Long-term culture of human bone marrow. I. characterization of adherent cells in flow cytometry.

Using long-term culture techniques, we were able to characterize the different adherent cell elements of the in vitro bone marrow microenvironment by flow cytometry. After 2 weeks of culture, four adherent cell subsets, L, MM, F, and M, were distinguished according to their intrinsic cellular characteristics of volume and spontaneous fluorescence. Using four immunological markers, we identified each population as a hematopoietic lymphocytic group (L), CD45+, VIM2-, CD14-; a hematopoietic myelomonocytic group (MM), CD45+, VIM2+, CD14-; a hematopoietic macrophage group (M), brightly autofluorescent, CD45+, VIM2-, CD14+; and a group of fibroblastoid cells (F) with a very high volume, CD45-, VIM2-, CD14-, and collagen III+. Isolation of the different hematopoietic and nonhematopoietic components of long-term bone marrow culture is thus possible using flow cytometry analysis according to the cell characteristic of volume and spontaneous fluorescence alone.