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tAvailableonlineaScholarsResearchLibraryDerPharmaciaLettre,2016,8(8):158-166(http://scholarsresearchlibrary.
com/archive.
html)ISSN0975-5071USACODEN:DPLEB4158ScholarResearchLibraryNewapproachesinthehorizonfortreatmentofAlzhimer'sdiseaseHanaaH.
Ahmed1,EhabR.
AbdelRaouf2,LailaA.
Rashed3andHadeerA.
Aglan1*1HormonesDepartment,MedicalResearchDivision,NationalResearchCentre,Giza,Egypt(AffiliationID:60014618)2ChildrenofSpecialNeedsDepartment,MedicalResearchDivision,NationalResearchCentre,Giza,Egypt(AffiliationID:60014618)3MedicalBiochemistryandMolecularBiologyDepartment,FacultyofMedicine,CairoUniversity,Cairo,EgyptABSTRACTThefocusofourinterestwastoexploretheroleofsingleintravenousdoseofmesenchymalstemcells(MSCs)derivedfrombonemarrow(BM-MSCs)andadiposetissue(ADMSCs)inmanagementofAlzheimer'sdisease(AD)incomparisonwithcerebrolysinasareferencedruginexperimentalmodel.
Theanimalsincludedinthestudyweredividedintofivegroups;thefirstoneservedashealthycontrol,while,theothergroupswereadministeredwithAlCl3orallytoinduceAD.
Then,groupofADratswereleftwithouttreatment(Group2)andtheothergroupsweretreatedwithcerebrolysin(Group3),BM-MSCs(Group4)andADMSCs(Group5).
ThelevelsofTGF-β1,MCP-1andBDNFweredeterminedinserumbyELISA.
NestingeneexpressionlevelwasdetectedinbraintissuesbysqRT-PCR.
While,ChATexpressionwasdeterminedinbraintissuebyimmunohistochemicalprocedure.
Also,histopathologicalexaminationofbraintissueswasperformed.
BM-MSCsandADMSCswereengraftedintoADaffectedbrainsandcausedinsignificantdeclineinserumTGF-β1andMCP-1levelsinconcomitantwithsignificantelevationinserumBDNFandbrainnestingeneexpressionlevels.
Furthermore,theengraftedcellselecitedsignificantincreaseintheexpressionofbrainChATandamelioratedtheneurodegenerationofhippocampus.
Inconclusion,thecurrentdataprovidedistinctevidenceabouttheimportanceofBM-MSCsandADMSCsasanoveltherapeuticavenueforADthroughtheiranti-inflammatoryeffect,neurotrophicandneurogenicpotentialsaswellasAβclearingactivity.
Keywords:Alzheimer'sdisease,mesenchymalstemcells,anti-inflammatoryeffect,neurotrophiccapacity,neurogenicpotential.
INTRODUCTIONAlzheimer'sdisease(AD)isthemostwell-knownneurodegenerativediseasefeaturingprogressiveimpairmentsinmemory,cognition,andbehaviorandultimatelyleadstodeath[1].
Ithasnumerousetiologicalfactorsincludinggenetics,environmentalfactors,andgenerallifestyles[2].
ThepathophysiologicalhallmarksofADincludeextracellularβ-amyloidprotein(Aβ)depositionintheformsofsenileplaquesandintracellulardepositsofthemicrotubuleassociatedproteintauasneurofibrillarytangles(NFTs)[3].
AconsequentcascadeofeventsoccursasaresultofAβaggregationanddeposition,includinganinflammatoryresponse,freeradicalformationandoxidativestress.
Theseprocessescontributetoneurotransmitterandsynapticdysfunction,suppressionofneurotrophicfactors,excitotoxicityandeventually,neuronaldeath[4].
Since,elevatedAβdepositionisthekeypathogenicfactorforADandthemaincauseforneuronallossinAD[5]andthecurrentdrugtherapiesforADtreatmentarehinderedduetopoorefficacyandsideeffects[6],thepromisingtherapeuticstrategiesforADhasfocusedonpreventing,reversing,andreducingAβdeposition[7].
Cerebrolysinisaneuropeptidepreparationwhichmimicstheactionofendogenousneurotrophicfactorsonbrainprotectionandrepair.
Furthermore,ithastheabilitytodecreasethedepositionofAβandthephosphorylationofmicrotubule-HadeerA.
AglanetalDerPharmaciaLettre,2016,8(8):158-166159ScholarResearchLibraryassociatedproteintauthroughregulatingglycogensynthasekinase-3βandcyclin-dependentkinase5activity,increasesynapticdensityandrestoresneuronalcytoarchitecture.
Theseeffectsprotectintegrityoftheneuronalcircuitsandthusresultinimprovedcognitiveandbehavioralperformance[8].
Ontheotherhand,ithasbeenreportedthatcelltherapyisapotentialtherapeuticapproachforneurodegenerativedisorders[9].
Recently,manygroupshavedemonstratedthatstemcellshaveregenerativeaswellasparacrineeffects[10-12].
Moreover,thestudiesofKimetal.
[13];Baeetal.
[14]andMaetal.
[15]revealedthattransplantingmesenchymalstemcellsderivedfromhumanumbilicalcord,bonemarrowandadiposetissueintothebrainsofAlzheimer'stransgenicanimalsdecreaseAβdeposition,amyloidprecursorprotein(APP)generation,andmicrogliaactivationleadingtoimprovementincognitiveandmemoryperformancesandneuronalsurvival.
Ithasbeenreportedthatlocalstemcelldeliverycausesbleedingandtissueinjury[16,17].
Basedon,thecurrentstudysoughttoclarifythemechanismsinvolvedinrepressingtheneurodeteriorationcascadeinchemicallyinducedADbysingleintravenousdoseofMSCsincomparisonwithmultipledosesofcerebrolysindrug.
MATERIALSANDMETHODSMesenchymalstemcellsMesenchymalstemcellswereisolatedfrombonemarrowandadiposetissueof6-week-oldmaleSpragueDawleyrats.
Thereafter,theywerecharacterizedmorphologicallybyinvertedmicroscopeexamination,PCRdetectionofCD14,CD29,CD34,CD44,CD45andCD106geneexpressionsandinvitrodifferentiationintoadipocytes,chondrocytesandosteocytesaccordingtopreviouslypublishedwork[18,19].
ChemicalsanddrugsAluminumchloridewasprovidedfromBDHLaboratorySupplies,England.
CerebrolysinampouleswerepurchasedfromEBEWEPharma,Austria.
ExperimentaldesignFortyadultfemaleSprague-Dawleyratsweighing130-150gwereobtainedfromtheAnimalHouseColonyoftheNationalResearchCentre,Giza,Egyptandacclimatizedinaspecificareawheretemperature25±1Candhumidity55%.
Ratswerecontrolledconstantlywith12hlight/darkcyclesatNationalResearchCentre,AnimalFacilityBreedingColony.
Ratswereindividuallyhousedwithadlibitumaccesstostandardlaboratorydietconsistedofcasein10%,saltmixture4%,vitaminmixture1%,cornoil10%,cellulose5%andcompletedto100gwithcornstarch[20]andtapwater.
Also,theywerecaredforaccordingtotheguidelinesforanimalexperimentswhichwereapprovedbytheEthicalCommitteeofMedicalResearchatNationalResearchCentre,Giza,Egypt.
Theanimalswereclassifiedinto5groups(8rats/group).
Thefirstgroupwashealthycontrolgroup.
Thegroupsfromsecondtofifthwereorallyadministeredwithaluminumchloride(AlCl3)inadoseof17mg/kgb.
wt.
[21],dailyfor75daysforinductionofADdisease.
Then,thesecondgroupwasleftwithouttreatmentfor2months;thethirdgroupwastreatedintraperitoneallywithcerebrolysininadoseof1.
08ml/kgb.
wt.
thatisequivalenttotherecommendedhumandose[22]accordingtoBarnesandPaget[23]equation,5days/weekforonemonthandthereaftertwotimesperweekforanothermonth.
Thefourthandfifthgroupswereinfusedintravenouslywithasingledoseof3x106cells/ratofBM-MSCsandADMSCsrespectively[24].
Inbrief,theADinducedratsweredeeplyanaesthetizedviadiethyletherandMSCsweresuspendedin100LPBSbeforetransplantationandthenslowlyinjectedintothetailveinin5minwitha27Gneedle.
Theneedlewaskeptinthetailveinforanother5mintoavoidregurgitationandthenwithdrawn.
Attheendoftheexperimentalperiod,allanimalswerefastedfor12handthebloodsampleswerecollectedfromretro-orbitalvenousplexusunderdiethyletheranaesthesia.
Thebloodsampleswerelefttoclotandtheserawereseparatedusingcoolingcentrifugation(4C)at1800xgfor10minandthenstoredimmediatelyat-20CincleanplasticEppendorfuntilanalyzed.
Meanwhile,thewholebrainofeachratwasrapidlyandcarefullydissected.
Then,eachbrainwassagitallydividedintotwoportions.
Thefirstportionwasimmediatelyfrozeninliquidnitrogenandstoredat80Cpriortoextractionformolecularstudy.
While,thesecondportionwasfixedinformalinbuffer(10%)forimmunohistochemicalexaminationandhistologicalinvestigation.
Detectionofmale-derivedMSCsinthebrainoffemalesThegenomicDNAwasisolatedfromthebraintissueoffemaleratswhichweretreatedwithBM-MSCsandADMSCsusingphenol/chloroformextractionandethanolprecipitationmethodaccordingtoSambrooketal.
[25]withminormodifications.
ThepresenceorabsenceofthesexdeterminationregionontheYchromosome(SRY)geneinrecipientfemaleratswasassessedbyPCRtechnique.
PrimersequencesforSRYgene(accessionno.
HadeerA.
AglanetalDerPharmaciaLettre,2016,8(8):158-166160ScholarResearchLibraryNC_000087.
7;forward5′-CATCGAAGGGTTAAAGTGCCA-3′,reverse5′-ATAGTGTGTAGGTTGTTGTCC-3′)wereobtainedfrompublishedsequences[26]andamplifiedtoaproductof104bp.
ThePCRconditionswereasfollows:incubationat94°Cfor4min;35cyclesofincubationat94°Cfor50s,60°Cfor30s,and72°Cfor1min;withafinalincubationat72°Cfor10min.
PCRproductswereseparatedusing2%agarosegelelectrophoresisandstainedwithethidiumbromide.
BiochemicalassaysSerumtransforminggrowthfactorβ1(TGF-β1)levelwasassayedbyenzymelinkedimmunosorbentassay(ELISA)techniqueusingkitpurchasedfromDRGDiagnosticsCo.
,Germany,accordingtothemethoddescribedbyKropfetal.
[27].
While,serummonocytechemoattractantprotein1(MCP-1)levelwasdeterminedbyELISAmethodusingkitpurchasedfromBenderMedSystemsGmbH,Europe,accordingtothemethoddescribedbyBaggiolinietal.
[28].
Serumbrainderivedneurotrophicfactor(BDNF)levelwasdeterminedbyELISAtechniqueusingkitpurchasedfromMilliporecorporation,USA,accordingtothemethoddescribedbyLaskeetal.
[29].
Semi-quantitativerealtimePCR(sqRT-PCR)detectionofnestingeneexpressionTotalRNAwasisolatedfrombraintissueoffemaleratsbythestandardTRIzolreagentextractionmethod(Invitrogen,USA).
Then,thecompletePoly(A)+RNAwasreversetranscribedintocDNAinatotalvolumeof20LusingRevertAidTMFirstStrandcDNASynthesisKit(MBIFermentas,Germany).
AnamountoftotalRNA(5g)wasusedwithareactionmixture,termedasmastermix(MM).
TheMMconsistedof50mMMgCl2,5xreversetranscription(RT)buffer(50mMKCl;10mMTris-HCl;pH8.
3;10mMofeachdNTP,50Moligo-dTprimer,20Uribonucleaseinhibitor(50kDarecombinantenzymetoinhibitRNaseactivity)and50UM-MuLVreversetranscriptase.
TheRTreactionwascarriedoutat25°Cfor10min,followedby1hat42°C,andthereactionwasstoppedbyheatingfor5minat99°C.
AfterwardsthereactiontubescontainingRTpreparationswereflash-cooledinanicechamberuntilbeingusedforDNAamplificationthroughsqRT-PCR.
AniQ5-BIO-RADCycler(Cepheid,USA)wasusedtodeterminetheratcDNAcopynumber.
PCRreactionsweresetupin25Lreactionmixturescontaining12.
5L1*SYBRPremixExTaqTM(TaKaRa,Biotech.
Co.
Ltd.
,Germany),0.
5L0.
2Mforwardprimer,0.
5L0.
2Mreverseprimer,6.
5Ldistilledwater,and5LofcDNAtemplate.
Primersequenceswereasfollows:nestin:(accessionno.
NM_012987.
1)F:5′-TGGAGCGGGAGTTAGAGGCT-3′,R:5′-ACCTCTAAGCGACACTCCCGA-3′[30]andβ-actin:(accessionno.
NM_031144.
3)F:5′-CTGTCTGGCGGCACCACCAT-3′,R:5′-GCAACTAAGTCATAGTCCGC-3′[31].
Thereactionprogramwasallocatedto3steps.
Firststepwasat95.
0°Cfor3min.
Secondstepconsistedof40cyclesinwhicheachcycledividedto3steps:(a)denaturationat95.
0°Cfor15sec;(b)annealingat55.
0°Cfor5secand60°Cfor30secfornestinandβ-actingenesrespectivelyand(c)extensionat72.
0°Cfor30sec.
Immunohistochemical(IHC)examinationofbraincholineacetyltransferase(ChAT)expressionFormalinfixedbrainswerewashedintapwaterandascendinggradeofethylalcohol(30,50,70,90%andabsolute)wasusedfordehydration.
Specimenswereclearedinxyleneandembeddedinparaffinat56oCinhotairovenfor24h.
Sectionswerecutinto4thickbyslidgemicrotomethenfixedonpositiveslidesina65oCovenfor1h.
Slideswereplacedinacoplinjarfilledwith200mLoftriologyworkingsolution(CellMarque,CA-USA)whichcombinesthethreepretreatmentsteps:deparaffinization,rehydrationandantigenunmasking.
Then,thejarissecurelypositionedintheautoclavewiththetemperatureadjustedtoreach120oCandmaintainedstablefor15minafterreleaseofpressure.
Aftercoolingfor30min,sectionswerewashedandimmersedinTris-buffersaline(TBS)toadjustthepH.
Then,quenchingendogenousperoxidaseactivitywasperformedbyimmersingslidesin3%hydrogenperoxidefor10min.
BroadspectrumLAB-SAdetectionsystem(Invitrogen,USA)wasusedtovisualizeanyantigen-antibodyreactioninthetissue.
Backgroundstainingwasblockedbyputting2-3dropsof10%goatnonimmuneserumblockeroneachslideandincubatingtheminahumiditychamberfor10min.
Excessserumwasdrainedandtwo-threedropsoftheworkingsolution(1:100)oftheprimaryantibodyforChAT(LifeSpanBioSciencesInc.
,USA)wereappliedandtheslideswereincubatedinthehumiditychamberovernightat4oC.
Henceforward,biotinylatedsecondaryantibodywasappliedoneachslidefor20minfollowedby20minincubationwiththestreptavidinhorsereddishperoxidase(HRP)enzymeconjugateandthen2-3dropsof3,3-diaminobenzidine(DAB)chromogenwereappliedoneachslidefor2min.
DABwasrinsed,afterwhichcounterstainingwithMayerhematoxylinandcoverslippingwereperformedasthefinalstepsbeforeslideswereexaminedunderthelightmicroscope(OlympusCx21withattacheddigitalcamera)[32].
ImageanalysiswasperformedusingtheimageJ,1.
41aNIH,(USA)analyzer.
HistopathologicalinvestigationofbraintissueofratsAfterfixationofbraintissuesin10%formalinbufferfor24h,thetissueswerewashedintapwateranddehydratedbyusingascendinggradeofethylalcohol(30,50,70,90%andabsolute).
Specimenswereclearedinxyleneandembeddedinparaffinat56oCinhotairovenfor24h.
Then,paraffinwaxtissueblockswerepreparedforsectioningHadeerA.
AglanetalDerPharmaciaLettre,2016,8(8):158-166161ScholarResearchLibraryat4thick,collectedonglassslides,deparffinizedandstainedbyhematoxylinandeosinstain[33]forhistopathologicalexaminationthroughtheelectriclightmicroscope.
StatisticalanalysisInthepresentstudy,allresultswereexpressedasMean+S.
Eofthemean.
Datawereanalyzedbyonewayanalysisofvariance(ANOVA)usingtheStatisticalPackagefortheSocialSciences(SPSS)program,version14followedbyleastsignificantdifference(LSD)tocomparesignificancebetweengroups[34].
DifferencewasconsideredsignificantwhenPvaluewas0.
05)whencomparedwiththegroupofratsleftuntreated.
Atthesametime,alltreatmentselevatedserumBDNFlevelsignificantly(Pcomparisonwiththegroupofratsleftuntreated.
Table(1):SerumTGF-β1,MCP-1andBDNFlevelsinADmodelratstreatedwithcerebrolysin,BM-MSCsorADMSCsGroupsTGF-β1(pg/mL)MCP-1(pg/mL)BDNF(pg/mL)Healthycontrol372.
2±2.
974.
3±1.
13943±56.
4ADuntreated485.
5±10.
9a90.
7±1.
1a3224±118.
0aAD+cerebrolysin450.
0±17.
084.
9±2.
73694±90.
9bAD+BM-MSCs455.
7±11.
785.
0±2.
23684±45.
2bAD+ADMSCs460.
0±5.
087.
1±1.
93627±51.
7baSignificantchangeatPcomparisonwiththehealthycontrolgroup.
bSignificantchangeatPcomparisonwiththeADuntreatedgroup.
Impactofcerebrolysin,BM-MSCsandADMSCsonbrainnestingeneexpressionlevelTable(2)clarifiedthatAlCl3administrationdown-regulatedtheexpressionlevelofnestingeneinbrainsignificantly(Pcomparedwiththegroupofratsleftuntreated.
Furthermore,injectionofAlCl3intoxicatedratswithBM-MSCsorADMSCsup-regulatedtheexpressionlevelofnestingeneinbrainsignificantly(PcomparedwiththoseinjectedwithBM-MSCs.
M123500bp400bp300bp200bp100bpHadeerA.
AglanetalDerPharmaciaLettre,2016,8(8):158-166162ScholarResearchLibraryTable(2):BrainnestingeneexpressionlevelinADmodelratstreatedwithcerebrolysin,BM-MSCsorADMSCsGroupsRelativeexpressionofnestingene(Nestin/β-actin)Healthycontrol1.
30±0.
02ADuntreated0.
67±0.
004aAD+cerebrolysin1.
09±0.
004bAD+BM-MSCs1.
20±0.
005bcAD+ADMSCs1.
15±0.
01bcdaSignificantchangeatPcomparisonwiththehealthycontrolgroup.
bSignificantchangeatPcomparisonwiththeADuntreatedgroup.
cSignificantchangeatPcomparisonwiththeAD+cerebrolysingroup.
dSignificantchangeatPcomparisonwiththeAD+BM-MSCsgroup.
Impactofcerebrolysin,BM-MSCsandADMSCsonbrainChATexpressionThedatainTable(3)andopticalmicrographsinFig.
(2)demonstratedthatAlCl3administrationdecreasedthenumberofChATexpressingcellsinbraintissuesignificantly(Pcomparedwiththehealthycontrolgroup.
While,treatmentofAlCl3intoxicatedratswithcerebrolysin,BM-MSCsorADMSCsincreasedthenumberofChATexpressingcellsinbraintissuesignificantly(Pcomparisonwiththegroupofratsleftuntreated.
Fig.
2:ImmunohistochemicalexaminationofChATexpressioninADmodelgroups.
(a):Healthycontrol,(b):ADuntreated,(c):AD+cerebrolysin,(d):AD+BM-MSCsand(e):AD+ADMSCsTable(3):NumberofChATexpressingcellsinbrainofADmodelratstreatedwithcerebrolysin,BM-MSCsorADMSCsNumberofChATexpressingcellsGroups2.
7±290.
0Healthycontrol6.
1a±142.
6ADuntreated10.
3b±194.
2AD+cerebrolysin7.
2b±211.
2AD+BM-MSCs5.
4b±208.
0AD+ADMSCsaSignificantchangeatPcomparisonwiththehealthycontrolgroup.
bSignificantchangeatPcomparisonwiththeADuntreatedgroup.
HistopathologicalalterationsinbraintissuesoffemaleratsTheopticalmicrographofacross-sectionedbraintissueofhealthycontrolgroupshowednormalhistologicalstructureofthehippocampusasrecordedinFig.
(3a).
While,theopticalmicrographofacross-sectionedbraintissueofAlCl3administeredgroupshowedencephalomelaciawithplaquesformationinthehippocampus(Figs.
3band3c).
Ontheotherhand,theopticalmicrographsofcross-sectionedbraintissuesofAlCl3intoxicatedratstreatedwithcerebrolysin,BM-MSCsorADMSCsshowednormalhistologicalstructureofthehippocampus(Figs.
3d,3eand3frespectively).
abcdebcHadeerA.
AglanetalDerPharmaciaLettre,2016,8(8):158-166163ScholarResearchLibraryFig.
3:Opticalmicrographofacross-sectionedbraintissueof(a):healthycontrolgroupshowsnormalhistologicalstructureofthehippocampus(hp);(bandc):untreatedADgroupshowsencephalomelacia(c)withplaquesformation(p)inthehippocampusand(d–f):ADgrouptreatedwithcerebrolysin,BM-MSCsorADMSCsshowsnormalhistologicalstructureofthehippocampus(hp)respectivelyDISCUSSIONThecapabilityofadultMSCstotransdifferentiateintoneuralcelltypeshasarousedgreatinterestinresearch.
SuchcapacityopensextensivepossibilitiesforusingMSCsasatherapeuticapproachesinavarietyofneurologicaldisorders[35].
Inthepresentstudy,weinvestigatethepotencyofasingledoseofintravenouslytransplantedMSCstorestraintheneurodegenerationinexperimentalmodelofADafter2months.
Forthispurpose,ADwasinducedchemicallyinexperimentalanimalsbyoraladministrationofAlCl3for75days.
VariouslinesofevidenceshaveindicatedthatintravenouslytransplantedMSCscouldmigrateandintegratelikeneuralstemcellsinthebrain[36,37].
Inconsistentwiththesestudies,thedataofthecurrentworkdemonstratedthattheintravenouslytransplantedMSCseitherderivedfromBM-MSCsorADMSCshadtheabilitytomigratetowardsinjuredbraintissues.
ThisfeaturecouldbealliedtoMSCsbroaderexpressionofhomingmolecules[38].
Moreindetails,Jietal.
[39]aswellasKarpandTeo[40]havereportedthatMSCsexpresschemokineC-Cmotifreceptor2(CCR2)thatinteractwithMCP-1andpromotetheirengraftment.
Moreover,anotherstudyhasdemonstratedthatupontransmigration,MSCssecretematrixmetalloproteinasestodegradetheendothelialbasementmembraneandfacilitateMSCsjourneyingtowardchemotacticagents[41].
ThecurrentdataindicatedthatAlCl3administrationincreasedserumTGF-β1andMCP-1levelssignificantly.
ThesefindingsareinconformitywiththepreviousstudiesofChaoetal.
[42]andGalimbertietal.
[43].
AccumulatedevidenceshavesuggestedthatAβdepositionplayacrucialroleinADdevelopmentasitoriginatesachronicinflammatoryresponse,whichlikelycontributestoneuronaldeath[44].
Furthermore,Praticoetal.
[45]reportedthatintoxicationwithAlcouldinducetheformationofreactiveoxygenspecies(ROS)whichinturnincreasebrainoxidativestressandlipidperoxidationthatpromotetheformationanddepositionofAβpeptide.
TheseAβpeptidesaggregatetoformfibrillardepositsthattriggersinflammatoryreactionsandactivatesmicrogliainADbrain.
IthasbeenreportedthatactivatedmicrogliacellswhicharelocalizedtofibrillarplaquesproduceTGF-β1mRNAandproteininresponsetoactivationbytheusualcohortofpro-inflammatorysignals[46].
Overandabove,Porcellinietal.
[47]reportedthatactivatedmicrogliaexpressalargenumberofbetachemokinesincludingMCP-1.
Theincreaseintheeffluxofcytokinesfrombraintoperipheralbloodsupply[48]couldexplaintheelevationinthelevelofserumTGF-β1andMCP-1.
Inthelightofthecurrentdata,treatmentofADratswithcerebrolysinfor2monthsreducedtheserumlevelofTGF-β1andMCP-1.
ThiseffectmightbeascribedtothecapabilityofcerebrolysintoreduceAβdepositsaswellasastroglialactivationasreportedbyXingetal.
[49].
Furthermore,ourdatashowedafter2monthsfromtreatmentofADratswithBM-MSCsorADMSCsdeclineinserumTGF-β1andMCP-1levels.
GrowingbodyofevidencehassuggestedthatimplantedMSCscouldmodulatethemicroglia/macrophageactivationincludinginflammatoryresponses[50].
Additionally,Leeetal.
[51]demonstratedthatBM-MSCshavetheabilitytopromotethereductionadefbcHadeerA.
AglanetalDerPharmaciaLettre,2016,8(8):158-166164ScholarResearchLibraryofAβdepositsandconsequentlysuppressmicrogliaactivation.
Inthesameline,ithasbeendocumentedthatadiposetissuederivedMSCshavetheabilitytodecreaseAβlevelthroughtheirsecretionofneprilysin[52].
Therefore,theobservedpotencyofthetransplantedMSCstodeclinetheestimatedseruminflammatorymarkersinthecurrentstudycouldbealliedtotheirabilitytoreduceAβdeposition.
EarlierstudiesshowedthatBDNFexpressionisextremelydiminishedinthehippocampusandsomecorticalareasinADpatients[53].
Also,Angeluccietal.
[54]statedthatdecreasedserumBDNFlevelmayreflectsimilaralterationsincentralnervoussystem.
Inlinewiththesefindings,thecurrentdatarevealedthatAlCl3administrationdecreasedserumBDNFlevelsignificantly.
ThisobservationcouldpossiblyexplainedbythefactthataccumulationofAlinthebraincausesinhibitionofBDNFfunctionsaswellasBDNFdepletion,andthattheexhaustionofBDNFpromotestheneurotoxicityofAβproteinandacceleratesADpathogenesis[55].
TreatmentofADratswithcerebrolysinproducedsignificantincreaseinserumBDNFlevel.
ThisfindingcomesinlinewiththepreviouslyreporteddataofSelianinaandKarakulova[56]anditcouldpossiblyascribedtothatcerebrolysinisamixtureofseveralactivepeptidefragmentsandneurotrophicfactorsincludingBDNFasdocumentedbyGeorgyetal.
[57].
Also,inthelightofthecurrentdata,injectionwithBM-MSCsorADMSCsincreasedthelevelofserumBDNFsignificantly.
ThisenhancingimpactmightbeattributedtotheirabilitytosecreteandaltertheexpressionofneurotrophicfactorsincludingtheBDNFasreportedbyJiangetal.
[58]andHanetal.
[59].
Accumulatedevidenceshavesuggestedthatcholinergichypoactivityhasadetrimentalinfluenceonneurogenesis[60].
Furthermore,ithasbeendemonstratedthatacetylcholineplaysanimportantroleinthebrainasagrowth-regulatorysignaltopromotetheproliferationofneuralstemcells[61].
Inlinewiththesestudies,ourresultsrevealedthatAlCl3administrationexperiencedsignificantdecreaseintheexpressionofbrainChATandnestingene.
ThiseffectcouldberelatedtothedegenerationofcholinergicterminalsincortexandhippocampusassociatedwithaluminumexposureasreportedbyPlattetal.
[62].
Inthecurrentstudy,injectionwithcerebrolysin,BM-MSCsandADMSCsincreasedtheexpressionofbrainChATandnestingenesignificantly.
TheenhancingeffectofcerebrolysinonthesemarkerslevelmightbeimputedtoitsneurotrophicandneurogeniceffectsasattestedbyRockensteinetal.
[63].
While,thepotencyofMSCstoincreasetheexpressionofthesemarkerscouldbeassignedtotheirmigrationthroughoutthebrainanddifferentiationintoneuronsandglialcellsthatexpressChATandnestinasreportedbyBalasubramanianetal.
[64],Mezeyetal.
[65]andParketal.
[66].
TheobservedalterationsintheestimatedmarkersbyAlCl3administrationinthecurrentworkwereconfirmedpathologicallybythepresenceofplaquesformationinthehippocampus.
ThisfindingisgreatlysupportedbythatofRodellaetal.
[67]whodemonstratedthatoralAlexposurecausestheaccumulationofbetaamyloidproteinandneurodegenerativedamageinAD-model.
Ontheotherhand,thereisnoevidenceofamyloidplaquesdepositioninthebrainoftheratstreatedwithcerebrolysin,BM-MSCsandADMSCs.
TheAβclearingeffectexertedbycerebrolysinadministrationcouldbeattributedtoitsabilitytoregulateAβdegradationandmodulateAPPexpression,maturation,orprocessingasreportedbyRockensteinetal.
[68].
While,theobservedclearanceofAβduetotreatmentwithMSCscouldbeexplainedbytheirabilitytoremoveAβdepositsandelevatethelevelsofAβ-degradingenzymesasdocumentedbyLeeetal.
[51]andMaetal.
[15].
CONCLUSIONTheresultsofthecurrentstudylendfurthercredencetothenotionthatMSCsaremultipotenttherapeuticapproachthatnotonlyreduceinflammationandclearAβdeposition,butalsoholdthepotentialtoincreaseneurotrophicfactorsandenhanceneurogenesis.
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