Stromal cells in long-term murine bone marrow culture: FACS studies and origin of stromal cells in radiation chimeras.

Adherent layers from hematopoietically active long-term bone marrow cultures (LTBMC), incubated with fluorescent beads, were analyzed for autofluorescence and phagocytic ability, using a fluorescence-activated cell sorter (FACS). Four groups of cells were separated from the adherent layers, including a group of large polygonal fibroblastoid stromal cells. Long-term chimeras were made by lethal irradiation of CBA/Ca (CBA) and C57Bl6/J (B6) mice and repopulation with phosphoglycerate kinase (PGK-1) alloenzyme-congenic bone marrow cells. Hematopoietically active LTBMC were established from such chimeras, and donor and host contributions of FACS-sorted adherent-layer cells were measured. While macrophages and other hematopoietic cells were of donor origin, the fibroblastoid stromal cells were mainly or entirely host derived.