The Content of Multipotent Stromal Cells in 3-4.5-Month Heterotopic Bone Marrow Transplants of CBA Mice Subjected to a Single Exposure to Osteogenic Stimuli (Curettage, BMP-2) or Antigens (S. typhimurium antigenic complex, LPS)

At the early stages of development (3 months), transplants from bone marrow donors subjected to single in vivo stimulation (curettage, administration of BMP-2 or antigenic complex of S. typhimurium) 1 day before transplantation were characterized by significantly elevated content of nucleated cells (by 1.4, 1.9 and 2.9 times, respectively), efficiency of cloning of multipotent stromal cells (by 3.8, 3.8 and 7.2 times), and total number of multipotent stromal cells (by 5, 7 and 21 times) and osteogenic multipotent stromal cells (by 5, 9 and 15 times) in comparison with the control (intact donors); more rapid increase in the weight of bone capsules was also noted. At later terms, the difference by these parameters between the control and experimental groups became less pronounced, but even in 4.5 months, the total number of multipotent stromal cells in the transplant in experimental groups exceeded the control values by 1.4-1.7 times and osteogenic multipotent stromal cells by 2 times. In donors exposed to the specified stimulations, the content of multipotent stromal cells in the femoral bone marrow in 1 day increased by 2.1 times (curettage), 2.6 times (administration of S. typhimurium antigens), and 3.3 times (LPS); administration of BMP-2 reduced this value by 50%. The content of osteogenic bone marrow multipotent stromal cells at this term increased by 1.7 times (BMP-2) and 5.5 times (curettage), after administration of S. typhimurium antigens, this parameter corresponded to the control. The concentration of osteogenic multipotent stromal cells in the bone marrow of intact donors was 22%; the maximum values were observed after curettage (57%) and BMP-2 administration (74%) and minimum after treatment with S. typhimurium antigens (8%). However, this parameter in all groups of transplants little differed and leveled as soon as by 3-4 months, which can be due to regulatory influences of the recipient body. The initial advantage in the content of bone marrow multipotent stromal cells in donors exposed to osteogenic stimuli and administration of antigens ensured considerably more rapid growth of the transplants in comparison with the control. These results can be useful for the development of optimal protocols of tissue grafting.