CELL - BASED NANOCOMPOSITES AND BIOMOLECULES FOR BONE TISSUE ENGINEERING - Advanced Biomaterials: Fundamentals, Processing, and Applications - page 558

Cell shape Soluble factors

Rho

Rock

hMSC

Tension

Osteoblast

Adipocyte

Figure 16.6. Cell shape, Rho A, Rock and cytoskeletal tension affects the fate of human MSCs
(hMSCs) to an osteogenic or adipocytic lineage in vitro . 106

modulation. Human MSCs (hMSCs) which were allowed to adhere and spread
underwent osteogenesis. Local cues in the microenvironment and plating density
were crucial for lineage-specifi c differentiation, as seen in the activation of the
Rho A-Rock signaling pathway depicted in Figure 16.6 106 .

16.3.5.2 Non-Mesenchymal Stem Cells (Non-MSCs)-Material Con-
structs. Osteoblasts were seeded on hybrid membranes made of PLLA and HA.
It was evident that the number of viable cells on PLLA/HA hybrid membranes
was greater than that of those on pure PLLA membranes. This indicated that HA
provided an osteoconductive environment for cell adhesion 91 . SaOS - 2 osteoblast -
like cells underwent biomineralization when cultured in the presence of multi-
phasic calcium phosphates that were synthesized via a self-propagating high
temperature combustion synthesis (SHS) process, despite the fact that culture
conditions favored cell quiescence 107 . Membrane vesicles with calcium phosphate
and porous plate-like calcium phosphate structures were found to be adjacent to
the cells. Pseudopodia and a fl attened morphology of the cells were observed,
suggesting that the cells had a normal metabolism and anchored to the heteroge-
neous calcium phosphates (mainly TCP and HA). The heterogeneous calcium
phosphates had distinct crystalline regions as well as amorphous regions and the
bulk porosity was spherical in nature. This heterogeneity and the hydrolysis of
the amorphous phase resulted in the availability of calcium and phosphate that
was said to have enhanced biomineralization 107 .
Nanocrystalline silicon-substituted hydroxyapatite (SiHA) coatings on
titanium (Ti) substrates were produced by magnetron co-sputtering and
increased Si content resulted in decreased crystallite size 108 . There was a signifi -
cant increase in osteoblast cell-growth density on coated SiHA Ti surfaces
compared to uncoated Ti surfaces. It was observed that fl attened cells were
attached on the coated surfaces with enhanced ECM synthesis. Moreover, a