Hemopoietic stromal precursors in long-term culture of bone marrow: II. Significance of initial packing for creating a hemopoietic microenvironment and maintaining stromal precursors in the culture.

Conversion of bone marrow cells to a single cell suspension prevents them from creating a hemopoiesis maintaining adherent cell layer (ACL) in culture. The ACL of such cultures is devoid of hemopoietic stromal precursors capable of transferring the hemopoietic microenvironment on implantation under the renal capsule of syngeneic mice. The regeneration of ACL after injury is possible in 1-wk-old, but not older, Dexter-type bone marrow cultures. The results prove the significance of the initial packing of the bone marrow cells in the differentiation of the hemopoietic stromal precursors. These data contradict previous reports which concluded that the structural orderliness of stromal tissue need not be preserved for the hemopoietic microenvironment to be transferred.