Biomedical Engineering Reference
In-Depth Information
FIGURE 6.4: Eective displacement (d = x(t = 3 h)x(t = 0h), where x is
the position of the cell center of mass) of unstimulated vascular endothelial cell
in a 3 h time lapse for experimental (horizontal line, see [309]) and simulated
case. Mean values over 10 simulations. Left plot has been used to estimate
the intrinsic motility of the cell T
0
, right plot to estimate its basal persistence
time
pers
0
.
underline that PM channels and pumps have been assumed to be uniformly
distributed over the entire cell surface, and that several membrane-localized
signal transduction proteins, that are known intermediates in AA and NO
generation, such as PLA2 and eNOS, have not been included.
6.3 Simulation Details and Parameter Estimates
The simulated domain consists in a 600 200 80 square lattice. One lattice
voxel is equivalent to 0.125 m
3
: thus the lattice represents a 300 m 100
m 40 m motility chamber with a volume of 1.2 10
6
m
3
. One Monte
Carlo Step corresponds to 10 s.
The TEC initially is an hemisphere with a diameter of 30 m, while the nu-
cleus is a full sphere with a diameter of 10 m, as estimated from experimental
images obtained by the Department of Life Sciences and Systems Biology of
the Universita degli Studi di Torino in classical cultures of TECs resting condi-
tions, i.e., in the presence of adequate nutrients and in the absence of external
forces [133, 390]. The biological variables are initiated at their typical levels: in
particular, there are no AA and NO within the cell. The local resting cytosolic
Ca
2+
concentration, c
0
= 0.05 M, and the external calcium concentration,
c
ext;0
= 2000 M, have been assumed uniform and taken from experimental
[33] and theoretical [283] works. The model parameters related to the basal
motility properties of the cell, T
0
, and the basal persistence parameter,
pers
0
,
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