Biological response to a synthetic cornea.

We have designed a synthetic cornea that has a transparent hydrogel optic and a porous skirt. The device has been implanted in rabbit corneas. We have shown that keratocytes migrate into the device and deposit a complex extracellular matrix. The immediate response is detected in the surrounding stroma, and the secondary response is seen after cells have deposited a matrix in the disc. After implantation, a decrease in keratan sulfate accompanied by an increase in dermatan sulfate was detected in the surrounding tissue compared to the unwounded corneal stroma. The glycosaminoglycans in the disc resemble that of an injured stroma. The appearance of heparan sulfate and growth factors, bFGF and TGFbeta, was not detected until 6 weeks after implantation. The growth factors were detected at the interface between the device and the tissue and become more diffuse over time. Methods of controlled release in vivo were used to enhance the rate of fibroplasia and wound repair. While these were successful in the cornea itself, when combined with the synthetic cornea the response was magnified and the initial attempts yielded neovascularization and edema. Currently, efforts are being directed at controlling the release within the porous haptic so that fibroplasia is enhanced while minimizing an inflammatory response.