This study is supported by the Japan Society for the Promotion of Science Overseas Research Fellowships (S.G.), a Loris and David Rich Postdoctoral Scholar (S.G.), and a grant from the National Eye Institute of the National Institutes of Health (R01EY012392; C.F.W.).

All animal care and treatments used in this study conformed to the ARVO Statement for the Use of Animals in Ophthalmic and Vision Research. The experimental protocols were approved by the Animal Care and Use Committee of the University of California, Berkeley.
1. Enucleation of the guinea pig eye
<ol>
	<li>Euthanize a guinea pig&#160;with an intracardiac injection of sodium pentobarbital delivered under anesthesia (5% isoflurane in oxygen).</li>
	<li>Enucleate the eyes with ...

<ol>
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F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+the+retinal+pigment+epithelium+in+eye+growth+regulation+and+myopia:+A+review.">The role of the retinal pigment epithelium in eye growth regulation and myopia: A review.</a> Visual Neuroscience. 22 (3), 251-261 (2005).</li><li>Wallman, 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=Moving+the+retina:+Choroidal+modulation+of+refractive+state.">Moving the retina: Choroidal modulation of refractive state.</a> Vision Research. 35 (1), 37-50 (1995).</li><li>Wu, 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=Scleral+hypoxia+is+a+target+for+myopia+control.">Scleral hypoxia is a target for myopia control.</a> Proceedings of the National Academy of Sciences of the United States of America. 115 (30), 7091-7100 (2018).</li><li>Troilo, D., 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=Imi+-+Report+on+experimental+models+of+emmetropization+and+myopia.">Imi - Report on experimental models of emmetropization and myopia.</a> Investigative Ophthalmology and Visual Science. 60 (3), 31-88 (2019).</li><li>Jiang, X., 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=Violet+light+suppresses+lens-induced+myopia+via+neuropsin+(OPN5)+in+mice.">Violet light suppresses lens-induced myopia via neuropsin (OPN5) in mice.</a> Proceedings of the National Academy of Sciences of the United States of America. 118 (22), e2018840118 (2021).</li><li>Zhang, Y., Wildsoet, C. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=RPE+and+choroid+mechanisms+underlying+ocular+growth+and+myopia.">RPE and choroid mechanisms underlying ocular growth and myopia.</a> Progress in Molecular Biology and Translational Science. 134, 221-240 (2015).</li><li>Jager, R. D., Mieler, W. F., Miller, J. W. <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.">Age-related macular degeneration.</a> New England Journal of Medicine. 358 (24), 2606-2617 (2008).</li><li>McLeod, D. 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=Relationship+between+RPE+and+choriocapillaris+in+age-related+macular+degeneration.">Relationship between RPE and choriocapillaris in age-related macular degeneration.</a> Investigative Opthalmology and Visual Science. 50 (10), 4982 (2009).</li><li>Bhutto, I., Lutty, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Understanding+age-related+macular+degeneration+(AMD):+Relationships+between+the+photoreceptor/retinal+pigment+epithelium/Bruch's+membrane/choriocapillaris+complex.">Understanding age-related macular degeneration (AMD): Relationships between the photoreceptor/retinal pigment epithelium/Bruch's membrane/choriocapillaris complex.</a> Molecular Aspects of Medicine. 33 (4), 295-317 (2012).</li><li>Shelton, L., 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=Microarray+analysis+of+choroid/RPE+gene+expression+in+marmoset+eyes+undergoing+changes+in+ocular+growth+and+refraction.">Microarray analysis of choroid/RPE gene expression in marmoset eyes undergoing changes in ocular growth and refraction.</a> Molecular Vision. 14, 1465-1479 (2008).</li><li>Wang, S., Liu, S., Mao, J., Wen, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+retinoic+acid+on+the+tight+junctions+of+the+retinal+pigment+epithelium-choroid+complex+of+guinea+pigs+with+lens-induced+myopia+in+vivo.">Effect of retinoic acid on the tight junctions of the retinal pigment epithelium-choroid complex of guinea pigs with lens-induced myopia in vivo.</a> International Journal of Molecular Medicine. 33 (4), 825-832 (2014).</li><li>He, L., Frost, M. R., Siegwart, J. T., Norton, T. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Altered+gene+expression+in+tree+shrew+retina+and+retinal+pigment+epithelium+produced+by+short+periods+of+minus-lens+wear.">Altered gene expression in tree shrew retina and retinal pigment epithelium produced by short periods of minus-lens wear.</a> Experimental Eye Research. 168 (3), 77-88 (2018).</li><li>Nickla, D. L., Wallman, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+multifunctional+choroid.">The multifunctional choroid.</a> Progress in Retinal and Eye Research. 29 (2), 144-168 (2010).</li><li>Zhang, Y., Liu, Y., Wildsoet, C. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bidirectional,+optical+sign-dependent+regulation+of+BMP2+gene+expression+in+chick+retinal+pigment+epithelium.">Bidirectional, optical sign-dependent regulation of BMP2 gene expression in chick retinal pigment epithelium.</a> Investigative Ophthalmology and Visual Science. 53 (10), 6072-6080 (2012).</li><li>Xin-Zhao Wang, C., Zhang, K., Aredo, B., Lu, H., Ufret-Vincenty, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+method+for+the+rapid+isolation+of+RPE+cells+specifically+for+RNA+extraction+and+analysis.">Novel method for the rapid isolation of RPE cells specifically for RNA extraction and analysis.</a> Experimental Eye Research. 102 (1), 1-9 (2012).</li><li>Goto, 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=Gene+expression+signatures+of+contact+lens-induced+myopia+in+guinea+pig+retinal+pigment+epithelium.">Gene expression signatures of contact lens-induced myopia in guinea pig retinal pigment epithelium.</a> Investigative Opthalmology and Visual Science. 63 (9), 25 (2022).</li><li>De Schaepdrijver, L., Simoens, P., Lauwers, H., De Geest, J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Retinal+vascular+patterns+in+domestic+animals.">Retinal vascular patterns in domestic animals.</a> Research in Veterinary Science. 47 (1), 34-42 (1989).</li><li>Araki, 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=Base-resolution+methylome+of+retinal+pigment+epithelial+cells+used+in+the+first+trial+of+human+induced+pluripotent+stem+cell-based+autologous+transplantation.">Base-resolution methylome of retinal pigment epithelial cells used in the first trial of human induced pluripotent stem cell-based autologous transplantation.</a> Stem Cell Reports. 13 (4), 761-774 (2019).</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> Nature Protocols. 4 (5), 662-673 (2009).</li><li>Fernandez-Godino, R., Garland, D. 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The authors declare no competing financial interests.

In this article, we describe a method for isolating RPE, appropriate for RPE gene expression analyses, from the eyes of young, pigmented guinea pigs. The merits of this protocol are that it yields high-quality RPE samples that are relatively free from contamination, with&#160;RNA suitably preserved for RNA-specific analyses and, yet, is relatively simple and efficient. While in the example provided here, the RPE samples were collected from the eyes of a young (2 weeks old)&#160;guinea pig, the protocol has also been used...

The RPE comprises a unique monolayer of pigmented cells located between the neural retina and the vascular choroid, and the RPE has well-recognized roles in the development and maintenance of normal retinal function, including phototransduction1,2. More recently, the RPE has been assigned an additional key role in eye growth regulation3 and, thus, the development of myopia4. This assignment is based on the RPE&#39;s critical location,&#160;interposed between the retina and choroid and the now broad acceptance that eye growth and, thus, refractive errors are regulated locally5. The RPE is believed to play a key role as a signal relay, linking the retina, the assumed source of growth modulatory signals, to the choroid and sclera, the two targets of the relayed signals6,7,8.
The increase in axial length that characterizes most myopia cannot be considered benign, with pathophysiological changes involving the retina, choroid, and/or sclera representing unavoidable and now well-recognized consequences of excessive ocular elongation7,9. In this context, the RPE is perhaps the most vulnerable, since, being a nonmitotic tissue, it is only able to accommodate the expanding vitreous chamber by the stretching and thinning of individual cells. While its role in myopia-related pathologies, such as myopic macular degeneration, is yet to be fully understood, the RPE has been implicated in the pathogenesis of a number of other retinal diseases, including geographic atrophy, one of the leading causes of blindness, which is associated with documented abnormalities in the retina, RPE, and choroid10,11,12.
The successful isolation of RPE cells, free from contamination from adjacent ocular tissues, potentially opens up many research opportunities to gain new insights into the mechanisms underlying a variety of eye/retinal diseases. However, the isolation of the RPE has proven challenging, with many published studies making use of combined retina/RPE or RPE/choroid samples for this reason13,14,15. Studies involving the successful isolation of the RPE of a quality suitable for molecular biology studies has been limited to chick and mouse eyes16,17. For example, the simultaneous RPE isolation and RNA stabilization (SRIRS) method described by Wang et al.18. To isolate RPE cells in mice does not appear to work well in guinea pig eyes. The protocol described here represents a refinement of an approach that was initially prototyped with tree shrew eyes by one of the authors (M.F.) and has proven to yield high-quality RPE samples, appropriate for RNA and other molecular biology analyses, from the eyes of young pigmented guinea pigs19.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>1 mL Syringe with Slip Tip</td>
			<td>Bd Vacutainer Labware Medical</td>
			<td>22-253-260</td>
			<td></td>
		</tr>
		<tr>
			<td>2-Mercaptoethanol</td>
			<td>Invitrogen</td>
			<td>21985-023</td>
			<td></td>
		</tr>
		<tr>
			<td>6 Well Tissue Culture Plate with Lid, Flat Bottom, Sterile</td>
			<td>pectrum Chemical Mfg. Corp</td>
			<td>970-95008</td>
			<td></td>
		</tr>
		<tr>
			<td>12 Well Tissue Culture Plate with Lid, Individual, Sterile</td>
			<td>Thomas Scientific LLC</td>
			<td>1198D72</td>
			<td></td>
		</tr>
		<tr>
			<td>Agilent 2100 Bioanalyzer</td>
			<td></td>
			<td></td>
			<td>automated electrophoresis to check RNA quality</td>
		</tr>
		<tr>
			<td>Balanced Salt Solutions</td>
			<td>Gibco</td>
			<td>10010031</td>
			<td></td>
		</tr>
		<tr>
			<td>Bonn Micro Forceps, Straight Smooth, 0.3 mm Tip, 7 cm</td>
			<td>Fine Science Tools, Inc.</td>
			<td>11083-07</td>
			<td></td>
		</tr>
		<tr>
			<td>Dumont forceps no. 5</td>
			<td>ROBOZ</td>
			<td>RS-5045</td>
			<td></td>
		</tr>
		<tr>
			<td>Hypodermic disposable needles</td>
			<td>Exelint International, Co.</td>
			<td>26419</td>
			<td></td>
		</tr>
		<tr>
			<td>Hypodermic disposable needles</td>
			<td>Exelint International, Co.</td>
			<td>26437</td>
			<td></td>
		</tr>
		<tr>
			<td>MiniSpin Microcentrifuges</td>
			<td>Eppendorf</td>
			<td>540108</td>
			<td>Max. Speed: 8,000 g</td>
		</tr>
		<tr>
			<td>RNAlater Stabilization Solution</td>
			<td>Invitrogen</td>
			<td>AM7020</td>
			<td>tissue storage reagent</td>
		</tr>
		<tr>
			<td>RNeasy Mini kits</td>
			<td>Qiagen</td>
			<td>74104</td>
			<td>RNA isolation kit</td>
		</tr>
		<tr>
			<td>Student Vannas Spring Scissors</td>
			<td>Fine Science Tools, Inc.</td>
			<td>91500-09</td>
			<td></td>
		</tr>
	</tbody>
</table>

isolation of retinal pigment epithelial cells from guinea pig eyes

This protocol describes the isolation of cells of the retinal pigment epithelium (RPE) from the eyes of young pigmented guinea pigs for potential application in molecular biology studies, including gene expression analyses. In the context of eye growth regulation and myopia, the RPE likely plays a role as a cellular relay for growth modulatory signals, as it is located between the retina and the two walls of the eye, such as the choroid and sclera. While protocols for isolating the RPE have been developed for both chicks and mice, these protocols have proven not to be directly translatable to the guinea pig, which has become an important and widely used mammalian myopia model. In this study, molecular biology tools were used to examine the expression of specific genes to confirm that the samples were free of contamination from the adjacent tissues. The value of this protocol has already been demonstrated in an RNA-Seq study of RPE from young pigmented guinea pigs exposed to myopia-inducing optical defocus. Beyond eye growth regulation, this protocol has other potential applications in studies of retinal diseases, including myopic maculopathy, one of the leading causes of blindness in myopes, in which the RPE has been implicated. The main advantage of this technique is that it is relatively simple and&#160;once perfected, yields high-quality RPE samples suitable for molecular biology studies, including RNA analysis.

The analysis of the RPE samples collected using the above protocol showed well-preserved RNA (RIN &#62;8.0, Figure 2B), with 240.2 ng &#177; 35.1 ng per eye (n = 8, NanoDrop, Figure 2B). To further evaluate the quality of the isolated RPE samples, particularly the absence of choroidal and scleral contaminants, we examined the expression of representative genes for each of the latter tissues in the RPE samples19. The RPE samples demonstrat...

Watch this Scientific Journal Video about Isolation of Retinal Pigment Epithelial Cells from Guinea Pig Eyes at JoVE.com

Isolation of Retinal Pigment Epithelial Cells from Guinea Pig Eyes

We describe a simple and efficient method for isolating cells of the retinal pigment epithelium (RPE) cells from the eyes of young pigmented guinea pigs. This procedure allows for follow-up molecular biology studies on the isolated RPE, including gene expression analyses.

This protocol describes the isolation of cells of the retinal pigment epithelium (RPE) from the eyes of young pigmented guinea pigs for potential ...

Retinal pigment epithelium or RPE is critical for the retinal health. And studying the isolated RPE is crucial for the retinal disease. This method of RPE isolation from the guinea pig, a popular myopia model, aids in solving the challenging problem.The main advantage of this technique is that it is relatively simple and yield high-quality RPE sample suitable for the biological molecular studies including the RPE analysis. By perfectly following the technique demonstrated and observing how to manipulate the dissecting tools, one can master this procedure quickly with some practice. After humanely euthanizing the guinea pig and enucleating the animal's eyes, immediately wash the eyes by transferring them to a 10 centimeter Petri dish containing sterile phosphate buffered saline or PBS.After washing, transfer the eyes to fresh PBS solution. Now working under a dissecting microscope, use an 18 gauge needle to make an initial small opening in the sclera of one eye, approximately one millimeter behind the limbal boundary between the cornea and sclera. Using scissors, remove the anterior segment, including the cornea, iris, ciliary body, and crystalline lens.Then working with a remaining posterior ocular segment, use forceps to grasp and gently tug on the zonule of Zinn, followed by detaching the retina from RPE/choroid/sclera complex, and peeling away the retina without fragmentation. After the retina has been completely removed, immerse the remaining posterior eye cup, which includes the RPE, choroid, and sclera in one of the wells of a 12-well plate containing two milliliters of tissue storage reagent and keep it immersed for five minutes. To rinse away the storage reagent, transfer the eye cup to another well filled with four milliliters of PBS for 10 seconds before moving it to a third well filled with two milliliters of PBS.Before proceeding to the final RPE isolation step, prepare a one milliliter syringe filled with PBS and attach a 30 gauge needle. Gently push on the syringe plunger to create a jet stream of PBS. Working under a microscope, first, aim this stream of PBS at the RPE to make a small tear or hole in it.Then direct the stream of PBS into the created opening to detach the RPE as a sheet from the choroid. After detaching the RPE from the choroid, collect the RPE cells in a needleless one milliliter syringe and transfer the collected sample to a 1.5 milliliter tube. Centrifuge the tube with the collected RPE at 8, 000 x g for one minute to obtain an RPE pellet.For samples to be used in RNA analyses, discard the supernatant, that is the PBS solution, and replace it with 350 milliliters of lysis buffer as included in RNA isolation kits. Pipet the content up and down 20 times to mix well and preserve the quality of the sample. For long-term storage and preservation, transfer the samples to a minus 80 degree Celsius freezer.Use an RNA isolation kit and follow the manufacturer's instructions to isolate and collect the RNA from the RPE samples before evaluating the quality of the sample via electrophoresis. In our study, the collected RPE samples showed well preserved RNA having an RNA integrity number or RIN greater than eight. The total RNA count of around 240 nanograms per eye.The expression level of the RPE specific gene, Rpe65, was found to be significantly higher in the RPE samples than in choroid and sclera. In contrast, the RPE samples showed minimal expression of the selected choroid sclera specific gene, collagen type alpha-one, indicating the absence of choroidal and scleral contaminants in the isolated RPE samples. The most important step of the procedure is the smooth removal of the retina without leaving behind any retinal fragment.This RPE isolation procedure warrants explanation in vitro cell culture studies with some important differences, including the choice of media for immersing the RPE cells after the isolation.

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2.0K Görüntüleme.  University of California, Berkeley. Retina pigment epiteli veya RPE, retina sağlığı için kritik öneme sahiptir. İzole RPE'nin incelenmesi retina hastalığı için çok önemlidir. Popüler bir miyopi modeli olan kobaydan RPE izolasyonunun bu yöntemi, zorlu problemin çözülmesine yardımcı olur.Bu tekniğin temel avantajı, nispeten basit olması ve RPE analizi de dahil olmak üzere biyolojik moleküler çalışmalara uygun yüksek kaliteli RPE örneği vermesidir. Gösterilen tekniği mükemmel bir şekilde t...