the limited availability of human donors due to the fact that most of these disorders lead to morbidity9, but not necessarily mortality10, thereby prevent the isolation of primary human RPE cells. This makes culturing RPE cells from nonhuman animal donors a preferred alternative. Rodents, particularly mice, are considered a great model for studying different ocular diseases since transgenic technology is more extensively established in these species11. Even though the use of cultured primary RPE cells offers many advantages, it has been difficult to maintain growing cells for many passages, or to store and reuse the cells. The main limitation of this protocol is the mice&#39;s age; mice that are used for RPE isolation should be of a very young age (18-21 days old is optimal) as it has been difficult to culture RPE cells from adult mice11,12,13. RPE cells can be isolated from mouse eyes at any age, however up to four cell passages was only successful with young mice (18-21 days old). RPE isolation from mouse retinas, using both C57BL6 mice and transgenic mice with deletion of the N-methyl-D-aspartate receptors (NMDARs) at the RPE cells, was performed to study the effect of elevated amino acid homocysteine on the development and progression of AMD14. In addition, isolated primary RPE cells helped in proposing a therapeutic target for AMD by inhibition of the NMDARs at RPE cells14. There are some NMDAR blockers that are approved by the Food and Drug Administration (FDA) and are currently used to treat moderate to severe confusion (dementia) related to Alzheimer&#39;s disease (AD), such as memantine16, which could be a potential therapeutic target for AMD14. Furthermore, isolated primary mouse RPE cells were used for the detection of inflammatory markers and the proposed induction of inflammation as an underlying mechanism for homocysteine-induced features of AMD and AD using a genetically modified mouse (CBS), which presents a high level of homocysteine16,17.
This protocol was used to isolate RPE cells from both wild-type C57BL/6 mice and transgenic mice developed in our lab as a simplified adaptation of other published isolation protocols13,18,19 to reach an easily applicable and reliable protocol. There is no sex preference in this protocol. While mice ages are critical for the isolation process, young, aged mice (18-21 days old) and older mice at any age (up to 12 months) were used for RPE isolation. However, we noticed that the RPE cells isolated from the young-aged mice lived longer, and up to four passages could be performed. The RPE cells isolated from older mice could be passaged once or twice, then they would stop growing at a normal rate and change their shape to be more elongated (fibroblast-like cells). Loss of pigmentation and decreased adhesion to the tissue culture plate followed by detachment was also observed.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Beaker : 100mL</td>
			<td>KIMAX</td>
			<td>14000</td>
			<td></td>
		</tr>
		<tr>
			<td>Collagenase from Clostridium histolyticum&#160;</td>
			<td>Sigma-Aldrich</td>
			<td>C7657-25MG</td>
			<td>For working enzyme, A</td>
		</tr>
		<tr>
			<td>Disposable Graduated Transfer Pipettes :3.2mL Sterile</td>
			<td></td>
			<td>13-711-20</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM/F12</td>
			<td>&#160;gibco&#160;</td>
			<td>11330</td>
			<td>Media to grow RPE cells&#160;</td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum (FBS)</td>
			<td>gibco</td>
			<td>26140079</td>
			<td>For complete RPE cell culture media</td>
		</tr>
		<tr>
			<td>Gentamicin Reagent Solution</td>
			<td>gibco</td>
			<td>15750-060</td>
			<td>For complete RPE cell culture media</td>
		</tr>
		<tr>
			<td>Hanks&#39; Balanced Salt Solution (HBSS)</td>
			<td>Thermo Scientific</td>
			<td>88284</td>
			<td>For working enzymes (A&#38;B)&#160;</td>
		</tr>
		<tr>
			<td>Heracell VISO 160i CO2 Incubator</td>
			<td>Thermo Scientific</td>
			<td>50144906</td>
			<td></td>
		</tr>
		<tr>
			<td>Hyaluronidase from bovine testes</td>
			<td>Sigma-Aldrich</td>
			<td>H3506-500MG</td>
			<td>For working enzyme A</td>
		</tr>
		<tr>
			<td>Kimwipes</td>
			<td>Kimberly-Clark</td>
			<td>34155</td>
			<td></td>
		</tr>
		<tr>
			<td>Luer-Lok Syringe with attached needle 21 G x 1 1/2 in., sterile, single use, 3 mL</td>
			<td>B-D</td>
			<td>309577</td>
			<td></td>
		</tr>
		<tr>
			<td>Micro Centrifuge Tube: 2 mL</td>
			<td>Grainger</td>
			<td>11L819</td>
			<td></td>
		</tr>
		<tr>
			<td>Mouse monoclonal anti-RPE65 antibody&#160;</td>
			<td>Abcam, Cambridge, MA, USA</td>
			<td>ab78036</td>
			<td>For IF staining&#160;</td>
		</tr>
		<tr>
			<td>Pen Strep</td>
			<td>gibco</td>
			<td>15140-122</td>
			<td>For complete RPE cell culture media</td>
		</tr>
		<tr>
			<td>Positive Action Tweezers, Style 5/45</td>
			<td>Dumont</td>
			<td>72703-DZ</td>
			<td></td>
		</tr>
		<tr>
			<td>Scissors Iris Standard Straight 11.5cm</td>
			<td>GARANA INDUSTRIES</td>
			<td>2595</td>
			<td></td>
		</tr>
		<tr>
			<td>Sorvall St8 Centrifuge</td>
			<td>ThermoScientific</td>
			<td>75007200</td>
			<td></td>
		</tr>
		<tr>
			<td>Stemi 305 Microscope</td>
			<td>Zeiss</td>
			<td>n/a</td>
			<td></td>
		</tr>
		<tr>
			<td>Surgical Blade, #11, Stainless Steel</td>
			<td>Bard-Parker</td>
			<td>371211</td>
			<td></td>
		</tr>
		<tr>
			<td>Suspension Culture Dish 60mm x 15mm Style</td>
			<td>Corning</td>
			<td>430589</td>
			<td></td>
		</tr>
		<tr>
			<td>Tissue Culture Dish : 100x20mm style</td>
			<td>Corning</td>
			<td>353003</td>
			<td></td>
		</tr>
		<tr>
			<td>Tornado Tubes: 15mL</td>
			<td>Midsci</td>
			<td>C15B</td>
			<td></td>
		</tr>
		<tr>
			<td>Tornado Tubes: 50mL</td>
			<td>Midsci</td>
			<td>C50R</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypsin EDTA (1x) 0.25%</td>
			<td>gibco</td>
			<td>2186962</td>
			<td>For working enzyme B</td>
		</tr>
		<tr>
			<td>Tweezers 5MS, 8.2cm, Straight, 0.09x0.05mm Tips</td>
			<td>Dumont</td>
			<td>501764</td>
			<td></td>
		</tr>
		<tr>
			<td>Tweezers Positive Action Style 5, Biological, Dumostar, Polished Finish, 110 mm OAL</td>
			<td>Electron Microscopy Sciences Dumont</td>
			<td>50-241-57</td>
			<td></td>
		</tr>
		<tr>
			<td>Underpads, Moderate : 23&#34; X 36&#34;</td>
			<td>McKesson</td>
			<td>4033</td>
			<td></td>
		</tr>
		<tr>
			<td>Vannas Spring Scissors - 2.5mm Cutting Edge</td>
			<td>FST</td>
			<td>15000-08</td>
			<td></td>
		</tr>
		<tr>
			<td>Zeiss AxioImager Z2</td>
			<td>Zeiss</td>
			<td>n/a</td>
			<td></td>
		</tr>
		<tr>
			<td>Zeiss Zen Blue 2.6</td>
			<td>Zeiss</td>
			<td>n/a</td>
			<td></td>
		</tr>
	</tbody>
</table>

isolation of primary mouse retinal pigmented epithelium cells

The retinal pigmented epithelium (RPE) layer lies immediately behind the photoreceptors and harbors a complex metabolic system that plays several critical roles in maintaining the photoreceptors' function. Thus, the RPE structure and function are essential to sustain normal vision. This manuscript presents an established protocol for primary mouse RPE cell isolation. RPE isolation is a great tool to investigate the molecular mechanisms underlying RPE pathology in the different mouse models of ocular disorders. Furthermore, RPE isolation can help in comparing primary mouse RPE cells isolated from wild-type and genetically modified mice, as well as testing drugs that can accelerate the development of therapy for visual disorders. The manuscript presents a step-by-step RPE isolation protocol; the entire procedure, from enucleation to seeding, takes approximately 4 hours. The media shouldn't be changed for 5-7 days after seeding, to allow the growth of the isolated cells without disturbance. This process is followed by the characterization of morphology, pigmentation, and specific markers in the cells via immunofluorescence. Cells can be passaged a maximum of three or four times.

Validation of the specificity, purity, and barrier function/formation of isolated RPE cells 
The isolated cells were examined under a light microscope to verify their viability, morphology, and pigmentation. Images from P0 and P1 (Figure&#160;1A,B) and images from P0 and P4 were captured (Figure 1C,D) to show the changes in the cells; shape, size, and pigmentation as the passages proceeded to the fourth passage (black arrows...

Watch this Scientific Journal Video about Isolation of Primary Mouse Retinal Pigmented Epithelium Cells at JoVE.com

Isolation of Primary Mouse Retinal Pigmented Epithelium Cells

This manuscript describes a simplified protocol for the isolation of retinal pigmented epithelium (RPE) cells from mouse eyes in a stepwise manner. The protocol includes the enucleation and dissection of mouse eyes, followed by the isolation, seeding, and culturing of RPE cells.

The retinal pigmented epithelium (RPE) layer lies immediately behind the photoreceptors and harbors a complex metabolic system that plays several critical ...

This protocol will outline an easy and efficient way to successfully isolate primary mouse retinal pigmented epithelium cells. Retinal pigmented epithelium cells play a very important role to maintain the photoreceptor cells and to ensure the normal function of the retina. Our lab has been isolating primary mouse pigmented epithelium cells as an important tool to study the outer blood-retinal barrier and related diseases such as age-related macular degeneration.To extract the mouse eyes, ethically euthanize the mouse according to your institution's approved methods, then place the mouse on a sterile underpad and nucleate the eye by pressing a 5/45-style tweezer on the orbital area to induce proptosis, then move the tweezer to the posterior of the eye and gently pull to remove the eye ensuring that the optic nerve is still intact. While using forceps, submerge the eyes in a 2-milliliter microcentrifuge tube containing 5%povidone iodine. Incubate the eyes at room temperature for 2 to 3 minutes.Remove the eyes from the povidone iodine and place them in a Petri dish. While using a sterile transfer pipette, wash the eyes with Hanks'Balanced Saline Solution until the orange color of the povidone iodine is gone. This takes approximately 2 to 3 washes.Place the eyes in a new Petri dish and submerge them in cold complete RPE cell growth media. From there, you can begin dissecting under a dissecting microscope. Under the microscope, use tweezers and/or Vannas scissors to pull or cut away connective tissue in extraocular muscles.Eyes can then be held for an hour in cold RPE cell culture media. However, it is preferred to proceed directly to the next step after cleaning the eyeball. Transfer the eyes to a 2-milliliter microcentrifuge tube containing the enzyme A solution, then incubate the eyes inside an incubator at 37 degrees Celsius for 40 minutes.Remove the eyes from the enzyme A solution and place them in a new 2-milliliter microcentrifuge tube containing the enzyme B solution, then place them inside an incubator and incubate at 37 degrees Celsius for 50 minutes. Remove the eyes from enzyme B and place them in a 60-millimeter Petri dish and submerge them and complete RPE cell growth media, then incubate the eyes at 4 degrees Celsius for 30 minutes. Place the dish under the dissecting microscope and begin dissecting.Use M5S forceps and a needle of a syringe to make an incision in the ora seratta section. Now with two forceps, grasp the inner part of the incision with one forcep and grasp the cornea with the other forcep. Begin to slowly tear the cornea from the retina by pulling the cornea.Be sure to tear in small increments and move down the tear as you remove the cornea. This will ensure that the RPE will remain mostly intact and you will get a cleaner tear. Once the cornea is completely detached, you should be able to see the iris and lens.Remove both the iris and lens with forceps to maintain the purity of the isolation. To remove the neural retina from the RPE layer, grasp the outer layer of the eyecup with one tweezer and position an arm of a second tweezer between both the RPE and neural layers. From there, gently pull or scoop the neural retina away from the RPE layer, then discard the neural retina.Move the RPE layer to a different place on the dish free of debris. To separate the RPE from the choroid and sclera, gently scrape the inside of the eyecup with a 5/45-style tweezer to ensure the separation of the RPE cells. The RPE cells appear cloudy when suspended and complete RPE cell growth media.Aspirate the cells using a 3.2-milliliter sterile transfer pipette and transfer to a new 15-milliliter centrifuge tube containing complete RPE cell growth media. The cells can be centrifuged at 300g for 10 minutes at room temperature. You can then aspirate out the supernatant and resuspend the pellet in warmed RPE cell growth media.Plate the cells on a 100-millimeter Petri dish and incubate at 37 degrees Celsius and 5%CO2. These images show a successful isolation at passage 0 and passage 1, which is evident by the pigmentation of the RPE cells. At passage 4, the cells become less characteristic and exhibit less pigment, show a spindle-like appearance or become more robust with a larger surface area.We validated the RPE cells with an RPE-specific marker, RPE65 and a cytoskeletal protein F-actin. We also checked for potential contamination with Muller cells by staining with a Muller cell-specific marker, vimentin. This protocol is a simplified adaptation of existing protocols.The protocol uses materials and associated equipment that are available in most research labs, which will help isolating primary mouse RPE cells in an effective way.

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Research

JoVE Journal

Biology

Isolation of Retinal Stem Cells from the Mouse Eye

The adult mouse retinal stem cell (RSC) is a rare quiescent cell found within the ciliary epithelium (CE) of the mammalian eye1,2,3. The CE is made up of non-pigmented inner and pigmented outer cell layers, and the clonal RSC colonies that arise from a single pigmented cell from the CE are made up of both pigmented and non-pigmented cells which can be differentiated to form all the cell types of the neural retina and the RPE. There is some controversy about whether all the cells within the spheres all contain at least some pigment4; however the cells are still capable of forming the different cell types found within the neural retina1-3. In some species, such as amphibians and fish, their eyes are capable of regeneration after injury5, however; the mammalian eye shows no such regenerative properties. We seek to identify the stem cell in vivo and to understand the mechanisms that keep the mammalian retinal stem cells quiescent6-8, even after injury as well as using them as a potential source of cells to help repair physical or genetic models of eye injury through transplantation9-12. Here we describe how to isolate the ciliary epithelial cells from the mouse eye and grow them in culture in order to form the clonal retinal stem cell spheres. Since there are no known markers of the stem cell in vivo, these spheres are the only known way to prospectively identify the stem cell population within the ciliary epithelium of the eye.

In this video, we will demonstrate how to isolate retinal stem cells from the ciliary epithelium of the mouse eye and grow them in culture to form clonal retinal spheres. The spheres that are isolated possess the cardinal properties of stem cells: self-renewal and multipotentiality.

The adult mouse retinal stem cell (RSC) is a rare quiescent cell found within the ciliary epithelium (CE) of the mammalian eye1,2,3. The CE is made up of ...

Isolation of Primary Mouse Trophoblast Cells and Trophoblast Invasion Assay

The placenta is responsible for the transport of nutrients, gasses and growth factors to the fetus, as well as the elimination of wastes. 
Thus, defects in placental development have important consequences for the fetus and mother, and are a major cause of embryonic lethality. The major cell type of the 
fetal portion of the placenta is the trophoblast. Primary mouse placental trophoblast cells are a useful tool for studying normal and abnormal placental development, 
and unlike cell lines, may be isolated and used to study trophoblast at specific stages of pregnancy. In addition, primary cultures of trophoblast from transgenic
mice may be used to study the role of particular genes in placental cells. The protocol presented here is based on the description by Thordarson et al.1, in which a 
percoll gradient is used to obtain a relatively pure trophoblast cell population from isolated mouse placentas. It is similar to the more widely used methods for 
human trophoblast cell isolation2-3. Purity may be assessed by immunocytochemical staining of the isolated cells for cytokeratin 74. Here, the isolated cells are 
then analyzed using a matrigel invasion assay to assess trophoblast invasiveness in vitro5-6. The invaded cells are analyzed by immunocytochemistry and stained 
for counting.

In this protocol, we describe the dissection of placentae from the mouse on pregnancy d10.5, followed by isolation of trophoblast cells using a Percoll gradient. We then demonstrate use of the isolated cells in a matrigel invasion assay.

The placenta is responsible for the transport of nutrients, gasses and growth factors to the fetus, as well as the elimination of wastes.  
Thus, defects ...

Isolation and Culture of Mouse Primary Pancreatic Acinar Cells

This protocol permits rapid isolation (in less than 1 hr) of murine pancreatic acini, making it possible to maintain them in culture for more than one week. More than 20 x 106 acinar cells can be obtained from a single murine pancreas. This protocol offers the possibility to independently process as many as 10 pancreases in parallel. Because it preserves acinar architecture, this model is well suited for studying the physiology of the exocrine pancreas in vitro in contrast to cell lines established from pancreatic tumors, which display many genetic alterations resulting in partial or total loss of their acinar differentiation.

In this publication, we describe a rapid and convenient procedure for isolating and culturing primary pancreatic acinar cells from the murine pancreas. This method constitutes a valuable approach to study the physiology of fresh primary normal/untransformed exocrine pancreatic cells.

This protocol permits rapid isolation (in less than 1 hr) of murine pancreatic acini, making it possible to maintain them in culture for more than one ...

MicroRNA Expression Profiles of Human iPS Cells, Retinal Pigment Epithelium Derived From iPS, and Fetal Retinal Pigment Epithelium

The objective of this report is to describe the protocols for comparing the microRNA (miRNA) profiles of human induced-pluripotent stem (iPS) cells, retinal pigment epithelium (RPE) derived from human iPS cells (iPS-RPE), and fetal RPE. The protocols include collection of RNA for analysis by microarray, and the analysis of microarray data to identify miRNAs that are differentially expressed among three cell types. The methods for culture of iPS cells and fetal RPE are explained. The protocol used for differentiation of RPE from human iPS is also described. The RNA extraction technique we describe was selected to allow maximal recovery of very small RNA for use in a miRNA microarray. Finally, cellular pathway and network analysis of microarray data is explained. These techniques will facilitate the comparison of the miRNA profiles of three different cell types.

The microRNA (miRNA) profiles of human induced-pluripotent stem (iPS) cells, retinal pigment epithelium (RPE) derived from human induced-pluripotent stem (iPS) cells (iPS-RPE), and fetal RPE, were compared.

The objective of this report is to describe the protocols for comparing the microRNA (miRNA) profiles of human induced-pluripotent stem (iPS) cells, ...

Isolation and Primary Culture of Mouse Aortic Endothelial Cells

The vascular endothelium is essential to normal vascular homeostasis. Its dysfunction participates in various cardiovascular disorders. The mouse is an important model for cardiovascular disease research. This study demonstrates a simple method to isolate and culture endothelial cells from the mouse aorta without any special equipment. To isolate endothelial cells, the thoracic aorta is quickly removed from the mouse body, and the attached adipose tissue and connective tissue are removed from the aorta. The aorta is cut into 1 mm rings. Each aortic ring is opened and seeded onto a growth factor reduced matrix with the endothelium facing down. The segments are cultured in endothelial cell growth medium for about 4 days. The endothelial sprouting starts as early as day 2. The segments are then removed and the cells are cultured continually until they reach confluence. The endothelial cells are harvested using neutral proteinase and cultured in endothelial cell growth medium for another two passages before being used for experiments. Immunofluorescence staining indicated that after the second passage the majority of cells were double positive for Dil-ac-LDL uptake, Lectin binding, and CD31 staining, the typical characteristics of endothelial cells. It is suggested that cells at the second to third passages are suitable for in vitro and in vivo experiments to study the endothelial biology. Our protocol provides an effective means of identifying specific cellular and molecular mechanisms in endothelial cell physiopathology.

The vascular endothelial cells play a significant role in many important cardiovascular disorders. This article describes a simple method to isolate and expand endothelial cells from the mouse aorta without using any special equipment. Our protocol provides an effective means of identifying mechanisms in endothelial cell physiopathology.

The vascular endothelium is essential to normal vascular homeostasis. Its dysfunction participates in various cardiovascular disorders. The mouse is an ...

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 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 ...

Efficient Dissection and Culture of Primary Mouse Retinal Pigment Epithelial Cells

Eye disorders affect millions of people worldwide, but the limited availability of human tissues hinders their study. Mouse models are powerful tools to understand the pathophysiology of ocular diseases because of their similarities with human anatomy and physiology. Alterations in the retinal pigment epithelium (RPE), including changes in morphology and function, are common features shared by many ocular disorders. However, successful isolation and culture of primary mouse RPE cells is very challenging. This paper is an updated audiovisual version of the protocol previously published by Fernandez-Godino et al. in 2016 to efficiently isolate and culture primary mouse RPE cells. This method is highly reproducible and results in robust cultures of highly polarized and pigmented RPE monolayers that can be maintained for several weeks on Transwells. This model opens new avenues for the study of the molecular and cellular mechanisms underlying eye diseases. Moreover, it provides a platform to test therapeutic approaches that can be used to treat important eye diseases with unmet medical needs, including inherited retinal disorders and macular degenerations.

This protocol, which was originally reported by Fernandez-Godino et al. in 20161, describes a method to efficiently isolate and culture mouse RPE cells, which form a functional and polarized RPE monolayer within one week on Transwell plates. The procedure takes approximately 3 hours.

Eye disorders affect millions of people worldwide, but the limited availability of human tissues hinders their study. Mouse models are powerful tools to ...

Isolation and Characterization of Mouse Primary Liver Sinusoidal Endothelial Cells

Liver sinusoidal endothelial cells (LSECs) are specialized endothelial cells located at the interface between the circulation and the liver parenchyma. LSECs have a distinct morphology characterized by the presence of fenestrae and the absence of basement membrane. LSECs play essential roles in many pathological disorders in the liver, including metabolic dysregulation, inflammation, fibrosis, angiogenesis, and carcinogenesis. However, little has been published about the isolation and characterization of the LSECs. Here, this protocol discusses the isolation of LSEC from both healthy and nonalcoholic fatty liver disease (NAFLD) mice. The protocol is based on collagenase perfusion of the mouse liver and magnetic beads positive selection of nonparenchymal cells to purify LSECs. This study characterizes LSECs using specific markers by flow cytometry and identifies the characteristic phenotypic features by scanning electron microscopy. LSECs isolated following this protocol can be used for functional studies, including adhesion and permeability assays, as well as downstream studies for a particular pathway of interest. In addition, these LSECs can be pooled or used individually, allowing multi-omics data generation including RNA-seq bulk or single cell, proteomic or phospho-proteomics, and Assay for Transposase-Accessible Chromatin using sequencing (ATAC-seq), among others. This protocol will be useful for investigators studying LSECs&#39; communication with other liver cells in health and disease and allow an in-depth understanding of the role of LSECs in the pathogenic mechanisms of acute and chronic liver injury.

Here we outline and demonstrate a protocol for primary mouse liver sinusoidal endothelial cell (LSEC) isolation. The protocol is based on liver collagenase perfusion, nonparenchymal cell purification by low-speed centrifugation, and CD146 magnetic bead selection. We also phenotype and characterize these isolated LSECs using flow cytometry and scanning electron microscopy.

Liver sinusoidal endothelial cells (LSECs) are specialized endothelial cells located at the interface between the circulation and the liver parenchyma. ...

Primary Culture of Porcine Retinal Pigment Epithelial Cells

The retinal pigment epithelium (RPE) is a monolayer of polarized pigmented epithelial cells, located between the choroid and neuroretina in the retina. Multiple functions, including phagocytosis, nutrient/metabolite transportation, vitamin A metabolism, etc., are conducted by the RPE on a daily basis. RPE cells are terminally differentiated epithelial cells with little or no regenerative capacity. Loss of RPE cells results in multiple eye diseases leading to visual impairment, such as age-related macular degeneration. Therefore, the establishment of an in vitro culture model of primary RPE cells, which more closely resembles the RPE in vivo than cell lines, is critical for the characteristic and mechanistic studies of RPE cells. Considering the fact that the source of human eyeballs is limited, we create a protocol to culture primary porcine RPE cells. By using this protocol, RPE cells can be easily dissociated from adult porcine eyeballs. Subsequently, these dissociated cells attach to culture dishes/inserts, proliferate to form a confluent monolayer, and quickly re-establish key features of epithelial tissue in vivo within 2 wks. By qRT-PCR, it is demonstrated that primary porcine RPE cells express multiple signature genes at comparable levels with native RPE tissue, while the expressions of most of these genes are lost/highly reduced in human RPE-like cells, ARPE-19. Moreover, the immunofluorescence staining shows the distribution of tight junction, tissue polarity, and cytoskeleton proteins, as well as the presence of RPE65, an isomerase critical for vitamin A metabolism, in cultured primary cells. Altogether, we have developed an easy-to-follow approach to culture primary porcine RPE cells with high purity and native RPE features, which could serve as a good model to understand RPE physiology, study cell toxicities, and facilitate drug screenings.

Here, an easy-to-follow method to culture primary porcine retinal pigment epithelial cells in vitro is presented.

The retinal pigment epithelium (RPE) is a monolayer of polarized pigmented epithelial cells, located between the choroid and neuroretina in the retina. ...

Staining of Sub-Retinal Pigment Epithelium (RPE) Deposits

To begin, dissolve Nile Red powder in acetone at three milligrams per milliliter concentration. Incubate the solution for 15 minutes at room temperature with periodic mixing. Filter the solution using a 0.22-micrometer filter once or twice depending on the amount of precipitate remaining in the solution.Then prepare the working solution by diluting the stock solution at a one-to-500 ratio in DPBS. Add 200 microliters of the working solution to the paraformaldehyde-fixed RPE cells and incubate for 30 minutes at room temperature on a shaker protecting from light. After incubation, wash the samples twice with DPBS, then add 200 microliters of DPBS, and store them at four degrees Celsius.For BODIPY staining, prepare a 3.8-millimolar stock concentration by dissolving BODIPY in anhydrous DMSO. Then prepare the working solution by diluting the stock solution at a one-to-300 ratio in DPBS. Add 200 microliters of the working solution of BODIPY to paraformaldehyde-fixed RPE cells and incubate overnight on a rocker at room temperature.The next day, wash the cells twice with DPBS and add 200 microliters of DPBS before storing them at four degrees Celsius. For APOE immunostaining, prepare a buffer solution by combining DPBS with 1%BSA, 0.5%Tween 20, and 0.5%Triton X-100. Block and permeabilize the paraformaldehyde-fixed RPE cells in 200 microliters of buffer solution for one hour.After incubation, add APPLE primary antibody diluted at one-to-100 in the buffer solution and incubate overnight at room temperature. The following day, wash the samples twice with DPBS. Then add 200 microliters of secondary antibody solution diluted at one-to-1000 for one hour at room temperature.After incubation, wash the cells twice with DPBS and add 200 microliters of DPBS before storing them at four degrees Celsius.