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Christian B. Allan, David Crockford, Kathryn S. Crawford, Laura J. Belen; Effects of Thymosin β4 in a Murine CAETM Model of Experimental Dry Eye. Invest. Ophthalmol. Vis. Sci. 2011;52(14):3782.
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The purpose of this study was to investigate the potential of Thymosin β4 (RGN-259) to ameliorate the signs of dry eye syndrome (DES) in a murine model.
Topical solutions containing 2.0%, 1.0%, or 0.1% Thymosin β4 in balanced salt solution (BSS) were tested against vehicle (BSS). A positive control (doxycycline 0.005%) group and an untreated non-DES group were also included. Forty C57BL/6 mice were housed in a controlled adverse environment (CAETM) for 20 days and dosed four times daily on days 7-20. On days 15-18, mice were injected with 0.5mg/0.2ml of scopolamine hydrobromide four times a day to further exacerbate signs of DES. All mice were evaluated on days 7, 15, 18, and 20 of CAE exposure. Corneal fluorescein staining was assessed microscopically in 5 corneal regions (modified NEI scale); tear production was measured using phenol red threads (Zone-Quick).
Thymosin β4 at the lowest concentration (0.1%) effectively reduced corneal fluorescein staining. On days 15 and 18 of CAE exposure, animals treated with Thymosin β4 0.1% showed a marked and statistically significant decrease in total fluorescein staining and in specific regions compared to the vehicle control group. Staining was reduced from pre-dose levels (5.8±0.7) to baseline levels (2.0±0.8). The reduction in staining was also greater in the Thymosin β4 group (0.1%) compared to the positive control group (doxycycline). As formulated, the higher concentrations (1.0% and 2.0%) of Thymosin β4 had no impact on corneal staining. None of the treatments had any effect on tear production in this study.
These results, along with other evidence demonstrating the wound healing properties of Thymosin β4, indicate that Thymosin β4 is a good candidate for a novel and effective dry eye therapy. Further investigation with additional concentrations, modifications in the formulation and different dosing regimens is warranted.
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