{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,27]],"date-time":"2026-08-27T07:16:03Z","timestamp":1787814963206,"version":"build-2784847793"},"reference-count":42,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2020,2,19]],"date-time":"2020-02-19T00:00:00Z","timestamp":1582070400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100002341","name":"Academy of Finland","doi-asserted-by":"publisher","award":["315085"],"award-info":[{"award-number":["315085"]}],"id":[{"id":"10.13039\/501100002341","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100003125","name":"Suomen Kulttuurirahasto","doi-asserted-by":"publisher","award":["(personal grant for L.H.)"],"award-info":[{"award-number":["(personal grant for L.H.)"]}],"id":[{"id":"10.13039\/501100003125","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["www.mdpi.com"],"crossmark-restriction":true},"short-container-title":["Pharmaceutics"],"abstract":"<jats:p>The retinal pigment epithelial (RPE) cell monolayer forms the outer blood\u2013retinal barrier and has a crucial role in ocular pharmacokinetics. Although several RPE cell models are available, there have been no systematic comparisons of their barrier properties with respect to drug permeability. We compared the barrier properties of several RPE secondary cell lines (ARPE19, ARPE19mel, and LEPI) and both primary (hfRPE) and stem-cell derived RPE (hESC-RPE) cells by investigating the permeability of nine drugs (aztreonam, ciprofloxacin, dexamethasone, fluconazole, ganciclovir, ketorolac, methotrexate, voriconazole, and quinidine) across cell monolayers. ARPE19, ARPE19mel, and hfRPE cells displayed a narrow Papp value range, with relatively high permeation rates (5.2\u201326 \u00d7 10\u22126 cm\/s. In contrast, hESC-RPE and LEPI cells efficiently restricted the drug flux, and displayed even lower Papp values than those reported for bovine RPE-choroid, with the range of 0.4\u201332 cm\u22126\/s (hESC-RPE cells) and 0.4\u201329 \u00d7 10\u22126 cm\/s, (LEPI cells). Therefore, ARPE19, ARPE19mel, and hfRPE cells failed to form a tight barrier, whereas hESC-RPE and LEPI cells restricted the drug flux to a similar extent as bovine RPE-choroid. Therefore, LEPI and hESC-RPE cells are valuable tools in ocular drug discovery.<\/jats:p>","DOI":"10.3390\/pharmaceutics12020176","type":"journal-article","created":{"date-parts":[[2020,2,25]],"date-time":"2020-02-25T08:12:22Z","timestamp":1582618342000},"page":"176","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":11,"title":["RETRACTED: Drug Flux across RPE Cell Models: The Hunt for an Appropriate Outer Blood\u2013Retinal Barrier Model for Use in Early Drug Discovery"],"prefix":"10.3390","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6090-1156","authenticated-orcid":false,"given":"Laura","family":"Hellinen","sequence":"first","affiliation":[{"name":"School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, 70210 Kuopio, Finland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2416-5673","authenticated-orcid":false,"given":"Heidi","family":"Hongisto","sequence":"additional","affiliation":[{"name":"Department of Ophthalmology, Institute of Clinical Medicine, University of Eastern Finland, 70210 Kuopio, Finland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5106-5873","authenticated-orcid":false,"given":"Eva","family":"Ramsay","sequence":"additional","affiliation":[{"name":"Drug Research Programme, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, P.O. Box 56, FI-00014 Helsinki, Finland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2600-8679","authenticated-orcid":false,"given":"Kai","family":"Kaarniranta","sequence":"additional","affiliation":[{"name":"Department of Ophthalmology, Institute of Clinical Medicine, University of Eastern Finland, 70210 Kuopio, Finland"},{"name":"Department of Ophthalmology, Kuopio University Hospital, P.O.Box 100, FI-70029 Kuopio, Finland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kati-Sisko","family":"Vellonen","sequence":"additional","affiliation":[{"name":"School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, 70210 Kuopio, Finland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4127-8792","authenticated-orcid":false,"given":"Heli","family":"Skottman","sequence":"additional","affiliation":[{"name":"Faculty of Medicine and Health Technology, BioMediTech, Tampere University, 33520 Tampere, Finland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marika","family":"Ruponen","sequence":"additional","affiliation":[{"name":"School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, 70210 Kuopio, Finland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2020,2,19]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"845","DOI":"10.1152\/physrev.00021.2004","article-title":"The Retinal Pigment Epithelium in Visual Function","volume":"85","author":"Strauss","year":"2005","journal-title":"Physiol. Rev."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"18","DOI":"10.1016\/j.ejpb.2019.08.008","article-title":"Role of Retinal Pigment Epithelium Permeability in Drug Transfer between Posterior Eye Segment and Systemic Blood Circulation","volume":"143","author":"Ramsay","year":"2019","journal-title":"Eur. J. Pharm. Biopharm."},{"key":"ref_3","first-page":"134","article-title":"Pharmacokinetic Aspects of Retinal Drug Delivery","volume":"57","author":"Rimpela","year":"2016","journal-title":"Prog. Retin. Eye Res."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"e106","DOI":"10.1016\/S2214-109X(13)70145-1","article-title":"Global Prevalence of Age-Related Macular Degeneration and Disease Burden Projection for 2020 and 2040: A Systematic Review and Meta-Analysis","volume":"2","author":"Wong","year":"2014","journal-title":"Lancet Glob. Health"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"215","DOI":"10.1016\/j.ejpb.2015.01.003","article-title":"Intravitreal Clearance and Volume of Distribution of Compounds in Rabbits: In Silico Prediction and Pharmacokinetic Simulations for Drug Development","volume":"95","author":"Vellonen","year":"2015","journal-title":"Eur. J. Pharm. Biopharm."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"111","DOI":"10.1016\/j.exer.2015.05.003","article-title":"Rabbit as an Animal Model for Intravitreal Pharmacokinetics: Clinical Predictability and Quality of the Published Data","volume":"137","author":"Urtti","year":"2015","journal-title":"Exp. Eye Res."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"94","DOI":"10.1016\/j.jconrel.2014.06.044","article-title":"A Critical Assessment of in Vitro Tissue Models for ADME and Drug Delivery","volume":"190","author":"Vellonen","year":"2014","journal-title":"J. Control. Release"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"1047","DOI":"10.1167\/iovs.04-0925","article-title":"Functional Characterization and Comparison of the Outer Blood-Retina Barrier and the Blood-Brain Barrier","volume":"46","author":"Steuer","year":"2005","journal-title":"Investig. Ophthalmol. Vis. Sci."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"641","DOI":"10.1167\/iovs.04-1051","article-title":"Permeability of Retinal Pigment Epithelium: Effects of Permeant Molecular Weight and Lipophilicity","volume":"46","author":"Pitkanen","year":"2005","journal-title":"Investig. Ophthalmol. Vis. Sci."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"155","DOI":"10.1006\/exer.1996.0020","article-title":"ARPE-19, a Human Retinal Pigment Epithelial Cell Line with Differentiated Properties","volume":"62","author":"Dunn","year":"1996","journal-title":"Exp. Eye Res."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"289","DOI":"10.1016\/j.ejps.2010.04.001","article-title":"Filter-Cultured ARPE-19 Cells as Outer Blood-Retinal Barrier Model","volume":"40","author":"Mannermaa","year":"2010","journal-title":"Eur. J. Pharm. Sci."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"23","DOI":"10.1016\/j.addr.2017.12.008","article-title":"Implications of Melanin Binding in Ocular Drug Delivery","volume":"126","author":"Rimpela","year":"2018","journal-title":"Adv. Drug Deliv. Rev."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"261","DOI":"10.1016\/j.jconrel.2018.05.034","article-title":"Melanin Targeting for Intracellular Drug Delivery: Quantification of Bound and Free Drug in Retinal Pigment Epithelial Cells","volume":"283","author":"Rimpela","year":"2018","journal-title":"J. Control. Release"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"10106","DOI":"10.1021\/acs.jmedchem.8b01281","article-title":"Understanding Molecular Drivers of Melanin Binding to Support Rational Design of Small Molecule Ophthalmic Drugs","volume":"61","author":"Jakubiak","year":"2018","journal-title":"J. Med. Chem."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1490","DOI":"10.1167\/iovs.12-10169","article-title":"Assessing a Novel Depot Delivery Strategy for Noninvasive Administration of VEGF\/PDGF RTK Inhibitors for Ocular Neovascular Disease","volume":"54","author":"Robbie","year":"2013","journal-title":"Investig. Ophthalmol. Vis. Sci."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1038\/s41598-019-50324-8","article-title":"Characterization of Artificially Re-Pigmented ARPE-19 Retinal Pigment Epithelial Cell Model","volume":"9","author":"Hellinen","year":"2019","journal-title":"Sci. Rep."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Hellinen, L., Pirskanen, L., Tengvall-Unadike, U., Urtti, A., and Reinisalo, M. (2019). Retinal Pigment Epithelial Cell Line with Fast Differentiation and Improved Barrier Properties. Pharmaceutics, 11.","DOI":"10.3390\/pharmaceutics11080412"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Pelkonen, L., Reinisalo, M., Morin-Picardat, E., Kidron, H., and Urtti, A. (2016). Isolation of Intact and Functional Melanosomes from the Retinal Pigment Epithelium. PLoS ONE, 11.","DOI":"10.1371\/journal.pone.0160352"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"328","DOI":"10.1038\/nbt.4114","article-title":"Phase 1 Clinical Study of an Embryonic Stem Cell-Derived Retinal Pigment Epithelium Patch in Age-Related Macular Degeneration","volume":"36","author":"Fynes","year":"2018","journal-title":"Nat. Biotechnol."},{"key":"ref_20","first-page":"283","article-title":"Molecular Characterization and Functional Analysis of Phagocytosis by Human Embryonic Stem Cell-Derived RPE Cells using a Novel Human Retinal Assay","volume":"15","author":"Carr","year":"2009","journal-title":"Mol. Vis."},{"key":"ref_21","first-page":"558","article-title":"Toward the Defined and Xeno-Free Differentiation of Functional Human Pluripotent Stem Cell-Derived Retinal Pigment Epithelial Cells","volume":"17","author":"Vaajasaari","year":"2011","journal-title":"Mol. Vis."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"659","DOI":"10.1007\/s12015-017-9754-0","article-title":"Stem Cell Derived Retinal Pigment Epithelium: The Role of Pigmentation as Maturation Marker and Gene Expression Profile Comparison with Human Endogenous Retinal Pigment Epithelium","volume":"13","author":"Bennis","year":"2017","journal-title":"Stem Cell. Rev. Rep."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"291","DOI":"10.1186\/s13287-017-0738-4","article-title":"Xeno- and Feeder-Free Differentiation of Human Pluripotent Stem Cells to Two Distinct Ocular Epithelial Cell Types using Simple Modifications of One Method","volume":"8","author":"Hongisto","year":"2017","journal-title":"Stem Cell. Res. Ther."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1038\/s41598-017-06233-9","article-title":"Comparative Proteomic Analysis of Human Embryonic Stem Cell-Derived and Primary Human Retinal Pigment Epithelium","volume":"7","author":"Hongisto","year":"2017","journal-title":"Sci. Rep."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"8047","DOI":"10.1016\/j.biomaterials.2012.07.033","article-title":"Generation of hESC-Derived Retinal Pigment Epithelium on Biopolymer Coated Polyimide Membranes","volume":"33","author":"Subrizi","year":"2012","journal-title":"Biomaterials"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"101","DOI":"10.1016\/j.yexcr.2017.08.004","article-title":"Contacting Co-Culture of Human Retinal Microvascular Endothelial Cells Alters Barrier Function of Human Embryonic Stem Cell Derived Retinal Pigment Epithelial Cells","volume":"359","author":"Skottman","year":"2017","journal-title":"Exp. Cell Res."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"162","DOI":"10.1016\/j.ejps.2017.07.027","article-title":"Melanin Binding Study of Clinical Drugs with Cassette Dosing and Rapid Equilibrium Dialysis Inserts","volume":"109","author":"Pelkonen","year":"2017","journal-title":"Eur. J. Pharm. Sci."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"605","DOI":"10.1021\/acs.molpharmaceut.6b00782","article-title":"LC-MS\/MS Based Quantitation of ABC and SLC Transporter Proteins in Plasma Membranes of Cultured Primary Human Retinal Pigment Epithelium Cells and Immortalized ARPE19 Cell Line","volume":"14","author":"Pelkonen","year":"2017","journal-title":"Mol. Pharm."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"206","DOI":"10.1007\/s11626-010-9286-2","article-title":"Derivation and Characterization of Three New Human Embryonic Stem Cell Lines in Finland. In Vitro Cell","volume":"46","author":"Skottman","year":"2010","journal-title":"Dev. Biol. Anim."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"2463","DOI":"10.1016\/j.xphs.2017.04.061","article-title":"Impact of Chemical Structure on Conjunctival Drug Permeability: Adopting Porcine Conjunctiva and Cassette Dosing for Construction of in Silico Model","volume":"106","author":"Ramsay","year":"2017","journal-title":"J. Pharm. Sci."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1915","DOI":"10.1002\/term.2089","article-title":"A Bruch\u2019s Membrane Substitute Fabricated from Silk Fibroin Supports the Function of Retinal Pigment Epithelial Cells in Vitro","volume":"11","author":"Shadforth","year":"2017","journal-title":"J. Tissue Eng. Regen. Med."},{"key":"ref_32","first-page":"60","article-title":"Appropriately Differentiated ARPE-19 Cells Regain Phenotype and Gene Expression Profiles Similar to those of Native RPE Cells","volume":"23","author":"Samuel","year":"2017","journal-title":"Mol. Vis."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"1716","DOI":"10.1167\/iovs.02-0287","article-title":"Polarized Expression of Monocarboxylate Transporters in Human Retinal Pigment Epithelium and ARPE-19 Cells","volume":"44","author":"Philp","year":"2003","journal-title":"Investig. Ophthalmol. Vis. Sci."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"5022","DOI":"10.1167\/iovs.19-27328","article-title":"Quantitative Protein Expression in the Human Retinal Pigment Epithelium: Comparison between Apical and Basolateral Plasma Membranes with Emphasis on Transporters","volume":"60","author":"Hellinen","year":"2019","journal-title":"Investig. Ophthalmol. Vis. Sci."},{"key":"ref_35","first-page":"622","article-title":"Structure and Barrier Properties of Human Embryonic Stem Cell-Derived Retinal Pigment Epithelial Cells are Affected by Extracellular Matrix Protein Coating","volume":"20","author":"Sorkio","year":"2014","journal-title":"Tissue Eng. Part A"},{"key":"ref_36","unstructured":"European Medicines Agency (2012). Guideline on the Investigation of Drug Interactions. 2012, PMP\/EWP\/560\/95\/Rev. 1 Corr. 2 **, Committee for Human Medicinal Products (CHMP)."},{"key":"ref_37","doi-asserted-by":"crossref","unstructured":"Juuti-Uusitalo, K., Vaajasaari, H., Ryhanen, T., Narkilahti, S., Suuronen, R., Mannermaa, E., Kaarniranta, K., and Skottman, H. (2012). Efflux Protein Expression in Human Stem Cell-Derived Retinal Pigment Epithelial Cells. PLoS ONE, 7.","DOI":"10.1371\/journal.pone.0030089"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"2906","DOI":"10.1021\/acs.molpharmaceut.5b00729","article-title":"Prediction of Ocular Drug Distribution from Systemic Blood Circulation","volume":"13","author":"Vellonen","year":"2016","journal-title":"Mol. Pharm."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1016\/j.addr.2017.12.009","article-title":"Expression, Activity and Pharmacokinetic Impact of Ocular Transporters","volume":"126","author":"Vellonen","year":"2018","journal-title":"Adv. Drug Deliv. Rev."},{"key":"ref_40","first-page":"107","article-title":"Drug Distribution to Retinal Pigment Epithelium: Studies on Melanin Binding, Cellular Kinetics, and SPECT\/CT Imaging","volume":"57","author":"Rimpela","year":"2016","journal-title":"Mol. Pharm."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"167","DOI":"10.1016\/j.ejps.2014.07.003","article-title":"A New Approach to Predict Human Intestinal Absorption using Porcine Intestinal Tissue and Biorelevant Matrices","volume":"63","author":"Westerhout","year":"2014","journal-title":"Eur. J. Pharm. Sci."},{"key":"ref_42","doi-asserted-by":"crossref","unstructured":"Kiamehr, M., Klettner, A., Richert, E., Koskela, A., Koistinen, A., Skottman, H., Kaarniranta, K., Aalto-Setala, K., and Juuti-Uusitalo, K. (2019). Compromised Barrier Function in Human Induced Pluripotent Stem-Cell-Derived Retinal Pigment Epithelial Cells from Type 2 Diabetic Patients. Int. J. Mol. Sci., 20.","DOI":"10.3390\/ijms20153773"}],"updated-by":[{"DOI":"10.3390\/pharmaceutics14030595","type":"retraction","label":"Retraction","source":"retraction-watch","updated":{"date-parts":[[2022,3,9]],"date-time":"2022-03-09T00:00:00Z","timestamp":1646784000000},"record-id":"36219"},{"DOI":"10.3390\/pharmaceutics14030595","type":"retraction","label":"Retraction","source":"publisher","updated":{"date-parts":[[2020,2,19]],"date-time":"2020-02-19T00:00:00Z","timestamp":1582070400000}}],"container-title":["Pharmaceutics"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1999-4923\/12\/2\/176\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,8,3]],"date-time":"2025-08-03T22:28:55Z","timestamp":1754260135000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1999-4923\/12\/2\/176"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2020,2,19]]},"references-count":42,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2020,2]]}},"alternative-id":["pharmaceutics12020176"],"URL":"https:\/\/doi.org\/10.3390\/pharmaceutics12020176","relation":{"retraction":[{"id-type":"doi","id":"10.3390\/pharmaceutics14030595","asserted-by":"object"}]},"ISSN":["1999-4923"],"issn-type":[{"value":"1999-4923","type":"electronic"}],"subject":[],"published":{"date-parts":[[2020,2,19]]}}}