Cell Migration in Extracellular Matrices - Cellular Potts Models: Multiscale Extensions and Biological Applications - page 181

FIGURE 9.8: Dependency of cell deformation on fiber stiffness. Variations of
cells' aspect ratio (dened as in Figure 9.5) during migration at dierent ber
elasticities: from bottom to top perimete F = 1; 5; 11. In particular, the pore
size is kept at 5 m. The values are given as means s.d. over 50 randomly
selected cells.

Figure 9.5(B). The rationale of this is that, in very loose tissues, cell migration
is not supported by fibers from all sides of the cell. Consequently, the cell only
migrates along single fibers that, however, when stiffened, again promote to
some extent traction and therefore migration.
Next, at intermediate mesh dimensions, both cell velocity and persistence
(and, consequently, the overall displacement) biphasically depend on matrix
elasticity. If the collagenous threads are too elastic (e.g., perimete F < 3),
they can be easily deformed, without representing a sucient anchor for the
pulling force generation required for cell motion. With a moderate stiffness
(e.g, 5 < perimete F < 9), the matrix fibers can be slightly arranged to form
contact guidance cues, thereby facilitating cell migration. On the contrary,
a too rigid network (e.g, perimete F > 9) forms steric obstacles that can be
somewhat less eciently overcome by moving individuals.
Finally, small pore sizes allow motility only within elastic matrices, whereas
migration is negligible for intermediate or high rigidities of the fibers. Migrat-
ing cells are able to move within small pores, in fact, only by significantly
deforming the matrix network, creating an open space to pass through. There-
fore, if the pore size is much smaller than the cell dimensions, the mechanical
matrix characteristics exert an increasing influence. When evaluating the plots
at constant rigidity, cell migration displays the same bimodal dependence on
pore size previously captured in Figure 9.5(B).
Such variations in fiber rigidity induce a suite of cell morphological changes
(see Figure 9.8). Cells plated within rigid scaffolds are typically well elongated
and exhibit multiple fiber-associated constrictions along their bodies. They