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Samuel J Berk, Lindsay Peterkin, Shandiz Tehrani, Ted S Acott, Mary J Kelley; Media borne factor that stimulates stem cell division following laser trabeculoplasty. Invest. Ophthalmol. Vis. Sci. 2019;60(9):5153. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Conditioned medium from anterior segments treated by clinical laser trabeculoplasty is able to stimulate trabecular meshwork (TM) stem cell division and subsequent migration to repopulate laser burn sites. The molecular component(s) responsible for this process are not known, although TNFa and IL-1β synergistically mediate the TM extracellular matrix remodeling that occurs simultaneously. Here we conducted studies to identify this mitogenic factor.
Human anterior segments were treated by selective laser trabeculoplasty (SLT) using 80 laser spots (0.8 mJ/shot) around 360° of the TM. Paired-eye sham controls were handled identically with the laser turned off. Segments were then allowed to condition media for 8 hours and this was used to treat human TM cells in culture. Parallel treatments with likely candidates included: TNFa (10 ng/mL), IL1a (10 ng/mL), IL1b (10 ng/mL), and PDGF-BB (25 ng/mL). Cells were treated concomitantly with Click-iT EdU to label dividing cells. EdU was then tagged with Alexa Fluor azide reagent using Click chemistry. Alexa Fluor labeled cells were counted to determine the fraction of total cells that had divided.
IL-1a and IL-1b slightly suppressed cell division when compared with media-only negative controls, but this was not statistically-significant. SLT-conditioned media stimulated cell division by approximately 40% of the positive serum treatment control. This was statistically significant. Sham conditioned media was similar to media-only negative controls. Both TNFa and PDGF-BB produced cell division levels comparable with the SLT-conditioned medium treatment, i.e. approximately equal to 40% of serum treatment.
These studies suggest that TNFa and/or PDGF-BB may contribute to the TM stem cell division that is triggered by SLT. Studies are underway to identify the mitogenic factor in conditioned media post SLT. This could lead to new potential therapeutic targets for TM cell restoration in glaucomatous patients.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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