R. K. Chailakhyan

SUMMARY Stromsil precursors ran bo detected in populations of homopoietic cells by their ability to form fibroblast colonies (clones) in monolayer cultures. The stable colony-forming efficiency is reached when the initial density of explanted bone marrow or spleen cells is not less than 104 cells/cm2 or when irradiated bone marrow cells are added in the capacity of a supplementary feeder. The clonogenic cells belong to slowly proliferating and extremely adhesive homopoietic tissue cells. Their radiation survival curve has a D0 of 178 R. Fibroblast strains originating by successive passages in vitro of cells from the initial colonies retain the capacity to form stromal tissue characteristic of the corresponding hemopoietic organ; retransplantation under the kidney capsule results in the formation of bone populated with myoloid cells when the fibroblasts are transplanted from bone marrow cultures, and reticular tissue populated with lymphoid cells when the fibroblasts are transplanted from spleen cultures. It is concluded that stromal precursors are the cells responsible for the transfer of the microenvironmont typical of the given homopoiotic tissue.

Fibroblast colonies (clones) were obtained by explantation of bone marrow single-cell suspensions and were used to establish multicolony and single-colony derived fibroblast cultures by successive passaging of either pooled or individual colonies. When transplanted in diffusion chambers after 20-30 cell doublings in vitro, the descendants of fibroblast colony-forming cells (FCFC), whether grown from single or pooled colonies, retained the ability for bone and cartilage formation. The content of osteogenic precursors in the cultured progeny significantly outnumbered the initiating FCFC. Thus the high proliferative potential of bone marrow FCFC and their ability to serve as common precursors of bone and cartilage-forming cells makes them probable candidates for the role of osteogenic stem cells.

The review is devoted to the current state of the investigation works concerning chitosan functionalization with carboxylic acids and derivatives of them, including oxidized carbon nanoparticles such as graphene oxide, oxidized nano diamonds and oxidized carbon nanotubes. The examples of a use of chitosan derivatives in the pharmacology, the regenerative medicine, and other areas are given.