脐血CD_(34)^+细胞迁移能力在体外扩增过程中的变化

Changes of the migration ability of the cord blood CD_(34)^+ cells during short-term ex vivo expansion

目的 比较扩增前、后脐血 (CB)CD34+ 细胞在体外的迁移能力及细胞表面趋化因子CXCR4的表达情况。方法 将从新鲜CB标本中纯化的CD34+ 细胞接种于已建立的扩增体系 ,分别于培养 7,10和 14d从扩增产物中再纯化CD34+ 细胞 ,检测培养不同时间CD34+ 细胞的自发迁移率和SDF 1诱导迁移率以及CD34 + 细胞表面CXCR4的表达。结果 ①原代和扩增不同时间CD34 + 细胞的SDF 1诱导迁移率均高于自发迁移率 ;②扩增 7d时CD34+ 细胞的自发迁移率和SDF 1诱导迁移率与原代CD34+ 细胞相当 ,但在第 2周的培养中 ,CD34+ 细胞的两种迁移率均明显下降 (P值均 <0 .0 5 ) ;③扩增后CD34 + CXCR4 + 细胞的数量明显增加 ,但CXCR4在CD34 + 细胞上的表达呈下降趋势 ,14d时显著低于原代细胞的表达水平 (P <0 .0 5 )。结论 CB造血干 祖细胞 (HSPC)在已建立的短期培养体系中扩增 1周可保持原有的迁移功能 ,但持续扩增则可能对HSPC的归巢潜能产生不利影响。

Objective To study the effect of ex vivo expansion on the migration ability and the CXCR4 expression of umbilical cord blood(CB) hematopoietic stem/progenitor cells (HSPC). Methods CD_ 34 + cells isolated from fresh CB samples were cultured in a serum-free and stroma-free culture system. On day 7,10 and 14,CD_ 34 + cells were re-selected from the expanded cells,and the expression of CXCR4 and the transmigration ability of these CD_ 34 + cells were evaluated respectively and compared with those of the precultured fresh CD_ 34 + cells. Results ① SDF-1 induced a higher migration percentage of fresh or expanded CB CD_ 34 + cells than that of uninduced ones. ② Both of the uninduced and SDF-1-induced migrations were slightly reduced in the first week and then much more reduced in the second week expansion( P<0.05). ③The number of the CD_ 34 +CXCR4 + cells were significantly increased during the culture period,but there was a downtrend of CXCR4 expression on CD_ 34 + subset;the expression levels on day 10 and 14 were lower than that on day 0. Conclusions The expanded HSPC would sustain the chemotactic activity during one-week-culture,but with further extended culture time their intrinsic homing potential would be partly impaired.