Effects of (60)co whole-body gamma-irradiation in different doses on the distribution of (188)Re-labeled autologous mesenchymal stem cells in wistar rats after intravenous (systemic) transplantation during different periods after exposure.

The effects of whole-body gamma-irradiation in different doses on the distribution of (188)Re-labeled mesenchymal stem cells obtained by culturing of the rat bone marrow cells were studied in different organs and tissues of animals after intravenous (systemic) injection. Irradiation stimulated homing of (188)Re-labeled mesenchymal stem cells in organs and tissues of animals in comparison with this process in intact non-irradiated rats. The intensity of homing increased with increasing the irradiation dose and decreased with prolongation of the period between irradiation and systemic transplantation. It was hypothesized that increased migration of transplanted mesenchymal stem cells into irradiated organs and tissues can be caused by developing cell death processes. It seems that systemic transplantation of mesenchymal stem cells shortly after irradiation can be used for stimulation of reparative processes in damaged tissues.

In vitro inhibitory effect of mesenchymal stem cells on zymosan-induced production of reactive oxygen species.

In vitro chemiluminescent test showed that human bone marrow mesenchymal stem cells and conditioned media dose-dependently inhibit production of reactive oxygen species by macrophages: 50% inhibition of chemiluminescence (compared to biocontrol) was observed at 1:1 mesenchymal stem cell/macrophage ratio or after addition of 20-25% conditioned media to the incubation medium. The observed mechanism of inhibition of production of reactive oxygen forms can play an essential role in the formation of local immunosuppressive microenvironment in the organism after allogenic transplantation of mesenchymal stem cells.