Globes from OMâaffected Cairn terriers and unaffected control eyes enucleated for reasons unrelated to this study were used for immunohistochemistry and to culture melanocytes for in vitro cell behavior assays.
The scleral plaques of six dogs were immunolabeled for HMBâ45, MelanA, PNL2, CD18, CD204, and Ibaâ1 and compared with the pigment cells accumulated within the irides.
Cultured uveal melanocytes from OMâaffected and control dogs were compared using conventional assays measuring cell proliferation, invasion capability, and melanin production.
Melanocytes isolated from OM eyes had significantly elevated levels of perâcell melanin content and production compared to controls. The majority of pigmented cells in the scleral plaques were HMB45 positive indicating a melanocytic origin.
Many were also CD18 positive.
No differences were observed between cultured melanocytes from OMâaffected and control uvea for standard in vitro proliferation or invasion assays.
Pigmented cells which accumulate in the sclera of OMâaffected Cairn terriers are predominantly melanocytes; however, in vitro assays of uveal melanocytes did not reveal differences in migratory behavior between OM and control cells.
Migratory behavior of OMâmelanocytes may be environmentâdependent.
We suggest that RNA sequencing and differential expression analysis would be a useful next step in understanding this disease.
Source: Ethan M. DawsonâBaglien Erica L. Noland Dodd G. Sledge Matti Kiupel Simon M. PetersenâJones, Physiological characterization of ocular melanosisâaffected canine melanocytes. Veterinary Ophthalmology, Early View.
First published: 27 April 2018 https://doi.org/10.1111/vop.12572
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