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Marzieh Tahmasebi, Robert James Casson, Glyn Chidlow, John P M Wood, Malcolm J Plunkett, Ophthalmic research laboratories; The response of the retinal pigmented epithelium to a novel, nanosecond laser, in vivo: comparison with a conventional continuous wave laser. Invest. Ophthalmol. Vis. Sci. 2014;55(13):427.
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© ARVO (1962-2015); The Authors (2016-present)
We have recently characterised the effects of a novel nanosecond pulse laser, the Retinal Regeneration Therapy (2RT) laser on the rat retina. It is believed, however, that the closely apposed retinal pigmented epithelium (RPE), which is selectively targeted by the 2RT laser, also plays an important role in the response of the retina to laser treatment. We therefore sought to disseminate the effects of the 2RT laser on the RPE cell layer, in situ.
Deeply anaesthetised pigmented Dark Agouti rats were treated in one or both eyes with either the 2RT laser, or a conventional, continuous wave (CW), non-RPE-selective laser, for comparative purposes. Animals were euthanized immediately, or after 6 hours, 24 hours, 3 days or 7 days. RPE whole-mounts were prepared and the physical status of cells and expression of factors of interest were delineated by immunohistochemistry and scanning electron microscopy (SEM).
Both lasers caused immediate ablation of RPE cells in irradiated regions. In both cases, repair of the RPE cell-layer over the subsequent 7 days occurred. Each laser also induced up-regulations in the expression of αβ-crystallin, heat shock 27kD protein (HSP27), nestin, basic fibroblast growth factor (FGF-2) and ciliary neurotrophic factor (CNTF) in RPE cells bordering irradiated regions. In all cases expression of these factors peaked at 1-3 days after laser-treatment. Interestingly, peak expression of such factors was concurrent with the expression of the cellular proliferation marker, proliferating cell nuclear antigen (PCNA). There were no significant differences between the induced expression changes seen in any of the factors of interest with either laser.
These findings demonstrate that either selective (2RT) or non-selective (CW) laser treatment of the RPE can promote similar gene expression changes within this cell layer in situ. Furthermore, the spatiotemporal expression pattern of such factors is demonstrated. Future research will explore the possibility of using the 2RT laser, in particular, to induce expression of potentially protective factors which may combat retinal disease, in situ.
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