Ability of the hemopoietic microenvironment in the induced bone to maintain the proliferative potential of early hemopoietic precursors.

A comparison of proliferative potential was made between spleen colony forming unit (CFU-S) from skeletal bones and those from ectopically induced ossicles. To this end, mice having two types of ectopic ossicles were used. Each animal was implanted s.c. with demineralized tooth matrix (which served as a source of bone-inducing activity) and again beneath the renal capsule with a femoral bone marrow plug (which was a source of viable osteogenic cells). Those recipient mice that had developed ectopic ossicles were lethally irradiated and then reconstituted with syngeneic bone marrow cells. At various times post-reconstitution, the proliferative potential (PP) of CFU-S in skeletal bones and ectopic ossicles of mice was studied in a double spleen colony test. Hemopoietic cells from each source were injected into lethally irradiated mice; in 11 days, spleen colonies were cut out, and their cells were reinjected into secondary irradiated recipients. The PP of CFU-S was evaluated by examining the development of daughter CFU-S. It was found that, in the hemopoietic microenvironment of induced ossicles, skeletal bone and ectopic ossicles developed by viable osteogenic cells, the PP of CFU-S is maintained to the same extent.