Effect of BMP-2 protein on the count and osteogenic properties of multipotent stromal cells and expression of cytokine genes in primary cultures of bone marrow and spleen cells from CBA mice immunized with bacterial antigens.

We studied the effect of BMP-2 added to the culture medium on osteogenic and proliferative properties of multipotent stromal cells (MSC) and on the expression of cytokine genes induced by immunization of experimental animals with bacterial antigens. It is shown that the presence of BMP-2 in the culture medium stimulates proliferation of bone marrow MSC and especially spleen MSC (which was seen from enlargement of MSC colonies); improves the efficiency of MSC cloning; increases osteogenic activity of mouse bone marrow MSC; induces osteogenic differentiation of splenic MSC (osteogenesis is normally not observed in the spleen); reduces the number of macrophages in cultures; inhibits synthesis of mRNA for proinflammatory cytokines (IL-1β, IL-6, IL-8, TNF-α) that typically occurs in cultures of the bone marrow and spleen from animals immunized with S. typhimurium or group A streptococcus antigens. Bearing in mind that proinflammatory cytokines negatively affect osteogenic activity of the bone marrow, we can hypothesize that BMP-2 not only stimulates osteogenesis, but also provides optimal conditions for its realization by suppressing the expression of genes encoding these cytokines.