title: Delayed near-infrared analysis permits visualization of rodent retinal pigment epithelium layer in vivo.
abstract: Patches of atrophy of the retinal pigment epithelium (RPE) have not been described in rodent models of retinal degeneration, as they have the clinical setting using fundus autofluorescence. We hypothesize that prelabeling the RPE would increase contrast and allow for improved visualization of RPE loss in vivo. Here, we demonstrate a new technique termed “delayed near-infrared analysis (DNIRA)” that permits ready detection of rat RPE, using optical imaging in the near-infrared (IR) spectrum with aid of indocyanine green (ICG) dye. Using DNIRA, we demonstrate a fluorescent RPE signal that is detected using confocal scanning laser ophthalmoscopy up to 28 days following ICG injection. This signal is apparent only after ICG injection, is dose dependent, requires the presence of the ICG filters (795/810 nm excitation/emission), does not appear in the IR reflectance channel, and is eliminated in the presence of sodium iodate, a toxin that causes RPE loss. Rat RPE explants confirm internalization of ICG dye. Together with normal retinal electrophysiology, these findings demonstrate that DNIRA is a new and safe noninvasive optical imaging technique for in vivo visualization of the RPE in models of retinal disease.
authors.affiliation: University of Toronto, Department of Laboratory Medicine and Pathobiology, 1 King's College Circle, Toronto, Ontario M5S 1A8, CanadabUniversity of Toronto, Department of Ophthalmology and Vision Sciences, 340 College Street, Toronto, Ontario M5T 3A9, Cana.
authors.forename: Natalie
authors.initials: N
authors.lastname: Pankova
authors.affiliation: St Michael's Hospital, Keenan Research Centre for Biomedical Science, 209 Victoria Street, Toronto, Ontario M5B 1W8, Canada.
authors.forename: Xu
authors.initials: X
authors.lastname: Zhao
authors.affiliation: St Michael's Hospital, Keenan Research Centre for Biomedical Science, 209 Victoria Street, Toronto, Ontario M5B 1W8, Canada.
authors.forename: Huiyuan
authors.initials: H
authors.lastname: Liang
authors.affiliation: University of Toronto, Department of Laboratory Medicine and Pathobiology, 1 King's College Circle, Toronto, Ontario M5S 1A8, CanadacSt Michael's Hospital, Keenan Research Centre for Biomedical Science, 209 Victoria Street, Toronto, Ontario M5B 1W8, Canad.
authors.forename: David Sung Hyeon
authors.initials: DS
authors.lastname: Baek
authors.affiliation: St Michael's Hospital, Keenan Research Centre for Biomedical Science, 209 Victoria Street, Toronto, Ontario M5B 1W8, Canada.
authors.forename: Hai
authors.initials: H
authors.lastname: Wang
authors.affiliation: University of Toronto, Department of Laboratory Medicine and Pathobiology, 1 King's College Circle, Toronto, Ontario M5S 1A8, CanadabUniversity of Toronto, Department of Ophthalmology and Vision Sciences, 340 College Street, Toronto, Ontario M5T 3A9, Cana.
authors.forename: Shelley
authors.initials: S
authors.lastname: Boyd
mesh_terms: D000818:Animals; D007208:Indocyanine Green / Q000737:chemistry* / Q000378:metabolism; D016014:Linear Models; D061848:Optical Imaging / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley; D055213:Retinal Pigment Epithelium / Q000737:chemistry / Q000166:cytology* / Q000378:metabolism; D019265:Spectroscopy, Near-Infrared / Q000379:methods*
chemical_list: D007208:Indocyanine Green