Preliminary Study on Biological Properties of Adult Human Bone Marrow-derived Mesenchymal Stem Cells

目的本研究拟建立成人骨髓间充质干细胞(mesenchymal stem cell,MSCs)体外培养和扩增的方法,探讨其生物学特性,为进一步将其应用于临床奠定理论和实验基础。方法取正常成人骨髓液5 mL,用Percoll分离液(密度1．073g/mL)经密度梯度离心法分离得到单个核细胞,以2×108个细胞／cm2的密度接种于含10％新生牛血清的LG-DMEM培养液。经培养、扩增后,进行倒置相差显微镜观察其形态,MTT法测定生长曲线,流式细胞仪行细胞表面抗原及细胞周期的检测,并在透射电镜下观察其超微结构。MtT法观察MSCs的免疫调节功能,观察MSCs对K562细胞生长的影响。检测MSCs培养上清中HA、IV-C、LN浓度的动态变化。结果培养扩增获取的成人骨髓MSCs形态均一,为梭形或纺锤形的成纤维细胞样外观,生长曲线示其增殖能力强。流式细胞仪检测显示有90％以上的细胞处于G0／G1期,表面标记物中CD4表达阳性,而造血细胞表面标志CD3、CD4、CD7、CD13、CD14、CD15、CD19、CD22、CD33、CD34、CD45和与移植排斥发生密切相关的HLA-DR表达阴性。超微结构显示细胞内有丰富的细胞器。成人骨髓MSCs抑制PHA诱导的异体淋巴细胞增殖转化,其增殖转化抑制率为60．68％(P<0．01)。抑制作用同样存在于培养上清中,其增殖转化抑制率为9．00％(P<0．05)。在有PHA刺激淋巴细胞增殖的情况下,培养上清中增殖转化抑制率达20．91％(P<0．01)。和单独的K562细胞生长曲线相比,与骨髓MSCs共孵育的K562细胞生长缓慢,无明显的指数生长期。由浓度变化曲线图可以看出,随着天数的延长,HA升高较迅速,而IV-C、LN则浓度变化不大。结论所建立的分离和培养方法可获取骨髓粘附细胞中一组独特的细胞群,具有MSCs的生物学特性。初步的生物学特性研究显示其具有免疫调节、抗肿瘤、造血支持等作用,可作为组织工程中的种子细胞。

Preliminary study on biological properties of adult human bone marrow-derived mesenchymal stem cells

Objective: To establish a method of culture and expansion of adult human bone marrow-derived MSCs in vitro and to explore their biological properties. Methods: Mononuclear cells were obtained from 5 mL adult human bone marrow by density gradient centrifugation with Percoll solution. Adult human MSCs were cultured in Dulbecco’s Modified Eagle’s Medium with low glucose (LG-DMEM) containing 10% fetal calf serum at a density of 2×10⁵ cell/cm². The morphocytology was observed under phase-contrast microscope. The cell growth was measured by MTT method. The flow cytometer was performed to examine the expression of cell surface molecules and cell cycle. The ultrastructure of MSCs was observed under transmission electron microscope. The immunomodulatory functions of MSCs were measured by MTT method. The effects of MSCs on the growth of K562 cells and the dynamic change of HA, IV-C, LN concentration in the culture supernatant of MSCs was also observed. Results: The MSCs harvested in this study were homogenous population and exhibited a spindle-shaped fibroblastic morphology. The cell growth curve showed that MSCs had a strong ability of proliferation. The cells were positive for CD44, while negative for hematopoietic cell surface marker such as CD3, CD4, CD7, CD13, CD14, CD15, CD19, CD22, CD33, CD34, CD45 and HLA-DR, which was closely related to graft versus host disease. Above 90% cells of MSCs were found at G0/G1 phase. The ultrastructure of MSCs indicated that there were plenty of cytoplasmic organelles. Allogeneic peripheral blood lymphocytes proliferation was suppressed by MSCs and the inhibition ratio was 60.68% (P<0.01). The suppressive effect was also existed in the culture supernatant of MSCs and the inhibition ratio was 9.00% (P<0.05). When lymphocytes were stimulated by PHA, the suppression effects of the culture supernatant were even stronger and the inhibition ratio was 20.91% (P<0.01). Compared with the cell growth curve of the K562 cells alone, the K562 cells cocultured with MSCs grew slowly and the exponential phase of growth wasn’t significant. Seeing from the concentration curve, as time passed, the concentration of HA increased quickly, while those of IV-C and LN didn’t change much. Conclusion: The method for culture and expansion of adult human bone marrow-derived MSCs in vitro has been successfully established in this study. MSCs were a homogenous population that had unique growth phenotype and multilineage potential. Preliminary study proved that it had the abilities of immunomodulatory function, antitumor, hematopoietic supporting and could act as seed cell of tissue engineering. Supported by the grant from Lanzhou Command Medical Research Foundation (No. LXH-2005013).