Experimental Study Of Human Fetal Retina Transplantation In Light-induced Retinal Degeneration Mini-pigs' Subretinal Space

Purpose: To evaluate the safety, morphology and function changes of neuroretina-RPE cografts and host retina after transplanting sheets of human fetal neural retina together with its retinal pigment epithelium (RPE) to light-induced retinal degeneration mini-pigs. And to explore the proper ways to store fetal retina in short, middle and long term periods.Methods: Firstly model light-induced retinal degeneration mini-pigs by constant white light exposing 6 months.Then store12-35 weeks fetal retina in Ames'medium,DX medium, 80 centigrade below zero refrigerator and freeze control systems in different term periods respectively.Histology and cell viability were evaluated. 25 eyes of light-induced retinal degeneration mini-pigs and 4 normal eyes of minipigs underwent transplantation of 12-30 weeks human fetal neurortina-RPE cografts. 3 eyes of light-induced retinal degeneration and 1 normal eyes received false operations. In the follow-up of 1 week,1,2,3,5 and 8 months, the morphology of grafts and host were showed by ophthalmoscope, fundus colour graphy,fundus fluorescence angiography (FFA),histology and fluorescence- immunohistochemistry, the hosts'function changes were evaluated by multifocal electroretinogram (mfERG) and multifocal visual evoked potential (mfVEP).Results:(1) After 6 months constant white light exposing, mini-pigs'mfERG showed worse results compared with normal eyes, especially the P1 wave's amplitude density in ring1 and 2. mfVEP displayed the prolonged latency of P1 wave in ring3 and 5. Electron microscopy showed swelled mitochondrion and lysised cytoplasm in photoreceptor layer.(2) In the storage of human fetal retina, Ames'medium showed best preservation in four hours, no longer than six hours. DX medium showed good preservation in one to two days. 80 centigrade below zero refrigerator could provide ordinary middle term preservation in one week. freeze control systems showed better preservation in one month period than 80 centigrade below zero refrigerator.(3) 23 eyes of the total 33 eyes(66.67%) underwent retinal transplantation successfully. In the 8 months follow-up, fundus fluorescence angiography showed no leak in fluorescein. In the survival period of 5 months,10 eyes specimens whose retina had been light- induced...