The Effect of Topical Amniotic Membrane Extract in a Desiccation Stress-Induced Dry Eye Mouse Model

초록

Purpose : The amniotic membrane (AM), the innermost layer of the placenta, promotes re-epithelialization and reduces inflammation through cytokines, growth factors, and other bioactive components. The safety and efficacy of AM extract eye drops in wound healing for severe ocular surface diseases have been demonstrated in prior studies. This study aims to evaluate the effects of topical AM extract on ocular surface changes and corneal nerve integrity in an environmental dry eye mouse model. Methods : An environmental dry eye mouse model was established using 8-week-old BALB/c mice exposed to a dry chamber with scopolamine (intraperitoneal injection, 3 times/day for 6 weeks, under <25% relative humidity and 0.6 m/s airflow). After 3 weeks of induction, mice were divided into two groups: the AM group (experimenta, AM extract eye drops, 4 times/day for 3 weeks) and the balanced salt solution (BSS) group (control, BSS, 4 times/day for 3 weeks). Mice remained in the dry chamber during the treatment period. Ocular surface changes were assessed with vital staining, tear production (phenol red thread test), and corneal sensitivity (Cochet-Bonnet esthesiometer). Corneal nerves were evaluated through whole-mount staining using anti-β-tubulin III antibody and confocal microscopy. Subbasal nerve plexus density and length were quantified using ImageJ and its plug-in NeuronJ. Results : At baseline, there were no significant differences between the two groups in ocular staining, tear production, or corneal sensitivity. At the final evaluation, the AM group demonstrated a significantly lower corneal staining score (2.00 ± 1.83) compared to the BSS group (5.33 ± 4.04, p = 0.034). Tear production did not differ significantly between the groups. Corneal sensitivity was significantly higher in the AM group (p = 0.021). Additionally, the AM group exhibited reduced central corneal nerve loss in both density (p = 0.021) and length (p = 0.008) compared to the control group. Conclusions : Topical AM extract eye drops mitigate corneal nerve damage and sensory loss in a desiccation stress-induced dry eye mouse model. These findings suggest that AM extract not only preserves ocular surface health but also exerts a neuroprotective effect on corneal nerves.