RESUMO
BACKGROUND: Although bone marrow (BM) CD34+cells and peripheral blood (PB) CD34+ cells are developmentally and functionally related, the recent data suggested that they may have different functional and clinical capabilities. Moreover, they have differential gene expression underlying the functional distinctions of primary human CD34+ hematopoietic stem and progenitor cells from BM and PB. The aim of this study was to investigate the plating efficiency of single CD34+ progenitor cell from BM, PB and umbilical cord blood (UCB). METHODS: After sorting, single CD34+ cells were cultured in individual wells of 96-well plates in serum-free medium containing selected hematopoietic growth factors, with or without G-CSF. Plating efficiency was microscopically determined by the presence of clusters of viable cells:[the number of positive (cells were present) wells/total wells]x100. CD34+ cell-derived colonies were classified according to the cell number per well. RESULTS: Although there was some variation of plating efficiency of CD34+ cells among six normal BMs, six PBs and five UCBs, overall average plating efficiency of single CD34+ cells from BM, PB and UCB was 30% (30.0+/-11.7, mean+/-SD), 79% (78.6+/-11.7) and 45% (45.3+/-9.3) respectively. As expected, the colony size was increased in the presence of G-CSF. CONCLUSION: The results of this study clearly showed that the different ex vivo expansion of single CD34+ progenitor cells from BM, PB and UCB. These might be an important data for understanding stem cell expansion in vivo and designing clinical application.