[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.