CELL - BASED NANOCOMPOSITES AND BIOMOLECULES FOR BONE TISSUE ENGINEERING - Advanced Biomaterials: Fundamentals, Processing, and Applications - page 543

hyaluronic acid and glycerol. Donor variability is another concern in determining
the osteoinductivity of the DBM material. It has been demonstrated that various
commercially-available DBMs exhibited different biological properties for the
induction of spinal fusion in an athymic rat model 8 . As such, there is a medical
need to address these pertinent issues by developing a new class of tissue-
engineered bone grafts for orthopedic applications.

16.2.2 Nanotechnology-Enabled Tissue Engineering
The principle of tissue engineering is to regenerate diseased/damaged tissue or
organ by the use of biodegradable materials with or without biological factors.
Through the extensive understanding of the structure and chemical composition
of natural bone, bone grafts can be designed to mimic the native bone to achieve
optimal performance.
The major components of natural bone are hydroxyapatite and Type I colla-
gen. Two-third of bone by weight is nanophase hydroxyapatite which is the
mineral constituent 9 . Type I collagen is the main structural protein, contributing
up to 30% of the dry weight of bone and 90-95% of the non-mineral (organic)
content 9,10 . Structurally, bone encompasses fi ber bundles made up of collagenous
nanofi brils. Besides collagen, non-collagenous proteins such as osteocalcin, osteo-
pontin, osteonectin, bone sialoprotein, and so on, are part of the composition of
bone. Other components also consist of calcium, phosphate, hydroxyl, carbonate,
fl uorine, sodium, magnesium, silicon, zinc and aluminum ions 9 . The hype of fabri-
cating nano-scale materials or the like is due to the current advancement in nano-
technology, in areas such as electronics, fi ltration, catalysts, textiles, drug delivery,
and so on.
In particular, tissue engineering is making waves in the research and develop-
ment arena because of the seminal discoveries of enhanced absorption of biomol-
ecules, such as vitronectin on the scaffold due to a high surface area-to-volume
ratio 11 , which is important for wound healing. The fi bers or scaffolds being in
nanometer scale (in diameter) are said to mimic the natural extracellular matrix
(ECM), creating a more favorable environment for cellular interaction. Biode-
gradable materials are popular options for this new class of bone grafts. These
materials can be either synthetic or natural polymers. Ultimately, researchers aim
to develop bone grafts which surpass the status quo of existing bone grafts. A
cocktail of growth factors and cells are usually integrated within the material as it
is believed that the synergistic interactions between the material, cells, and
growth factors will augment the effectiveness of such regenerative therapies in
bone repair, as depicted in Figure 16.1.

16.2.3 Factors for Bone Regeneration
Besides diseases and trauma, several other factors affect osteogenesis. In
cell culture experiments, dexamethosone, ascorbic acid,

- glycerophosphate,
1,25-Dihydroxyvitamin D3 are supplements to formulate an osteogenic media to

β