Biomedical Engineering Reference
In-Depth Information
Bone volume
100.09
100.08
100.07
100.06
100.05
100.04
100.03
100.02
100.01
100
0
10
20
30
40
50
60
70
80
90
Time [days]
FIGURE 8.5
Bone volume percentage dynamics during 3-month PEMF application.
The concentration dynamics of OPG during the simulated 3-month PEMF
application are shown in FigureĀ 8.2. Consistent with experimental observa-
tions, the OPG concentration increases during the first 10 days' simulation.
Surprisingly, in the simulation, the concentration of OPG starts to drop from
the 10th day. Because most in vitro experiments have been performed over
2 weeks, there is no available experimental data for comparison. The pat-
tern of OPG concentration might be explained by the fact that because of
the stimulus effect of the PEMF, OPG concentration increases for a relatively
short period after the onset of PEMF application, and then the binding of
OPG with RANKL catches up as bone remodeling occurs. More OPGs are
consumed than produced by osteoblast cells; as a result, OPG concentration
drops until the end of the simulation.
FigureĀ 8.3 shows the RANKL concentration dynamics during the 3-month
PEMF application. As can be observed from the graph, within 2 weeks the
RANKL concentration drops, compared with the initial value. However, it
was not expected that the RANKL concentration would significantly increase
immediately after the simulation began, followed by a dramatic decrease and
the maintenance of a similar level throughout the rest of the simulation. A pos-
sible reason for this development pattern is that the number of preosteoblast
cells that produce RANKL is increased by the stimulus effect of PEMF on the
proliferation of bone marrow mesenchymal stem cells [16] immediately after
 
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