title: Vectorial release of matrix metalloproteinases (MMPs) from porcine RPE-choroid explants following selective retina therapy (SRT): towards slowing the macular ageing process.
abstract: The purpose of this study was to investigate release of matrix metalloproteinases (MMP) 2 and 9 during retinal pigment epithelium (RPE) wound healing after Selective Retina Therapy (SRT) with laser energy levels below and above the threshold of RPE cell death. Following exposure to SRT using a prototype pulsed Nd:YLF laser with energies of 80-180 mJ/cm(2) fresh porcine RPE-monolayers with Bruch's membrane and choroid were cultured in modified Ussing chambers which separate the apical (RPE-facing) and basal (choroid facing) sides of the RPE monolayer. Threshold energy for RPE cell death and wound healing were determined with calcein-AM viability test. Inactive and active forms of MMP 2 and 9 were quantified within tissue samples and in the culture medium of the apical and basal compartments of the Ussing chamber using gelatine zymography. Laser energies of 160-180 mJ/cm(2) resulted in cell death within 1 h while 120-140 mJ/cm(2) resulted in delayed death of exposed RPE cells. All cells survived 80 and 100 mJ/cm(2). Laser spots healed within 6 days after SRT accompanied by a transient vectorial increase of MMPs. SRT with 180 mJ/cm(2) increased active MMP 2 by 1.9 (p < 0.05) and 1.6 (p < 0.05) fold in tissue and basal compartments, respectively, without alterations in the apical compartment. Pro-MMP 2 levels were also significantly increased in all compartments (p < 0.05). Release of MMP 9 was not altered. Laser energy below the threshold of RPE cell death did not alter the release of MMP 2 or 9. The findings suggest that the release of active MMP 2 on the basal side of the RPE during wound healing following SRT may address age-related pathological changes of Bruch's membrane with a potential to slow degenerative macular ageing processes before irreversible functional loss has occurred.
authors.affiliation: Department of Ophthalmology, University Medical Center Schleswig-Holstein, Kiel, Germany. ftreumer@auge.uni-kiel.de
authors.forename: F
authors.initials: F
authors.lastname: Treumer
authors.forename: A
authors.initials: A
authors.lastname: Klettner
authors.forename: J
authors.initials: J
authors.lastname: Baltz
authors.forename: A A
authors.initials: AA
authors.lastname: Hussain
authors.forename: Y
authors.initials: Y
authors.lastname: Miura
authors.forename: R
authors.initials: R
authors.lastname: Brinkmann
authors.forename: J
authors.initials: J
authors.lastname: Roider
authors.forename: J
authors.initials: J
authors.lastname: Hillenkamp
mesh_terms: D000818:Animals; D016923:Cell Death; D002470:Cell Survival; D002829:Choroid / Q000201:enzymology* / Q000473:pathology; D015194:Diffusion Chambers, Culture; D005452:Fluoresceins / Q000378:metabolism; D053685:Laser Therapy; D053844:Lasers, Solid-State; D008268:Macular Degeneration / Q000201:enzymology / Q000473:pathology / Q000601:surgery*; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D009924:Organ Culture Techniques; D055213:Retinal Pigment Epithelium / Q000201:enzymology* / Q000473:pathology; D012684:Sensory Thresholds; D013552:Swine; D014945:Wound Healing / Q000502:physiology*
chemical_list: D005452:Fluoresceins; C085925:calcein AM; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9