中文摘要：

在模拟骨髓造血壁龛（hematopoietic niche）的氧分压条件下,探讨微囊化成骨细胞（osteoblasts,OB）对脐血造血干/祖细胞（HSPC）体外扩增的支持和调控机理.分离培养人髂骨OB,采用聚电解质络合法将第3代的OB以密度为8×105ml包埋在直径为0.5mm的明胶-海藻酸钠-壳聚糖（GAC）微胶珠中.将微珠＋造血干/祖细胞（A′组）、造血干/祖细胞（B′组）及微珠（C′组）置于6孔板,在5%氧分压下进行培养.同时在20%常氧条件下设置同样分组培养作为对照（A,B,C）.通过流式细胞分析和半固体细胞集落培养,观察比较各培养体系中造血干/祖细胞的扩增,并检测体系内白血病抑制因子（LIF）和白介素-6（IL-6）的含量变化以探讨作用机理.经过倒置相差显微镜观察,人成骨细胞在微珠中分散均匀,生长状态良好.微珠内部有丰富的孔道供营养物质传递,有大量造血干/祖细胞弱黏附于微珠表面.经过7天的培养,A′、B′、A、B四组造血细胞的扩增倍数分别为（49.0±4.6）,（3.3±0.5）,（17.7±1.2）和（1.9±0.2）.A′、B′、A组的CD34＋细胞分别扩增了（87.6±8.3）,（2.2±0.3）和（14.9±1.0）倍,B组则出现下降.A′、B′、A、B四组CFU-Cs集落扩增倍数分别为（9.8±0.8）,（3.5±0.4）,（6.9±0.7）和（2.6±0.2）.低氧共培养体系比常氧共培养体系和非共培养体系对造血干/祖细胞的扩增有更大的促进作用.A′、B′、C′中IL-6和LIF含量明显高于对应的A、B、C组,与扩增倍数的差异相对应.微囊化成骨细胞对造血干/祖细胞扩增有明显的促进作用,5%氧分压接近体内造血壁龛氧环境,在此环境中成骨细胞分泌细胞因子量增多并通过其对造血干/祖细胞的扩增进行调节.

英文摘要：

Microencapsulated osteoblasts were cocultured with hematopoietic stem/progenitor cells （HSPCs） under hematopoietic niche oxygen concentration to investigate the promoting effort of hematopoietic microenvironment on the expansion of umbilical cord blood HSPCs. The osteobalsts were isolated from human iliac bone and cultured, the third passage of osteoblasts at a density of 8 xl05 cells/ml were encapsulated in gelatin-alginiate-chitosan （GAC） beads with a diameter of 0.5 mm by the polyelectrolyte-complexation method. Three groups of cells were cultured in 5% oxygen incubator, A＇ group with microencapsulated osteoblasts and hematopoietic cells, B＇ with only hematopoietic cells and C＇ with only microencapsulated osteoblasts. Meanwhile, the similarly grouped cells were cultured under 20% oxygen condition, named as A, B and C groups, respectively. The expansion of HSPCs was evaluated by flow cytometry analysis and colony-forming assays. And the concentrations of two kinds of cytokines, LIF and IL-6, were tested to investigate the mechanism of osteoblast＇s action. The results showed that human osteoblasts dispersed uniformly and grew well in microbeads. There were amount of micro holes in the beads for nutrients transmission. Lots of hematopoietic cells adhered weakly on the surface ofmicrobeads. After 7 days of culture, the hematopoietic cell expansion folds were （49.0± 4.6）, （3.3 ±0.5）, （17.7 ± 1.2） and （1.9± 0.2） respectively for group A＇, B＇, A and B. And CD34＋ cells in groups A＇, B＇ and A were expanded （87.6 ± 8.3）-fold, （2.2± 0.3）-fold and （14.9 ± 1.0）-fold, but CD34＋ cells in group B descended. CFU-Cs expansion folds in group A＇, B＇, A and B were （9.8 ± 0.8）, （3.5 ± 0.4）, （6.9 ± 0.7） and （2.6 ± 0.2） respectively. It was indicated that Hypoxic co-culture system could promote HSPCs expansion much more than normoxic co-culture system and somatic cell-free culture system. IL-6 and LIF concentrations in A＇, B＇ and C＇ were sign