To investigate the effects of pulsating electromagnetic fields (PEMF) on the growth of murine osteosarcoma (resistent and non-resistent to ADR) in combination with the anti tumor agent Adriamycin (ADR) and human fibroblast cells in vitro.
Self-prepared resistent osteosarcoma cells expressed P-glycoprotein and had resistance to ADR more than 10 times that of their nonresistant parent cells. P-glycoprotein is considered to be clinically the most important factor associated with the ineffectiveness of chemotherapy against metastasis.
The authors expected, that, if the growth of well-differentiated cells (e.g. fibroblast cells) is inhibited by exposure to PEMF under certain conditions, the growth of well-differentiated drug-resistant cells may also be suppressed by exposing them to PEMF under the same conditions. Moreover, the growth of undifferentiated cells may also be promoted in the same manner. These phenomena, if confirmed, will be evidence that PEMF is effective to control drug resistance.
|magnetic flux density||800 µT||maximum||cf. remarks||-||400 to 800 µT|
Exposure to PEMF, promoted the growth of nonresistant cells in an ADR-free medium but supressed the growth of more differentiated resistant cells, which expressed P-glycoprotein, and of human fibroblasts.
Exposure to PEMF supressed the growth of nonresistant cells incubated in media containing ADR at the IC50 (0.03 µg/ml) or above.
Furthermore, it inhibited the growth of P-glycoprotein positive resistant cells incubated in all ADR-containing and ADR-free media.
The data suggest that PEMF promotes the growth of undifferentiated cells but progressively suppresses the growth of more differentiated cells, i.e., PEMF controls cell growth depending on the degree of cell differentiation. Thus, the findings show the potentiality of PEMF as an adjunctive treatment method for malignant tumors.