Regulation of lineage commitment of hematopoietic stem cells by the stromal cells

为了解骨髓基质细胞对造血干细胞定向分化的调控机制，将分选后的造血干细胞与2个已建立的基质细胞共培养。TBR 59基质细胞支持分选的干细胞的骨髓增生和淋巴细胞生成。另一种细胞系TBR 31 -1显示出特异性诱导B淋巴细胞生成。在这两种共培养物中，观察到干细胞向髓样和淋巴样分化的承诺，而无需外源性添加可溶性因子。最终获得两株依赖于基质细胞的永生化干细胞样细胞系。一种是B淋巴干细胞样细胞系，另一种是具有表面标志的干细胞样细胞系，两种细胞系都可以分化，我们检测了基质细胞和干细胞之间相互作用的分子，发现c-Kit及其配体SCF、VLA-4（整合素）或VCAM-1（VLA-4的配体）是必需的因子。为了了解基质细胞中的其他因子，我们制备了针对每个基质细胞系的单克隆抗体，并获得了针对一种基质细胞的特异性单克隆抗体。然后，从两个细胞系制备的表达cDNA文库用于筛选这些抗体识别的抗原分子。

To know the regulatory mechanism of lineage commitment of hematopoietic stem cells by the stromal cells in bone marrow, the sorted stem cells were cocultured on 2 established stromal cells. TBR59 stromal cells support myelopoisis and lymphopoiesis of the sorted stem cells. Another cell line, TBR31-1 was shown to specifically induce B-lymphopoiesis. In both cocultures, the commitment of differentiation of the stem cells toward myeloid and lymphoid was observed without exogenously added soluble factors. Finally we obtained two immortalized stem-like cell lines depending on the stromal cells. One is B-lymphoid stem-like cell line and the other is stem cell-like cell lines with surface markers and both cell lines can be differentiated.We examined molecules involved in the interaction between the stromal and stem cells and found that c-Kit and its ligand, SCF,VLA-4, an integrin, or VCAM-1, a ligand for VLA-4, are necessary factors. To know other factors involved in the stromal cells, we made monoclonal antibodies to each stromal cell line and obtained specific monoclonal antibodies to one type of the stromal cells. Then, the expression cDNA library made from the two cell lines was used for screening of the antigenic molecules recognized by these antibodies.