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Elisabeth Richert, Stefan Koinzer, Alexa Karina Klettner, Ralf Brinkmann, Jost Hillenkamp, Johann Roider; Response of RPE-Choroid Explants to Thermal Stimulation Therapy of the Retinal Pigment Epithelium (TS-R). Invest. Ophthalmol. Vis. Sci. 2016;57(12):4442.
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© ARVO (1962-2015); The Authors (2016-present)
The TS-R is a sublethal laser technique for thermal stimulation of the retinal pigment epithelium (RPE)-Bruchs membrane-complex which avoids cell destruction of RPE and neuroretina. The aim of this study was to investigate the influence of TS-R on the release of AMD-relevant cell mediators such as Matrix-Metalloproteinases (MMPs), Vascular Endothelial Growth Factor (VEGF) and Pigment Epithelium Derived Factor (PEDF) using different laser spot sizes.
Porcine RPE-Bruchs membrane-choroid explants were irradiated with a 532 nm continuous wave laser and the threshold of cell death was investigated by calcein staining. Explants were irradiated with grids of sub-lethal spots (15 mW at 100 µm and 45 mW at 300 µm spot size, pulse duration 100 ms) and cultivated in modified Ussing chambers which enabled the differentiation of basal and apical cytokine release. The release of MMP 2 and 9 was investigated by zymography and secretion of VEGF and PEDF was analyzed by ELISA. Statistics were performed with Students T-test.
Laser powers of 15 mW (100 µm spot size) and 45 mW (300 µm spot size) applied over 100 ms did not induce cell death in RPE cells. After TS-R with 300 µm spot size we observed a significant increase of active MMP2 after 4 days to 1.56 fold of control (SD±0.45, p<0.05) in basal compartments. The content of PEDF increased significantly to 1.2 fold (SD±0.23, p<0.01) in treated explants in comparison to controls while basolateral VEGF secretion was not influenced by TS-R with 300 µm spots. Cytokine analysis following TS-R with small 100 µm spots showed a significant increase of PEDF to 1.28 fold (SD±0.32, p<0.01) compared to control but no significant effect on MMP 2 and 9.
The TS-R represents a possible RPE stimulating treatment for early AMD which could improve the flux across Bruchs membrane. TS-R increases the basolateral release of active MMP2 dependent on laser spot size, which might reverse age related thickening of BrM. Basolateral VEGF secretion was not triggered by TS-R while anti-angiogenic PEDF was increased by TS-R, indicating an induction of an anti-angiogenic environment by TS-R.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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