Bioengineered, In Situ-Crosslinked Collagen Gels for Suture-Free Stromal Defect Reconstruction of the Cornea

Abstract

Purpose : Cadaveric donor tissue to surgically address corneal blindness is in short supply worldwide. Our goal is to engineer a transparent gel that self-forms in situ to fill and stabilize deep corneal wounds and promote epithelial regeneration and stromal remodeling without the need for a catalyst, light-activation, sutures, or donor tissue.

Methods : We have developed an array of transparent gels comprised of combinations of conjugated collagen that form rapidly after being applied to deep corneal wounds without the need for a catalyst or light energy source. Strain promoted azide-alkyne cycloaddition (SPAAC), a bio-orthogonal form of copper-free click chemistry, as well as multi-functional succinimide active esters were used to crosslink collagen gels. In vitro cell culture, ex vivo organ culture, and in vivo rabbit corneal keratectomy models were used to evaluate the biologic activity of the gel constructs. Slit lamp exam, fluorescein staining, anterior segment optical coherence tomography, and immunohistochemistry were used to evaluate the corneas post-treatment.

Results : Collagen gels crosslinked by both SPAAC and succinimidyl chemistry form in situ within minutes when applied to deep keratectomy wounds under ambient conditions without the need for a catalyst or light energy. We found that the hydrogels could be cured under an air interface or under a bandage contact lens, and could restore the smooth outer curvature of a keratectomized cornea. Both succinimide and SPAAC crosslinking yielded gels support multi-layered surface epithelialization when seeded with cultured epithelial cells and when used to fill keratectomy wounds both ex vivo in organ culture and in vivo in rabbit corneas that were followed out to one week.

Conclusions : Collagen gels form under ambient conditions when crosslinked by succinimide active ester and copper-free click chemistry without the need for an external catalyst or light energy source. The gels are transparent and can support surface epithelialization both in vitro and in vivo and are promising biomaterials for suture-free reconstruction of deep corneal defects.

This is a 2020 ARVO Annual Meeting abstract.