Biomedical Engineering Reference
In-Depth Information
of novel delivery and targeting systems of genetic material encoding
osteogenic growth factors, and the fabrication of nanofi brous scaffolds to
support cell growth and differentiation through morphologically-favored
architectures [113]. Polymeric nanofi ber matrices have been explored to be
biologically similar to the native bone extracellular matrix architecture and,
when incorporated onto biodegradable microscopically porous polymeric
3D scaffolds, have the potential to be used as bone biomimetic regenera-
tion substrates. Their nanoscale topography enhances cellular adhesion and
MSCs stimulation to produce bone mineral, while the scaffold's open geom-
etry and porosity promotes cell penetration and nutrient transport [114].
Carbon nanotubes have recently attracted attention in bone regenera-
tion materials due to their excellent mechanical strength, their promotion
to cell attachment and proliferation and their pro-osteogenic properties
showing support to osteoblastic growth and modulation of the osteo-
blastic phenotype. Besides, they can be readily incorporated as reinforc-
ing agents into the 3D architectures of a polymeric scaffold [115-117] that
would not otherwise perform as effi ciently [118].
On the other hand, nanoscale strategies are being developed to include
in the scaffold functional motif sequences of complex biomimetic materi-
als or short peptides that promote cellular adherence and osteogenic dif-
ferentiation and maturation [119-121]. Modifi cations of polymer surface
with BMP-related peptide [122, 123], full length BMP [124] or osteocalcin
crosslinked to nano-HA [125, 126] have been employed to mimic extra-
cellular matrix signaling and have been shown to enhance osteoblastic
cell attachment and bone matrix synthesis. As compared to conventional
polymers, the adsorption and conformation of proteins that regulate
osteoblasts adhesion and functions (such as fi bronectin and vitronectin)
were enhanced on nanophase surfaces [127]. Regarding a yet limited
application for dental tissue, scaffold coating with RGD integrins recogni-
tion sequence resulted in more mineralized osteodentin-like tissue [128].
Being similarly mineralized collagenous tissues, such nanoengineering
approaches could be applied for dentin and cementum, however, poten-
tial avenues and directions have yet to be fully exploited [110].
In conclusion, nanoscale technologies offer compelling benefi ts in terms
of controlling scaffold architecture, biomechanics, growth factor delivery,
vascularity, cellular spatial orientation and temporal signaling.
6.6
Biomimetic Surfaces, Implications for Dental
and Craniofacial Regeneration; Biomaterial as
Instructive Microenvironments
When a surface of an implant material comes in contact with biologi-
cal systems, initial events are dominated by protein adsorption, blood
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