Design of Mobile Supramolecular Biointerfaces for Regulation of Biological Responses - Biointerfaces: Where Material Meets Biology - page 358

12.4.4 The Effect of Hydrated Viscoelastic Properties on the
Adhering Morphology of the Fibroblasts
Adhesion morphology of cells plays a key role in the maintenance process of
a living body such as directing tissue architecture, tissue repair, and the
regulation of cell proliferation. 47-49 The morphology of adhering cells is
determined by the orientation of the actin cytoskeleton linked with dy-
namically distributed endoplasmic proteins such as paxillin, vinculin, and
tensin, etc. 50 The density and distribution of these phosphorylated endo-
plasmic proteins are determined by dynamic contact of integrin with
extracellular matrix (ECM). 51 Therefore, the adsorption states of ECM on
materials surfaces is also considered as a critical factor affecting adhesion
morphology of cells. The morphology of adhering cells on the dynamic
surfaces was investigated by using NIH3T3 fibroblasts. In order to clearly
estimate the effect of the dynamic properties on the adhesion morphology of
fibroblasts, several types of PRXs containing different number of a-CDs and
different compositions of hydrophobic methoxy groups were synthesized.
A fibroblast is a key cell to maintain the structure of connective tissues, and
is known to easily change its morphology depending on the microenviron-
ment of the adhering sites. 52 The number of adhering fibroblasts, the pro-
jected area, and the morphology of adhering fibroblasts were sequentially
considered in terms of the density of the cell-binding motifs on ECM and the
degree of hydrated viscoelastic factor (Mf), respectively. 53 Figure 12.12
summarizes the relationships between each adhesion behaviors of fibro-
blasts and the density of cell-binding motifs, or Mf. The projected cell area is
linearly increased as the amount of the surface fibronectin. Because inter-
action between materials and cells are induced by the surface proteins, this
result is well-consistent with the fact that protein-materials interaction is
the primary concern to induce cellular responses on the materials surfaces.
The number of adhering fibroblasts after longer-term adhesion test (1 day)
also shows the similar relationship to the fibronectin density on the surface.
As a result, it could be confirmed that the number of adhering fibroblasts is
strongly dependent on the projected cell area at the early stage of cell ad-
hesion as shown in Figure 12.12. However, no significant relationship be-
tween the adhesion morphology (aspect ratio) and the projected cell area. It
is known that the morphology of adhering cells is not directly related to the
quantity of surface proteins. Instead, physical or geometrical characteristics
such as stiffness or surface morphology are known to contribute to the
morphology of adhering cells. 54 The projected cell area and the aspect ratio
of adhering fibroblasts were plotted with the Mf value as shown in
Figure 12.12. Although, the projected cell area revealed a strong relationship
with the density of fibronectin and the number of adhering cells, no sig-
nificant relationship is found with the Mf value. This result indicates that
the dynamic nature of the polymer surfaces is not directly related to the
amount of protein adsorption or cell adhesion. Instead, a strong linear re-
lationship between the aspect ratio and the Mf value was found. The exact

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