Investigation of the effects of 50 Hz magnetic fields on purified human hematopoietic progenitors

Alterations of Hematologic and Hematopoietic Parameters in Mice Exposed to Pulsed Electromagnetic Field

Effects of pulsed electromagnetic field (PEMF) on hematology and hematopoiesis might vary with different PEMF parameters. The purpose of this study was to evaluate the possible effects of PEMF exposure at different pulses on hematologic and hematopoietic parameters in mice. Groups of male BALB/c mice were whole body exposed or were sham exposed (control) to PEMF at 100, 1000, and 10000 pulses. After PEMF exposure, blood samples and bone marrow cells of mice were collected for hematologic examinations, bone marrow nucleated cell counting, colony-forming units of granulocyte-macrophage (CFU-GM) colony assay, and serum granulocyte-macrophage colony-stimulating factor (GM-CSF) assay. Compared with the control group, white blood cells (WBC) and lymphocytes (LYM) in the 100 and 1000 pulses exposed groups were significantly increased but not changed in the 10000 pulses exposed group. Red blood cells (RBC), hemoglobin (HGB), and platelets (PLT) were not changed in all exposed groups. There was no significant difference in mouse bone marrow nucleated cell number between the control group and each exposed group 7 days after PEMF exposure. The CFU-GM clone number of bone marrow cells and serum GM-CSF level were significantly increased in the 100 and 1000 pulses exposed group but not changed in the 10000 pulses exposed group. Our results indicated that the PEMF exposure at fewer pulses may induce statistically significant alterations in some hematologic and hematopoietic parameters of mice but no changes can be found in the more pulses PEMF-exposed groups.

Effects of exposure to gradient magnetic fields emitted by nuclear magnetic resonance devices on clonogenic potential and proliferation of human hematopoietic stem cells

This study investigates effects of gradient magnetic fields (GMFs) emitted by magnetic resonance imaging (MRI) devices on hematopoietic stem cells. Field measurements were performed to assess exposure to GMFs of staff working at 1.5 T and 3 T MRI units. Then an exposure system reproducing measured signals was realized to expose in vitro CD34+ cells to GMFs (1.5 T-protocol and 3 T-protocol). CD34+ cells were obtained by Fluorescence Activated Cell Sorting from six blood donors and three MRI-exposed workers. Blood donor CD34+ cells were exposed in vitro for 72 h to 1.5 T or 3 T-protocol and to sham procedure. Cells were then cultured and evaluated in colony forming unit (CFU)-assay up to 4 weeks after exposure. Results showed that in vitro GMF exposure did not affect cell proliferation but instead induced expansion of erythroid and monocytes progenitors soon after exposure and for the subsequent 3 weeks. No decrease of other clonogenic cell output (i.e., CFU-granulocyte/erythroid/macrophage/megakaryocyte and CFU-granulocyte/macrophage) was noticed, nor exposed CD34+ cells underwent the premature exhaustion of their clonogenic potential compared to sham-exposed controls. On the other hand, pilot experiments showed that CD34+ cells exposed in vivo to GMFs (i.e., samples from MRI workers) behaved in culture similarly to sham-exposed CD34+ cells, suggesting that other cells and/or microenvironment factors might prevent GMF effects on hematopoietic stem cells in vivo. Accordingly, GMFs did not affect the clonogenic potential of umbilical cord blood CD34+ cells exposed in vitro together with the whole mononuclear cell fraction.

Assessing the potential leukemogenic effects of 50 Hz magnetic fields and their harmonics using an animal leukemia model

To answer the still unresolved question of the possible leukemogenic effects of extremely low frequency magnetic fields (ELF-MFs) and of their harmonics on the incidence of B acute lymphoblastic leukemia in children, we used an animal model to explore the possible co-initiating or co-promoting effects of ELF-MFs on the development of leukemia. We used a rat model in which B acute lymphoblastic leukemia is chemically induced by a nitrosurea derivative. From the onset of the chemical treatment, the animals were also exposed to ELF-MFs (100 microT, sinusoidal 50 Hz MFs), with or without harmonics. The experiment was conducted on 280 rats. We compared body weight and survival time, percentage of bone marrow blast cells, cumulative incidence of leukemia and type of leukemia in the unexposed groups and in the groups exposed to 50 Hz MFs, with and without harmonics. The results showed no significant differences between exposed and unexposed rats for any of these parameters (p > 0.05). Significant changes in the leukemia type obtained after gamma-irradiation of the leukemia model, showed its sensitivity to a physical agent. Our results do not support the hypothesis that ELF-MFs, with or without harmonics, affect the development of B acute lymphoblastic leukemia in children.

Regenerated soft tissue survival using repulsive force of magnetized devices: preliminary report

BACKGROUND

Large full-thickness cartilage defects in the weight-bearing area are difficult to treat. A new therapeutic strategy called the total joint regeneration (TJR) system is proposed for such large defects. The purpose of this study was to evaluate the effects of the magnet-type TJR device using a rabbit model.

METHODS

The magnetized devices were implanted in full-thickness chondral defects on the patellofemoral joints of rabbits. The specimens and surrounding tissue were harvested 4 weeks after the surgery and observed macroscopically and histologically. The thickness of the regenerated soft tissue on the femur joint surface was measured and compared. The difference between the two groups (magnetized and nonmagnetized) was significant at P < 0.05.

RESULTS

Some cartilaginous regeneration was seen in the repair tissue. However, about half of the experimental knees were omitted from the study because of some trouble, such as loosening of the device or patella fracture.

CONCLUSIONS

This study suggested that magnetized devices were useful for regenerating soft tissue by maintaining the joint space. Some hyaline cartilage-like tissue was regenerated partially on the magnetized devices. It was suggested that these devices might be useful for cartilage regeneration if the devices are improved.

Effects of a 50 Hz sinusoidal magnetic field on cell adhesion molecule expression in two human osteosarcoma cell lines (MG-63 and Saos-2)

The possibility that a sinusoidal 50 Hz magnetic field with a magnetic flux density of 0.5 mT can induce variations in the expression of cell adhesion molecules (CAMs) in two human osteosarcoma cell lines (MG-63 and Saos-2) was investigated. In particular, the expression of two important integrins, VLA-2, the receptor for collagen, and VLA-5, the receptor for fibronectin, as well as CD44, were examined in both cell lines after these had been exposed for 7 and 14 days to a 50 Hz, 0.5 mT field. Cell surface morphology (scanning electron microscopy), cell growth characteristics (growth curves and cell cycle phase distribution), and cell death (necrosis and apoptosis) were also examined. The results demonstrate that no variations in surface morphology and cell death occurred between control and exposed cells in both MG-63 and Saos-2 cells, while significant changes were noted in cell growth and fibronectin and CD44 expression in MG-63 cells. The results are discussed in view of the important role that CAMs play in controlling various cancer cell functions, particularly proliferation and metastasis.

Effects of 50 Hz magnetic field exposure on tumor experimental models

The aim of this study was to investigate the interaction between a 50 Hz, 2 mT magnetic field (MF) exposure and cell growth of mammary murine adenocarcinoma, injected into experimental mice. Six different experimental protocols were performed over 2 years; several different protocols of timing of exposure were tested. X-ray radiation was adopted as the positive control. Tumor incidence and the tumor development time were calculated. No effect was observed in any experiment, and there was no statistically significant difference related to time courses among the protocols used. Neither the time of tumor cell injection nor the time of exposure produced differences between unexposed, sham, and exposed mice. When X-ray radiation was applied, the cytotoxic effect of ionizing radiation was clear, but was not increased or modified by MF exposure. Finally, the study revealed how the host-tumor system has shown a distinctive variability, unmodified by MF exposure.

Effect of electromagnetic fields on several CD markers and transcription and expression of CD4

We carried out flow cytometric analysis for multiparametric evaluation of cell surface markers related to cellular functions. Specifically, we studied the expression of CD4, CD8, CD3, CD16, CD19, HLA-DR, and CD14 macrophage receptors expression and cell cycle progression on cells exposed to ELF-EMF. In addition, we tested the effects of ELF-EMF on CD4 mRNA protein transcription and translation and the cell-cycle progression using an immunofluorescence method. Our data show that same CD surface marker expression are weakly influenced by electromagnetic fields, with no differences between cells exposed or not exposed to ELF-EMFs. However, when the CD4 protein generation was studied, an indication of protein production was found in lymphocytes exposed to ELF-EMF, as evidenced by immunofluorescence, Western blotting and RT-PCR analysis. CD16 and CD14 expression were affected by EMF exposure at all times studied (24, 48, 72 h). The results obtained with cell cycle analysis show that after 48 h of exposure to ELF-EMF, PHA-activated and not activated cells in S phase increase with respect to non-exposed cells. The findings from this study demonstrate that under our defined experimental conditions there is evidence that ELF-EMF has a slight effect on CD4, CD14 and CD16 receptor expression, while the other CD receptors are not affected.