Biomedical Engineering Reference
In-Depth Information
ibers. as. the. scaffold,. and. a. combination. of. micron-sized. ibers. with. codeposition. of. a.
hyaluronic.acid.(HA)-derived. hydrogel,.Heprasil..In.the.irst.procedure,.PCL/COL.solu-
tion.was.electrospun.in.the.presence.of.PEO,.which.was.then.removed.selectively.in.order.
to. increase. the. scaffold. porosity.. In. the. second. approach,. PCL/COL. was. electrospun. in.
micrometer-sized.PCL/COL.(µmPCL/COL)..The.third.method.involved.the.cospraying.of.
µmPCL/COL.matrix.with.Heprasil..All.the.scaffold.types.supported.attachment.and.pro-
liferation. of. human. fetal. osteoblasts. (hFOB).. While. selective. leaching. improved. cellular.
iniltration.to.a.low.degree.compared.to.meshes.obtained.by.conventional.electrospinning,.
µmPCL/COL. microibers. allowed. better. penetration.. This. effect. was. more. pronounced.
when.Heprasil.regions.were.present.in.the.structure.
A.fabrication.method.that.can.be.used.to.solve.the.low.penetration.problem.is.the.use.
of. electrospun. nano/microibers. in. combination. with. 3D. macroiber. deposition.. In. this.
design,. macroibers. are. expected. to. play. a. role. in. the. structural. integrity. and. mechani-
cal.properties.of.the.scaffolds,.whereas.the.nano/microibers.can.act.as.a.cell.entrapment.
system.and.a.cell.adhesion.promoter..The.inluence.of.this.nano/microibrous.network.on.
the.behavior.of.endothelial.cells.(EC).seeded.onto.a.scaffold.based.on.a.starch.and.PCL.
blend.was.studied.by.Santos.et.al..(2008)..They.have.shown.that.the.nanoibers.inluenced.
cell.morphology.and.the.maintenance.of.the.physiological.expression.pattern..They.also.
showed. these. EC-seeded. scaffolds. to. be. sensitive. to. pro-inlammatory. stimulus;. that. is,.
the.cells.could.migrate.and.form.capillary-like.structures.within.a.3D.gel.of.collagen.in.
response.to.some.angiogenesis-stimulating.factors.(Santos.et.al.,.2008).
A.procedure.that.has.been.recently.reported.is.on-site.layer-by-layer.(LBL).tissue.regen-
eration,.which.involves.electrospinning.one.layer.of.the.polymeric.solution,.then.seeding.
the. cells. onto. this. layer. and. repeating. these. steps. to. create. a. 3D. scaffold. with. the. cells.
already. inside.. This. method. is. advantageous. in. that. a. highly. speciic. 3D. environment.
can.be.created.by.varying.the.composition.of.the.ibrous.layers,.iber.thickness,.diameter,.
and. orientation. as. desired,. and. the. neotissue. formation. can. be. unambiguously. reduced.
(Agarwal.et.al.,.2009).
Another.way.to.improve.cell.carrier.properties.is.surface.modiication.of.the.ibers..A.
higher.degree.of.spreading.and.growth.of.Saos-2.on.PHBV.and.some.of.its.blends.has.been.
shown.by.our.research.group.by.treating.with.oxygen.plasma.in.order.to.increase.hydro-
philicity.by.adding.some.functional.groups.on.the.scaffold.surface.(Ndreu.et.al.,.2008).
An. appropriate. biomechanical. property. is. another. challenge. in. bone. tissue. engineer-
ing,.since.the.engineered.tissue.must.be.able.to.retain.its.shape.and.withstand.the.forces.
applied.after.implantation..It.is.well.known.that.a.signiicant.part.of.the.bone.is.constituted.
of.calcium.phosphate.mineral.phase..The.presence.of.bone-inducing.inorganic.components.
within.bone.substitutes.enhances.calcium.phosphate.deposition.after.the.osteogenic.dif-
ferentiation.process..The.apatite.minerals.and.proteins/peptides,.as.well.as.drugs.encap-
sulated.within.the.nanoibers,.are.a.promising.strategy.used.for.nanoibrous.materials.to.
achieve.adequate.mechanical.properties.and.bone-speciic.bioactivity.(Jang.et.al.,.2009).
HAp.plays.a.crucial.role.in.the.biomechanics.of.bone.tissue,.especially.in.increasing.the.
compressive.strength..Therefore,.an.increase.in.the.number.of.papers.reporting.the.addi-
tion.of.this.material.to.nanoibrous.scaffolds.is.being.seen..Gelatin-HAp.electrospun.nano-
ibrous.scaffolds.were.produced.by.Kim.et.al..(2005).to.mimic.the.human.bone.matrix,.and.
higher. cellular. activity. was. reported. with. these. scaffolds,. compared. to. those. prepared.
with.only.gelatin..Zhang.et.al..(2008).have.reported.the.use.of.electrospinning.in.combina-
tion.with.an.in.situ coprecipitation.synthesis.in.the.preparation.of.nanocomposite.ibers.of.
HAp/chitosan.(CHI)..Production.of.continuous.nanoibers.was.possible.after.addition.of.a.
iber-forming.polymer,.ultrahigh.molecular.weight.PEO..Continuous.HAp/CHI.nanoibers.
Search WWH ::




Custom Search