Technical characters of model establishment of penetrating corneal transplantation in rats

Huimin XU; Yanhua HU; Wei ZHAO; Qiming WANG

ABSTRACT

BACKGROUND:

The expression of main histocompatibility antigen in cornea of rats is similar to that of human. It is verified in early experiments that penetrating corneal transplantation in rats is more repetition and reliability, and the operation difficulty is lower than that in mice.

OBJECTIVE:

To establish rat model of penetrating corneal transplantation and analyze the reasons of complications during model preparation and the corresponding managements and probe into the method for improving the success rate of rat model of corneal transplantation.

DESIGN:

Randomized controlled experiment was designed.

SETTING:

Department of Ophthalmology , Union Hospital, Tongji Medical College, Huazhong University of Science and Technology.MATERIALS The experiment was performed in Department of Ophthalmology in Union Hospital Affiliated to Tongji Medical College of Huazhong University of Science and Technology from March to May 2004. Seventysix outbred female Wistar rats of two months old were employed and randomized into experimental group and control group with 38 rats in each,without eye disease, of clean grade, body mass varied from 180 to 200 g and their right eyes were taken as acceptors. Thirty-eight SD female rats were employed and their both eyes were taken as donors. All of the animals were provided from Experimental Animal Center of Tongji Medical College of Huazhong University of Science and Technology.

METHODS:

Central penetrating corneal transplantation in situ was adopted and the model was established on the right eye of Wistar rat. Ten minutes before operation, tropicamide eye drops was administrated twice to amplify adequately the pupil of the right eye up to 4.0 mm. According to body mass, general anesthesia was done with abdominal injection of 3.0 mL/kg chloral hydrateand dicaine eye drops was applied twice 5 minutes before the operation with 0.1 volume fraction. Routine sterilization was done on the head of rat, the eyes kept in horizontal level and respiration kept smooth. The clip in dental-ophthalmology department was used to fix the posterior of the operated eye and make it to be semiluxated. The ring driller 3.5 mm in diameter was used to collect corneas of both eyes in SD rat as the implant tissue and place in culture dish with endothelial part upward, covered with methyl cellulose of 20 g/L mass weight concentration. The ring driller, 3.0 mm in diameter was used to collect the cornea of the right eye in Wistar rat to be the graft foreman, and the implant tissue was sutured into the graft foreman on the right eye of Wistar rat with 10-0nylon thread intermittently. Eight stitches were done in corneal transplantation in the experimental group and 6 stitches in the control group. After operation, ofloxacin eye drops was administrated and the operated eye was covered with plaster. Corneal rejection was observed and the evaluation was done in 3 items, named, turbidity, edema and neogenetic vessel. The total score of 3 items was taken as the rejection index on the day. Rejection was determined if the rejection index on the day ≥5 or corneal turbidity reached the 3nd grade. x2 and Fisher definite probability methods were used for statistical examination.plant tissue and corneal rejection.

RESULTS:

Of 76 Wistar rat acceptors, 5 rats were dropped out, among which, 1 rat was died accidentally after operation in the experimental group, 2 rats were died accidentally after operation in the control and 2 rats were injured cornea on the operated eyes due to fighting. But by supcomplications after corneal transplantation In the experimental group, the number with anterior adhesion of sclera, non-round pupil; limited wound healing and non-formation of anterior chamber was lower than that in the implant tissue and corneal rejection the survival time of corneal implant tissue was similar basically in both experimental group and the control [(8.9±2.3), (8.6±2.3) days, P ＞ 0.05]. Rejection presented in both groups in 16 days after corneal transplantation and the incidence of rejection was 100%.

CONCLUSION:

With stitches maintained and without intervention, the acute rejection is similar in rat corneal transplantation and human corneal transplantation. It is explained in the experiment that 8 stitches in corneal transplantation in which the rat implant tissue of 3.5 mm matches graft foreman of 3.0 mm can reduce the complications of rat corneal transplantation and becomes a satisfactory animal model of corneal transplantation.Skillful microscopic operation techniques, satisfactory operation instruments and adequate amplilfied pupil can reduce to the most extent the postoperation complications in rats.