Light-activatedbacteriaprotectratsfromheartattacks

Injectingphotosyntheticmicrobesintooxygen-starvedhearttissuecanimprovecardiacfunctioninrodents.

RatcardiomyocytewithS.elongatusbacteriaCOHENETAL.,SCIENCEADVANCES,.

STANFORDUNIVERSITYSCHOOLOFMEDICINE,DEPARTMENTOFCARDIOTHORACICSURGERY

Whenaheartattackstrikes,bloodstopsflowingtopartsoftheheart,starvingthetissueofoxygenandkillingcardiaccells.Scientistshavelongspeculatedthatiftheycouldprovidethosecellswithanemergencysupplyofoxygenuntilsurgeonsrestoredbloodflowwithacoronarybypass,somepermanentdamagetocardiactissuecouldbeprevented,therebypreservingheartfunction.Anewstudywithratssuggestsaninnovativewaytodothat:infectingtheheartwithphotosynthesizingbacteriathatnaturallyproduceoxygenwhenexposedtolight.

Thetechniquewaseffectiveatpreservingcardiacfunctionintherodents,yetexpertsnotetherearesignificantobstaclestoimplementingitasahumantherapy.“Thisisafascinating,radicalidea,andI’mgladit’sbeingtested,”saysHinaChaudhry,acardiologistatMountSinaiHospitalinNewYorkCity,“butit’salongroadfromsmallanimalstohumans.IfIwereabettingperson,I’dbetit’snotgoingtotranslate.”

ThebacteriumusedwasSynechococcuselongatus,which,likeplants,photosynthesizeslightforenergyandconvertscarbondioxideandwaterintooxygen.It’swellknownamongbioengineers,someofwhomstudyitasatooltoenhancebiofuelproductionorasamodelorganismtoinvestigatecircadianrhythms.

Wonderingwhetherthesemicrobescouldprovideoxygenondemandtoatissue,researchersatStanfordUniversityinPaloAlto,California,infectedtheheartmusclesofratswiththebacteria,theninducedaheartattackbyopeningthechestandblockingtheorgan’smainblood-supplyingartery.Theylefttheheartexposedtothelaboratory’snaturallightandthebacteriawenttowork,resultingina25-foldincreaseinthetissue’soxygenlevels10minutesaftertheheartattack.Forty-fiveminutesaftertheheartattack,theheartsofthebacteria-lacedratspumpedabout60%morebloodthandidratsthatalsohadheartattacksbutwerenotgiventhebacteria,and30%morebloodthanratsthatwereinfectedwiththebacteriabutleftinthedark.

Inhumans,preservingthatmuchheartfunctionfollowingaheartattack“wouldhaveprofoundclinicalimplications,likelyrepresentingthedifferencebetweenahealthypatientandonesufferingfromheartfailure,”theresearchersreporttodayinScienceAdvances.Basedonbloodsamplestakenfromtheratsduringthefirstweekoftheirrecovery,theteamfoundnoevidencethatthebacteriahadspreadorcausedanytoxiceffects,andit’snotknowntobeahumanpathogen.

Buttherearemajorhurdlesinthewayofthetechniqueworkinginpeople,Chaudhrysays.Foronething,shesays,humanshavethickercardiacmusclesthanrats,makingitunlikelythatlightcouldpenetratedeeplyenoughtoreachthebacteria.Shealsoisunconvincedthebacteriumisasharmlessastheresearchersreport,claimingtheirinvestigationintotherodentimmuneresponsetoitwas“superficialandcursory.”

Postedin:BiologyHealth

DOI:10./science.aan

来源：国外网站

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