IMMUNOLOGICAL INDICATORS IN ANIMAL ORGANISMS UNDER THE INFLUENCE OF ALLOGENEIC ADIPOSE TISSUE-DERIVED MESENCHYMAL STEM CELLS

The studies were conducted on 2–3 months old males of C57BL/6 mice, weighing 20–24 g. Our work aimed at studying the functional state of the organs of the immune system in mice after administration of allogeneic mesenchymal stem cells of adipose tissue origin. Obtaining and cultivating mesenchymal stem cells were carried out in a sterile laminar box with compliance of asepsis and antiseptic conditions. The abdominal adipose tissue from C57BL/6 mice was cultured in a CO2 incubator at 37 °C and 5% CO2 in DMEM with 10–15% of fetal bovine serum, 1% of antibiotic/antimycotic solution (Sigma-Aldrich, USA). The following groups of animals were formed: 1 group – intact (control); 2 group – animals, to whom 0.5 cm3 of 0.9% NaCl solution (placebo) were injected into the caudal vein; 3 group – animals, to whom 104 of allogeneic mesenchymal stem cells from adipose tissue in 0.5 cm3 of phosphate buffer solution were injected into the caudal vein. The weight index, the content of lymphoid cells in the thymus and spleen in C57BL/6 mice were examined on days 7, 18, and 25 after the administration of mesenchymal stem cells. To assess the lymphocyte content in lymphoid organs, they were weighed (whole thymus, 50 mg of spleen), triturated, and filtered through the nylon cloth. After that, the tissue homogenate was applied to Ficoll-Urografin density gradient (d = 1.077) in a ratio of 3:2. The test tubes were centrifuged at 1500 rpm for 30–40 minutes. After centrifugation, plasma and layer of lymphocytes were above the density gradient; lymphocytes were collected by a Pasteur pipette and washed twice with an arbitrary amount of Hank’s solution by centrifugation at 1500 rpm for 10 minutes. After washing, 1 cm3 of Hank’s solution was added to lymphocytes and they were counted in the Goryaev chamber. Calculation of the cellularity of lymphoid organs was performed in 1 mg of tissue. The transplantation of allogeneic adipose-derived mesenchymal stem cells affects the central and peripheral organs of the immune system. Administration of allogeneic adiposederived mesenchymal stem cells causes a significant increase in the content of lymphoid cells in the thymus on days 7, 18, and 25 by 71%, 57, and 53% (P < 0.05), respectively, compared to the control. At the 7 and 18 days of the immune response, lymphoid cell content in the spleen significantly increases by 33% (P < 0.01) and 19% (P < 0.05), respectively, compared to the control under the administration of allogeneic adipose-derived mesenchymal stem cells. On day 25, values of lymphoid cell content and spleen index return to normal. The thymus and spleen weight indices directly correlate with their lymphoid cell content.