成骨细胞及血管内皮细胞与造血干细胞微环境的关系

Correlation of osteoblasts and vascular endothelial cells to the microenvironment of hematopoietic stem cells

造血干细胞微环境是指在成体组织中干细胞进行自我更新并能产生大量祖细胞的特定场所,已有实验证据表明成骨细胞及血管内皮细胞是造血干细胞微环境的重要组成部分。成骨细胞可以通过多种信号分子及黏附分子调节造血干细胞的功能。具有高浓度氧和生长因子的窦状隙内皮细胞,通过提供营养丰富的微环境促进干细胞增殖及分化,还可以辅助造血干细胞跨内皮迁移,在其归巢及动员过程中具有重要作用,此外可能分配一些细胞定位于脾等髓外场所,这些细胞能够在骨髓抑制情况下替代骨髓微环境。基于众多实验研究提出这样一个假说,即成骨细胞是维持造血干细胞自我更新特性的重要内环境,而血管内皮细胞等血管微环境则促进造血干细胞的增殖及分化。

Hematopoietic stem cell microenvironment is a special place that plays an essential role in regulating stem cell self-renewal and differentiation in adult tissues. Accumulated experimental evidences indicated that the hematopoietic stem cell niche is mostly composed of the osteoblasts and vascular endothelial cells. Osteoblasts can regulate the function of hematopoietic stem cells by numerous signaling and adhesion molecules. The sinusoidal endothelium promotes proliferation and differentiation of stem cells by providing higher concentration of oxygen and growth factors. The vascular niche is essential for both hematopoietic stem cell homing and their mobilization; besides, some cells can localize at the spleen, and these cells can change bone marrow microenvironment under bone marrow inhibition. Osteoblastic niche supports the hematopoietic stem cell maintenance, while the vascular endothelial cell niches provide a microenvironment for hematopoietic stem cell proliferation and differentiation.