Biomedical Engineering Reference
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analogous relationship has been instead found in the case of embryonic neural
crest cells moving on bidimensional dishes coated with fibronectin molecules,
where cell-substrate adhesiveness has been varied with the use of antibod-
ies possessing dierent anities for the 1 subunit of bronectin receptors
(FnRs).
On the other hand, motile biphasic trends have been provided in recent
3D assays in the case of
Human prostrate carcinoma cells, both parental and EGF-receptor over-
expressed, whose speed has been plotted as a function of an adhesiveness
parameter incorporating changes in functional ligands and receptor den-
sity at given Matrigel concentrations [422].
Melanoma cells, cultured in collagen scaffolds, and stimulated with dif-
ferent concentrations of integrin-binding peptide RGD [50].
Finally, in [242] the authors have found that cell speed varied nonlinearly
with modulations of the amount of ligand concentration, as it first increases,
reaches a maximum, and then decreases again.
9.7 Varying Fiber Elasticity of 3D Matrix Scaffold
In the body, extracellular tissues display a range of elastic characteristics that
are modulated by
1. The collagen content.
2. The amount of cross-links between collagenous molecules.
3. The presence of elastic fibers.
Rigid tissues are then dense and elastic tissues are often loose, and increasing
the matrix density will increase their rigidity. In experimental studies using
3D ECM that were either modulated in density, i.e., fiber concentration [417],
or rigidity [295, 296, 362, 367], the other component becomes influenced as
well. However, to separate the related effects, we here simulate both varying
scaffold stiffness (regulated by
perimete
F
) and the geometrical microstructure.
To quantify such convoluting factors, we provide contour plots as joint func-
tions of pore size and fiber elasticity that illustrate cell motile parameters as
dierently colored \landscapes" (see Figure 9.10). It is useful to emphasize
that elastic fibers are also characterized by a low constant T
F
= 0:2, as they
are no longer rigid but can deform.
In Figure 9.10(A; top panels) at high pore size (i.e., 20 m), cells display a
reduced motile behavior, regardless of the fiber stiffness, as already shown in
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