Biomedical Engineering Reference
In-Depth Information
mechanical.properties.and.also.lose.mechanical.strength.very.quickly.due.to.degradation,.
while.synthetic.polymers.alone.are.generally.too.hydrophobic.and.lack.binding.sites.for.
cell.adhesion.(Gupta.et.al.,.2009)..Consequently,.a.blend.or.a.graft.of.natural.and.synthetic.
polymers. is. an. effective. way. to. obtain. scaffolds. with. desirable. properties.. A. summary.
of.nano/microibrous.scaffolds.used.in.vitro.and.in.vivo.in.nerve.regeneration.studies.is.
given.in.Table 10.2.
Electrospinning. is. a. straightforward. technique. to. obtain. random. and. aligned. nano/
microibers..Even.though.the.randomly.oriented.ibers.are.easier.to.obtain.and.are.more.
frequently.used.in.nerve.tissue.engineering,.the.use.of.the.aligned.ibers.is.a.challenging.
but. rewarding. approach. in. mimicking. the. unidirectional. orientation. to. maintain. func-
tion.of.the.nerve.tissue.(Table 10.2)..Fibers.aligned.longitudinally.(parallel.to.nerve.axis).
may.provide.a.suitable.environment.that.encourages.contact.guidance.and.the.directional.
neuronal/axonal.growth.desired.in.nerve.tissue.engineering..Yang.et.al..(2005).observed.
the.positive.effect.of.contact.guidance.by.aligned.ibrous.scaffolds.(diameters.of.aligned.
micro-.and.nanoibers:.1.5.µm.and.300.nm,.respectively).on.neural.stem.cells.that.had.been.
induced.to.elongate.neurites.parallel.to.the.iber.axis..The.cell.elongation.and.the.neurite.
outgrowth.were.random.on.the.randomly.oriented.mats.(diameters.of.random.micro-.and.
nanoibers:.1.25.µm.and.250.nm,.respectively),.proving.the.signiicance.of.guidance..This.
guidance. was. observed. on. aligned. nano/microibers. regardless. of. iber. diameter.. The.
effect.of.iber.arrangement.was.also.observed.in.our.studies.carried.out.with.neural.stem.
cells.seeded.on.ibrous.mats..Electrospun.PHBV-PLGA.ibers.were.produced.under.opti-
mized.conditions.(PHBV-PLGA.solution:.1:1.w/w,.15%.w/v,.in.chloroform:.dimethylforma-
mide.(CHL:DMF)).with.a.diameter.of.ca..1.5.µm.(Yucel.et.al.,.2010)..The.stem.cells.seeded.
on.the.aligned.ibers.were.well.oriented.along.the.axis.of.the.ibers,.while.the.cells.on.the.
random.ibers.appeared.to.be.in.clusters.distributed.in.all.directions.(Figure 10.
2
)..Similar.
results. were. also. obtained. with. dorsal. root. ganglion. (DRG). explants. cultured. on. PLLA.
nanoibers. (Patel. et. al.,. 2007).. Signiicant. extension. of. neurites. was. observed. on. aligned.
ibers,.while.there.was.no.neurite.outgrowth.on.randomly.oriented.ibers..Like.other.cells,.
human.Schwann.cells.responded.to.the.iber.orientation.with.elongation.along.the.ibers.
A
B
FIGURE 10.2
CLSM.images.of.neural.stem.cells.on.ibronectin-coated.PHBV-PLGA.scaffolds..(A).Randomly.oriented.and.(B).
aligned.ibers.(100×;.scale.bar,.250.µm;.two-sided.arrow,.direction.of.iber.axis;.Acridine.orange.stain)..Insets.
show.the.SEM.images.of.the.ibrous.mats.
