Study On Prevention Adhesion After Rabbit Orbital Trauma By Chitosan Membrane

Application of Chitosan to Prevent Adhesion After Rabbit Orbital TraumaObjectiveTo approach the feasibility to establish a model of rabbit tissue adhesion after trauma; To approach result and the mechanism of preventing postoperation adhesion after trauma on the orbit tissue by chitosan membrane. Offer an experimental base for clinical use. Pathology and immunohistochemical analysis were perform to verify application of chitosan membrane can prevent adhesion after rabbit orbital trauma and its mechanism. Electrophysiological test were done to rabbits both before operation and postoperation to find wether chitosan has effect on optic nerve and visual function or not.Method1. Establishment on the model of rabbit orbital adhesion12 white rabbits (twenty eyes) were adopted on the experiment. Superior fornix conjunctiva was cutted to find superior rectus and corresponding periosteum after normal degermation and anesthesia. Orbital injury was made between the superior rectus (1cm) and corresponding periosteum(area 1cm²), using operation knife scraping 10 times on each surface. The superior rectus and corresponding periosteum were sutured as fix suture. And conjunctiva incision were sutured, too. after 3D,7D,14D,30D of the operation, rabbit was executed and operation area was test by pathematology and immunohistochemistry ways.2. Study on application of chitosan membrane to prevent adhesion after rabbit orbit trauma in earlier period.15 white rabbits (30 eyes) were were randomly divided in 3 groups which included group A(saline), B(SHA), C(CM). and 5 rabbit (10 eyes) were in each group. The operation was performed on both eyes of rabbits under general anesthesia. Superior fomix conjunctiva was cutted to find superior rectus and corresponding periosteum. Orbital injury was made between the superior rectus and corresponding periosteum, saline, SHA, CM were filled between the trauma surface in corresponding group. And the degree of adhesion on wound sites were scored. HE staining sections of wound site were performed to observe inflammation reaction, and immunohistochemical staining were performed to demonstrate TGF-β₁. Experimental data were analyzed with SPSS 12.0.Visual evoked potential were done to all the rabbits before operation and 6D after operation. Amplitude of wave and latent era of wave were recorded. The numbers were analysised with SPSS12.0. Electrophysiological test and histopathology test were done to rabbits both before operation and postoperation to find wether chitosan has effect on optic nerve and visual function or not.Result1. establishment of rabbit orbital adhesion modelUnder light microscope, inflammation reaction and fibrae were seen on the wound site. After 3D, inflammation cells infiltration was the major phenomenon and fibroblast proliferation was seen. The superior rectus and corresponding periosteum were sutured as fix suture. After 7D, inflammation cells infiltration and a large mount of fibroblast proliferation were major phenomenon. After 14D inflammation reaction was mitigated fibroblasts were reduced, and fibroplasias appeared. After 30 compact fiber tissue were formed.2. Application chitosan membrane to reduce adhesion in rabbit2.1 General evaluation Adhesion on A groups was compact fibrae tissue. The adhesions in B, C groups were curmbly tissue. Result of Classification of the adhesion on general specimens showed that: there were 4 eyes with 3 score, 4 eyes with 2score, 1 eyes with 2 score in A group. There were o eyes with 3 score,1 eyes with 2 score, 3 eyes with 1 score,6 eyes with 0 score. The degree of adhesion from general specimens had statistical difference between A and C group(P＜0.01). It didn't have statistical difference between B and C group(P＞0.01).2.2 Pathology evaluationPeriosteum effusion appeared in the wound site in A group, and there were lager mount of fibroplasias and new vessles on subperiosteum. Massive fibroblasts and lymphocytes can be seen among fiber which arrayed compactly. Adhesion between periosteum and rectus was tight. And reaction on periosteum was light in wound site on B and C group, and there were little fibroplasias. Little fibroblasts and lymphocyte can be seen among fiber which arrayed regularly and lossly, betwwen periosteum and rectus there was an obvious fissure which boundary was clearly. Classification of inflammatory reaction showns that. On A group there were 6 eyes with 3 score, 4 eyes with 2 score, 0 eyes with 1 score. On B group there were 0 eye with 3 score, 1 eye with 2 score, 2 eyes with 1 score, 7 eyes with 0 score. On C group there were 0 eye with 3 score, 1 eye with 2 score, 2 eye with 1 score, 8 eyes with 0 score. The level of inflammation reaction had statistical difference between A and C groups (P＜0.01). It didn't have statistical difference between B and C group (P＞0.01).The number of fibroblasts in every visual field had significant difference in two groups (P＜0.01).2.3 Immunohistochemical evaluation The positive cells expressing TGF-β₁ in experimental and control groups were appeared in the wound site. And the population of expressing TGF-β₁ in experimental group was fewer than A group.Histological analysis of optic nerve show that the adjacent optical tissue arraied regularly. There was no inflammatory cell infiltration and fibroplasias. Optic nerve is normal without any degeneration or colloid cell proliferation.P₁wave ridge of preoperative average is 8.589±1.870mv, and P₁ wave ridge of postoperative average is 9.847±2.320mv. The outcome of P wave ridge between preoperative and postoperative is not significant deviation(P＞0.01).Conclusion1. The orbital adhesion model can be established through injuring rectus and corresponding periosteum.2. Application of chitosan membrane can decrease inflammation reaction and inhibition the expression of TGF-βin earlier period.3. Insertion of chitosan membrane has no effect to optic nerve and visual function.