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

为了了解骨髓基质细胞对造血干细胞谱系承诺的调控机制，我们将分选的干细胞与2个已建立的基质细胞共培养。TBR59基质细胞支持分选干细胞的骨髓生成和淋巴生成。另一种细胞系TBR31-1被证明能够特异性诱导b淋巴生成。在这两种共培养中，在没有外源添加可溶性因子的情况下，观察到干细胞向髓系和淋巴系分化的承诺。最终，我们获得了两种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记的干细胞样细胞系，两种细胞系都可以分化。我们检查了参与基质细胞和干细胞相互作用的分子，发现c-Kit及其配体SCF、整合素vca -4或VCAM-1 （vca -4的配体）是必要因素。为了了解与基质细胞有关的其他因素，我们制作了针对每种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，利用两种细胞系的表达cDNA文库筛选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.