Transplantation Of Human Fetal Retinal Pigment Epithelial Cells In The Treatment Of Retinal Degenerative Diseases

Background:Retinal degeneration,including age related degeneration(AMD)and retinitis pigmentosa(RP),is a group of refractory retinal diseases.Common causes for retinal degeneration are oxidative stress,inflammation,metabolic disorders,and genetic factors,which will further lead to dysfunction of retinal pigment epithelium(RPE),and degeneration and dystrophy of photoreceptors and choroid.Since retina is a type of terminally differentiated nervous tissue,which is non-renewable,and thus making retinal degeneration untreatable.Cell transplantation is one of the most promising treatments for RPE degeneration.Embryonic stem cells(ESCs)are found as the most important among all types of cells that has been used for treating retinal degeneration due to its totipotency and unlimited proliferation.However,the immunological rejection,tumor risk,uncontrollable proliferation,and ethical problems of ESCs largely restrict its clinical application.iPSCs have similar morphology and differentiate capacity as ESCs,while its much more expensive,complicated,and with less totipotency.The genetic risks of iPSCs have terminated its human clinical experiments.The derivation and culture of flRPE are much easier when compared with ESCs and iPSCs.Its high proliferative ability and low immunogenicity in vitro have made it effective in the treatment of central nervous system diseases.However,its application in retinal degeneration has been rarely reported.Animal model is very important to investigate pathogenesis and treatment of a disease.Although mice models with retinal degeneration can be used in biological and genetic investigations,they are not the ideal model for retinal degeneration due to the lack of macula.Primates have similar macula as human.In this study,we for the first time trans-carotid arterial inject sodium iodate into the machin to build retinal degeneration model,and transplanted fRPE to treat the RPE degeneration.We have also observed the living status and effectiveness of the treatment.Methods:1.Eight healthy male machin were randomly grouped and trans-bilateral carotid arterial injected with sodium iodate of different dosages,including 10 mg/kg,15 mg/kg,20 mg/kg and 25 mg/kg,respectively.The offside eye was used as the control eye.We then observe the mo logical and functional changes of the retina with ERG,fundus photo,FFA,and OCT to screen out the most moderate dosage.2.Primary fRPE was obtained from aborted fetus,and was then derived,cultured,observed,and identified using flow cytometry and immunofluorescent staining.The cultured fRPE were then transplanted into the machin neuro retina under operation microscope.The retinal morphology and function were then observed using ERG,funduscope,FFA,and OCT.The living status of RPE was detected with histological section.Results:1.RPE degeneration and depigmentation were found in the fundus photo and FFA of machin models one week after treatment with different dosages of sodium iodate.Dosage dependent atrophy of RPE was found six weeks after the injection.Machin treated with 20 mg/kg sodium iodate showed obvious RPE atrophy and depigmentation by funduscope,OCT,and FFA.Both a-and b-waves of F-ERG were significantly decreased initially after sodium iodate injected and were then picked up slowly.ERG presentations recovered in machin treated with 10 mg/kg or 15 mg/kg six weeks after treatment,which those treated with 20 mg/kg or 25 mg/kg remained in a low level.2.The derived fRPE can be cultured in vitro with biological markers,like ZO-1 and RPE65,been detected.OCT examination after transplantation found retinal vacuole-like upheaval.Cloddy pigmentations were found four weeks after transplantation by funduscope,which were rough and thick as revealed by OCT.Slight elevations were found in both a-and b-waves of ERG,while no statistical difference was found between the two groups.Proliferated pigmental cells were detected by histological examinations.Conclusion:1.Trans-carotid arterial injection of 20 mg/kg sodium iodate into the machin would cause its RPE and retinal degeneration,which is safe and controllable for building animal models with retinal degeneration.2.Transplantation of RPE under operation microscope directly is an easy method with high success rate.3.fRPE can survive without obvious immunological rejection,but no obvious ERG improvement be found.