Changes in cell proliferation due to environmental non-ionizing radiation 1. ELF electromagnetic fields

Private scientific organizations exert a great deal of influence in the regulation of some technological risks. The high level of expertise of their members is arguably a good reason for them to participate in making and monitoring risk regulations, in order to adjust these to scientific progress. Nevertheless, there are also sound reasons why governments shouldn’t uncritically follow the views expressed by such organizations. Taking the role played by the International Commission on Non–Ionizing Radiation Protection in the regulation of electromagnetic fields as an illustrative example, this paper shows that private scientific organizations such as these are structurally less well suited than democratic authorities when it comes to managing those risks.

Download Full-text

Effects of Low-Intensity Electromagnetic Fields on the Proliferation and Differentiation of Cultured Mouse Bone Marrow Stromal Cells

Physical Therapy ◽

10.2522/ptj.20110224 ◽

2012 ◽

Vol 92 (9) ◽

pp. 1208-1219 ◽

Cited By ~ 13

Author(s):

Cheng Zhong ◽

Xin Zhang ◽

Zhengjian Xu ◽

Rongxin He

Keyword(s):

Bone Marrow ◽

Cell Proliferation ◽

Electromagnetic Fields ◽

Stromal Cells ◽

Bone Marrow Stromal Cells ◽

Marrow Stromal Cells ◽

Control Group ◽

Mouse Bone Marrow ◽

Low Intensity ◽

Hematoxylin And Eosin

Background Electromagnetic fields (EMFs) used in stem-cell tissue engineering can help elucidate their biological principles. Objective The aim of this study was to investigate the effects of low-intensity EMFs on cell proliferation, differentiation, and cycle in mouse bone marrow stromal cells (BMSCs) and the in vivo effects of EMFs on BMSC. Methods Harvested BMSCs were cultured for 3 generations and divided into 4 groups. The methylthiotetrazole (MTT) assay was used to evaluate cell proliferation, and alkaline phosphatase activity was measured via a colorimetric assay on the 3rd, 7th, and 10th days. Changes in cell cycle also were analyzed on the 7th day, and bone nodule formation was analyzed on the 12th day. Additionally, the expression of the collagen I gene was examined by reverse transcription-polymerase chain reaction (RT-PCR) on the 10th day. The BMSCs of the irradiated group and the control group were transplanted into cortical bone of different mice femurs separately, with poly(lactic-co-glycolic acid) (PLGA) serving as a scaffold. After 4 and 8 weeks, bone the bone specimens of mice were sliced and stained by hematoxylin and eosin separately. Results The results showed that EMFs (0.5 mT, 50 Hz) accelerated cellular proliferation, enhanced cellular differentiation, and increased the percentage of cells in the G2/M+S (postsynthetic gap 2 period/mitotic phase + S phase) of the stimulation. The EMF-exposed groups had significantly higher collagen I messenger RNA levels than the control group. The EMF + osteogenic medium–treated group readily formed bone nodules. Hematoxylin and eosin staining showed a clear flaking of bone tissue in the irradiated group. Conclusion Irradiation of BMSCs with low-intensity EMFs (0.5 mT, 50 Hz) increased cell proliferation and induced cell differentiation. The results of this study did not establish a stricter animal model for studying osteogenesis, and only short-term results were investigated. Further study of the mechanism of EMF is needed.

Download Full-text

Nonlinear ionizing radiation-induced changes in eye lens cell proliferation, cyclin D1 expression and lens shape

Open Biology ◽

10.1098/rsob.150011 ◽

2015 ◽

Vol 5 (4) ◽

pp. 150011 ◽

Cited By ~ 23

Author(s):

Ewa Markiewicz ◽

Stephen Barnard ◽

Jackie Haines ◽

Margaret Coster ◽

Orry van Geel ◽

...

Keyword(s):

Cell Proliferation ◽

Ionizing Radiation ◽

Cyclin D1 ◽

Cell Density ◽

Peripheral Region ◽

X Rays ◽

Dna Double Strand Breaks ◽

Cell Nuclei ◽

Γh2ax Foci ◽

Biological Responses

Elevated cataract risk after radiation exposure was established soon after the discovery of X-rays in 1895. Today, increased cataract incidence among medical imaging practitioners and after nuclear incidents has highlighted how little is still understood about the biological responses of the lens to low-dose ionizing radiation (IR). Here, we show for the first time that in mice, lens epithelial cells (LECs) in the peripheral region repair DNA double strand breaks (DSB) after exposure to 20 and 100 mGy more slowly compared with circulating blood lymphocytes, as demonstrated by counts of γH2AX foci in cell nuclei. LECs in the central region repaired DSBs faster than either LECs in the lens periphery or lymphocytes. Although DSB markers (γH2AX, 53BP1 and RAD51) in both lens regions showed linear dose responses at the 1 h timepoint, nonlinear responses were observed in lenses for EdU (5-ethynyl-2′-deoxy-uridine) incorporation, cyclin D1 staining and cell density after 24 h at 100 and 250 mGy. After 10 months, the lens aspect ratio was also altered, an indicator of the consequences of the altered cell proliferation and cell density changes. A best-fit model demonstrated a dose-response peak at 500 mGy. These data identify specific nonlinear biological responses to low (less than 1000 mGy) dose IR-induced DNA damage in the lens epithelium.

Download Full-text