Biocompatibility of chitosan carrier with rabbit corneal endothelium

Abstract

Background There are a lot of studies about the carrier of corneal endothelial transplantation,but the best carrier has not been defined.Objective This study was to investigate the biocompatibility of chitosan carrier with rabbit corneal endothelium in vivo.Methods Fresh eye-balls were obtained from 10 New Zealand white rabbits.Rabbit corneal endothelial cells (CECs) were isolated and cultured on chitosan carrier in vitro.The morphology and density of rabbits CECs were observed every day,and the expressions of fibronectin (FN),collagen-1 (Coil-I) and Zonula occludens 1 (ZO-1) were detected by immunoinfluorescence.The morphology and ultrastructure of CECs were observed under the scanning and transmission electron microscope.Chitosan carrier with CECs was implanted into the anterior chamber of the left eyes in ten healthy New Zealand white rabbits,and only paracentesis of anterior chamber was performed in the right eyes as controls.The inflammation of ocular anterior segment was examined under the slit lamp microscope,and corneal thickness was measured 1 week,4 and 8 weeks after operation.Corneal endothelium cell density and morphology were examined under the corneal endothelial microscope at postoperative 2 weeks.Corneal samples were collected for the regular histopathological examination to observe the inflammatory reaction at postoperative 1 month and 3 months.Paired t test was used for statistical analyses between the control group (left eyes) and the experimental group (right eyes).The use and care of the animals followed the Statement of ARVO.Results CECs formed an intact monolayer of cells with the uniform shape and size on the chitosan membrane after incubated for 5 days.The cells reached confluence of 90％ 7 days after cultured with the 40％ hexagon cells.Under the scanning electron nicroscope,rabbit CECs showed the round or polygon in the shape with the microvillus on the cell surface.The cells connected closely by desmosome.The processes,pseudopodiums and microvillus on the cellular surface,vacuole in the cytoplasm,expanded endoplasmic reticulum with ribosome and abundant chromatin were exhibited under the transmission electron microscope.The immunofluorescence examination revealed the positive expressions of FN,Coll-Ⅰ and ZO-1 in the CECs on the chitosan carrier.In the in vivo experiment,the exudation in the anterior chamber and corneal edema were seen under the slit lamp microscope 3 days after implantation of chitosan carrier with CECs.However,the inflammation was gone 14 days after operation.The differences of the corneal thickness were no significant between the experimental group and the control group 1 week and 4,8 weeks after operation (t =1.377,P=0.265;t =1.795,P=0.165 ; t =0.390,P =0.760).In addition,no significant differences were found in the CECs density and the hexagon cells rate between the two groups(P =0.365,0.062).The histopathological examination showed that the inflammatory cells around the chitosan membrane were disappeared 3 months after operation and showed a good corneal structure.Conclusions Chitosan carrier has a good biocompatibility with rabbit CECs and anterior chamber,and it may be a potentially good carrier for CECs transplantation. Key words: Chitosan; Cornea; Endothelial cell; Biocompatibility; Biotoxity; Rabbit