Abstract
Purpose :
Serious visual impairment from corneal damage affects millions of people worldwide, but the shortage of cadaveric donor corneas limits treatment. In situ-forming biomaterial matrices that fill and regenerate corneal defects have shown promising results to address this major clinical need. Scaffold biointegration with host tissue is necessary to assess proper tissue regeneration. Here, we aimed to study the added effect of epidermal growth factor (EGF) when loaded into in situ-forming collagen gels on corneal regenerative capacity in vivo.
Methods :
EGF was added to a neutralized collagen solution and crosslinked via N-hydroxysuccinimide chemistry using 8-arm PEG. To stimulate a corneal defect, manual anterior lamellar keratoplasty was performed on the corneas of Brown Norway rats with 2mm diameter area and 50% depth. The defect was filled with EGF-loaded collagen-PEG gel, collagen-PEG gel, and no treatment. Corneal wound healing and thickness were assessed using the slit lamp exam and optical coherence tomography on days 0, 1, 2, 3, 4, and 7. After 7 days, phenotypic responses of epithelial and stromal cells of the treated corneal tissue were studied.
Results :
A 50%+/-5% cut depth was achieved without significant difference in all groups. On days 1 to 4, the collagen-PEG-EGF group resulted in faster wound closure, compared to the group without EGF. On day 7, however, overall stromal and epithelial thickness in the corneas treated with collagen-PEG were not significantly different whether EGF was present. No statistically significant difference in corneal opacity was observed between the two collagen-PEG groups. The presence of ASMA, ZO-1, and CK12 in both types of PEG-collagen gels exhibited normal epithelial cell phenotype, and minimal ZO-1 expression in the control group indicated otherwise. The PEG-collagen-EGF group expressed higher levels of KI67, showing that EGF further promotes cell proliferation in the area of defect.
Conclusions :
While EGF-loaded collagen-PEG gels accelerated wound closure, collagen-PEG gels with or without EGF resulted in complete epithelial healing by the end of the study. Corneas treated with both groups restored thickness, maintained clear opacity, and exhibited biomarkers indicative of normal epithelial phenotype. Thus, this in-vivo study further supports collagen-PEG gels both with and without EGF as strong candidates for corneal regenerative therapy.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.