A study for the mechanism of hematopoietic regulation by bone marrow stromal cells

正常造血的特点是造血干细胞与形成血细胞生成的微环境部分的细胞和分子之间的平衡相互作用。这反过来表明，这种微环境中某些元素的改变可能导致血细胞产生异常。骨髓基质细胞是一种异质间充质细胞，在骨髓培养中作为粘附层生长，是微环境的重要组成部分。本研究对基质细胞的体外造血调节机制进行了研究。通过引入含有SV40早期基因的重组SV40腺病毒载体，从骨髓增生异常综合征（MDS）难治性贫血（RA）患者中克隆了一株基质细胞系（LS801）。在共培养系统中，LS801诱导了造血细胞的凋亡变化。结果表明，LS801通过产生扩散因子和直接细胞相互作用诱导造血细胞凋亡。从菌株LS801的培养基中分离到一种超分子低聚物环聚乳酸。发现该低聚物可诱导造血细胞凋亡变化。这种作用的机制尚不清楚，然而，造血细胞的糖酵解酶、磷酸果糖激酶和己糖激酶的活性受到这种低聚物的抑制。MDS患者骨髓间质细胞通过产生TNFα诱导造血细胞凋亡。我们发现，维生素K2抑制了这些基质细胞TNFα的产生，并刺激了这些基质细胞培养的造血功能。这些结果表明基质细胞对造血细胞的增殖和分化具有刺激和抑制作用。

Normal hematopoiesis is characterized by a balanced interplay between hematopoietic stem cells and the cells and molecules that form the portion of the microenvironment in which blood cell production takes place. This in turn suggests that alterations in some of the elements of this microenvironment may result in abnormal production of blood cells. Bone marrow stromal cells, a heterogeneous collection of mesenchymal cells that grow as an adherent layer in bone marrow culture, are an essential component of the microenvironment. In this study, the hematopoietic regulatory mechanisms of stromal cells were investigated in vitro.1.A cloned stromal cell line (LS801) was established from an myelodysplastic syndrome(MDS) refractory anemia(RA) patient by introducing recombinant SV40-adenovirus vector containing the SV40 early gene. LS801 induced an apoptotic change in hematopoietic cells in a coculture system.2.LS801 was shown that induced an apoptotic change of hematopoietic cells by producing diffusible factor(s) and via direct cellular interactions. A supramolecular oligomer, cyclic polylactate was isolated from the culture medium of LS801. This oligomer was found to induce apoptotic change in hematopoietic cells. The mechanism responsible for this action remains unclear, however, the activities of glycolytic enzymes, phosphofructokinase and hexokinase, of hematopoietic cells were suppressed by treatment with this oligomer,3.In some stromal cells originated from MDS patients induced apoptotic change of hematopoietic cells by producing TNFα. We found that the treatment with vitamin K2 suppressed the production of TNFα from these stromal cells, and hematopoiesis in culture with these stromal cells was stimulated.All these findings suggest that stromal cells possess both stimulatory and inhibitory action for the proliferation and differentiation of hematopoietic cells.