Response of Retinal Pigment Epithelium (RPE)-Choroid Explants to Thermal Stimulation Therapy of the RPE (TSR)

Elisabeth Richert; Julia Papenkort; Alexa Klettner; Jan Tode; Stefan Koinzer; Ralf Brinkmann; Christine Fink; Thomas Roeder; Ralph Lucius; Johann Roider

doi:10.1002/lsm.23288

Response of Retinal Pigment Epithelium (RPE)-Choroid Explants to Thermal Stimulation Therapy of the RPE (TSR)

Lasers Surg Med. 2021 Mar;53(3):359-369. doi: 10.1002/lsm.23288. Epub 2020 Jun 21.

Authors

Affiliations

¹ Department of Ophthalmology, University Medical Center, Christian-Albrechts University of Kiel, Arnold-Heller-Street 3, House 3B, Kiel, 24105, Germany.
² Medical Laser Center Lübeck, Peter-Monnik-Weg 4, Lübeck, 23562, Germany.
³ Molecular Physiology, Zoological Institute, Christian-Albrechts University of Kiel, Am Botanischen Garten 1-9, Kiel, 24118, Germany.
⁴ Institute of Anatomy, Christian-Albrechts University of Kiel, Olshausenstraße, Kiel, 24118, Germany.

PMID: 32567146
DOI: 10.1002/lsm.23288

Abstract

Background and objectives: The thermal stimulation therapy of the retinal pigment epithelium (TSR) is a sublethal laser technique for thermal stimulation of the retinal pigment epithelium (RPE)-Bruch's membrane (BrM)-complex. The aim of this study was to investigate the influence of TSR on the release of age-related macular degeneration (AMD)-relevant cell mediators.

Study design/materials and methods: Porcine RPE-BrM-choroid explants were irradiated with a 532 nm continuous wave laser using different spot sizes (100-300 µm, duration 100 milliseconds, 15-100 mW). Cell death was investigated by calcein staining. Explants were treated with grids of sublethal spots and cultivated in modified Ussing chambers. The effect on matrix metalloproteinase-2 (MMP-2) and -9 was investigated by zymography and quantitative reverse transcription polymerase chain reaction. Secretion of vascular endothelial growth factor (VEGF), pigment epithelium derived factor (PEDF), and transforming growth factor-β (TGF-β) was analyzed by enzyme-linked immunosorbent assay and expression of HSP70 was examined by western blot. Integrity of the RPE/BrM-complex was analyzed by scanning electron microscopy.

Results: Laser powers of 15 mW (100 µm) and 45 mW (300 µm) did not induce RPE cell death. The integrity of the RPE/BrM-complex was not impaired after TSR. After TSR with 300 µm spot size, we observed a significant increase of active MMP-2 in the basal compartments. The content of PEDF significantly increased in treated explants in both compartments with 100 and 300 µm spot sizes. VEGF and TGF-β secretion was not triggered by TSR.

Conclusions: TSR represents a possible RPE stimulating treatment for dry AMD. TSR increases the basal release of active MMP-2, which might reverse age-related thickening of BrM. VEGF secretion was not triggered by TSR while anti-angiogenic PEDF was increased, indicating an induction of an anti-angiogenic and neuroprotective environment. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.

Keywords: age-related macular degeneration; matrix metalloproteases; pigment epithelium derived factor; retinal pigment epithelium; thermal stimulation therapy of the retinal pigment epithelium; transforming growth factor-β; vascular endothelial growth factor.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Cells, Cultured
Choroid
Macular Degeneration* / therapy
Matrix Metalloproteinase 2
Retinal Pigment Epithelium*
Swine
Vascular Endothelial Growth Factor A

Substances

Vascular Endothelial Growth Factor A
Matrix Metalloproteinase 2