Name: differentiation, maintenance, and analysis of human retinal pigment epithelium cells: a disease-in-a-dish model for best1 mutations
Uploaded: 2018-08-24T12:30:00
Description: Watch this Scientific Journal Video about Differentiation, Maintenance, and Analysis of Human Retinal Pigment Epithelium Cells: A Disease-in-a-dish Model for BEST1 Mutations at JoVE.com

This project was funded by NIH grants EY025290, GM127652, and University of Rochester start-up funding.

1. Differentiation of hPSC to RPE
<ol>
	<li>Maintain and passage hPSCs as previously described18. 
	NOTE: All cells (including hPSCs and hPSC-RPEs) are grown in 37 &#176;C at 5% CO2 throughout the duration of the growth and differentiation protocols.</li>
	<li>Prior to differentiation, split confluent hPSCs to pre-coated 6-well plates.
	<ol>
		<li>To coat plates, thaw basement membrane matrix on ice for about 1 h, suspend liquidized matrix in 4 &#176;C DMEM mediu...

<ol>
	<li>Allikmets, R., 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=Evaluation+of+the+Best+disease+gene+in+patients+with+age-related+macular+degeneration+and+other+maculopathies.">Evaluation of the Best disease gene in patients with age-related macular degeneration and other maculopathies.</a> Hum Genet. 104 (6), 449-453 (1999).</li><li>Burgess, R., 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=Biallelic+mutation+of+BEST1+causes+a+distinct+retinopathy+in+humans.">Biallelic mutation of BEST1 causes a distinct retinopathy in humans.</a> Am J Hum Genet. 82 (1), 19-31 (2008).</li><li>Davidson, A. E., 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=Missense+mutations+in+a+retinal+pigment+epithelium+protein,+bestrophin-1,+cause+retinitis+pigmentosa.">Missense mutations in a retinal pigment epithelium protein, bestrophin-1, cause retinitis pigmentosa.</a> Am J Hum Genet. 85 (5), 581-592 (2009).</li><li>Kramer, 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=Mutations+in+the+VMD2+gene+are+associated+with+juvenile-onset+vitelliform+macular+dystrophy+(Best+disease)+and+adult+vitelliform+macular+dystrophy+but+not+age-related+macular+degeneration.">Mutations in the VMD2 gene are associated with juvenile-onset vitelliform macular dystrophy (Best disease) and adult vitelliform macular dystrophy but not age-related macular degeneration.</a> Eur J Hum Genet. 8 (4), 286-292 (2000).</li><li>Marquardt, 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=Mutations+in+a+novel+gene,+VMD2,+encoding+a+protein+of+unknown+properties+cause+juvenile-onset+vitelliform+macular+dystrophy+(Best's+disease).">Mutations in a novel gene, VMD2, encoding a protein of unknown properties cause juvenile-onset vitelliform macular dystrophy (Best's disease).</a> Hum Mol Genet. 7 (9), 1517-1525 (1998).</li><li>Petrukhin, K., 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=Identification+of+the+gene+responsible+for+Best+macular+dystrophy.">Identification of the gene responsible for Best macular dystrophy.</a> Nat Genet. 19 (3), 241-247 (1998).</li><li>Yardley, 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=Mutations+of+VMD2+splicing+regulators+cause+nanophthalmos+and+autosomal+dominant+vitreoretinochoroidopathy+(ADVIRC).">Mutations of VMD2 splicing regulators cause nanophthalmos and autosomal dominant vitreoretinochoroidopathy (ADVIRC).</a> Invest Ophthalmol Vis Sci. 45 (10), 3683-3689 (2004).</li><li>Yang, T., Justus, S., Li, Y., Tsang, S. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=BEST1:+the+Best+Target+for+Gene+and+Cell+Therapies.">BEST1: the Best Target for Gene and Cell Therapies.</a> Mol Ther. 23 (12), 1805-1809 (2015).</li><li>Marmorstein, A. 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=Bestrophin,+the+product+of+the+Best+vitelliform+macular+dystrophy+gene+(VMD2),+localizes+to+the+basolateral+plasma+membrane+of+the+retinal+pigment+epithelium.">Bestrophin, the product of the Best vitelliform macular dystrophy gene (VMD2), localizes to the basolateral plasma membrane of the retinal pigment epithelium.</a> Proc Natl Acad Sci U S A. 97 (23), 12758-12763 (2000).</li><li>Boon, C. 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=The+spectrum+of+ocular+phenotypes+caused+by+mutations+in+the+BEST1+gene.">The spectrum of ocular phenotypes caused by mutations in the BEST1 gene.</a> Prog Retin Eye Res. 28 (3), 187-205 (2009).</li><li>Marmorstein, A. D., Cross, H. E., Peachey, N. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+roles+of+bestrophins+in+ocular+epithelia.">Functional roles of bestrophins in ocular epithelia.</a> Prog Retin Eye Res. 28 (3), 206-226 (2009).</li><li>Fujii, S., Gallemore, R. P., Hughes, B. A., Steinberg, R. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+evidence+for+a+basolateral+membrane+Cl-+conductance+in+toad+retinal+pigment+epithelium.">Direct evidence for a basolateral membrane Cl- conductance in toad retinal pigment epithelium.</a> Am J Physiol. 262, C374-C383 (1992).</li><li>Gallemore, R. P., Steinberg, R. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+DIDS+on+the+chick+retinal+pigment+epithelium.+II.+Mechanism+of+the+light+peak+and+other+responses+originating+at+the+basal+membrane.">Effects of DIDS on the chick retinal pigment epithelium. II. Mechanism of the light peak and other responses originating at the basal membrane.</a> J Neurosci. 9 (6), 1977-1984 (1989).</li><li>Gallemore, R. P., Steinberg, R. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Light-evoked+modulation+of+basolateral+membrane+Cl-+conductance+in+chick+retinal+pigment+epithelium:+the+light+peak+and+fast+oscillation.">Light-evoked modulation of basolateral membrane Cl- conductance in chick retinal pigment epithelium: the light peak and fast oscillation.</a> J Neurophysiol. 70 (4), 1669-1680 (1993).</li><li>Li, Y., Nguyen, H. V., Tsang, S. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Skin+Biopsy+and+Patient-Specific+Stem+Cell+Lines.">Skin Biopsy and Patient-Specific Stem Cell Lines.</a> Methods Mol Biol. 1353, 77-88 (2016).</li><li>Milenkovic, 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=Bestrophin+1+is+indispensable+for+volume+regulation+in+human+retinal+pigment+epithelium+cells.">Bestrophin 1 is indispensable for volume regulation in human retinal pigment epithelium cells.</a> Proc Natl Acad Sci U S A. 112 (20), E2630-E2639 (2015).</li><li>Moshfegh, Y., 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=BESTROPHIN1+mutations+cause+defective+chloride+conductance+in+patient+stem+cell-derived+RPE.">BESTROPHIN1 mutations cause defective chloride conductance in patient stem cell-derived RPE.</a> Hum Mol Genet. 25 (13), 2672-2680 (2016).</li><li>Li, Y., 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=Patient-specific+mutations+impair+BESTROPHIN1's+essential+role+in+mediating+Ca2+-dependent+Cl-+currents+in+human+RPE.">Patient-specific mutations impair BESTROPHIN1's essential role in mediating Ca2+-dependent Cl- currents in human RPE.</a> Elife. 6, (2017).</li><li>Marmorstein, L. Y., 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+light+peak+of+the+electroretinogram+is+dependent+on+voltage-gated+calcium+channels+and+antagonized+by+bestrophin+(best-1).">The light peak of the electroretinogram is dependent on voltage-gated calcium channels and antagonized by bestrophin (best-1).</a> J Gen Physiol. 127 (5), 577-589 (2006).</li><li>Volland, S., Esteve-Rudd, J., Hoo, J., Yee, C., 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=A+comparison+of+some+organizational+characteristics+of+the+mouse+central+retina+and+the+human+macula.">A comparison of some organizational characteristics of the mouse central retina and the human macula.</a> PLoS One. 10 (4), e0125631 (2015).</li><li>Kamao, 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=Characterization+of+human+induced+pluripotent+stem+cell-derived+retinal+pigment+epithelium+cell+sheets+aiming+for+clinical+application.">Characterization of human induced pluripotent stem cell-derived retinal pigment epithelium cell sheets aiming for clinical application.</a> Stem Cell Reports. 2 (2), 205-218 (2014).</li><li>Idelson, 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=Directed+differentiation+of+human+embryonic+stem+cells+into+functional+retinal+pigment+epithelium+cells.">Directed differentiation of human embryonic stem cells into functional retinal pigment epithelium cells.</a> Cell Stem Cell. 5 (4), 396-408 (2009).</li><li>Mandai, 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=Autologous+Induced+Stem-Cell-Derived+Retinal+Cells+for+Macular+Degeneration.">Autologous Induced Stem-Cell-Derived Retinal Cells for Macular Degeneration.</a> N Engl J Med. 376 (11), 1038-1046 (2017).</li><li>Maminishkis, 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=Confluent+monolayers+of+cultured+human+fetal+retinal+pigment+epithelium+exhibit+morphology+and+physiology+of+native+tissue.">Confluent monolayers of cultured human fetal retinal pigment epithelium exhibit morphology and physiology of native tissue.</a> Invest Ophthalmol Vis Sci. 47 (8), 3612-3624 (2006).</li><li>Maruotti, 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=A+simple+and+scalable+process+for+the+differentiation+of+retinal+pigment+epithelium+from+human+pluripotent+stem+cells.">A simple and scalable process for the differentiation of retinal pigment epithelium from human pluripotent stem cells.</a> Stem Cells Transl Med. 2 (5), 341-354 (2013).</li><li>Yang, T., He, L. L., Chen, M., Fang, K., Colecraft, H. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bio-inspired+voltage-dependent+calcium+channel+blockers.">Bio-inspired voltage-dependent calcium channel blockers.</a> Nat Commun. 4, 2540 (2013).</li><li>Yang, T., Hendrickson, W. A., Colecraft, H. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preassociated+apocalmodulin+mediates+Ca2+-dependent+sensitization+of+activation+and+inactivation+of+TMEM16A/16B+Ca2+-gated+Cl-+channels.">Preassociated apocalmodulin mediates Ca2+-dependent sensitization of activation and inactivation of TMEM16A/16B Ca2+-gated Cl- channels.</a> Proc Natl Acad Sci U S A. 111 (51), 18213-18218 (2014).</li><li>Yang, T., 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=Structure+and+selectivity+in+bestrophin+ion+channels.">Structure and selectivity in bestrophin ion channels.</a> Science. 346 (6207), 355-359 (2014).</li><li>Yang, T., Puckerin, A., Colecraft, H. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Distinct+RGK+GTPases+differentially+use+alpha1-+and+auxiliary+beta-binding-dependent+mechanisms+to+inhibit+CaV1.2/CaV2.2+channels.">Distinct RGK GTPases differentially use alpha1- and auxiliary beta-binding-dependent mechanisms to inhibit CaV1.2/CaV2.2 channels.</a> PLoS One. 7 (5), e37079 (2012).</li><li>Yang, T., Suhail, Y., Dalton, S., Kernan, T., Colecraft, H. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetically+encoded+molecules+for+inducibly+inactivating+CaV+channels.">Genetically encoded molecules for inducibly inactivating CaV channels.</a> Nat Chem Biol. 3 (12), 795-804 (2007).</li><li>Yang, T., Xu, X., Kernan, T., Wu, V., Colecraft, H. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rem,+a+member+of+the+RGK+GTPases,+inhibits+recombinant+CaV1.2+channels+using+multiple+mechanisms+that+require+distinct+conformations+of+the+GTPase.">Rem, a member of the RGK GTPases, inhibits recombinant CaV1.2 channels using multiple mechanisms that require distinct conformations of the GTPase.</a> J Physiol. 588 (Pt 10), 1665-1681 (2010).</li><li>Gong, 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=Differentiation+of+Human+Protein-Induced+Pluripotent+Stem+Cells+toward+a+Retinal+Pigment+Epithelial+Cell+Fate.">Differentiation of Human Protein-Induced Pluripotent Stem Cells toward a Retinal Pigment Epithelial Cell Fate.</a> PLoS One. 10 (11), e0143272 (2015).</li><li>Zhang, Y., 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=ATP+activates+bestrophin+ion+channels+through+direct+interaction.">ATP activates bestrophin ion channels through direct interaction.</a> Nat Commun. 9 (1), 3126 (2018).</li></ol>

The most important procedure for the disease-in-a-dish approach is to differentiate hPSCs with a disease-causing mutation to the correct cell lineage, which is RPE for BEST1. Thus, after each differentiation experiment, the resulting hPSC-RPE cells should be carefully validated for their mature status by RPE-specific morphologies and protein markers16,17,18. To minimize clonal artifact, multiple hiPSC clones from the sa...

It has been documented that at least five retinal degenerative diseases are caused by genetic mutations in the BEST1 gene1,2,3,4,5,6,7,8, with the number of reported mutations already over 200 and still increasing. These BEST1-associated diseases, also known as bestrophinopathies, cause progressive vision loss and even blindness, and there are currently no effective treatments. The protein product of BEST1, namely BESTROPHIN1 (BEST1), is a Ca2+-activated Cl- channel (CaCC) specifically expressed in the retinal pigment epithelium (RPE) of the eyes5,6,8,9. Importantly, a clinical phenotype of BEST1-associated diseases is the reduced visual response to light stimuli, called light peak (LP) measured in the electrooculogram10,11; LP is believed to be mediated by a CaCC in RPE12,13,14. In order to better comprehend the pathological mechanisms of BEST1 mutations and to work towards potential therapies, it is essential to study mutant BEST1 channels endogenously expressed in human RPE cells.
However, obtaining RPE cells directly from live patients is highly impractical. Although native RPE cells can be harvested from biopsies of human cadavers and fetuses, the difficult accessibility to these sources significantly limits scientific research. Therefore, it is critical to have alternative RPE sources other than human eyes. This call has been answered by recent advancements in stem cell techniques, as functional RPE cells can now be differentiated from human&#160;pluripotent stem cells (hPSCs), including embryonic stem cells (hESCs) and induced pluripotent stem cells (hiPSCs), the latter being generated by reprogramming primary skin fibroblasts from donors16,17,18. Importantly, the self-renewal and pluripotency of hPSCs ensure a reliable source to generate RPEs, while the patient-specificity of hiPSCs and genomic modification potential of hESCs (e.g., by CRISPR) offer a versatile disease-in-a-dish model for desired BEST1 mutations.
hPSC-RPE has several advantages over mice RPE models: 1) BEST1 knockout mice do not display any retinal abnormality19, raising the possibility of different genetic requirement of BEST1 in RPE between mice and humans; 2) only 3% of human RPE cells are binucleate, in contrast to 35% in mice20; 3) hiPSC-RPE potentiates autologous transplantation in clinical treatment of retinal disorders21. Nevertheless, animal models are still indispensable for studying RPE physiology and pathology in a live system, and the oncogenic potential of hiPSC cannot&#160;be overlooked.
The procedure here describes a useful and moderately simple hPSC to RPE differentiation protocol that can be used for research and clinical purposes. This protocol uses nicotinamide (vitamin B3) to augment differentiation of hPSCs to neural tissue, which is further induced to differentiate into RPE by treatment with activin-A. Nicotinamide treatment has been shown to increase the number of pigmented cells (a sign of differentiation into RPE), possibly by attenuating the apoptotic activity of differentiating cells22. The resulting hPSC-RPE cells display the same key markers, cobblestone morphology, and cellular functionality as native human RPE cells22. Thus, in a research setting, the resulting hPSC-RPE cells are suitable for downstream functional analyses including immunoblotting, immunostaining, and whole-cell patch clamp, for which detailed experimental procedures are also provided. Clinically, RPE cells derived from stem cells have shown great potential for transplantation treatment of macular degeneration in both animal studies and human trials23.

<table>
	<tbody>
		<tr>
			<td>Knock-Out (KO) DMEM</td>
			<td>ThermoFisher</td>
			<td>10829018</td>
			<td></td>
		</tr>
		<tr>
			<td>KO serum replacement</td>
			<td>ThermoFisher</td>
			<td>10829028</td>
			<td></td>
		</tr>
		<tr>
			<td>Nonessential amino acids</td>
			<td>ThermoFisher</td>
			<td>11140050</td>
			<td></td>
		</tr>
		<tr>
			<td>Glutamine</td>
			<td>ThermoFisher</td>
			<td>35050061</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin-streptomycin</td>
			<td>ThermoFisher</td>
			<td>10378016</td>
			<td></td>
		</tr>
		<tr>
			<td>Nicotinamide</td>
			<td>Sigma-Aldrich</td>
			<td>N0636</td>
			<td></td>
		</tr>
		<tr>
			<td>Human activin-A</td>
			<td>PeproTech</td>
			<td>120-14</td>
			<td></td>
		</tr>
		<tr>
			<td>MEM (a modification)</td>
			<td>Sigma-Aldrich</td>
			<td>M4526</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum</td>
			<td>VWR</td>
			<td>97068-085</td>
			<td></td>
		</tr>
		<tr>
			<td>N1 supplement</td>
			<td>Sigma-Aldrich</td>
			<td>N6530</td>
			<td></td>
		</tr>
		<tr>
			<td>Glutamine-penicillin-streptomycin</td>
			<td>Sigma-Aldrich</td>
			<td>G1146</td>
			<td></td>
		</tr>
		<tr>
			<td>Nonessential amino acids</td>
			<td>Sigma-Aldrich</td>
			<td>M7156</td>
			<td></td>
		</tr>
		<tr>
			<td>Taurine</td>
			<td>Sigma-Aldrich</td>
			<td>T0625</td>
			<td></td>
		</tr>
		<tr>
			<td>Hydrocortisone</td>
			<td>Sigma-Aldrich</td>
			<td>H0386</td>
			<td></td>
		</tr>
		<tr>
			<td>Triiodo-thyronin</td>
			<td>Sigma-Aldrich</td>
			<td>T5516</td>
			<td></td>
		</tr>
		<tr>
			<td>mTeSR-1 medium</td>
			<td>Stemcell Technologies</td>
			<td>5850</td>
			<td></td>
		</tr>
		<tr>
			<td>Matrigel</td>
			<td>Corning</td>
			<td>356230</td>
			<td></td>
		</tr>
		<tr>
			<td>Collagenase</td>
			<td>Gibco</td>
			<td>17104019</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypsin</td>
			<td>VWR</td>
			<td>45000-664</td>
			<td></td>
		</tr>
		<tr>
			<td>M-PER mammalian protein extraction reagent</td>
			<td>Pierce</td>
			<td>78501</td>
			<td></td>
		</tr>
		<tr>
			<td>proteinase inhibitor cocktail</td>
			<td>Sigma-Aldrich</td>
			<td>4693159001</td>
			<td></td>
		</tr>
		<tr>
			<td>RPE65 antibody</td>
			<td>Novus Biologicals</td>
			<td>NB100-355</td>
			<td></td>
		</tr>
		<tr>
			<td>CRALBP antibody</td>
			<td>Abcam</td>
			<td>ab15051</td>
			<td></td>
		</tr>
		<tr>
			<td>BEST1 antibody</td>
			<td>Novus Biologicals</td>
			<td>NB300-164</td>
			<td></td>
		</tr>
		<tr>
			<td>Beta Actin antibody</td>
			<td>ThermoFisher</td>
			<td>MA5-15739</td>
			<td></td>
		</tr>
		<tr>
			<td>Alexa Fluor 488-conjugated donkey anti-mouse IgG</td>
			<td>ThermoFisher</td>
			<td>A-21202</td>
			<td></td>
		</tr>
		<tr>
			<td>Goat anti-mouse IgG</td>
			<td>ThermoFisher</td>
			<td>SA5-35521</td>
			<td></td>
		</tr>
		<tr>
			<td>Goat anti-Rabbit IgG</td>
			<td>LI-COR Biosciences</td>
			<td>926-68071</td>
			<td></td>
		</tr>
		<tr>
			<td>Hoechst 33342</td>
			<td>ThermoFisher</td>
			<td>62249</td>
			<td></td>
		</tr>
		<tr>
			<td>HEKA EPC10 patch clamp amplifier</td>
			<td>Warner Instruments</td>
			<td>895000</td>
			<td></td>
		</tr>
		<tr>
			<td>Patchmaster</td>
			<td>Warner Instruments</td>
			<td>895040</td>
			<td></td>
		</tr>
	</tbody>
</table>

differentiation, maintenance, and analysis of human retinal pigment epithelium cells: a disease-in-a-dish model for best1 mutations

Although over 200 genetic mutations in the human BEST1 gene have been identified and linked to retinal degenerative diseases, the pathological mechanisms remain elusive mainly due to the lack of a good in vivo model for studying BEST1 and its mutations under physiological conditions. BEST1 encodes an ion channel, namely BESTROPHIN1 (BEST1), which functions in retinal pigment epithelium (RPE); however, the extremely limited accessibility to native human RPE cells represents a major challenge for scientific research. This protocol describes how to generate human RPEs bearing BEST1 disease-causing mutations by induced differentiation from human pluripotent stem cells (hPSCs). As hPSCs are self-renewable, this approach allows researchers to have a steady source of hPSC-RPEs for various experimental analyses, such as immunoblotting, immunofluorescence, and patch clamp, and thus provides a very powerful disease-in-a-dish model for BEST1-associated retinal conditions. Notably, this strategy can be applied to study RPE (patho)physiology and other genes of interest natively expressed in RPE.

The most technically challenging step is the manual isolation, which aims to achieve a high purity of a differentiated P0 hPSC-RPE population. After a successful isolation, &#62;90% cells in the P0 population will grow and mature to display signature RPE morphologies (Figure 1C). The existence of a minor portion of non-RPE or immature RPE cells in the P0 population is almost inevitable, but will not interfere with the downstre...

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Differentiation, Maintenance, and Analysis of Human Retinal Pigment Epithelium Cells: A Disease-in-a-dish Model for BEST1 Mutations

Here we present a protocol to differentiate retinal pigment epithelium (RPE) cells from human pluripotent stem cells bearing patient-derived mutations. The mutant cell lines may be used for functional analyses including immunoblotting, immunofluorescence, and patch clamp. This disease-in-a-dish approach circumvents the difficulty of obtaining native human RPE cells.

Differentiation, Maintenance, and Analysis of Human Retinal Pigment Epithelium Cells: A Disease-in-a-dish Model for BEST1 Mutations

Although over 200 genetic mutations in the human BEST1 gene have been identified and linked to retinal degenerative diseases, the pathological mechanisms ...

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