Development of amine functional hydrogels for corneal regeneration

The aim of this thesis was to develop a synthetic polymethacrylate based hydrogel capable of regenerating a corneal epithelium for the purposes of treating blindness caused by limbal stem cell deficiency. Deficiency of limbal epithelial cells (LECs) causes conjunctival epithelial cells to move over the cornea, resulting in painful scaring, vascularisation and corneal opacity. Unilateral defects can be treated using LEC cultured from the unaffected eye, transplanting them to the affected cornea after scar tissue is removed. The underlying wound bed is often damaged, however, hence the need to develop a corneal inlay to aid in corneal re-epithelialisation, while replacing damaged stromal tissue. Transparent epoxy-functional polymethacrylate networks were synthesised using a combination of glycerol monomethacrylate, ethylene glycol dimethacrylate, lauryl methacrylate and glycidyl methacrylate that produced different bulk hydrogel compositions or “Bases” with different equilibrium water contents (EWC) (Base 0, 1 and 2) and different quantities of epoxy functionality (Bases 1.B, 1.15, 1.20 and 1.30). Sets of amine-functional hydrogels were produced following reaction of the epoxide groups with excesses of ammonia, 1,2-diamino ethane, 1,3-diamino propane, 1,4-diamino butane or 1,6- diamino hexane. The gels were assessed for their capacity to support the growth and proliferation for both rabbit limbal fibroblasts (rLFs) and rabbit limbal epithelial cells (rLECs). Overall no series of hydrogels supported the proliferation of rLFs irrespective of amine functionalisation, however gels functionalised with longer alkyl amines supported the adhesion and proliferation of rLECs, particularly when functionalised with 1,4-diamino butane. With Base 1 hydrogels (less so with Bases 0 and 2) a vigorous epithelial outgrowth was seen from small limbal explants and a confluent epithelial layer was achieved in vitro within 6 days. The data in this thesis support the development of hydrogels capable of selectively regenerating corneal epithelium with minimal stromal cell contamination.