Abstract: The objective was to explore the optimal cytokine combinations for in vitro amplification of the cord blood CD34⁺ cell. We collected the cord blood from normal full-term deliveries, and isolated CD34⁺ cells using mini MACS laboratory separation system. The purified CD34⁺cells were cultured in static short-term serum free culture system with different combinations of SCF, FLT3-L, TPO and IL-3. Result: Within the three different cytokine combinations, the combination of SCF, FLT3-L, TPO and IL-3 was proved to be the most effective, and the notable result was that the amplification of CD34⁺/CD38^- subsets reached 197.9 folds. Conclusion: The SCF, FLT3-L, TPO and IL-3 combination is the optimal cytokine combination for in vitro cord blood CD34⁺ cell amplification.

Key words: cord blood hematopoietic stem cell, progenitor cell, in vitro CD34⁺ cell amplification, CD34⁺/CD38^- subsets