Flow cytometric analysis of CD34⁺ cells from cord blood or mobilized adult blood after different days of culture in the presence of SCF and PEG-rHuMGDF.

(A) Triple staining of cultured adult and neonate CD34⁺cells at day 6 after stimulation by SCF and PEG-rHuMGDF. Gate R2 in yellow corresponds to CD41⁺CD42⁻ cells, and R3 in pink to CD41⁺CD42⁺ cells. In the 2 last panels (gates R2 + R3), the expression of CD34 and CD42 in the CD41⁺ cells is compared in neonates and adults. (B) Cord blood (neonate) or mobilized (adult) CD34⁺ cells were labeled after purification (D0) or daily from day 2 to day 5 with antibodies against CD34 and CD41. The CD41 antigen on fresh cord blood CD34⁺ cells partly corresponds to platelet fragments and diminishes after neuraminidase or elastase treatment. In the CD34-CD41 plot, 9.74% and 6.8% correspond to the CD34⁺CD41⁺CD42⁻ cell population. (C) Schematic pathways for acquisition of CD41 and CD42 surface antigens from CD34⁺ cells in neonates and adults.