BIOCERAMIC SCAFFOLD—BONE TISSUE ENGINEERING - Intelligent Scaffolds for Tissue Engineering and Regenerative Medicine - page 88

Administration(FDA)asbonesubstitutesinhumans.Ceramic-based
bone graft substitutes include calcium phosphate, calcium sulfate,
and bioglass used alone or in combination. Cell spreading is an
essential function of a cell that has adhered to any surface and
precedes the function of cell proliferation. Out of the bone and the
ceramicmaterialinteractionsthattakeplaceatthematerialsurface,
the interaction of osteoblasts is crucial in determining the tissue
response at the biomaterial surface. 15 Attachment and spreading of
specificbone-formingcellsincellculturehavebeenutilizedforpre-
dicting the behavior of the calcium phosphate materials in vivo . 16
The process of cell interaction on materials is highly dynamic and
depends on various parameters influencing the cell responses. It is
well known that the size and shape of the cell-spreading area, as
well as the number, size, shape, and distribution of focal adhesion
plaques are decisive for further migratory, proliferative, and differ-
entiation behavior of anchorage-dependent cells. 17 Cells usually do
not survive if the attached cells are round and are not spreading.
If the cell material contact area is significantly high, the cells tend
to skip the proliferation phase and enter sooner the differentiation
program. If the adhesion is intermediate the cells are most active in
migration and proliferation.
Needle-like ceramic nanoparticles based on calcium phosphate
andzincphosphatewithanaverageparticlesizeoflessthan100nm
have been developed. 18 A nanophase matrix (ZnCaMgP) developed
from these nanoparticles in the presence of magnesium ions exhib-
ited excellent attachment and proliferation of osteoblast cells. This
demonstrates its superior surface properties that are favorable
for cell growth, cell matrix interaction, and tissue formation. For
developing an ideal nanophase bone graft material, factors that are
capable of triggering osteogenesis, that is, osteoinductive growth
factors like bone morphogenic proteins, also need to be incorpo-
rated into the nanophase matrix. An important objective of bone
tissue engineering is to develop improved scaffold materials or an
arrangement to control osteoblast behavior, significantly affecting
its response. Osteoblastic cells on HA exhibited unique attachment
and subsequent behavior in vitro , which may explain why miner-
alized tissue formation is better on HA. Divalent cations, includ-
ing Mg 2 + , are known to be active in cell adhesion mechanisms. 19 , 20