Biomedical Engineering Reference
In-Depth Information
Fig. 10. Quantification of cell elongation for osteoblast and mesenchymal stem cells on
nanotubes with different diameters ranging from 30-100nm. There is a trend of increased
elongation with increasing nanotube diameter.
gross elongated cytoskeletal morphology of the cell. It has been reported that cell shape
maintained by the cytoskeletal assembly may also facilitate nuclear shape distortion which
may promote DNA synthesis by releasing mechanical restraints to DNA unfolding,
changing nucleocytoplasmic transport rates, or alternating the distribution and function of
DNA regulatory proteins that are associated with the nuclear protein matrix (Maniotis,
Chen, and Ingber 1997). A change in the nuclear structure has an effect on the 3-dimensional
internal organization (Getzenberg et al. 1991). It appears that the osteoblasts and
mesenchymal stem cells are adapting to the nanotube substrate nanotopography by
organizing both external and internal shapes.
A concept developed by Dalby et al. (Dalby et al. 2008) suggests that MSC osteo-
differentiation is determined by mechanotransductive pathways that were stimulated
because the cell was under tension caused by way the cell was adhering and the shape it
assumed due to the underlying nanostructure surface. Cell morphology/spreading
dominates cell fate. McBeath et al. showed that commitment of stem cell differentiation to
specific lineages is dependent upon cell shape (McBeath et al. 2004). In a single cell
experiment with micropatterned surfaces the critical role of cell spread/shape in regulating
cell fate was determined.
Nonetheless there is a need to better understand the mechanism by which such
nanosurfaces direct MSC osteogenesis, and to optimize the culture conditions in order to
maximize MSC expansion and differentiation. For bone growth, it requires cell proliferation
and selective differentiation, and these processes are found to occur at different but discrete
nanosurface topography conditions such as variations in nanotube diameter.
5.2 Conclusions and considerations for further orthopaedic considerations
Establishing possible connections between mechanical properties of MSCs in differentiation
is valuable to the field of mechanobiology. It can be speculated that natural forces that MSCs
