Experimental model for the development of the artificial bone marrow

骨髓微环境已被认为在造血现象中起重要作用。基质细胞一直被强调为这种微环境的重要组成部分，然而，基质细胞群体的复杂性使得研究它们与造血细胞相互作用的性质变得困难。为了阐明基质细胞的造血支持功能，从骨髓中克隆了基质细胞系，并分析了基质细胞的特异性。纯化的骨髓造血干细胞（CD34+）与克隆的基质细胞（体外骨髓细胞培养系统；LTMC系统）共培养时，CD34+细胞比无基质细胞对照增加100倍，并维持8周以上。进一步研究表明基质细胞通过以下机制支持造血干细胞的增殖和分化；1)可溶造血调节因子的产生，2)通过基质细胞表面表达的粘附分子进行细胞间的物理相互作用。发现造血因子的产生不仅受多种细胞因子的调控，还受神经递质的调控。利用细胞印迹技术在基质细胞表面发现了一种新的Kd35蛋白，该蛋白与造血干细胞的增殖和分化有关，目前正在进行克隆研究。利用LTMC系统，研究了基质细胞在造血疾病中的作用。首先，澄清了vesnarinone，一种治疗心力衰竭的口服药物，通过损害造血生长因子从基质细胞产生而引起粒细胞缺血症。其次，骨髓增生异常综合征患者间质细胞缺乏造血支持功能。这些结果表明，LTMC系统为体外研究造血现象提供了重要的工具。少

The bone marrow microenvironment has been suggested to play a important role in hematopoietic phenomenon. Stromal cells has been emphasized to be a essential component of this microenvironment, however, the complexity of the stromal cell populations makes it difficult to study the nature of their interaction with hematopoietic cells. To elucidate the hematopoietic supportive function of stromal cells, cloned stromal cell line from bone marrow was eatablished and the specific character of stromal cell was analyzed.1. When purified bone marrow hematopoietic stem cells (CD34+) were cocultivated with cloned stromal cell (in vitro bone marrow cell culture system ; LTMC system), CD34+cells were increased one-hundred higher than that of stromal cell free control and these cells were maintained for more than 8 weeks. Further study showed that the stromal cells support the hematopoietic stem cell proliferation and differentiation by the mechanisms of ; 1)production of soluble hematopoietic regu … More latory factors and 2)physical cell-to-cell interactions through the adherent molecules expressed on the surface of stromal cells. It was found that the production of hematopoietic factors from stromal cells was regulated by not only various cytokines but also neurotransmitters. A novel Kd35 protein, which involved in the proliferation and differentiation of hematopoietic stem cells was detected on the surface of stromal cells by cell blotting technique and a study for cloning of this protein is now on going.2. By using the LTMC system, a role of stromal cell in hematopoietic disorders was studied. First, it was clarified that vesnarinone, an oral therapeutic agent for cardiac failure, caused agranulocytosis through the impairment of the production of hematopoietic growth factors from stromal cells. Second, a lack of hematopoietic supportive function of stromal cells was found in the patients with myelodysplastic syndrome. All these findings suggest that LTMC system provides an essential tool for studying the hematopoietic phenomenon in vitro. Less