Biomedical Engineering Reference
In-Depth Information
14.3 Nanofibrous Materials for Bone Tissue Engineering
14.3.1
Biodegradable Polymers
As a matrix for bone cell culturing and regeneration of hard tis-
sues, a range of biopolymers with synthetic origin have been
used, which include poly(
α
-hydroxyl acid), such as poly(lactic acid)
(PLA), poly(glycolic acid) (PGA), and poly(
ε
-caprolactone) (PCL),
and poly(hydroxyalkenoate), such as poly(hydroxybutyrate) (PHB)
and poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV). Moreover,
naturalpolymerssuchascollagen,gelatin,silk,andchitosanarealso
considered attractive material choicesfor boneregeneration.
For the electrospinning of synthetic polymers, organic solvents
such as chloroform, dichloromethane, and tetrahydrofuran have
beenused,whilstawater-basedsolventsystemisgenerallyrequired
to dissolve natural polymers. Otherwise, fluorinated solvents, such
as hexafluoropropanol and trifluoroethanol, can be introduced to
dissolvecollagenandgelatin,aswellastheirmixtureswithsynthetic
polymers.
PCL has long been studied as a degradable nanofiber matrix for
bone regeneration.
11
Rat bone marrow stem cells (rBMSCs) were
demonstrated to develop a bone matrix after 4 weeks of culturing
on PCL nanofibers, such as secretion of type I collagen and calcium
mineralization.PLAnanofibersalsoshowedgoodresponsestobone
cells(MC3T3-E1).
12
Shin
et al
.investigatedthatPCLnanofiberswell
supported the growth of cells and bonelike tissue formation
in vivo
when the cell-nanofiber construct was implanted in the rat for 4
weeks, suggesting the potential of PCL nanofibers for bone tissue
engineering.
13
PHB and PHBV electrtospun fibers were shown to
have higher osteoblastic cell growth level than their equivalent flat
films, whilemaintainingosteoblasticphenotypes.
14
Although synthetic polymers have shown the potential as a cell
and tissue matrix, their hydrophobic nature needs to be overcome
to find extended uses in the tissue regeneration area. One simple
approach is to blend the synthetic polymers with natural polymers,
as the natural components will increase hydrophilicity and initial
cellular events.
15
,
16
PCL was blended with gelatin in a co-solvent
and electrospun into a nanofibrous matrix without the formation of
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