Mutation Research/Genetic Toxicology and Environmental Mutagenesis
Effects of radiation quality and dose rate on radiation-induced nucleoplasmic bridges in human peripheral blood lymphocytes
Introduction
With the development and utilization of nuclear energy and radiation resource, accidental exposures are frequently occurring. These accidents, such as Chernobyl accident in 1986 or Fukushima accident in 2011, are attracting increased attention because radiation significantly pollutes the environment and affects the health status of populations in a long period. In addition to mass casualty accidents, isolated radiation accidents or industrial accidents can also cause human death and injury. Biological dose assessment of individuals is the key to emergency preparedness and clinical treatment, thus an accurate and rapid radiation biodosimetry is very important after radiation accident [1]. Moreover, biodosimetry for the determination of biological effects should also be focused.
The cytokinesis-block micronucleus (CBMN) assay for scoring micronuclei (MN) has been the efficient method in the field of radiation emergencies [2]. CBMN assay is a rapid and simple method for measuring DNA damage events. Since 2007, this method has been developed as the CBMN cytome assay by Fenech [3] and becomes a comprehensive system for measuring chromosome breakage, DNA misrepair, chromosome loss, nondisjunction, necrosis, apoptosis and cytostasis [4]. Nucleoplasmic bridge (NPB) is a continuous DNA-containing structure linking the two main nuclei in a binucleated cell, which could also be scored because it is a biomarker of chromosome rearrangement, DNA misrepair, and telomere end fusions [5].
NPB frequencies in human peripheral blood lymphocytes and lymphoblastoid cell lines increase after exposure to X-ray, neutron and radon [[6], [7], [8]]. Our previous studies have shown that the yield of cobalt-60 γ-rays-induced NPB in human peripheral blood lymphocytes are dose-dependent [9,10], similar results have also been found by Cheong et al. and Thomas et al. [11,12]. These studies have suggested that NPB is a sensitive biomarker of ionizing radiation exposure, and NPB frequencies increase with the increased absorbed dose of ionizing radiation.
NPB frequencies in binucleated cells are strongly correlated with dicentric and ring chromosome (dic + r) frequencies in metaphases of the same environment condition cultures [9,12,13] Moreover, the background frequency of NPB in healthy population is relatively low [[14], [15], [16]], which is close to the background frequency of dic + r, but much lower than that of MN. NPB can also be easily identified because of its simple morphological criteria, and may have the possibility of autonomous analysis [17,18]. Therefore, NPB combines the advantages of chromosome aberration (CA) and CBMN assays.
When nuclear or radiation accidents occur, high and low linear energy transfer (LET) radiations at different dose rates are usually combined. LET is the energy deposited per unit length along the trajectory of an ionizing radiation quantum or particle. The biological effects of ionizing radiation depend on the absorbed dose; and these effects are also affected by energy distribution. High LET radiations are generally based on an energy deposition peak (Bragg peak) at the end of their tracks. When exposed to the same dose of ionizing radiation, biological effect induced by high LET radiation is higher than that by low LET radiation. High LET radiations also lead to a higher relative biological effectiveness (RBE) value than low LET radiation for cell killing, reduced oxygen effect and cell cycle [19]. The RBE of an ionizing radiation, which depends on radiation quality, dose and cell radiosensitivity, is the most important parameter of information in clinical radiobiology and radiotherapy. This value is generally measured for a particular biological endpoint relative to observation made in a reference field, such as the cobalt-60 γ-rays or X-ray. Therefore, information on both radiation quality and dose rate is indispensable for accurately estimated the biological dose.
An ideal radiation biodosimeter should have a good dose-dependent manner on both high and low LET ionizing radiations. However, effects of radiation quality and dose rate on radiation-induced NPB have not been systematically investigated yet. This study aimed to establish the dose-response curve of NPB in human peripheral blood lymphocytes induced by carbon ions, to explore the RBE values of carbon ions to cobalt-60 γ-rays, and the dose rate effect of γ-rays-induced NPB.
Section snippets
Subjects and human peripheral blood samples
This work was conducted at the National Institute for Radiological Protection (NIRP), Chinese Center for Disease Control and Prevention. The ethics committee of NIRP approved all the designed experiments in this study. The scope of this study was explained to each subject, and signed informed consents were obtained.
Human peripheral blood samples, donated by 2 males, were collected to establish the carbon ion-induced NPB dose-response curve as well as to explore the dose rate effect on NPB. The
Dose-response curve of carbon ion-induced NPB
To establish the dose-response curve of carbon ion-induced NPB, around 125–2000 binucleated cells were analyzed from each dose level. The number of binucleated cells available for each sample decreased with the increased absorbed dose of carbon ions (Table 1). About 1000 or more binucleated cells could be observed after exposure to around 0–4.0 Gy of carbon ions, whereas the number of binucleated cells available was less than 300 after exposure to more than 6.0 Gy of irradiation. NDI decreased
Discussion
In the present study, high LET ionizing radiation (carbon ions)-induced NPB in human peripheral blood lymphocytes in vitro was investigated. The dose-response curve between the NPB yield and the absorbed doses of carbon ions (0–8.0 Gy) was established. The RBE value of carbon ions to cobalt-60 γ-rays and the dose rate effect of ionizing radiation-induced NPB were also analyzed.
To establish the dose-response curve of carbon ion-induced NPB, sufficient binucleated cells from each dose level were
Conclusions
NPB is a sensitive biomarker of early chromosome damage events induced by both high and low LET ionizing radiations. High LET ionizing radiation (carbon ions)-induced NPB in human peripheral blood lymphocytes have a good dose-response relationship at 0–8 Gy. Carbon ions has higher RBE value than cobalt-60 γ-rays. Cobalt-60 γ-rays-induced NPB frequencies are affected by the specific dose rate.
Funding
National Natural Science Foundation of China [Grant number: 81573081].
Declaration of Competing Interest
The authors have no conflict of interest to declare.
Acknowledgments
This work was supported by the National Natural Science Foundation of China [grant number 81573081]. We thank the blood donors in this study for their contributions.
References (33)
- et al.
Measurement of micronuclei in lymphocytes
Mutat. Res.
(1985) Cytokinesis-block micronucleus assay evolves into a "cytome" assay of chromosomal instability, mitotic dysfunction and cell death
Mutat. Res.
(2006)- et al.
Nucleoplasmic bridges as a biomarker of DNA damage exposed to radon
Mutat. Res.
(2017) - et al.
Cytogenetic damage in human blood lymphocytes exposed in vitro to radon
Mutat. Res.
(2009) - et al.
Genomic health status assessed by a cytokinesis-block micronucleus cytome assay in a healthy middle-aged Korean population
Mutat. Res.
(2017) - et al.
The effect of age, sex, and lifestyle factors on micronucleus frequency in peripheral blood lymphocytes of the Bosnian population
Mutat. Res.
(2013) - et al.
Effects of age and gender on the baseline and 2 Gy 60Co γ-ray-induced nucleoplasmic bridges frequencies in the peripheral blood lymphocytes of Chinese population
Mutat. Res.
(2018) - et al.
The potential for complete automated scoring of the cytokinesis block micronucleus cytome assay using imaging flow cytometry
Mutat. Res.
(2018) - et al.
Overexpression of GML promotes radiation-induced cell cycle arrest and apoptosis
Biochem. Biophys. Res. Commun.
(1997) - et al.
The cytokinesis-blocked micronucleus assay: dose estimation and inter-individual differences in the response to gamma-radiation
Mutat. Res.
(2014)
Rejoining kinetics of G1-PCC breaks induced by different heavy-ion beams with a similar LET value
Mutat. Res.
Relative biological effectiveness and dose rate effect of tritiated water on chromosomes in human lymphocytes and bone marrow cells
Mutat. Res.
State-of-the-art advances in radiation biodosimetry for mass casualty events involving radiation exposure
Radiat. Res.
Cytokinesis-block micronucleus cytome assay
Nat. Protoc.
Cytogenetic Dosimetry: Application in Preparedness for and Response to Radiation Emergencies
Effects of the DNA repair inhibitors, cytosine arabinoside and 3-aminobenzamide, on the frequency of radiation-induced micronuclei, nuclear buds, and nucleoplasmic bridges
Genes Genomics
Cited by (3)
Persons chronically exposed to low doses of ionizing radiation: A cytogenetic dosimetry study
2024, Mutation Research - Genetic Toxicology and Environmental MutagenesisCytogenetic monitoring of peripheral blood lymphocytes from medical radiation professionals occupationally exposed to low-dose ionizing radiation
2021, Mutation Research - Genetic Toxicology and Environmental MutagenesisCitation Excerpt :Such a DNA-containing connection forms a NPB after one cell division. Ionizing radiation-induced NPB frequency increases with absorbed dose [20,21]. Our previous studies indicated favorable dose-effect relationships for NPB frequency at both high doses and relatively low doses.
A study on Amygdalin's genotoxicological safety and modulatory activity in human peripheral lymphocytes in vitro
2023, Environmental and Molecular Mutagenesis