Analysis of bone marrow stem cell.

In this study we define hematopoietic stem cells (HSCs) as a population of cells that, when sorted as single cells, gives rise to both myeloid as well as lymphoid progeny. We sorted single cells from four populations of CD34+ cells from fetal bone marrow: (1) CD38- HLA-DR-, (2) CD38- HLA-DR+, (3) CD38+ HLA-DR-, and (4) CD38+ HLA-DR+ into liquid culture media supplemented with interleukin-3 (IL-3) IL-6, stem cell factor (SCF), granulocyte-macrophage colony-stimulating factor, erythropoietin, basic fibroblast growth factor (bFGF) and insuline-like growth factor (IGF-1). The HSCs were found in the cell populations lacking CD38, the plating efficiency was highest in the CD34+ CD38- HLA-DR+ cell population (48% n = 12); however, only a small proportion of the CD34+ CD38- HLA-DR+ cells showed both lymphoid and myeloid growth potential. When the identical cell populations were sorted into liquid culture media supplemented with bFGF and IGF-1, cell growth was noted from only 1%-5% of the sorted CD34+ CD38- HLA-DR- cells. The cells have the potential to grow and differentiate in vitro to form complex structures that recapitulate normal bone formation. Serial passages of the progeny from these cultures resulted in the formation of similar structures.