Lytvynchuk K. Experimental evaluation of the 2-mercaptobenzothiazole radioprotective agent for morphofunctional cell parameters in vitro

The dissertation for the candidate degree in Мedical Sciences in specialty 03.00.01 – Radiobiology (Medical Sciences). State Institution «National Research Center for Radiation Medicine of National Academy of Medical Sciences of Ukraine», Kyiv, 2019. The dissertation is devoted to the study of biological effects in cells in vitro under the combined effect of ionizing radiation alongside with an organic compound with radioprotective properties, – 2-mercaptobenzothiazole (2-MBT), a derivative of dithiocarbamic acid. Investigation of morphofunctional properties of L929 and PTP cell lines (proliferative and mitotic activity, morphological composition heterogeneity) showed that incubation with 2-MBT in physiological concentrations for cells (0.003 –3.000 μg/ml) did not change the density of cell population in monolayer cultures cells, but increased mitotic activity in the terminal period of cultivation (5th–6th day). This indicates the radiogenic nature of their death. Incubation of cells before and after irradiation with 2-MBT reduced radioinduced cell damage, increased proliferation and mitotic activity. Reduced number of polycarocyte cells in a cell culture indicates the gene-protective properties of the reagent. At the same time, an elevated level of apoptosis in these conditions indicates the elimination of radiation-damaged cells from culture. The highest values of the protective factor (0.31–0.36) of 2-mercaptobenzothiazole in the L929 cell culture test system were showed at a concentration of 3μg/ml after irradiation at a dose of 1 Gy. At the same time, the dose reduction factors (DRF) calculated for LD50 at 2-MBT concentrations of 0.03 μg/ml and 0.30 μg/ml were 1.5 and 1.8, respectively, and at the concentration of 3.00 μg/ml DRF was maximum – 4. Radioprotective properties of 2-mercaptobenzothiazole are also established for the untransformed inoculated cell culture of epithelial cells – the PTP line. Irradiation of cells with neutrons in the 1Gy spectrum resulted in the death of 68% of the L929 line cell culture. Application of 2-mercaptobenzothiazole at concentrations of 0.3 μg/ml and 3.0 μg/ml increased the survival of irradiated cells by 1.3 and 1.6 times respectively. It has been found that the incubation of rat embryonic myogenic cells with 2-MBT at concentrations of 0.3 and 3.0 μg/ml does not significantly affect the process of differentiation (compared to intact cultures). The irradiation of the culture of myogenic cells by gamma-quants 60Co in a dose of 10 Gy resulted in the inactivation of fibroblast-like cells and caused the death of virtually all myoblasts, as the most radiosensitive, less differentiated cells. Differentiation in cell culture was not observed. Cell irradiation at the same conditions but in the presence of 2-MBT at a concentration of 3.0 μg/ml substantially altered cellular composition and morphological structure of culture, namely: significant increase of mitotic cells, myoblasts and myosimplasts of small sizes.