Cellular Radiobiology Research Articles

ЕДИНАЯ ИНФОРМАЦИОННАЯ СИСТЕМА УРАЛЬСКОГО НАУЧНО-ПРАКТИЧЕСКОГО ЦЕНТРА РАДИАЦИОННОЙ МЕДИЦИНЫ ФМБА РОССИИ

A great amount of scientific information on the effect of radiation on the human body in various fields of knowledge from genetics and molecular biology to radiation epidemiology has been accumulated over a long-term period of activity of the URCRM of the FMBA of Russia. To get the best out of the use of numerous registers and databases maintained in the URCRM and to make interdisciplinary research possible, a Unified Information System was created, which consists of two parts: information complex REGISTR and complex Storage. The creation of the Storage complex makes it possible to ensure the safety of scientific data obtained in the departments of the URCRM, as well as methods/techniques elaborated to obtain them. The development of the REGISTR complex, the creation of new functionality in it, have significantly increased the use of information resources, which allows for strategic planning of new research. The paper describes in detail the basic functionality of the Unified Information System. The technical aspect of the usage of the REGISTR complex is presented. An example of the use of the Selections Constructor for planning of the study performed in the Laboratory of Molecular and Cellular Radiobiology of the URCRM of the FMBA of Russia is given. Keywords: unified information system, the Register complex, the Storage complex, personal data protection, prospects for the development of the REGISTER complex For citation: Nikiforov VS, Krivoshchapov VA, Startsev NV. Unified Information System of The Urcrm of Fmba of Russia. Medical Radiology and Radiation Safety. 2023;68(6):13–19. (In Russian). DOI:10.33266/1024-6177-2023-68-6-13-19

Diamond-based sensors for in vitro cellular radiobiology: Simultaneous detection of cell exocytic activity and ionizing radiation

The investigation of secondary effects induced by ionizing radiation represents a new and ever-growing research field in radiobiology. This new paradigm cannot be investigated only using standard instrumentation and methodologies, but rather requires novel technologies to achieve significant progress. In this framework, we developed diamond-based sensors that allow simultaneous real-time measurements with a high spatial resolution of the secretory activity of a network of cells cultured on the device, as well as of the dose at which they are exposed during irradiation experiments. The devices were functionally characterized by testing both the above-mentioned detection schemes, namely: amperometric measurements of neurotransmitter release from excitable cells (such as dopamine or adrenaline) and dosimetric evaluation using different ionizing particles (alpha particle and X-ray photons). Finally, the sensors were employed to investigate the effects induced by X-rays on the exocytotic activity of PC12 neuroendocrine cells by monitoring the modulation of the dopamine release in real-time.

СПРАВОЧНО-ИНФОРМАЦИОННЫЙ КОМПЛЕКС REGISTR УРАЛЬСКОГО НАУЧНО-ПРАКТИЧЕСКОГО ЦЕНТРА РАДИАЦИОННОЙ МЕДИЦИНЫ ФМБА РОССИИ

Currently, the Urals Research Center for Radiation Medicine has collected arrays of socio-demographic, dosimetric and medical and biological information. The manuscript presents reference and information complex REGISTR recently developed in the URCRM to optimize the use of multiple registers and data bases. The development of reference and information complex enabled to significantly increase the use of various information resources, and provides strategic planning of new integral studies. A description of archive and actual registers and data bases of the URCRM scientific departments is presented in the manuscript. The issues of possible integration of information saved in various formats were addressed. The manuscript shows that a unified system of coding patients can be treated as a way of integration of information. The manuscript contains a capability description of reference and information complex REGISTR for facilitating research planning and possibility of integration of information obtained in different URCRM scientific departments. A technical implementation of the complex development was described. The article shows an illustration of how the REGISTR complex was used for planning of the research performed in the Laboratory of Molecular and Cellular Radiobiology. The development direction of REGISTR complex was considered.

Diamond-Based Sensors for in Vitro Cellular Radiobiology: Simultaneous Detection of Cell Exocytic Activity and Ionizing Radiation

Diamond-Based Sensors for in Vitro Cellular Radiobiology: Simultaneous Detection of Cell Exocytic Activity and Ionizing Radiation

Developments towards an Advanced Ion Therapy Research Center in the US

The purpose of these developments is to establish an Advanced Ion Therapy Research Center in the US. The proposed center will be the first linac-based ion therapy facility in the world, with the advantage of much desired fast energy and ion beam species switching capability. Such a facility would prove a unique platform to stage the development of pre-clinical studies to prepare for FDA clearance for carbon and other ion beam therapies in the US, and pave the way to establishing clinical ion therapy facilities in this country. The proposed center will enable a breadth of research and applications such as cellular radiobiology, comparative studies of different ion beam therapies and the development of real-time imaging for precise and accurate dose delivery. A multi-institutional collaboration is proposing an innovative center for ion therapy research that will combine an advanced compact carbon ion linac, a compact superconducting carbon beam gantry and real-time MRI-guided beam delivery for therapy. Research and Development towards the realization of the proposed center is underway along three major axes. First, the development of high-gradient accelerating structures for the linac, second, the development of compact curved, combined-function bending magnets and beam scanning magnets for the gantry, and third, the development to combine real-time MRI imaging with ion beam delivery systems. A conceptual design for a compact carbon ion therapy linac has been recently developed. The linac is 45 meters long and capable of accelerating ion beams from proton to neon up to an energy of 450 MeV/u. Prototypes of high-gradient accelerating structures required for the linac are being fabricated and tested. A design of a compact superconducting carbon gantry was also developed and a compact carbon beam scanner magnet is being prototyped. A preliminary concept for MRI-guided ion beam delivery was most recently developed. Other imaging options and range verification techniques, including prompt gamma, positron emission tomography, ionoacoustics and ion beam CT are being considered. Progress made in these areas of development will be presented. Linac-based technology for ion therapy allows more flexibility in beam tuning than synchrotron-based technology with much faster energy modulation and ion beam switching. The reported developments will enable this technology and pave the way to establishing the proposed therapy research center as a national and international resource.

Mechanistic modelling of radiotherapy-induced lung toxicity

This work explores the biological basis of a mechanistic model of radiation-induced lung damage; uniquely, the model makes a connection between the cellular radiobiology involved in lung irradiation and the full three-dimensional distribution of radiation dose. Local tissue damage and loss of global organ function, in terms of radiation pneumonitis (RP), were modelled as different levels of radiation injury. Parameters relating to the former could be derived from the local dose-response function, and the latter from the volume effect of the organ. The literature was consulted to derive information on a threshold dose and volume-effect mechanisms. Simulations of local tissue damage supported the alveolus as a functional subunit (FSU) which can be regenerated from a single surviving stem cell. A moderate interpatient variation in stem cell radiosensitivity (15%) resulted in a great variation in tissue response between 8 and 20 Gy. The threshold of FSU inactivation within a critical functioning volume leading to RP was found to be approximately 47% and the degree of health status variation (influencing the volume effect) in a population was estimated at 25%. This work has shown that it is possible to make sense of the way the lung responds to radiation by modelling RP mechanistically, from cell death to tissue damage to loss of organ function. Simulations were able to provide parameter values, currently not available in the literature, related to the response of the lung to irradiation.

The Fate of a Normal Human Cell Traversed by a Single Charged Particle

The long-term “fate” of normal human cells after single hits of charged particles is one of the oldest unsolved issues in radiation protection and cellular radiobiology. Using a high-precision heavy-ion microbeam we could target normal human fibroblasts with exactly one or five carbon ions and measured the early cytogenetic damage and the late behaviour using single-cell cloning. Around 70% of the first cycle cells presented visible aberrations in mFISH after a single ion traversal, and about 5% of the cells were still able to form colonies. In one third of selected high-proliferative colonies we observed clonal (radiation-induced) aberrations. Terminal differentiation and markers of senescence (PCNA, p16) in the descendants of cells traversed by one carbon ion occurred earlier than in controls, but no evidence of radiation-induced chromosomal instability was found. We conclude that cells surviving single-ion traversal, often carrying clonal chromosome aberrations, undergo accelerated senescence but maintain chromosomal stability.

Effect of radiation treatment on newly established human breast cancer cell lines MACL-1 and MGSO-3

The characterization of new cell lines is an important tool to understand the biological processes involved in cancer treatments. In the present study, we used two newly established epithelial human breast cancer cell lines from primary sites MACL-1 and MGSO-3 and compared their susceptibility to the treatment with ionizing radiation (IR) with the commercial cell line MDA-MB-231. In the doses used (10 or 20 Gy), IR induced a reduction in cell viability and cell death, measured as DNA fragmentation, at 48 and 72 h after treatment. In addition, 48 h after treatment with IR, we observed an enhancement in the percentage of apoptotic cells. The broad-range caspases inhibitor zVAD-FMK inhibited cytotoxicity induced by IR. After 24 h, treatment with IR activated caspase-9 in MACL-1 and MDA-MB-231 but not in MGSO-3 cells. Thirty hours after treatment with IR (20 Gy), we observed an activation of caspases 8 and 3. These results suggest the involvement of caspases in the cell death induced by IR in two newly established cell lines. These cells may be useful in studies of breast cancer in defining basic mechanisms in molecular and cellular radiobiology and may contribute to the rational design of future models of cancer therapies.

From Cellular to High-Throughput Predictive Assays in Radiation Oncology: Challenges and Opportunities

Substantial research efforts into predictive radiation oncology have so far produced very little in terms of clinically applicable assays. This may change with the development of novel high-throughput assays that are of potential interest in a radiation oncology setting. However, it seems that much current research is opportunistic, driven by the available technologies rather than addressing pertinent clinical or biological questions. This review looks at the experience gained from the attempts to develop cellular radiobiology assays. The research process and, in particular, the need for rigorous validation of any promising assay in an independent dataset are stressed. Some common design problems are discussed using examples from radiation oncology. The statistical challenges and some of the key concepts in analyzing dense datasets from high-throughput assays are briefly reviewed. Single nucleotide polymorphisms, immunohistochemical markers, and DNA microarray gene signatures are used as examples of assays that show promise in radiation oncology applications. Some recent studies suggest a differential treatment response between tumor stem cells and other tumor cells. If this is a general pattern, then future predictive assays may have to be performed on stems cells rather than on unselected tumor cells. Advances in radiogenomics or radioproteomics will come from large collaborative research networks, collecting high-quality dosimetric and clinical outcome data and combining state-of-the-art laboratory techniques with appropriate biostatical methods.

Cellular parameters and RBE-LET dependences for modelling heavy-ion radiotherapy

Sets of four parameters (m, E0, sigma0 and kappa) of the cellular track structure model of Katz have been fitted to recently published data concerning human melanoma (AA) and mammalian (V79) cells exposed to a variety of lighter ions and to mixed ion-Co60 and ion-ion irradiation. Using these parameters, model predictions of V79 survival were verified against experimental data. RBE-LET dependences were calculated and compared with experimental data obtained for V79 cells after exposure to 3He, 12C and 20Ne ion beams. The presented track-segment approach used in track structure calculations, while satisfactory for heavier ions, may be of limited value for predicting the RBE-LET dependence of proton and helium radiotherapy beams in regions close to the distal range of these particles. We discuss the predictive capability of this model and propose standards in reporting cellular radiobiology data for application in modelling heavy ion beam radiotherapy.

Target cells in radiation pneumopathy

Radiation pneumopathy is the reaction of the organ lung to radiation effects in various target cells. It starts as an exudative inflammation, with the clinical picture of interstitial pneumonia 6–12 weeks after irradiation, and proceeds to a productive chronic inflammation lasting several months and terminating, as other chronic inflammations do, in scar formation, called lung fibrosis. Lung fibrosis is the common end point after lung damage from a wide range of damaging agents. The pathogenetic process leading to the signs and symptoms of radiation pneumopathy is an integrated response of the complex organization of lung tissue. Clinical and pathologic data in patients do not support the hypothesis that the early inflammatory phase of radiation “pneumonitis” and late “radiation fibrosis” are independent pathogenetic processes in the same way as acute radiodermatitis and subcutaneous fibrosis are separate pathologic entities. The target cell population that initiates the pathogenetic process in the lung is not known, and it has been suggested that no single identifiable target exists. The entire process is the result of complex functional alterations in endothelial cells, pneumocytes, macrophages, and other resident and transient cells. No evidence has been found for a role of stem cell sterilization, for impaired transit cell proliferation, or for hypoplasia, which is the hallmark of other acute inflammatory normal tissue damage (i.e., in the mucosa). The radiobiologic concepts developed in cellular radiobiology are not adequate for the quantitative analysis of radiation pneumopathy. A new analytical framework based on structurally defined intercellular interaction by signaling molecules and their activation needs to be developed. This would not be only an abstract radiobiologic paradigm but would be the key to the development of potential therapeutic interventions in irradiated patients.

Cell membrane oxidative damage induced by gamma-radiation and apoptotic sensitivity.

Ionizing radiation-generated reactive oxygen species (ROS) resulting in oxidative damage to the cell membrane and its consequent role in the mechanism of apoptotic cell death have been receiving growing attention in cellular radiobiology. In recent years, evidence has accumulated to suggest that it is the damage to the cell membrane that contributes to the radiation cell killing. It has been demonstrated that degradation of membrane-bound sphingomyelinase (SMase) after irradiation of bovine endothelial cell produces ceramide, which initiates an apoptotic cascade, suggesting membrane-triggered events in the mechanism of cellular apoptosis. Fluorescence and electron spin resonance (ESR) studies from gamma-irradiation ofliposomal vesicles have shown that radiation-mediated lipid damage was modified by the inclusion of structure-modulating agents (e.g., cholesterol) and antioxidants (e.g., tocopherol, eugenol). The magnitude of the modification of the damage was found to be dependent on the concentration of these modifiers. Moreover, experiments on dipalmitoyl phosphatidyl choline (DPPC) unilamellar liposomes demonstrated a biphasic behavior of radiation damage, which was remarkably modified by ascorbic acid and alpha-tocopherol in a concentration-dependent fashion. The comparison of their protective effects showed that ascorbic acid was less effective than tocopherol against radiation damage to liposomes. Studies on irradiated mouse thymocytes employing FDA fluorescence probe have suggested post-irradiation time- and dose-dependent changes in membrane permeability. The determination of induction of apoptosis in irradiated thymocytes showed a time-dependent DNA fragmentation, suggesting that radiation-induced permeability changes and occurrence of apoptotic death in thymocytes were closely correlated. These results are discussed, with an emphasis on membrane-damage-mediated apoptotic death with relevance to improvement of cancer radiotherapy.

62. The Radiotherapy of IMRT

Intensity Modulated Radiotherapy (IMRT) is going to revolutionise treatment planning and delivery of radiotherapy in the next few years. Although there are still technological constraints, IMRT allows delivery of a specified dose-distribution that is superior to what is realistically achievable with 3D conformal radiotherapy using standard techniques. This forces a re-think of the whole process of delivering radiotherapy. With our current technology, the physics has overtaken the biology and it appears that to realise the full potential of IMRT, a major research effort on the biological aspects of radiotherapy is needed. This goes far beyond traditional cellular radiobiology. New powerful assays in molecular biology and bioimaging will be key elements in the biological optimisation of radiotherapy. In this lecture, I will try to identify some of the research areas that will need to be further developed in order to get the full therapeutic benefit from IMRT.

Lung Cancer Risk at Low Doses: What Can Cellular Radiobiology Tell Us?

The inevitable interaction of confounding factors limits the validity of any epidemiological estimate of lung cancer risk at low, environmental exposures to radon progeny. The present study therefore investigates how the functional form of the dose-effect relationship can be derived from in vitro radiobiological observations at the cellular level relevant for radiation carcinogenesis. The way by which the initial cellular response may be modified by the specific in vivo exposure conditions of individual cells in an organised tissue structure is then discussed.

Lung Cancer Risk at Low Doses: What Can Cellular Radiobiology Tell Us?

Abstract The inevitable interaction of confounding factors limits the validity of any epidemiological estimate of lung cancer risk at low, environmental exposures to radon progeny. The present study therefore investigates how the functional form of the dose-effect relationship can be derived from in vitro radiobiological observations at the cellular level relevant for radiation carcinogenesis. The way by which the initial cellular response may be modified by the specific in vivo exposure conditions of individual cells in an organised tissue structure is then discussed.

Fitting the Armitage-Doll Model to Radiation-Exposed Cohorts and Implications for Population Cancer Risks

The Armitage-Doll model of carcinogenesis is fitted to Japanese bomb survivors with the DS86 dosimetry and to three other radiation-exposed cohorts. The model is found to provide an adequate description of solid cancer incidence and also, to a lesser extent, of that of leukemia as a function of radiation dose when up to two radiation-affected stages are assumed. For non-leukemias the optimal model is one in which there are two radiation-affected stages separated by two additional stages. In the case of leukemia one radiation-affected stage or two adjacent stages provide suitable fits. There appear to be significant differences between the optimal models fitted to each cohort, although there is no heterogeneity within the Japanese data set by sex, by cancer type, or by age at exposure. Low-dose and low-dose-rate population risks for a population having the cancer and overall mortality rates of the current UK population are calculated on the basis of the optimal models fitted to the Japanese data to be about 8.3 x 10(-2) excess cancer deaths person-1 Sv-1, 10.1 x 10(-2) radiation-induced cancer deaths person-1 Sv-1, or 1.40 years of life lost person-1 Sv-1. Risks for a population having the mortality rates of the current Japanese population are about 6.5 x 10(-2) excess cancer deaths person-1 Sv-1, 7.8 x 10(-2) radiation-induced cancer deaths person-1 Sv-1, or 0.89 years of life lost person-1 Sv-1. It is a feature of the Armitage-Doll model, and other multistage models of carcinogenesis, that if radiation acts at more than one stage then (inverse) dose-rate effects may arise as a result of interactions between the effects of a protracted dose at the various radiation-affected stages. However, it is shown in this paper that these three measures of cancer risk in general display fairly slight dependence on administered dose in the range 0.001 to 1.0 Sv and on the length of the time over which the dose is administered in the range 1 to 100 years. Dose-rate effects resulting from the protraction of a radiation exposure over many years acting on (the same) cells at various stages of a multistep process of carcinogenesis are therefore expected to be slight. Dose-rate effects which have been observed in epidemiological studies and cellular radiobiology may thus find their explanation in other phenomena such as short-term intracellular repair.

Cellular Kinetics, Dosimetry, and Radiobiology of α-Particle Radioimmunotherapy: Induction of Apoptosis

Though clinical results for radioimmunoconjugate therapy of most common epithelial tumors have been disappointing, dramatic responses have been observed repeatedly in the treatment of high- and low-grade malignant lymphomas. This high clinical responsiveness after radioimmunoconjugate therapy sometimes appears to be out of proportion to the calculated radiation dose absorbed by the lymphoma tissue. Here we describe some key aspects of the kinetics, dosimetry, and cellular radiobiology of murine lymphoma cells exposed to 212Bi-radiolabeled alpha-particle-emitting immunoconjugates specific for the differentiation antigen Thy 1.2. Approximately 25 cell-bound alpha-particle-emitting immunoconjugates per target cell were required to reduce clonogenic survival by 90% (the radiobiological D10). Serial kinetic analyses of the antibody and radioisotope components of the immunoconjugates revealed significant levels of dechelation and up to 7.5% cellular internalization of the isotope. Cellular radiation dosimetry performed by Monte Carlo computer simulation of alpha-particle energy deposition patterns based on the observed radiopharmacokinetics showed that the D10 resulted from approximately four alpha-particle traversals through the nucleus, corresponding to an absorbed radiation dose of approximately 0.95 Gy to the cell nucleus. Electron micrographs and DNA gel studies of murine lymphoma cells undergoing radioimmunoconjugate therapy in vivo and in vitro demonstrated bizarre blebbing patterns, condensation of chromosomal material, and internucleosomal DNA fragmentation patterns characteristic of programmed cell death (apoptosis). We conjecture that the efficacy of radioimmunoconjugates against responsive cell types may be the result of passive DNA damage by ionizing radiation and the initiation of apoptosis in response to radioimmunotherapy.

Radon: current challenges in cellular radiobiology.

Radon is by far the most important contributor to the collective dose equivalent. Most of what is known about the hazards of radon daughters comes from epidemiological studies of miners. There are a few well defined areas in which in vitro research can complement such studies: First, more data on the relative effects of differing energy (LET) alpha-particles would help: (1) understand the significance of the depth of sensitive cells in the bronchial epithelium--which varies between individuals, as well as between smokers and non-smokers, and between miners and non-miners; (2) understand the relative hazards of radon and thoron daughters. Second, reliable methods for predicting high LET responses from low LET response, would enable Japanese A-bomb survivor data to be applied with confidence. Third, understanding the effects of single-particle traversals of cells relative to multiple traversals could allow reliable extrapolation of epidemiological miner data to low exposures. Fourth, a better understanding of the nature of the interaction between tobacco and radiation damage would help predict the effect of radon on non-smokers.

The Role of Variability of Dose in Dose-Response Relationships for Alpha Emitting Radionuclides

Radiation protection requires predictions of the effects of radiation at low mean organ doses. Since epidemiological data are restricted to moderate to high doses, extrapolation functions must be developed. The present paper derives such a function from theoretical considerations of the ability of radiation to initiate, promote and kill cells. The resulting function, however, is unable to account for the continued increase in cancer incidence amongst uranium miners and 224Ra cases at mean organ doses of several tens of grays. This failure is ascribed to the use of mean organ dose as an appropriate variable in dose-response equations. By an explicit incorporation of variability in cellular doses, the model developed here is shown to display the general features of the epidemiological data when model parameters are made consistent with findings from cellular radiobiology. This indicates that variability of cellular dose may play an essential role in determining the shape of epidemiologically based dose-response curves.

Molecular studies on the nature of the repair defect in ataxia-telangiectasia and their implications for cellular radiobiology.

We have utilized DNA transfer and recombinant DNA techniques to probe DNA double-strand break repair in the human ionizing radiation-sensitive genetic syndrome ataxia-telangiectasia (A-T). Using restriction enzyme-generated double-strand breaks in the coding sequence of a selectable gene we have detected a significantly greater frequency of mis-repair of such breaks in a permanent A-T cell line compared with cell lines of normal radiosensitivity. This mis-repair in A-T can plausibly explain many of the clinical features of the disease but was insufficiently detailed to address the broad problem of DNA repair mechanisms relevant to ionizing radiation-induced damage. To extend these observations of DNA double-strand break mis-repair we have now applied this type of repair assay to novel, de novo induced mammalian X-ray-sensitive cell lines and to appropriate Escherichia coli mutants. In both cellular systems we have now found some equivalence to the A-T repair defect. In particular, studies on one E. coli mutant have provided evidence suggesting an involvement of a topoisomerase activity in DNA double-strand break mis-repair, which may be relevant to the biochemical defect in A-T.