Reconstruction of corneal surface layer using human amniotic epithelial cells modified by lentiviral vector-mediated EGFP gene / 中华实验眼科杂志

ABSTRACT

Background Studies demonstrated that human amniotic epithelial cells (AECs) have some characteristics of embryonic stem cells and they were used to re-establish the surface of eyes. Human AECs may serve as new seed cells in tissue engineering for corneal epithelium reconstitution in the future. Objective The present study was to investigate the application value of human amniotic epithelium cells transfected by lentiviral vectormediated enhanced green fluorescent protein (EGFP) gene as new seed cell source for engineering the corneal surfacelayer. Methods Lentiviral vector carrying the objective gene EGFP was transfected into human amniotic epithelial cells (pLenti6/V5-DEST),and the transient expression of the transgene in the human amniotic epithelial cells was observed under the fluorescence microscope. Flow cytometry was used to detect the positive expression rates of EGFP in transfected cells. The transfected human amniotic epithelial cells were seeded onto the fresh corneal stromal surface of New Zealand white rabbit and cultured in vitro. The stem cell deficiency ( SCD ) models were established by cutting off the limbus of cornea in 20 eyes of New Zealand white rabbits, and the model rabbits were then divided into 2 groups randomly. The transplanted grafts carrying the pLenti6/V5-DEST-EGFP gene-transferred human amniotic epithelium cells were regarded as the pLenti6/V5-DEST-EGFP group, and the corneal stroma graft without any epithelial cell served as the control group. The opacity of stroma and corneal conjunctivalization and vascularization were observed daily. The rabbits' eyes were extracted one month after operation. The expression of EGFP in the cornea was detected under the fluorescence microscope, and the expression of CK8, CK18 and CK12 in cornea was detected by immunohistochemical staining. Results The shape of the transferred human amniotic epithelial cells resembled normal human amniotic epithelial cells. 48 hours after the transient transfection of EGFP presented with the highest expression level throughout the observation duration, with a positive expression rate of EGFP of 61.5% ,showing significant differences in comparison with that of 12 ( 5.24% ) , 24 ( 38.27% ) or 96 ( 39. 10% ) hours ( P ＜0. 05) post-transfection; but no obvious difference was found in the positive rate of transiently transfected EGFP between 48 hours and 72 hours ( 58.36% ) ( P＞0. 05 ). Six cornea grafts were clear in 1 month and two corneas were rejected during the observation period in the pLenti6/V5-DEST-EGFP group. A few new blood vessels were seen around the graft. Ten corneas of the control group became opaque and cloudy with new blood vessels growth around the grafts. Imunohistochemistry revealed the positive expressions of CK8, CK1 8 and CK12 in the corneal epithelial layer in the pLenti6/V5-DEST-EGFP group. However,the expression of CK12 was absent in the control group. Conclusion Human amniotic epithelium cells transfected with the pLenti6/V5-DEST-EGFP gene is a new and ideal feed cell type to reconstruct the corneal surface layer. Lentivirus is a relatively safe gene transfection vector.