Cartilage-tissue-engineering-PLLA-scaffold

1、Biomaterials26(2005)1253–1259CartilagetissueengineeringPLLAscaffoldwithsurfaceimmobilizedcollagenandbasicﬁbroblastgrowthfactor$ZuweiMa,ChangyouGao*,YihongGong,JiacongShenDepartmentofPolymerScienceandEngineering,ZhejiangUniversity,Hangzhou310027,ChinaReceived27January2004;accepted8April2004Availableonline21July2004AbstractApreviouslyreported‘‘graftingandcoating’’method(J.Biomed.Mater.Res.(Appl.Biomater.)63(2002)838)wasmodiﬁedandusedtointroducestablecollagenlayerandincorporatebasicﬁbroblastgrowth。

2、factor(bFGF)onPLLAscaffoldsurfacetopreparetissueengineeringscaffoldwithimprovedbiocompatibility.Tomakethemodiﬁcationofthe3-DporousPLLAscaffoldpossible,graftingofpolymethacrylicacid(PMAA)ontothePLLAsurfacewasinitiatedbythe–OOH/Fe2+systeminsteadoftheUVlightusedintheformermethod.WatersolublecarbodimmidechemistrywasappliedtograftcollagenontothePLLAscaffoldsurface,followedbyphysicalcoatingofthecollagensolutionwithorwithoutbasicﬁbroblastgrowthfactor(bFGF).Surfacemodiﬁcationof2-DPLLAmembranewasalsodone。

3、forfundamentalunderstandingofthemodiﬁcation.The–COOHdensityon/inthePMAAgraftedPLLAmembrane/scaffoldwasmeasuredbycolorimetricmethodandthecollagencontenton/inthecollagenimmobilizedPLLAmembrane/scaffoldwasmeasuredbyninhydrinmethod.ChondrocyteculturingonthecollagenimmobilizedPLLAsurfacesshowedsigniﬁcantlyimprovedcellspreadingandgrowth.Incorporationofﬁbroblastgrowthfactorsinthecollagenlayerfurtherenhancedthecellgrowth.Thisconvenientandeffectivemethodcanbeusedtopreparebioactivescaffoldswithextracellul。

4、armatrix(ECM)-mimiccompositionfortissueengineering.r2004ElsevierLtd.Allrightsreserved.Keywords:PLLA;Surfacemodiﬁcation;Scaffold;Tissueengineering;Growthfactor1.IntroductionInspiteofthegreatvarietyinthematerialsandmethodsemployedinthefabricationoftissueengineer-ingscaffolds,theprincipleforthescaffolddesigningremainsclear:thescaffoldshouldbedesignedbymimickingthenativeextra-cellularmatrix(ECM)asmuchaspossible,bothintermsofchemicalcompositionandphysicalstructure.TherolethattheECMplaysisfarmoregreat。

5、erthanjustprovidingaphysicalsupportforthecells.Itprovidesasubstratecontainingadhesionproteinsforcelladhering,andregulatescellulargrowthandfunctionbypresentingdifferentkindsofgrowthfactorstothecells.AnidealECM-mimictissueengineeringscaffoldshouldcontainbothadhesionproteinsandgrowthfactors.Syntheticbiodegradablepolymersarenowwidelyusedintissueengineeringduetotheirgenerallygoodstrengthandadjustabledegradationspeed[2].However,thechemicallyandbiologicallyinertpolymericmaterialsareunlikelytoinducecell。

6、adhesionandtissueforma-tion.Toovercomethisdrawbackofthesyntheticmaterials,naturallyoccurringpolymersextractedfromthenativeECMlikecollagenhavebeenwidelyusedtomodifythesyntheticmaterialtoimprovethecelladhesionproperties[3].Inadditiontothenaturallyoccurringstructuralpolymers,cellgrowthfactorsshouldalsobeincorpo-ratedintothetissueengineeringscaffoldtoenhancecellgrowthrateandadjustcellfunctions.AlthoughthebasicprinciplesforregulatingtheassemblyofcellsintothefunctionaltissuesarefarfrombeingwellARTICLE。

7、INPRESS$Financialsupport:TheMajorStateBasicResearchProgramofChina(G1999054305).*Correspondingauthor.Tel.:+86-571-87951108;fax:+86-571-87951948.E-mailaddresses:nnimzw@nus.edu.sg(Z.Ma),cygao@mail.hz.zj.cn(C.Gao).0142-9612/$-seefrontmatterr2004ElsevierLtd.Allrightsreserved.doi:10.1016/j.biomaterials.2004.04.031understood,itisclearthatthegrowthfactorsprovidepowerfultoolstocontrolmanycellularbehaviorsassociatedwithsuccessfultissueformation[4].Manymethodshavebeenusedtohybridizethegrowthfactorwithtissu。

8、eengineeringscaffolds.Thechallengeliesinhowtomixthewater-solublegrowthfactorsandthehydrophobicsyntheticmaterialsevenly.Differentpro-teindeliverytechnologiessuchaswater/oilemulsiontechnique,polymermicro-spheresandpolymerhydro-gelshavebeenusedforgrowthfactordeliveryfromtissueengineeringscaffolds[5–8].Inapreviousworkweintroducedaconvenient‘‘graftingandcoating’’methodtoobtainstablecollagenlayeron2-DPLLAmembranesurfaces[1].Inthatwork,UV-inducedgraftingpolymerizationofmethacrylicacid(MAA)onPLLAsurface。

9、wasﬁrstcarriedouttointroduce–COOHgroups,followedbythechemicalgraftingofcollagentypeIusingwater-solublecarbodimmideascouplingagent.Atthesametime,thephysicallycoatedcollagenwasretainedtoobtainastablecollagenlayeronthePLLAmembranesurface.Inthiswork,toextendthesurfacemodiﬁcationtechniqueto3-DPLLAscaffolds,theUV-inducedpolymerizationofMAAwasreplacedbythe–OOH/Fe2+-inducedpolymerization,whichmadethesurfacemodiﬁcationof3-DPLLAscaffoldspossible.Usingthemodiﬁedtechnique,stablecollagenlayerwasformedontothe。

10、wallofthe3-DPLLAscaffolds.Finally,bFGFwasintroducedintothePLLAscaffoldviamixingwithcollagensolution.Chondrocyteculturingwasperformedtoevaluatethebiocompatibilityofthesurfacemodiﬁedscaffolds.2.Experiment2.1.MaterialsandreagentsPLLA(Mn=200,000,Mw=400,000)wassynthesizedusingthemethoddescribedin[9].PLLAmembraneswereobtainedbythesolutioncastingmethod.3-DPLLAscaffoldswithaporediameterof280–450mmandporosityof98%werepreparedusingaparafﬁnsphereleachingmethoddescribedin[10].Thescaffoldswerecutinto1.51.51。