中文摘要：

成骨细胞是造血干/祖细胞生态位区的重要组成部分，而较低的氧分压则是这一区域的另一特点。本研究在体外模拟造血生态位区，考察成骨细胞在低氧环境中对造血干／祖细胞特性维持和数量扩增的调控作用。采用聚电解质络合法将成骨细胞包埋，随后与人脐带血单个核细胞（CB-MNCs）分别在低氧（5％氧分压）和常氧（20％氧分压）培养箱中共培养，设置非共培养组作对照，培养7d。每天取样计细胞数，检测体系葡萄糖、乳酸浓度，并做CFU-Cs集落和CD34^＋含量检测。结果表明：经过7d的培养，低氧下与载成骨细胞GAC微珠共培养的CB-MNCs扩增了18．7±1．6倍；CD34^＋细胞含量由培养前的2．0％上升到2．5％，细胞数扩增了23．4±2．0倍；CFU-Cs产率为培养前的11．6±0．9倍。扩增效果显著优于常氧共培养和非共培养体系。析因方差分析结果表明，成骨细胞对造血干／祖细胞扩增有非常显著的作用，而低氧条件只在成骨细胞存在时才有明显促进作用。本实验结果为进一步了解成骨细胞对造血干／祖细胞生长调节的作用机制以及造血干／祖细胞的体外大规模扩增培养提供了新思路。

英文摘要：

Osteoblasts play an essential role in the construction of hematopoietic stem/progenitor cell （HSPCs） niches, and hypoxic condition is another characteristic in these areas. This study was aimed to create a novel culture system, which simulates the hematopoietic microenvironment by applying osteoblasts-gelatin-alginate-chitosan microcapsules and hypoxia incubator in order to investigate their supporting effects on ex vivo expansion of HSPCs. The osteoblasts were encapsulated by the polyelectrolyte-complexation method and then co-cultured with isolated cord blood mononuelear cells （CB-MNCs） in hypoxia and normoxia incubators, respectively, and the culture of CB-MNCs in single-culture system was conducted, which was regarded as control. The expansion of HSPCs was evaluated by counting the CB-MNCs number, colony-forming assay and CD34^＋ flow cytometric analysis. Meanwhile the pH value, glucose and lactic acid concentrations were detected every day. After culture of 7 days, the expansion of CB-MNCs co-cultured with encapsulated osteoblasts under hypoxia condition is 18.68±1.60 folds （p〈0.01）. At the same time, the percentage of CD34^＋ cells increase from 2.0% to 2.5%, the cell number expands 23.36±2.01 folds （p〈0.01）, and the number of CFU-Cs increases 11.6 ±0.9 folds （p〈0.01）. ANOVA results indicate that the osteoblasts have significant effect on HSPCs expansion; however, the hypoxia condition demonstrated its influence largely only under the existence of osteoblasts. The investigation provides an experimental basis for further research on the mechanisms of regulation of HSPCs by osteoblasts and the new method for large-scale expansion of HSPCs in vitro.