简介：Thedistributionofacetylcholinesterase(AChE)-positivestructuresinthedevelopingratspinalcordwasstudiedwithAChE-histochemistry.AChE-positiveperikaryawerefirstseenonembryonicday14(E14)intheventrolateralportionofthespinalcord.Fromthattimeonward.AChE=containingcellsappearedgraduallyintheintermediategray,dorsalhornandlateralspinalnucleusofthespinalcordinaventral-to-dorsal,andlateral-to-medialorder.Noobviousrostral-to-caudalsequencewasfound.Atbirth,thedistributionpatternofAChE-positiveperikaryawasbasicallysimilartothatinadults.AfterbirthadramaticincreaseintheAChEstainingintensityextendedfrompostnatalday5(P5)topostnatalday21(P21),Inaddition,twophasesoftransientAChEstainingwereobservedintheexternalsurfaceofthedorsalhornfromembryonicday15(E15)toembryonicday21(E21)andinthemarginallayerfromembryonicday21(E21)topostnatalday14(P14),respectively.

简介：Withtheexceptionofmatureerythrocytes,cellswithinthehumanhematopoieticsystemarecharacterizedbythecellsurfaceexpressionofthepan-leukocytereceptorCD45.Here,weidentifyanovelsubsetamongmononuclearcordbloodcellsdepletedoflineagecommitmentmarkers(Lin-)thataredevoidofCD45expression.Surprisingly,functionalexaminationofLin-CD45-cellsalsolackingcellsurfaceCD34revealedtheywerecapableofmultipotentialhematopoieticprogenitorcapacity.Co-culturewithmouseembryoniclimbbudcellsdemonstratedthatLin-CD45-CD34-cellswerecapableofcontributingtocartilagenodulesanddifferentiatingintohumanchondrocytes.BMP-4,amesodermalfactorknowntopromotechondrogenesis,significantlyaugmentedLin-CD45-CD34-differentiationintochondrocytes.Moreover,unlikeCD34+humanhematopoieticstemcells,Lin-CD45-CD34-cellswereunabletoproliferateorsurviveinliquidcultures,whereassingleLin-CD45-CD34-cellswereabletochimerizetheinnercellmass(ICM)ofmurineblastocystsandproliferateinthisembryonicenvironment.OurstudyidentifiesanovelpopulationofLin-CD45-CD34-cellscapableofcommitmentintobothhematopoieticandchondrocyticlineages,suggestingthathumancordbloodmayprovideamoreubiquitoussourceoftissuewithbroaderdevelopmentalpotentialthanpreviouslyappreciated.

简介：Humanplacenta-derivedmononuclearcells(MNC)wereisolatedbyaPercolldensitygradientandculturedinmesenchymalstemcell(MSC)maintenancemedium.Thehomogenouslayerofadherentcellsexhibitedatypicalfibroblastlikemorphology,alargeexpansivepotential,andcellcyclecharacteristicsincludingasubsetofquiescentcells.Invitrodifferentiationassaysshowedthetripotentialdifferentiationcapacityofthesecellstowardadipogenic,osteogenicandchondrogeniclineages.FlowcytometryanalysesandimmunocytochemistrystainshowedthatplacentalMSCwasahomogeneouscellpopulationdevoidofhematopoieticcells,whichuniformlyexpressedCD29,CD44,CD73,CD105,CD166,laminin,fibronectinandvimentinwhilebeingnegativeforexpressionofCD31,CD34,CD45andα-smoothmuscleactin.Mostimportantly,immuno-phenotypicanalysesdemonstratedthatthesecellsexpressedclassImajorhistocompatibilitycomplex(MHC-Ⅰ),buttheydidnotexpressMHC-Ⅱmolecules.Additionallythesecellscouldsuppressumbilicalcordblood(UCB)lymphocytesproliferationinducedbycellularornonspecificmitogenicstimuli.Thisstronglyimpliesthattheymayhavepotentialapplicationinallografttransplantation.SinceplacentaandUCBarehomogeneous,theMSCderivedfromhumanplacentacanbetransplantedcombinedwithhematopoieticstemcells(HSC)fromUCBtoreducethepotentialgraft-versus-hostdisease(GVHD)inrecipients.