人胎盘CD133^＋细胞具有LTC-IC集落启动细胞特性

本研究从功能上评价人胎盘CD133^＋细胞是否具有长期造血重建功能。采用免疫磁殊激活分选系统（MACS）富集胎盘CD133^＋细胞作为测试细胞，采用有限稀释法（LDA）设置4种不同浓度的测试细胞，用胎儿原代骨髓基质细胞制备的饲养层细胞共培养于长期培养体系中，以检测测试细胞中长期培养启动细胞（LTC—IC）的发生率及其增殖分化能力。结果表明：人胎盘CD133^＋细胞群中含有LTC—IC，其发生率为1／645；LTC—IC具有增殖分化为粒-单集落形成单位（CFU—GM）和混合集落形成单位（CFU—Mix）的能力；在所有LTC—IC阳性孔中，产生CFU—GM的孔占总阳性孔的71．4％，产生CFU—GM和CFU—Mix的孔占总阳性孔的28．6％。结论：人胎盘组织CD133^＋细胞群中存在LTC—IC，并具有造血早期祖细胞集落形成能力。

CD133+ Cells Derived from Human Placenta Identified as Initiating Cells for LTC-IC Colony Formation

The aim of this study was to evaluate whether human placenta CD133 ^＋ cells have an ability to reconstitute long-term hematopoiesis. Magnetic-activated cell sorting （MACS） was applied to enrich human placental CD133^＋ cells. The isolated human placental CD133^＋ cells of four different densities were established by limiting-dilution assay and primary fetal bone marrow stromal cells separated from bone marrow as feeder layer cells were co-cultured in long-term culture system so as to observe the incidence of long-term culture initiating-cells （LTC-IC） and their ability of proliferation and differentiation. The results showed that human placenta derived CD133^＋ cells contained LTC-IC with frequency of 1/ 645 which have an ability to proliferate and differentiate into granulocyte/macrophage colony-forming units （CFU-GM） and mixed colony-forming units （CFU-Mix）. In all LTC-IC positive wells, 71.43% form only CFU-GM and 28.57% display both CFU-GM and CFU-Mix formation. It is concluded that human placental CD133^＋ cells possess LTC-IC with colony-forming capacity of hematopoietic early progenitor cells.