CELL - BASED NANOCOMPOSITES AND BIOMOLECULES FOR BONE TISSUE ENGINEERING - Advanced Biomaterials: Fundamentals, Processing, and Applications - page 560

Figure 16.7. Anorganic bone mineral (ABM) embedded in hyaluronate hydrogel. 118

those samples in the perfusion culture system exhibiting a greater and homoge-
nous distribution of bone formation in a rat model. This was indicative that the
fl ow velocity of the perfusion culture system accelerated the osteogenic differen-
tiation of the MSCs 115 .
A pivotal cell-binding domain of human Type I collagen located in the - 1 (I)

chain sequence (P-15) has been studied 116,117 . The P-15 peptide was said to facili-
tate bone formation; therefore, this peptide had been used as a coating to mimic
bone matrix components 118 . For instance, P-15 peptides were coated on anorganic
bone mineral (ABM) particles and suspended in injectable hydrogels (such as
hyaluronate (Hy) as seen in Figure 16.7, sodium alginate, carboxymethylcellu-
lose) promoted cellular adhesion, osteoblastic activity, and mineral deposition.
Preferential adhesion of osteoblast-like cells was observed on the hydrogels with
P-15 peptide, with more cell coverage and scattering, suggestive that P-15 peptide
also reinforced cellular migration. In the presence of P-15 peptide on ABM (with
or without hydrogel), more actin and stress fi bers were seen compared to ABM
surfaces, which had little cell spreading and stress fi bers, indicative of the adhe-
sive properties of P-15 peptide. The upregulation of gene expression such as
ALP, BMP-2 and BMP-7 after ten days of culture and mineralized matrix deposi-
tion after two weeks of culture in ABM/P-15/Hy were more prominent than those
in ABM/Hy 118 .
From the above-mentioned results, P-15 peptides seemed to stimulate bone
repair and had a synergistic effect on osteogenic inductors such as BMPs. Studies
have shown that BMPs and TGF-

α

interact with collagen to promote osteoblastic
processes 119,120 . Instead of using reconstituted collagen, some advantages of P-15
peptide include minimal batch variations, possible large-scale production, ease of
handling, greater stability, and so on 121,122 . One of the advantages of hydrogels is
that they can be used in any bony defect, regardless of size and shape, although
one must be cautious about cell viability, and the possibility of hampering cell
migration may occur.

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