Homogeneous stromal cell population from normal human adult bone marrow expressing alpha-smooth muscle actin filaments

BACKGROUND: Hematopoietic microenvironment has a crucial role homing and regulating precursor cell growth both in physiologic and pathologic conditions. Fibroblast, endothelial cells, macrophages, adipocytes, and myoid cells, are the cellular component recognized in human bone marrow cultures. The presence of myoid cells in human bone marrow has been observed during fetal life, whereas during adult life, it is strictly related to pathologic conditions. EXPERIMENTAL DESIGN: The aim of this study was to isolate a homogeneous stromal cell population. The mononuclear fraction obtained from the vertebral body of living humans was cultured without hydrocortisone and horse serum to inhibit foam cell differentiation. RESULTS: The immunocytochemistry and electron microscopy characterization indicate that the cellular population we isolated had an homogeneous ''myoid'' differentiation. Moreover, these cells were able to support blast cell colony formation in vitro. CONCLUSIONS: This method allowed the preparation of homogeneous myoid cell cultures depleted of other bone marrow stromal components. The isolation of a single stromal population is relevant in order to study the function of contractile filaments in allowing close-binding interactions with hematopoietic precursor cells.