Collagenase Type 2 As A Tool To Mimic Keratoconus-Like Changes In An Ex Vivo Porcine Cornea Model

To damage the porcine cornea by collagenase type II to induce corneal remodeling and weakening comparable to that in keratoconus patients.

Laboratory investigation, Experimental Eye Research Institute at University Eye Hospital, Ruhr-University Bochum, Bochum, Germany.

Ex vivo porcine corneas were placed in 6 groups. Five groups were incubated with collagenase type II to induce keratoconus like damage: (1) 5 U/ml, (2) 10 U/ml, (3) 15 U/ml, (4) 20 U/ml, or (5) 30 U/ml for 4 days. Untrated corneas were used as a control group (6). All six study groups were cultivated for a total of 4 days. Cornea samples were processed for histology with H&E (n=5/group). Afterwards total cornea thickness and epithelial layer thickness was evaluated. Supernatants of cultivated corneas were analyzed by Enzyme-linked immunosorbent assays for the amount of immunoglobulin E (IgE) and galectin-1 (n=8/group).

The measurement of total corneal thickness showed a significant reduction in the 20 U/ml group (69.46 µm) compared to the control group (99.88 µm; p=0.042). All other groups revealed no significant changes. Interestingly, the epithelial layer of both the 20 U/ml (18.72 µm) and the 30 U/ml group (20.44 µm) was significantly increased compared to the control situation (11.60 µm, 20 U/ml: p= 0.022; 30 U/ml: p=0.004). Additionally, secreted immunoglobulin and cytokine levels were analyzed in the supernatants. For galectin-1, no differences were detectable between all six groups. Regarding IgE levels, an increased amount was observable in the supernatants of the 30 U/mL group (183.14 ng/ml) compared to the control group (2.30 ng/ml; p=0.014).

Using high collagenase concentrations, changes in the corneal structure and the secreted medium could be observed. This is a first step towards establishing an ex vivo model for keratoconus, which will be used to decipher unknown mechanisms and gain deep insights into the pathological and physiological processes of the disease. It can serve as a cornerstone for a future controlled evaluation of new, innovative therapeutic strategies.