It is known that multipotent stromal cells (MSCs) and thymocytes possess membrane affinity and interaction in the thymic niches that is essentially important for thymocytes differentiation. However there are no data about possible influence of intercellular contacts in the reverse direction: from the thymocytes to the MSCs.Materials and methods. The MSCs were obtained from the thymuses of С57ВL mice, using the explants technique, and cultivated under standard conditions during 8-12 passages. Thymocytes or bone marrow cells (106) were added to 4×104 MSCs for 24 hours. Thereafter they were eliminated and standard culture medium was changed by osteogenic or adipogenic differentiation medium and cultured during 10 days. After fixation the cells were stained by 1 % alizarin red S solution or 0.2 % solution of oil red О respectively. After extraction of the stains with 10 % acetic acid or isopropyl alcohol the optic density of extracts at 520 nm was measured.Results. We found that thymic multipotent stromal cells of the C57BL mice were effectively differentiated in vitro into the osteogenic and adipogenic lineages in the appropriate differentiation media that was evidenced by alizarin red and oil red staining of cell cultures. According to the results of measurement of optic density of the dye extracts, it was found that effectiveness of thymic MSCs differentiation into the osteogenic lineage after prior short-term co-cultivation with the thymocytes is increased.Conclusions. The contact of thymic stromal cells with thymocytes but not with bone marrow cells in the previous 24 hours potentiates the osteogenic differentiation and has no effect on the adipogenic cells maturation.
The effect of transplantation of syngeneic bone marrow cells (BMCs) after their contact in vitro with thymus-derived multipotent stromal cells (MSCs) for regeneration of damaged by cyclophosphamide immune system of mice was studied.Materials and methods. MSCs were obtained from C57BL/6 mice’s thymus by explants method. BMCs were obtained by flushing the femurs. BMCs were induced for 2 hours on the monolayer of thymus-derived MSCs. The immune deficiency of mice was modelled using cyclophosphamide injection. After that, cell transplantation was performed and the state of the immune system was assessed. The number of erythrocytes, hematocrit, hemoglobin concentration in the peripheral blood; the phases of the cell cycle and apoptosis of mesenteric lymph node cells were determined. The amount of antibody-producing cells in the spleen and the delayed hypersensitivity response was determined. The study of proliferative and cytotoxic activity of natural killer lymphocytes, the analysis of phagocytosis, spontaneous and induced bactericidal activity of peritoneal macrophages were performed.Results. It was shown that unlike intact bone marrow cells, BMCs induced by thymus-derived MSCs provided increased spontaneous proliferative activity of lymphocytes with a decrease in the number of lymph node cells in G0/G1 phase by 6.2 % and an increase the number of lymphocytes in S+G2/M phase by 28 % in comparison with the group of mice treated with cyclophosphamide, as well as the recovery of cellularity of the bone marrow, lymph nodes and spleen. At the same time in the lymph nodes, the number of cells in the apoptosis increased. BMCs induced by MSCs showed a pronounced negative effect on natural cytotoxicity, reducing its rates by 3 times compared with the group of cyclophosphamide-treated mice, and on adaptive immunity: the rates of delayed hypersensitivity response decreased by 1.7 times, number of antibody-producing cells by 1.8 times. Red blood cell regeneration was stimulated by intact BMCs, which was manifested by the normalization of hematocrit and hemoglobin and an increase in the number of reticulocytes in the blood by 2.2 times compared with the group of mice treated with cyclophosphamide.Conclusion. Transplanted BMCs improve erythropoiesis in mice after cyclophosphamide treatment, and BMCs, previously induced by thymus-derived MSCs, lose this ability. BMCs after co-culture are strongly activated to impact on the immune system, which is most likely due to the effect of contact interaction with thymus-derived MSCs, which is known, effectively affect hematopoietic cells and possess immunomodulatory properties.
The multipotent stromal cells (MSCs) are considered as one of the most promising agents for regenerating the immune system due to its powerful secretion of reparative factors and immunomodulatory properties.The purpose of the study is to investigate the effect of co-transplantation of bone marrow hematopoietic stem cells (HSCs) and thymic multipotent stromal cells (MSCs) on regeneration of murine immune system damaged by cyclophosphamide.Materials and methods. MSCs were obtained from thymuses of C57BL mice using explant technique. Bone marrow cells (BMCs) were obtained by flushing out the femur with nutrient medium. The immune deficiency of mice was modelled by the treatment with cyclophosphamide. After that, the cells were co-transplanted and the parameters of the immune system was evaluated. We determined the total number of erythrocytes, hematocrit, and hemoglobin concentration in peripheral blood; phases of the cell cycle and apoptosis of the cells of the mesenteric lymph nodes; the number of antibody-producing cells in the spleen; delayed type hypersensitivity (DTH); proliferative and cytotoxic activity of natural killer lymphocytes; phagocytic activity, level of spontaneous and induced bactericidal activity of peritoneal macrophages.Results. It was shown that in contrast to BMCs, the use of MSCs alone or co-transplantation of these cells increased the spontaneous proliferative activity of lymphocytes with a significant decrease in the number of lymph node cells in G0/G1 phase by 9.2 % and an increase in the number of lymphocytes in G2-M+S phase by 35 %, as well as restoring cellularity of bone marrow, thymus and lymph nodes in mice treated with cyclophosphamide. Regeneration of erythropoiesis was stimulated by BMCs, which was manifested by the normalization of hematocrit and hemoglobin, and an increase in the number of reticulocytes in the blood by 2.2 times compared with the group of mice receiving cyclophosphamide. Co-transplantation had less pronounced, but similar effect. Transplantation of thymic MSCs stimulated the natural cytotoxicity of splenocytes by 2.7 times and substantially increased the number of antibody-producing cells in the spleen by 1.7 times compared with the group of mice receiving cyclophosphamide. Co-transplantation had a pronounced suppressive effect on the blast transformation reaction induced by phytohemagglutinin by 1.7 times, but showed a stimulating effect on DTH response by 1.46 times. Transplantation of BMCs did not affect the functional activity of the immune system.Conclusion. The effects of co-transplantation of BMCs and thymic MSCs are realized in the several parts: stimulation of hematological parameters recovery (like under the effect of BMCs separately), normalization of cell number of lymphoid organs (as under the impact of thymic MSCs); inhibition of blast transformation activity and stimulation of DTH are the effects of co-transplantation.
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