Selective proliferation of lymphoid cells from lineage-c-Kit+ Sca-1+ cells by a clonal bone marrow stromal cell line

To understand the regulatory mechanisms involved in the development of hematopoietic stem cells, we cultured lineage-negative, c-Kit+ Sca-1+ stem cells sorted from bone marrow cells by a fluorescence-activated cell sorter (FACS) on layers of bone marrow stromal cell lines established from SV40 T-antigen gene transgenic mice. We previously reported that the TBR59 stromal cell line induced two sequential cobblestone formations: the first formation committed to the myeloid and the second to the lymphoid lineage. After examination of many other bone marrow stromal cell lines, we found that TBR31-1 stromal cells supported only lymphoid development of the sorted stem cells. The sorted stem cells proliferated by forming cobblestones and the cells were released from the cobblestones. Most released cell populations were B220-positive lymphoid cells; cell production continued for 2 months. Addition of G-CSF or M-CSF produced only a slight effect on myeloid development. FACS analysis of the released cells showed that the B-lymphoid-committed progenitors developed into mature B-cells by expressing surface immunoglobulin M. These results indicate that TBR31-1 bone marrow stromal cells selectively support B-lymphoid development, whereas TBR59 cells support both myeloid and lymphoid development of stem cells.