Biomedical Engineering Reference
In-Depth Information
with.a.diameter.of.214.±.25.nm.were.produced.successfully,.and.the.HAp.nanoparticles.
were.incorporated.into.the.electrospun.nanoibers..In.vitro.cell.culture.with.hFOB.showed.
that.the.incorporation.of.HAp.nanoparticles.into.CHI.nanoibrous.scaffolds.led.to.signii-
cantly.more.bone.formation.than.that.with.electrospun.pure.CHI.scaffolds.(Zhang.et.al.,.
2008)..In.another.study,.COL.and.HAp.were.combined.in.PLLA,.forming.three.different.
scaffold.types:.PLLA,.PLLA/HA,.and.PLLA/COL/HAp..In.these.scaffolds.COL.and.HAp.
were.expected.to.provide.cell.recognition.sites.and.introduce.osteoconductivity,.an.impor-
tant.issue.in.bone.mineralization,.respectively..Fiber.diameter.was.found.to.decrease.upon.
the.addition.of.HAp.and.COL.to.PLLA..Human.fetal.osteoblasts.were.found.to.adhere.and.
grow.actively.on.PLLA/COL/HAp.nanoibers,.with.mineral.deposition.increased.by.57%.
in.comparison.to.PLLA/HAp.nanoibers.(Prabhakaran.et.al.,.2009).
Some.other.ingredients.introduced.to.polymers.to.improve.the.biomechanical.properties.
and.material-cell.interaction.for.bone.tissue.engineering.applications.are.calcium.carbon-
ate. (CaCO
3
). and. β-TCP. nanoparticles.. Fujihara. and. his. co-workers. (2005). used. a. guided.
bone.regeneration.(GBR).approach.with.the.aim.of.producing.a.calcium-rich.and.mechani-
cally.stable.membrane..This.was.achieved.by.the.preparation.of.PCL.nanoibers.contain-
ing.CaCO
3.
nanoparticles..A.PCL-based.membrane.was.compared.with.that.based.on.PCL/
CaCO
3
,.and.a.higher.cell.adherence.was.observed.in.the.latter..The.tensile.strength.of.PCL.
nanoibrous.membranes.decreased.when.the.amount.of.calcium.carbonate.nanoparticles.
was.increased;.that.is,.an.increase.in.the.amount.of.CaCO
3
.resulted.in.more.brittle.mem-
branes..However,.it.was.stated.that.these.membranes.have.suficient.tensile.strength.for.
guided.bone.regeneration.(Fujihara.et.al.
,
2005).
Functionally.graded,.nonwoven.mats.of.PCL.with.β-TCP.nanoparticles.were.produced.
by. using. a. hybrid,. twin-screw. extrusion/electrospinning. (TSEE). process. (Erisken. et. al.,.
2008)..This.procedure.allows.feeding.of.various.liquid.and.solid.materials,.achieving.melt-
ing,.dispersion,.pressurization,.and.electrospinning.within.a.single.process,.with.the.com-
position.changing.in.a.time-dependent.manner..The.potential.of.these.scaffolds.for.tissue.
engineering. and. bone-cartilage. interface. formation. was. demonstrated. by. using. mouse.
calvaria-derived.murine.preosteoblast.(MC3T3-E1).cells..The.ability.to.control.the.incorpo-
ration.of.β-TCP.resulted.in.a.better.mimicking.of.the.compositional.and.structural.charac-
teristics.of.bone.tissue.(Erisken.et.al.,.2008).
10.5.2 Nerve Tissue Engineering
The.structure.of.the.nervous.system.is.important.for.its.functionality;.therefore,.the.archi-
tecture.of.the.nerve.tissue.should.be.well.known.in.order.to.be.able.to.design.the.most.suit-
able.nerve.substitute.for.nerve.regeneration..In.nervous.tissue.the.axons.are.bundled.into.
cables.that.provide.long-distance.communication.between.the.brain.and.spinal.cord.and.
the.rest.of.the.body..The.nerves.in.the.peripheral.nervous.system.(PNS).are.composed of.
bundled. motor. and. sensory. axons. in. parallel. arrays. in. connective. tissue. and. are. called.
the.nerve.trunk.(Schmidt.and.Leach,.2003)..The.individual.axons.and.their.Schwann.cell.
sheaths.are.surrounded.by.endoneurium,.which.is.composed.predominantly.of.oriented.
collagen. ibers.. Groups. of. axons. are. wrapped. by. the. perinerium,. which. is. composed. of.
many. layers. of. lattened. cells. (i.e.,. ibroblasts). and. collagen. to. form. fascicles.. An. outer.
sheath.of.loose.ibrocollagenous.tissue,.the.epineurium,.assembles.individual.nerve.fas-
cicles. into. a. nerve. trunk.. The. vascularization. in. these. nerves. is. provided. by. capillaries.
within.the.support.tissue.of.the.nerve.trunk,.or.by.vessels.penetrating.into.the.nerve.from.
surrounding.arteries.and.veins..Within.the.central.nervous.system.(CNS),.the.brain.and.
spinal. cord,. such. bundled. together. axons. are. called. nerve. tracts.. Typically,. the. neuron.
