Phenotypic characterization of immunomagnetically purified umbilical cord blood CD34+cells

This study describes the multilineage differentiation pattern of purified C D34+ stem cells obtained from human umbilical cord blood. CD34+ cells were collected from 49 umbilical cord blood samples. Following immunomagnetic pu rification, cells were double stained with anti CD34 and CD71, CD61, CD7, C D19, CD33, CD36 and triple stained with anti CD34, CD38 and HLA-DR. Analyse s were performed using a FACScan flow cytometer. After purification, the me an CD34+ cells' purity was 85.49 +/- 7.08%. Several subpopulations of umbil ical cord blood CD34+ cells were identified indicating different lineage co mmitment. The majority of CD34+ cells expressed both CD38 and HLA-DR (91.74 +/- 3.76%), while those lacking CD38 were 3.43 +/- 2.12% (CD38-DR+) and 1. 81 +/- 1.54% (CD38-DR-). These data were compared to the expression of line age commitment markers on purified CD34+ cells from 5 mobilized peripheral blood samples. The percentage of peripheral blood CD34+CD38-DR+ and CD34+CD 38-DR- cells was significantly lower than umbilical cord blood, 0.24 +/- 0. 18% and 0.04 +/- 0.03% respectively. The knowledge and standardization of u mbilical cord blood CD34; cells phenotype is critical since umbilical cord blood volume is limited. The homogeneity of CD34+ subpopulation phenotype s uggests that monitoring of lineage differentiation antigens may not be rele vant for clinical use of umbilical cord blood samples. However, the observe d higher percentage of pluripotent CD34+38- stem cells in umbilical cord bl ood compared to peripheral blood, that might explain the successful clinica l use of umbilical cord blood even when low number of cells are used, candi dates these antigens as the predictive parameter for clinical use of umbili cal cord blood samples. (C) 1999 Academic Press.