Corneal fibrosis, clinically referred to as corneal scarring, disrupts the normal architecture and transparency of the cornea and remains a major cause of visual impairment worldwide. Although corneal transplantation can restore vision, its effectiveness is constrained by limited accessibility, donor tissue shortages, and the risk of allograft rejection. Treatments with human corneal stromal stem cells (hCSSCs) have demonstrated scarless healing in preclinical models of acute corneal injury. Here, we report that hCSSCs also modulated pre-existing corneal opacities. We established a reproducible in vivo model of chronic corneal opacity. Given that scar severity varies among corneas even after identical injuries, we developed a non-invasive, image-based method to quantify opacity volume longitudinally in individual corneas. Using this approach, we evaluated the scar-reducing potential of three hCSSC batches previously shown to inhibit acute scarring. Following cell treatment, the pre-existing opacity volumes gradually decreased. In vitro, hCSSCs exposed to pro-inflammatory stimulus exhibited increased metalloproteinase (MMP) activity relative to tissue inhibitor of metalloproteinase (TIMP), as indicated by an elevated MMP2/TIMP2 ratio. This shift may promote matrix remodeling and scar resolution. Overall, our findings provide proof-of-concept for hCSSC-based therapy as a strategy to reduce established corneal scarring and restore corneal transparency.

Epigenetics regulates gene activity without altering the underlying DNA sequences. Numerous studies have highlighted the importance of epigenetics in diverse physiological processes, including cell growth, differentiation, and tissue development. Increasingly, epigenetic modifications are recognized for their involvement in various diseases, notably corneal disorders. Corneal fibrosis, a common consequence of ocular injury or infection, significantly contributes to visual impairment and blindness worldwide. Recent evidence indicates that epigenetic changes regulate key processes in corneal pathogenesis, such as inflammation, wound healing, extracellular matrix remodeling, fibrosis, and neovascularization. These findings underscore the potential of developing novel therapeutic strategies that specifically target epigenetic mechanisms to treat or mitigate corneal pathology. Nevertheless, bringing epigenetic therapies into clinical practice remains challenging given the complexity of epigenetic regulation. Future research leveraging multi-omics technologies and specific gene manipulation will be essential to elucidate the mechanisms underlying epigenetic regulation in corneal diseases and to identify specific therapeutic targets. Such advancements will drive the development of effective, clinically relevant treatments for corneal fibrosis and related disorders.