Blindmicerecoveringeyesight
NineresearchersfromUniversityCollegeLondonandMoorefieldEyeHospitalinLondontookoutretinalphotoreceptorcellprecursorsfromtheeyesof3to5day-oldpups,Transplantthemintotheeyesofmiceblindedbycongenitalgeneticdefects.Theconditionoftheseblindmiceissimilartothatofhumanblindnesscausedbymaculardegeneration.
TheBritish"Guardian"saidthattheresearcherstransplantedabout500,000cellprecursorstoeacheyeoftheseblindmice.After300to1,000precursorsdevelopedintophotoreceptorcells,theyweresuccessfullyconnectedandresponsible.Theopticnervethattransmitsvisualsignals.
Indevelopedcountries,thenumberofblindnesscausedbyphotoreceptorcelldeathexceedsthetotalnumberofotherblindnesscases.Sincescientistscannotreversethedamageofphotoreceptorcells,findingsuitablereplacementcellshasbecomethemaindirectionofscientists.
Theresearchersputthemicethathadreceivedcelltransplantsintolight.Theyfoundthatthemouse'spupilsshrinkwhenexposedtolight.Atthesametime,thedetectionoftheelectricalactivityoftherat'sretinarevealedthatthetransplantedphotoreceptorcellstransmitsignalstotheopticnerve,andtheopticnerveultimatelytransmitsthesignaltothebrain'svisualcenter.Studieshavedemonstratedforthefirsttimethatthetransplantedphotoreceptorcellscanself-adjustandcommunicatewiththeopticnervetoachievenormal"communication"betweentheretinaandthevisualcenterofthebrain.
Thephotoreceptorcellstransplantedinthisstudyaremostlyrod-shapedcellsresponsibleforblackandwhiteimagevision.Theresearchteamfoundthattransplantationofmaturerod-shapedcellsandcompletelyundevelopedretinalstemcellscannotplayaroleinrepairingvision.
Brightprospects
Bringinggoodnewstothetreatmentofblindness
Expertssaythatiftheoperationissuccessfullyextendedtohumans,thentheblindwillbecausedbythedeathofphotoreceptorcells.Theblindwillbeabletoseethesunagain.
Photoreceptorcells
Retinitispigmentosacausesphotoreceptorcelldeathinonecasein3,500people.Maculardegenerationisthemaincauseofblindnessinpatientsover55yearsofage.Inaddition,thereisblindnessduetocomplicationsofdiabetes.Allthesepatientscanbenefitfromthelatestresearch.
Intheabove-mentionedmousestudy,thephotoreceptorcellprecursorsweretakenfromtheeyesofnewbornmicewithsimilargenestoreducetheriskofrejectionbytheimmunesystem.Inthisrespect,humanbeingshaveaninherentadvantage.
TheGuardiansaidthatscientistsbelievethatthisphotoreceptorcellprecursorgrowsnearthehumaniris,sothatblindpeoplecangettheprecursorfortransplantationfromthemselveswithoutworryingaboutimmunesystemrejection.RobinAli,theleaderoftheresearchteam,said:"Thesecellscanbeobtainedthroughasmalloperation,culturedinthelaboratoryandimplantedintotheretina."saidRobertMcLaren,aresearcheratMoorefieldEyeHospital"Wearenowconfidentthatthroughthisapproach(celltransplantation),wecanfindawaytohelpthousandsofblindpatientsrestoretheirvision."
Andrew,ProfessorofOphthalmology,UniversityofBristol,UK·Dickalsosaid:"Likeanybasicresearch,wemustbecarefulnottoover-proclaim.However,thisisanamazingstudy,whichmayenablehuman(photoreceptorcell)transplantationinthenearfuturetoalleviatetheblindnessofpatients.Pain."
Stillbudding
Photoreceptorcells
Manyimportanttestsareneededforhumansurgery
Onthebasisofthisresearch,Scientistshavemademanyideas.
Thekeyroleintheexperimentisthephotoreceptorcellprecursorsofnewbornmice.Inordertoobtaincellprecursors,scientistsaretryingtogrowembryonicstemcellsinlargenumbersinthelaboratoryandletthemdevelopintophotoreceptorprecursors.Inaddition,theresearchersbelievethatbyincreasingthenumberandtypesofphotoreceptorcellsusedintransplantation,recoverywillbebetter.
Previously,publishedresearchalsofoundthataftertransplantingmicewithcellsthatprovidenutrientsforphotoreceptorcells,blindnesscausedbyinsufficientnutritioncanbereversed.
Althoughtheresearchonphotoreceptorcelltransplantationhasbroughtrevolutionarybreakthroughsinophthalmictreatment,scientistssaythatsuchresearchisstillinitsinfancy,anditwilltakeatleast10yearsforhumanstoundergothistypeofsurgery.
AnandSwarup,professorofophthalmologyattheMichiganMedicalCollege,saidthattherearemanyimportanttestswaitingforscientiststocomplete,suchasdeterminingthesurvivaltimeoftransplantedcellsinmiceandwhethertheywillcauseintraoculartumors.