Purchase this article with an account.
Falk Schroedl, Alexandra Kaser-Eichberger, Andrea Trost, Christian Runge, Daniela Bruckner, Barbara Bogner, Clemens Strohmaier, Herbert A Reitsamer, Jody A Summers; Morphological classification of RALDH2-positive cells in the human choroid. Invest. Ophthalmol. Vis. Sci. 2018;59(9):308.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
A key signal molecule in postnatal eye growth is all-trans-retinoic acid and it has been speculated that all-trans-retinoic acid is involved in the regulation of scleral matrix regulation. Apparently choroidal RALDH2 represents the key-player in ocular growth inhibition, also in postnatal eyes. While RALDH2-positive cells have been recently detected within the choroid, it is not clear up to now if these RALDH2-expressing cells are an independent cell population or a sub-type of cells in the already known canon of choroidal cells. Therefore, aim of this study is to morphologically identify and classify this cell-population with immunohistochemical methods in the human choroid.
Human eyes were obtained from the Salzburg Eye Bank, in full accordance with the Declaration of Helsinki. Choroids were dissected free and prepared for double-immunohistochemistry of RALDH2 and CD31 (vascular endothelium), CD146 and NG2 (pericytes), smooth-muscle actin (ASMA), CD68 and LYVE1 (macrophages), IBA1 (microglia), PGP9.5 (pan-neuronal) and vimentin. Confocal laser-scanning microscopy in single optical section mode was used for documentation.
Within the choroidal stroma, RALDH2+ cells displayed short and more circumferential arranged processes. Others were located adjacent to choroidal blood vessels, these displayed scare cytoplasm and long processes with polar arrangement. Vessel-associated cells were negative for CD146 and NG2, and were further not co-localized with CD31 or ASMA. RALDH2+ cells were negative for LYVE1 and CD68, were negative for CD146 and NG2, and were lacking IBA1 and PGP9.5. Some, but not all RALDH2+ cells were co-localized with vimentin. Intrinsic choroidal neurons were lacking RALDH2, as were melanocytes when identified in epi-detection mode.
With the markers used here, RALDH2+ cells seem to represent an independent cell-population within the human choroid. While some RALDH2+ cells were positive for the intermediate filament vimentin, this could indicate a mesenchymal origin. Additional markers are necessary to further classify this new cell-population and the possible contribution in ocular pathologies
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
This PDF is available to Subscribers Only