The inhibition of angiogenesis could represent a possible therapeutic strategy in diseases where an excessive angiogenesis is involved (for example cancer).
For the in vivo experiments, exposed (72 hours) or not exposed mouse endothelial cells (MS-1, tumor promoting) cells were injected subcutaneously into the flanks of mice and tumor development was observed for 7 days. For the in vitro experiments, MS-1 cells and human umbilical endothelial cells (HUVECs) cells were exposed for up to 24 and 72 hours, respectively.
Vascular endothelial growth factor (VEGF) is a signal protein that (amongst others) stimulates angiogenesis.
|Chamber||Helmholtz coils were placed in an incubator at 37°C, 5 % CO2, 95 % air and 100 % relative humidity|
|Setup||Helmholtz coils had a mean radius of 13 cm, in each coil the number of turns was 800 with a 2 mm² wire giving a resulting resistance of 2.4 Ohm and an inductance of ca. 39 mH, mean vertical distance between the coils was 13.5 cm; simultaneous exposure of a maximum of 6 culture plates|
|Sham exposure||A sham exposure was conducted.|
|magnetic flux density||2 mT||-||measured||-||-|
Mice inoculated with magnetic field exposed MS-1 cells developed significant smaller tumors than mice inoculated with sham exposed MS-1 cells. The histopathological examination of the tumors indicated a reduction of hemangioma (a benign tumor) size, of blood-filled spaces, and in hemorrhage in mice with exposed cells compared to mice with sham exposed MS-1 cells. Also in vitro analysis of MS-1 cells showed that the magnetic field exposure significantly decreased cell proliferation.
In exposed human umbilical vein endothelial cells, cell proliferation, migration and formation of tubule-like formation was significantly dereased compared to sham exposed cells. Additionally, the protein expression level of vascular endothelial growth factor and phosphorylated vascular endothelial growth factor was significantly down-regulated in exposed human umbilical vein endothelial cells compared to sham exposed ones.
The authors conclude that the magnetic field exposure reduced the ability of endothelial cells to form new vessels in vivo and in vitro, probably via an vascular endothelial growth factor pathway. These findings could help to develop therapeutic applications for the treatment of diseases with involved angiogenesis.