No abstract

Corneal injury and aberrant wound healing commonly result in corneal fibrosis and subsequent vision loss. Intermediate-conductance calmodulin/calcium-activated K+ channels (KCa3.1) have been shown to promote fibrosis in non-ocular and ocular tissues via upregulation of transforming growth factor beta (TGFβ). TRAM-34 is a selective inhibitor of KCa3.1 and reduces fibrosis by downregulation of TGFβ-induced transdifferentiation of stromal fibroblasts to myofibroblasts. Ascorbic acid has been demonstrated to be effective in promoting corneal re-epithelialization and reduction of neovascularization via anti-VEGF and anti-MMP mechanisms. This study evaluates tolerability and efficacy of a novel combination of TRAM-34 (25μM) and ascorbic acid (10%) topical treatment for corneal fibrosis using an established in vivo rabbit model and conducting clinical eye examinations. Markers of corneal fibrosis were evaluated in all corneas at study endpoint via histopathology, immunofluorescence, and quantitative real-time PCR. The eyedrop treated eyes showed significantly improved clinical outcomes based on modified McDonald Shadduck scores, reduction of clinical haze on Fantes scores, and reduction of central corneal thickness (CCT). At cellular and molecular levels, eyedrop treatment also significantly reduced expression of alpha smooth muscle actin (α-SMA) mRNA and protein, collagen III mRNA, and fibronectin mRNA compared to non-treated eyes. Our study suggests that a tested new bimodal eyedrop is well tolerated and effectively reduces corneal fibrosis/haze in rabbits in vivo.

Purpose: To determine the safety and efficacy of a novel combination of TRAM-34 and ascorbic acid applied topically in vivo in native and alkali injured rabbit corneas. Methods: Twelve New Zealand rabbits were randomly assigned into 2 groups (6 rabbits/group). Native healthy eyes were treated OD BIDx5 days with either treatment (combination TRAM-34 25[mu]M (Tocris Biosciences, Bristol, UK) and ascorbic acid 10 percent (TVC)) or control (BSS). Rabbits underwent an axial corneal wound OS using an established model. Groups were treated OS BIDx5 days. Degree of corneal opacity, ocular health, safety, and efficacy were determined utilizing the Fantes grading scale and modified McDonald-Shadduck (mMS) scoring system. Immunohistochemical and microscopy techniques evaluated corneal fibrotic markers at study conclusion (day 28). Results: Combination therapy was well tolerated in all eyes, with no significant differences in mMS scores, IOP, or central corneal thickness (CCT) between treatment and control groups. Significant differences in mMS scores between groups were found at day 1 (p=0.0001), 2 (p=0.0001), 3 (p=0.0001), 4 (p=0.0285), 14 (p=0.0041) and 28 (p=0.0002). Significant differences in Fantes scores were detected between groups at day 7 (p=0.001), 14 (p=0.0027), and 28 (p=0.0001). Significant differences in CCT between groups were found at days 7 (p=0.036), 14 (p=0.0495), and 28 (p=0.0487). Laboratory testing of corneal tissues demonstrated decreased fibrosis in treatment versus control groups at day 28. Conclusions: Novel bi-modal TVC topical therapy was well tolerated and demonstrated improved corneal wound healing and reduction in fibrotic changes in TVC treated rabbits compared to controls.