Proliferation and differentiation of transplantable rabbit epithelial sheets engineered with or without an amniotic membrane carrier

PURPOSE. To report a novel method of engineering transplantable, carrier-free corneal epithelial sheets by using a biodegradable fibrin sealant and to compare its characteristics with epithelial sheets cultivated on denuded amniotic membrane carriers. METHODS. Stratified corneal epithelial sheets were prepared in culture dishes coated with biodegradable fibrin glue. Amniotic membrane (AM) carriers served as the control. The quality of cultivated sheets was compared by immunohistochemistry for cytokeratin (K)3, K12, K14, p63, occludin, and integrin β1; electron microscopy; and colony-forming assays. K3 protein expression was compared by Western blot analysis. In a limbal-deficient rabbit transplantation model, postoperative adaptation and proliferation of BrdU-labeled cell sheets were examined by histology and anti-Ki67 staining. RESULTS. Epithelial sheets were successfully engineered by using a biodegradable fibrin sealant. Cell sheets in both groups were multilayered, expressed K3, K12, and K14, and had functioning occludin ⁺ apical tight junctions as well as p63 and integrin β1 staining in basal cells. The carrier-free sheets appeared to be more differentiated than the AM sheets, which was also demonstrated by the higher levels of K3 in the Western blots. The colony-forming efficiency of dissociated cells was similar in both groups, although larger colonies were observed on the AM sheets. AM sheets retained higher levels of BrdU-labeled cells and fewer Ki67⁺ cells compared with carrier-free sheets after transplantation. CONCLUSIONS. Tissue engineering with a commercially available fibrin sealant was an effective means of creating a carrier-free, transplantable corneal epithelial sheet. Carrier-free sheets were more differentiated compared with AM sheets, while retaining similar levels of colony-forming progenitor cells.