REINFORCED SCAFFOLD FOR TISSUE ENGINEERING - Intelligent Scaffolds for Tissue Engineering and Regenerative Medicine - page 568

28.3.2 Bioartificial Bone
Bonefractureorinjuriesoccurforvariousreasons,includingdegen-
erative,surgical,andtraumaticprocesses.Suchinjuriescompromise
the quality of life. There are some critical-size defects above which
bone will not regenerate and will instead require clinical repair.
When using a biodegradable material for tissue repair, the biocom-
patibilityandtoxicityofboththescaffolditselfandby-productsofits
degradation and subsequent metabolites must all be considered. 41
Various synthetic and natural materials have been used to facilitate
the repair of bone, including PGA, PLLA, polylactic-co-glycolic acid
(PLGA), PCL, poly(ethylene-co-vinyl alcohol), HA, tricalcium phos-
phate (TCP), demineralized bone matrix (DMB), SIS, collagen, chi-
tosan,andhyaluronate. 42 − 59 Suchmaterialsareusedeitheraloneor
in mixtures, but the mechanical properties of the porous or blended
scaffold are still much lower than that ofnatural sponge bone.
Regarding scaffolds used to repair bone, it is generally agreed
that a highly porous structure and a large surface area are conduc-
tivetocellgrowthandthatasatisfactoryscaffoldshouldpossessbio-
compatibility and satisfactory mechanical properties. Indeed, only
materials that possess proper mechanical properties can enable the
scaffoldtomaintainitsshapeandstructureafterbeinginimplanted
in the defect.
Li et al . attempted to increase the mechanical strength of scaf-
folds using nano-HA and collagen sponge reinforced with chi-
tosan fiber. It has been reported that chitin induces fibroblasts to
release IL-8, which is involved in the migration and proliferation
of fibroblasts and vascular endothelial cells. 60 , 61 Chitosan fibers
can enhance the compressive strength of the scaffold by about
four times, and a human marrow MSC culture revealed that the
reinforced scaffold was more cytocompatible than a scaffold with-
out reinforcement. 14 Additionally, bone regeneration was evaluated
after implantation by radiography, histology, bone mineral density,
and mechanical strength. The results revealed that only the chitin
reinforcedimplantsshowednearlyperfectregenerationat15weeks
after operation. 15 Reinforcement of PGA fiber resulted in a collagen
sponge having increased compression in vitro and in vivo . In addi-
tion, when rat MSCs were seeded into scaffolds, more attached cells