Effect of a Humic-Fulvic Acid Preparation on the Quantitative Yield of Residual γH2AX Foci and Proliferative Activity in Irradiated Human Mesenchymal Stromal Cells

Abstract

Purpose: To evaluate the influence of a humic-fulvic acid substance on the quantitative yield of residual foci of the DNA double-strand break (DSB) repair protein-marker - phosphorylated histone H2AX (γH2AX) and proliferation activity in a culture of human mesenchymal stromal cells (MSCs) 24, 48, and 72 h after exposure to X-ray radiation at doses of 2, 4 and 10 Gy. Material and methods: Through 24 hours after incubation of MSCs with a substance of humic-fulvic acids (Humic Complex, OOO Sistema-BioTechnologies, Russia) at a dilution of 1/1000. Cells were irradiated on an X-ray biological device RUB RUST-M1 at a voltage of 200 kV, beam current 2×5 mA, aluminum filter 1.5 mm, absorbed dose rate 0.85 Gy/min. Immunocytochemical staining was used to quantify the residual γH2AX foci and the percentage of proliferating cells using antibodies to γH2AX and Ki-67 (a marker protein for cell proliferation), respectively. Statistical analysis of the obtained data was carried out using the statistical software package Statistica 8.0 (StatSoft). To assess the significance of differences between samples, Student’s t-test was used. Results and conclusion: The conducted studies showed that on the cell model used and under the above experimental conditions, the humic-fulvic acid substance does not affect the efficiency of repair of radiation-induced DNA DSBs, however, it significantly reduces the proliferation activity of both irradiated and non-irradiated MSCs. It is advisable to conduct detailed studies of the molecular and cellular mechanisms of the antiproliferative effect of humic and fulvic acids.