Ionizing radiation-induced damage in cancer and normal cells leads to apoptosis and cell death, through the intracellular oxidative stress, DNA damage and disorders of their metabolism. Irradiation doses that do not lead to the death of tumor cells can result in the emergence of radioresistant clones of these cells due to the rearrangement of metabolism and the emergence of new mutations, including those in the genes responsible for DNA repair. The search for the substances capable of modulating the functioning of the tumor cell repair system is an urgent task. Here we analyzed the effect of cerium(III) fluoride nanoparticles (CeF₃ NPs) on normal (human mesenchymal stem cells–hMSC) and cancer (MCF-7 line) human cells after X-ray radiation. CeF₃ NPs effectively prevent the formation of hydrogen peroxide and hydroxyl radicals in an irradiated aqueous solution, showing pronounced antioxidant properties. CeF₃ NPs are able to protect hMSC from radiation-induced proliferation arrest, increasing their viability and mitochondrial membrane potential, and, conversely, inducing the cell death of MCF-7 cancer cells, causing radiation-induced mitochondrial hyperpolarization. CeF₃ NPs provided a significant decrease in the number of double-strand breaks (DSBs) in hMSC, while in MCF-7 cells the number of γ-H2AX foci dramatically increased in the presence of CeF₃ 4 h after irradiation. In the presence of CeF₃ NPs, there was a tendency to modulate the expression of most analyzed genes associated with the development of intracellular oxidative stress, cell redox status and the DNA-repair system after X-ray irradiation. Cerium-containing nanoparticles are capable of providing selective protection of hMSC from radiation-induced injuries and are considered as a platform for the development of promising clinical radioprotectors.

The antimicrobial, anti-inflammatory and tissue-stimulating effects of cold argon atmospheric plasma (CAAP) accelerate its use in various fields of medicine. Here, we investigated the effects of CAAP at different radiation doses on mesenchymal stem cells (MSCs) and human osteosarcoma (MNNG/HOS) cells. We observed an increase in the growth rate of MSCs at sufficiently low irradiation doses (10–15 min) of CAAP, while the growth of MNNG/HOS cells was slowed down to 41% at the same irradiation doses. Using flow cytometry, we found that these effects are associated with cell cycle arrest and extended death of cancer cells by necrosis. Reactive oxygen species (ROS) formation was detected in both types of cells after 15 min of CAAP treatment. Evaluation of the genes’ transcriptional activity showed that exposure to low doses of CAAP activates the expression of genes responsible for proliferation, DNA replication, and transition between phases of the cell cycle in MSCs. There was a decrease in the transcriptional activity of most of the studied genes in MNNG/HOS osteosarcoma cancer cells. However, increased transcription of osteogenic differentiation genes was observed in normal and cancer cells. The selective effects of low and high doses of CAAP treatment on cancer and normal cells that we found can be considered in terms of hormesis. The low dose of cold argon plasma irradiation stimulated the vital processes in stem cells due to the slight generation of reactive oxygen species. In cancer cells, the same doses evidently lead to the formation of oxidative stress, which was accompanied by a proliferation inhibition and cell death. The differences in the cancer and normal cells’ responses are probably due to different sensitivity to exogenous oxidative stress. Such a selective effect of CAAP action can be used in the combined therapy of oncological diseases such as skin neoplasms, or for the removal of remaining cancer cells after surgical removal of a tumor.

A technique for the fabrication of bacterial cellulose-based films with CeO₂ nanofiller has been developed. The structural and morphological characteristics of the materials have been studied, their thermal and mechanical properties in dry and swollen states having been determined. The preparation methodology makes it possible to obtain composites with a uniform distribution of nanoparticles. The catalytic effect of ceria, regarding the thermal oxidative destruction of cellulose, has been confirmed by TGA and DTA methods. An increase in CeO₂ content led to an increase in the elastic modulus (a 1.27-fold increase caused by the introduction of 5 wt.% of the nanofiller into the polymer) and strength of the films. This effect is explained by the formation of additional links between polymer macro-chains via the nanoparticles’ surface. The materials fabricated were characterized by a limited ability to swell in water. Swelling caused a 20- to 30-fold reduction in the stiffness of the material, the mechanical properties of the films in a swollen state remaining germane to their practical use. The application of the composite films in cell engineering as substrates for the stem cells’ proliferation has been studied. The increase in CeO₂ content in the films enhanced the proliferative activity of embryonic mouse stem cells. The cells cultured on the scaffold containing 5 wt.% of ceria demonstrated increased cell survival and migration activity. An analysis of gene expression confirmed improved cultivation conditions on CeO₂-containing scaffolds.

Cerium oxide nanoparticles (nanoceria) are believed to be the most versatile nanozyme, showing great promise for biomedical applications. At the same time, the controlled intracellular delivery of nanoceria remains an unresolved problem. Here, we have demonstrated the radioprotective effect of polyelectrolyte microcapsules modified with cerium oxide nanoparticles, which provide controlled loading and intracellular release. The optimal (both safe and uptake efficient) concentrations of ceria-containing microcapsules for human mesenchymal stem cells range from 1:10 to 1:20 cell-to-capsules ratio. We have revealed the molecular mechanisms of nanoceria radioprotective action on mesenchymal stem cells by assessing the level of intracellular reactive oxygen species (ROS), as well as by a detailed 96-genes expression analysis, featuring genes responsible for oxidative stress, mitochondrial metabolism, apoptosis, inflammation etc. Hybrid ceria-containing microcapsules have been shown to provide an indirect genoprotective effect, reducing the number of cytogenetic damages in irradiated cells. These findings give new insight into cerium oxide nanoparticles’ protective action for living beings against ionising radiation.

Recently, human mesenchymal stem cells (hMSc) have attracted a great deal of attention as potential therapeutic agents in the treatment of socially significant diseases. Despite substantial advances in stem-cell therapy, the biological mechanisms of hMSc action after transplantation remain unclear. The use of magnetic resonance imaging (MRI) as a non-invasive method for tracking stem cells in the body is very important for analysing their distribution in tissues and organs, as well as for ensuring control of their lifetime after injection. Herein, detailed experimental data are reported on the biocompatibility towards hMSc of heavily gadolinium-doped cerium oxide nanoparticles (Ce_0.8Gd_0.2O_2−x) synthesised using two synthetic protocols. The relaxivity of the nanoparticles was measured in a magnetic field range from 1 mT to 16.4 T. The relaxivity values (r₁ = 11 ± 1.2 mM⁻¹ s⁻¹ and r₁ = 7 ± 1.2 mM⁻¹ s⁻¹ in magnetic fields typical of 1.5 and 3 T MRI scanners, respectively) are considerably higher than those of the commercial Omniscan MRI contrast agent. The low toxicity of gadolinium-doped ceria nanoparticles to hMSc enables their use as an effective theranostic tool with improved MRI-contrasting properties.