Biomedical Engineering Reference
In-Depth Information
Fig. 11.1
Morphology of
migrating cells. (
a
) Amoeboid
migration. (
b
) Mesenchymal
pattern of migration
a
b
and migrating while fi rmly attached to the ECM through well mature focal
adhesion—develop the spindle-shaped mesenchymal pattern of migration
(Fig.
11.1b
). Cells loosely attached to the ECM migrate faster than those fi rmly
attached. For instance, leukocytes can move virtually within any substrate found in
the body at speeds up to 100 times faster than mesenchymal cells that remain fi rmly
attached to the ECM even when migrating (Friedl and Wolf
2010
).
Collective cell migration plays a key role for embryonic development, tissue
formation and regeneration. The maintenance of fi rm cell-cell adhesion can lead to
confi ned migratory activity in cells inside a population, yet supports cytoskeletal
activity at outward edges or at basal cell surfaces. The resulting collective migration
forms a multicellular spherical acinus or tube inside a structural constraint with a
curved surface (Zhu and Nelson
2013
; Brownfi eld et al.
2013
; Nelson et al.
2006
).
11.2.2
Dynamic Memory for Guiding Cell Fate
In addition to endogenous force generation, actin cytoskeleton is thought to work as
a dynamic memory for guiding cell fate, specifi cally cell proliferation and differen-
tiation. In this section, we fi rst explain the biophysical basis: mechanism via which
cells sense and respond to physical cues in Sect.
11.2.2.1
. Then, we show actin
cytoskeletal modulation in cell proliferation and stem cell differentiation in
Sects.
11.2.2.2
,
11.2.2.3
and
11.2.2.4
.
11.2.2.1
Dynamic Mechanical Link for Interaction Between Cell
and Extracellular Matrix
Figure
11.2
illustrates the major direct mechanical and indirect mechanochemical
links between the ECM niche and cytoplasm that are necessary for cells in order to
sense, integrate, transduce, and respond to topographical and mechanical cues pro-
vided by ECM niche. ECM topographical and mechanical properties affect the bal-
anced force between a cell and ECM. The mechanical perturbations are transmitted
through transmembrane receptors directly (the right-hand part of Fig.
11.2
) inside
to the cytoplasm and change conformation of the actin cytoskeleton, and/or are
indirectly converted into biochemically relevant signals (the left-hand part of
Fig.
11.2
) (Collier et al.
2010
).
