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J M. Heur, Shuliang Jiao, Gage Crump; Functional Characterization of the Zebrafish Corneal Endothelium. Invest. Ophthalmol. Vis. Sci. 2012;53(14):6006. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
The zebrafish offers many advantages for studying human diseases. The purpose of this study was to ascertain the extent to which zebrafish could be used as a model for diseases of the human corneal endothelium by investigating the functional characteristics of the zebrafish corneal endothelium.
Zebrafish were handled per University of Southern California IACUC approved protocols and in accordance with the ARVO Statement for the Use of Animals in Ophthalmic and Vision Research. Central corneal thickness (CCT) was calculated by measuring the pixel numbers between the front and back boundaries of the cornea in the OCT image relative to the full imaging depth and dividing by the refractive index of the cornea. Anesthetized fish were placed on a petri dish, for endothelial injury of the right eye using a bent 30-gauge needle (n = 6) or intracameral injection of 100µm ouabain (n = 4). Zebrafish were recovered post-procedure in system water and CCT was measured at 1-week post-procedure. Specular microscopy was performed on zebrafish immediately following surgical injury (n = 15) and at 1-day (n = 15) and 1-week (n = 17) post injury.
Endothelial injury and intracameral ouabain injection were found to induce corneal edema in zebrafish. The corneal endothelium in zebrafish was found to regenerate following surgical injury. There were significant differences in average CCT between uninjured corneas, 47µm ± 12 µm, versus injured corneas, 77µm ± 27 µm (paired T-test, p = 0.044), and between ouabain-injected eyes, 79.3µm ± 19.6µm, versus uninjected contralateral eyes, 48.0µm ± 2.5µm (paired T-test, p = 0.048). There was no difference in CCT between BSS injected eyes, 51.6µm ± 10.6µm, versus uninjected contralateral eyes, 52.7µm ± 8.4µm (paired T-test, p = 0.608). All eyes that were imaged immediately following scraping showed an absence of endothelial cells in the scraped area (15 of 15 eyes). At 1-day postop 86.7% (13 of 15) eyes showed an absence of endothelial cells, and at 1-week postop 36.8% (7 of 19) eyes showed an absence of endothelial cells. There were statistically significant differences in proportions of eyes with endothelial cells in scraped areas between immediate and 1-week postop groups (X2 tests, p = 0.00014) and 1-day and 1-week postop groups (X2 tests, p = 0.0034).
The results show that the zebrafish corneal endothelium, like the human corneal endothelium, has a pump function, and suggests that zebrafish corneal endothelial cells regenerate following injury. This study implies that the zebrafish model system can be exploited to elucidate mechanism important in endothelial regeneration, which in turn could lead to novel treatment strategies for diseases that currently require transplantation.
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