间充质干细胞对脐血CD34+细胞体外扩增和黏附分子表达的影响

目的研究间充质干细胞(MSC)对脐血CD34+细胞体外扩增能力和黏附分子表达的影响.方法从正常人骨髓中分离扩增MSC,通过免疫表型和向成骨细胞及脂肪细胞分化能力对其鉴定;将脐血CD34+细胞接种到MSC或其他培养液中,比较不同培养条件对造血细胞扩增能力、集落形成能力及黏附分子表达的影响.结果MSC表达Thy-1、SH2、SB10、CD44、CD13、CD49e和CD29,不表达CD34、CD45、HLA-DR、CD14和CD31,经过诱导可以向成骨细胞和脂肪细胞分化;实验组在MSC和细胞因子作用下,扩增8 d后有核细胞、CD34+、CD34+CD38-、CD34+CD62L+细胞和CFU-Cs分别扩增145.57±17.89,37.47±13.78,69.78±50.07,10.74±5.89和20.73±5.54倍,均显著高于对照组;扩增后CD34+细胞的ALCAM、VLA-α4、VLA-α5、VLA-β1、HCAM、PECAM和LFA-1表达较扩增前无明显变化,虽然ICAM-1和L-选择素表达下降,但实验组CD34+CD62L+和CD34+CD54+细胞的绝对数显著增加.结论MSC可为造血干细胞体外扩增提供适宜的微环境,有助于抑制HSC分化并保持其造血重建潜能和归巢能力.

Effects of mesenchymal stem cells on expansion potential and adhesion molecules expression of cord blood CD34+ cells

OBJECTIVE: To explore the effects of bone marrow mesenchymal stem cells (MSCs) on in vitro expansion potential, the adherent molecules expression of cord blood (CB) CD34(+) cells. METHODS: MSCs were obtained from human bone marrow and their differentiation function and phenotype were identified. CB CD34(+) cells were expanded in culture systems with or without MSC layer. Hematopoietic progenitor cells and adhesion molecules expression were assessed by semisolid culture assay and flow cytometry. RESULTS: Thy-1, SH2, SB10, CD44, CD13, CD49e and CD29 were highly expressed on MSCs with no expressions of CD34, CD45, HLA-DR, CD14 and CD31. The MSCs could differentiate into adipocytes and osteoblasts under specific induction conditions. After culturing on MSCs layer with supplement of cytokines for 8 days, the absolute numbers of nuclear cells, CD34(+), CD34(+)CD38(-), CD34(+)CD62L(+) cells and CFU-Cs were increased by 145.57 +/- 17.89, 37.47 +/- 13.78, 69.78 +/- 50.07, 10.74 +/- 5.89 and 20.73 +/- 5.54-folds, respectively, being significantly higher than that cultured with cytokines alone. The expression of ALCAM, VLA-alpha4, VLA-alpha5, VLA-beta1, HCAM, PECAM and LFA-1 on CD34(+) cells remained unaffected. The expressions of ICAM-1 and L-selectin were downregulated during expansion, while the absolute numbers of CD34(+)CD62L(+) and CD34(+)CD54(+) cells were increased. CONCLUSIONS: MSCs layer improves expansion of CB CD34(+) cells while inhibiting their differentiation and retaining their homing ability.