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    Cellular and Molecular Bioengineering

    (D-137) EFFECTS of LOW ENERGY X-RAY RADIATION at VARYING DOSE RATES on HUMAN AORTIC SMOOTH MUSCLE in vitro

    Thursday, October 12, 2023
    9:30 AM – 10:30 AM PDT
    Location: Exhibit Hall - Row D - Poster # 137
    Introduction:: Although the effects of high-doses of radiation are known to cause DNA damage and negatively influence cell proliferation, the precise biological effects of low-dose ionizing x-ray irradiation are not well understood1. These effects, however, are significant in the medical field due to their prevalent use in diagnostic imaging and therapeutic radiation sources2. Therefore, the aim of this study was to determine the effects of low dose x-ray irradiation on cells in vitro by varying the dosing rate and dosage, with vascular smooth muscle cells being the specific cell type studied due to their role in vascular

    Materials and Methods:: A novel characteristic x-ray irradiation cabinet housed in a cell incubator that generates characteristic “monochromatic” x-rays was used to study the effects of x-rays at varying dose rates on the proliferation of human smooth muscle cells (SMCs). Immunofluorescence imaging of SMC markers, cell live/dead assays, proliferation assays, and PCR were performed starting from Day 0 and until Day 3, or 2 for PCR.

    Results, Conclusions, and Discussions:: The low-dose radiation (0.2mGy total) at 0.05 mGy/min appears to affect proliferation the first two days of exposure, then return to normal levels after Day 3 (Fig. 1). However, both the 0.16 mGy/min and 0.50 mGy/min rates resulted in affected levels of proliferation with no return to normal levels after Day 3 of exposure. The majority of the irradiated samples were statistically significant to their corresponding control, and every irradiated point yielded statistically significant results below a p-value of 0.05 at at least two time points. A trend in Figure 1 reveals that in most cases, a higher dosing rate correlates to a higher proliferation rate on Day 1. Immunofluorescence images and RT-PCR also showed increased expression in Smooth Muscle Actin and Collagen I.

    We concluded changing the dose rate, while the total dose (0.2 mGy) received was kept constant, has an impact on smooth muscle cells. Since smooth muscle cells rapidly proliferate when they shift from a contractile to a more synthetic phenotype, increasing the dosing rate is believed to shift the smooth muscle cell phenotypes away from the more quiescent contrite phenotype. Further research is required to confirm that proliferation rates return to normal after Day 3 of low-dose radiation and to analyze proliferation trends within 4 to 8 hours. Additional research will be conducted to see if this phenotypic shift occurs in other cell lines, like tenocytes, for example.


    Acknowledgements (Optional): : Clemson Creative Inquiry for funding. Donald Medlin and Leon Zheng for design of the irradiation cabinet. Justin Napolitano, Andrew Rifkin, and Natalie Anderson for preliminary data.

    References (Optional): :


    1. Houldsworth et al. Nucleic Acids Res. 8(16), 1980



    2. UNSCEAR, Sources, Effects, and Risks of Ionizing Radiation (2020/2021). New York: United Nations.