Potentiation of directed osteogenic differentiation of thymic multipotent stromal cells by prior co-cultivation with thymocytes

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.