Purpose
To assess the integration and resistance to enzymatic degradation of porcine corneas impregnated with polyethylene glycol (PEG) or coated with polydopamine (PDA). The aim is to be able to use each modified tissue as a carrier for the Boston Keratoprosthesis.
Methods
Porcine corneas were lyophilized then rehydrated in either A) phosphate buffer saline (PBS), B) PEG solution (10% w/v) for one day then cross-linked with ultraviolet light, C) dopamine solution (2mg/mL in Tris buffer, pH 8.7) for one day, which polymerized (polydopamine, PDA) and coated the corneas. (n = 15 trephined buttons in each group). Integration of PEG hydrogel with cornea was evaluated by scanning electrom microscopy (SEM) as well as by measuring the compressive moduli. Resistance of the corneas to enzymatic degradation was evaluated by exposure to clostridium collagenase solution.
Results
Porcine corneas coated with PDA (Group C) showed significantly longer degradation time (>91h) than both control (5.0±0.7 h) and PEG treated groups (26±2.7 h). Mechanical strength testing revealed a difference between both PEG and PDA treated groups compared to the control group.
Conclusions
PEG- and PDA-modified corneas showed a markedly increased resistance to enzymatic degradation. The creation of a mussel inspired PDA coating on corneas may increase the strength and effectiveness of keratoprosthesis carrier tissue. In addition, PDA-modified corneas turn black which would reduce glare - a major problem in many keratoprosthesis cases (aniridia, etc.). Further in vivo studies are needed to assess the viability and safety of these modified corneas.
Keywords: 575 keratoprostheses •
480 cornea: basic science