Human umbilical cord blood CD34+ cell purification with high yield of early progenitors.

Human umbilical cord blood CD34+ cells were purified using a two-step procedure by elimination of the soybean agglutinin-binding cells and by a positive panning selection with a CD34 monoclonal antibody. The isolated fraction was 88-97% pure CD34+ cells. A yield of 48.5% was obtained when comparing the number of cells recovered in the CD34(+)-purified fraction and the number of CD34+ cells detected in the initial mononuclear cell fraction. By flow cytometry, we observed that the CD34+ cells that were not recovered were those that had the lower expression of CD34 antigen and were therefore the more mature cells. A high recovery of CFU-GEMM progenitors (73.9%) was also observed. These data suggest the possibility of purifying CD34+ umbilical cord blood cells for clinical applications, in particular for umbilical cord blood banking.