ABSTRACT
Purpose: Long-term culture- initiating cells(LTC-IC) are stem cells that have the capacities of long-term engraftment and helping to establish hematopoietic microenvironment. For evaluation of the LTC-IC, we measured the counts and function with multidimentional flowcytometry in long-term culture media. METHODS: Samples were obtained from umbilical cord blood, leukapheresis products and bone marrow(BM). LTC-IC were counted with flowcytometric analysis using anti- CD34, anti-CD38, and anti-HLA-DR antibodies at 0, 5, and 8 weeks. Cell adhesion molecule related with stem cell were evaluated with flowcytometric analysis also using anti-VCAM-1(CD106) and anti-VLA-4(CD49d) at 0 and 8 weeks. RESULTS: The proportion of CD34+/CD38- cell from fractionated mononuclear cells at 0 week were 0.46%, 0.044%, and 0.038% for BM, leukapheresis products, and umbilical cord blood respectively and then rapidly decreased at 5 weeks, but still persisted at 8 weeks in all three groups. The proportion of CD34+/HLA-DR- cells was the same tendency to CD34+/CD38-. VCAM+ expression rate from fractionated CD34+ cells at 0 and 8 weeks were 67.3% and 40.2% for BM and 64.1% 44.2% for umbilical cord blood but it was very low 31.2% and 5.1% for leukapheresis products. VLA-4+ expression rate for fractionated CD34+ cells at 0 and 8 weeks were similar tendency to VCAM+ cells. CONCLUSION: This study suggest that the count of LTC-IC decreased with time but still persisted until 8 weeks. Umbilical cord blood including BM help to establish the hematopoietic microenvironments.