PRODUCTION OF NEOCOLLAGEN BY CELLS INVADING HYDROGEL SPONGES IMPLANTED IN THE RABBIT CORNEA

Background: Poly(2-hydroxyethyl methacrylate) sponges are artificial t issue-equivalent matrices with potential value as materials for the pe ripheral zone of artificial corneas. A keratoprosthetic device was dev eloped incorporating a poly(HEMA) spongy skirt which allowed cellular invasion. The present in vivo study investigated the biosynthetic acti vity of stromal fibroblasts growing within a poly(HEMA) sponge implant ed into the rabbit cornea. Methods: A porous poly(HEMA) hydrogel was s ynthesized by polymerization in a large excess of water. Specimens wit h a pore size larger than 10 mu m were impregnated with collagen type I and then implanted into the limbal region of cornea in four rabbits. The animals were followed clinically for 28 days, when they were anae sthetized and new sponge specimens were implanted in their second eye. After 2 h, both eyes were enucleated. The 28-day and 2-h explants wer e subjected to autoradiographic analysis following labelling with trit iated proline and to an immunostaining technique using antibodies to c ollagen types I-VI. Results: The autoradiographic analysis showed that the fibroblasts within the 28-day explants continued to be synthetica lly active and deposited proteins. Using the immunostaining technique, the deposition was most clearly demonstrated by the localization of c ollagen type III in the tissue invading the sponge. Both techniques fa iled to indicate any cellular activity in the short-time implants. Con clusions: The presence of collagen type III is consistent with a norma l healing response of the stromal fibroblasts and indicates that poly( HEMA) sponges are able to function as tissue-equivalent matrices.