| ObjectiveTo investigate the turnover and influencing factors for amniotic me- mbrane transplantation to different ocular tissues. To provide experimental foundation for the clinical application in the future.The study includes three parts:Experiment I: Study on the turnover of amniotic membrane tran- splantation under conjunctivaExperiment II: Study on the turnover of amniotic membrane tran- splantation into scleral stoma.Experiment III: Study on the turnover of amniotic membrane tran- splantation into corneal stroma.MethodsExperiment I: Amniotic membrane stained with 0.5%DTAF was implanted under conjunctivas of 20 New Zealand white rabbits. After transplantation, we observed the clinical change. The week 3,5,8,12,16 after surgery,4 rabbits were sacrificed at every time. The tissue samples from grafted area were observed by HE staining and laser confocal microscope to trace amniotic membrane.Experiment II: Scleral flap model was produced. Amniotic membra- ne stained with 0.5%DTAF was implanted into scleral stroma of 20 New Zealand white rabbits. After transplantation, we observed the situation of ocular surface and anterior chamber. The week 3,5,8,12,16 after surgery, 4 rabbits were sacrificed at every time. The tissue samples from grafted area were observed by HE staining and laser confocal microscope to trace amniotic membrane.Experiment III: 15 New Zealand white rabbits,using for establishing corneal pocket model. Amniotic membrane stained with 0.5%DTAF was implanted into corneal pocket. After transplantation, we observed the clinical change of corneas on slit-lamp. The week 4,8,13,17,22 after surgery, 3 rabbits were sacrificed at every time. The tissue samples from grafted area were observed by HE staining and laser confocal microscope , and the tissue samples at the week 22 after surgery from grafted area were also observed by transmission electron microscopy.ResultsExperiment I:1.The clinical observation: the upper bulbar conjunctiva of rabbit was obviously hyperaemic. Yellowish dense tissue was seen by unaided eye at the week 1 after surgery. With the passage of time, the color of yellowish dense tissue gradually faded. The upper bulbar conjunctiva with surrounding conjunctival tissue had the same appearance at the week 6 after surgery.2.Histopathological analysis show: the amniotic membrane was intact at the week 3 after surgery. It was bandshaped and began dissolved at the week 5 after surgery. Remnants of the amniotic membrane could be identified at the week 8 after surgery. The amniotic membrane basically dissolved, but remnants of curmbly erythroic tissue were locally left at the week 12 after surgery. It totally dissolved at the week 16 after surgery. The types of inflammatory cells were mainly plasma cells, mononucleimacrop- hages and lymphocytes. At the week 3 after surgery, the inflammatory reaction reached the peak,then the inflammatory cells decreased.3.Laser confocal microscope examination demonstrated that yellow- green fluorescent amniotic membrane strip existed in the background of red fluorescence up to the week 12 after surgery.Experiment II:1.The clinical observation: the upper bulbar conjunctiva of rabbit was obviously hyperaemic and edema at the week 1 after surgery. Yellowish amniotic membrane could not be identified by unaided eye and slit lamp. No abnormal appearance of bulbar conjunctiva was observed to the 4 week after surgery. 2.Histopathological analysis show: the amniotic membrane was intact at the week 3 after surgery. A large number of inflammatory cells gathered, mainly plasma cells. The amniotic membrane was bandshaped and began dissolved at the week 5 after surgery. The number of plasma cells decresed. It dissolved into a discontinuous and non-uniform thickness of the pink stripe at the week 8 after surgery. Inflammatory cells were mainly mononucleimacrophages. The small piece of residual amniotic membrane existed at the week 12 after surgery, only a small number of lymphocytes. It totally dissolved at the week 16 after surgery, and inflammatory cells disappeared.3.Laser confocal microscope examination demonstrated that yellow- green fluorescent amniotic membrane strip existed to the week 12 after surgery.Experiment III:1.The clinical observation: there was no corneal opacity. However, trace of yellow tissue was see in the implanted area. With the passage of time, the color of yellowish tissue gradually faded. At the end of experiment, the yellowish mark also existed.2.Histopathological analysis show: the amniotic membrane was intact. It was stained red homogeneous structure at the week 4 after surgery. At the week 8 and 13 after surgery, the strip structure of amniotic membrane was ambiguous. Amniotic membrane-like debris was obviously seen at the week 17 after surgery. The small piece of residual amniotic membrane existed in corneal stroma at the week 22 after surgery. Corneal structure was stable. There was no rejection.3.Laser confocal microscope examination demonstrated that yellow- green fluorescent amniotic membrane strip existed in the background of red fluorescence up to the week 22 after surgery. With time, yellow-green fluorescence decreased over the previous. There was no leakage of yellow-green fluorescence in the surrounding corneal stroma.4.Transmission electronic microscopy revealed that collagen fibers of amniotic mmbrane matrix integrated into corneal stroma were irregular. The ultrastructure of host corneal stroma did not change.ConclusionOur task studied the turnover and influencing factors for amniotic membrane transplantation to different ocular tissues. The conclusion as follow:1.The amniotic membrane implanted under conjunctiva persisted for 12 weeks, and the amniotic membrane implanted into scleral stroma also persisted for 12 weeks, or even longer,but the amniotic membrane com- pletely dissolved, absorbed at the week 16 after surgery. Chronic inflam- mation occurred in response to local tissue, but fibroblast proliferation was not obvious. 2.Amniotic membrane can be used as good bio-engineering materials to treatment eye disease,such as symblepharon, conjunctival defect and scleral defect. Amniotic membrane also avoids scar formation in glaucoma surgery.3.With the passage of time, the part of amniotic membrane implanted integrated into the corneal stroma and became a part of the structure of the cornea. The amniotic membrane integrated into corneal stroma would not cause corneal rejection. This situation prompts that amniotic membrane can be used as cornea tissue reconstruction material to repair corneal defects.4.Transplant environment and operation can affect the turnover of amniotic membrane. Transplant environment is a important factor. |
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