144
Electromagnetic Fields in Biological Systems
These findings indicated that PEMF can directly stimulate osteoprogenitor cells toward
osteogenic differentiation.
Sun et al. (2009) investigated the effect of a PEMF (15 Hz, 1.8 mT, 8 h/day for 8 days)
on the proliferation and differentiation potential of human bone marrow mesenchymal
stem cells (BMMSCs). Results showed that more viable BMMSCs were obtained in the
PEMF-exposed cultures. Although the growth rates of BMMSCs during the exponential growth phase were not significantly affected, 20%–60% higher cell densities were
achieved during the exponentially expanding stage. Many newly divided cells appeared
from 12 to 16 hours after PEMF treatment. These results suggested that PEMF could
enhance BMMSC proliferation during the exponential phase and that this possibly
resulted from the shortening of the lag phase. In addition, the PEMF-exposed BMMSCs
showed multilineage differentiation potential similar to the control group.
Tsai et al. (2009) examined the effect of a PEMF (7.5 Hz, 0.13 mT, 2 mV/cm) on the
proliferation and osteogenic differentiation of human mesenchymal stem cells (hMSCs).
The production of ALP was significantly enhanced at day 7 with PEMF treatment in
both basal and osteogenic cultures compared with the controls. The expressions of other
early osteogenic genes, including Runx2/Cbfa1 and ALP, were also partially modulated
by PEMF, indicating that osteogenesis in hMSC was associated with the specific PEMF.
Based on ALP and alizarin red S staining, the accumulation of ALP protein produced by
the hMSC as well as calcium deposits reached their highest levels at day 28. The results
indicated that findings on PEMF stimulation provide insights into the development of
PEMF as an effective technology in regenerative medicine.
3.3.2.2 Cell Membrane and Metabolic Activity
Shen, Chao, and Du (2007) examined the effects of an SMF (125 mT) on two types
of voltage-gated potassium channel (VGPC) currents, I and I(K,V), in rat trigeminal
root ganglion (TRG) neurons by whole-cell patch-clamp experiments. The results
demonstrated that SMFs could influence the inactivation kinetics of these two VGPC
currents by altering the inactivation rate and velocity. No significant change was
observed in activation properties. These findings support the hypothesis that biological
membranes would be deformed and physiological characteristics of ion channels on the
membrane would be influenced in moderate-intensity SMFs.
Martino, Perea, et al. (2010) examined the response of human umbilical vein endothelial cells (HUVECs) to weak SMFs (60 and 120 μT). The authors investigated proliferation, viability, and the expression of functional parameters such as endothelial NOS
(eNOS), NO, and also the gene expression of vascular endothelial growth factor (VEGF).
An SMF of 120 μT increased HUVEC proliferation by 40% in 48 hours, compared with
the group shielded in a micrometal cylinder (0.2–0.7 μT). The HUVECs showed sensitivity to both magnetic field intensity and exposure time; HUVECs responded to SMFs
as low as 60 μT. However, both SMF exposures for 1 hour had no effect on proliferation. The HUVEC functionality increased after SMF exposure, which upregulated eNOS
expression. The SMF had no effect on VEGF gene expression, which indicated there
was no increased potential for tumor development by the overexpression of VEGF.
Although SMF increased eNOS-positive HUVECs, NO concentration remained unaltered throughout the culture period. The authors assumed that weak SMFs may open
Electromagnetic Fields in Biological Systems
These findings indicated that PEMF can directly stimulate osteoprogenitor cells toward
osteogenic differentiation.
Sun et al. (2009) investigated the effect of a PEMF (15 Hz, 1.8 mT, 8 h/day for 8 days)
on the proliferation and differentiation potential of human bone marrow mesenchymal
stem cells (BMMSCs). Results showed that more viable BMMSCs were obtained in the
PEMF-exposed cultures. Although the growth rates of BMMSCs during the exponential growth phase were not significantly affected, 20%–60% higher cell densities were
achieved during the exponentially expanding stage. Many newly divided cells appeared
from 12 to 16 hours after PEMF treatment. These results suggested that PEMF could
enhance BMMSC proliferation during the exponential phase and that this possibly
resulted from the shortening of the lag phase. In addition, the PEMF-exposed BMMSCs
showed multilineage differentiation potential similar to the control group.
Tsai et al. (2009) examined the effect of a PEMF (7.5 Hz, 0.13 mT, 2 mV/cm) on the
proliferation and osteogenic differentiation of human mesenchymal stem cells (hMSCs).
The production of ALP was significantly enhanced at day 7 with PEMF treatment in
both basal and osteogenic cultures compared with the controls. The expressions of other
early osteogenic genes, including Runx2/Cbfa1 and ALP, were also partially modulated
by PEMF, indicating that osteogenesis in hMSC was associated with the specific PEMF.
Based on ALP and alizarin red S staining, the accumulation of ALP protein produced by
the hMSC as well as calcium deposits reached their highest levels at day 28. The results
indicated that findings on PEMF stimulation provide insights into the development of
PEMF as an effective technology in regenerative medicine.
3.3.2.2 Cell Membrane and Metabolic Activity
Shen, Chao, and Du (2007) examined the effects of an SMF (125 mT) on two types
of voltage-gated potassium channel (VGPC) currents, I and I(K,V), in rat trigeminal
root ganglion (TRG) neurons by whole-cell patch-clamp experiments. The results
demonstrated that SMFs could influence the inactivation kinetics of these two VGPC
currents by altering the inactivation rate and velocity. No significant change was
observed in activation properties. These findings support the hypothesis that biological
membranes would be deformed and physiological characteristics of ion channels on the
membrane would be influenced in moderate-intensity SMFs.
Martino, Perea, et al. (2010) examined the response of human umbilical vein endothelial cells (HUVECs) to weak SMFs (60 and 120 μT). The authors investigated proliferation, viability, and the expression of functional parameters such as endothelial NOS
(eNOS), NO, and also the gene expression of vascular endothelial growth factor (VEGF).
An SMF of 120 μT increased HUVEC proliferation by 40% in 48 hours, compared with
the group shielded in a micrometal cylinder (0.2–0.7 μT). The HUVECs showed sensitivity to both magnetic field intensity and exposure time; HUVECs responded to SMFs
as low as 60 μT. However, both SMF exposures for 1 hour had no effect on proliferation. The HUVEC functionality increased after SMF exposure, which upregulated eNOS
expression. The SMF had no effect on VEGF gene expression, which indicated there
was no increased potential for tumor development by the overexpression of VEGF.
Although SMF increased eNOS-positive HUVECs, NO concentration remained unaltered throughout the culture period. The authors assumed that weak SMFs may open