Biomedical Engineering Reference
In-Depth Information
Anisotropic cytoskeletal tension
Isotropic cytoskeletal tension
Cell-generated force
Cadherin/integrinCell/ECM/substrate
Figure 11.4
Schematic illustration of the concept of force isotropy applied to cells. This figure is
extracted from Nava
et al
. [87] by permission from Hindawi Publishing Corporation: Journal of
Biomedicine and Biotechnology.
the nucleus from the focal adhesions. The stretched nuclei on nano-grooved surfaces can be
explained by the concept of “force isotropy” proposed by Nava
et al
. (Figure 11.4) [87]. The
cytoskeletal tensional state depends on the balance between the intracellular actomyosin con-
tractility and the reaction forces exerted by the underlying substrate. If cell adhesion-mediated
traction forces, exerted by the cell on the underlying substrate, differ in magnitudes at different
spatial orientations, then the cell nucleus tends to elongate (anisotropic cytoskeletal tension in
Figure 11.4). On the contrary, the cell nucleus tends to remain a round shape if the traction
forces remain similar at different orientation (isotropic cytoskeletal tension in Figure 11.4).
The fact of nucleus deformation on nanotopographic surfaces provides a clue for stem-cells-
nanotopology interactions. The intranuclear environment contains structurally interconnected
nuclear matrix elements that are responsible for modulation of gene expression [88]. Dang and
Leong proposed that the stretching of nuclei in the cells on the nanotopographic surfaces may
alter the internal matrix structure sufficiently enough to change the expression profile of genes
[77]. However, direct evidence for the reprogamming of the gene expression profile in the cells
cultured on nanotopographic substrates is still under investigation.
Conclusions
More and more evidence indicates that surface nanotexture exerts significant impacts on
directing stem-cell differentiation. However, this area remains less explored. We believe that
with more knowledge regarding stem-cell-nanotopology interactions, researchers can
design better strategies combining biochemical and topographic cues for tissue engineering
and regenerative medicine.
References
[1]
Ding S and PG Schultz (2004). A role for chemistry in stem cell biology. Nature Biotechnology
22: 833-840.
[2]
Kraehenbuehl TP, R Langer and LS Ferreira (2011). Three-dimensional biomaterials for the
study of human pluripotent stem cells. Nature Methods 8: 731-736.
[3]
Mizuno H, M Tobita and AC Uysal (2012). Concise review: adipose-derived stem cells as a novel
tool for future regenerative medicine. Stem Cells 30: 804-810.
[4]
Scadden DT (2006). The stem-cell niche as an entity of action. Nature 441: 1075-1079.
[5]
Discher DE, DJ Mooney and PW Zandstra (2009). Growth factors, matrices, and forces combine
and control stem cells. Science 324: 1673-1677.
