BACKGROUND

An optimal system for the expansion of pluripotent HPCs would ideally eliminate the use of cytokines and animal-derived serum. We have shown previously that a 3D, tantalum-coated porous biomaterial (Cytomatrix) supports the maintenance and expansion of human BM HPCs in the absence of cytokines.

METHODS

Umbilical cord blood (UCB) derived HPC were cultured in the Cytomatrix in the absence of exogenous cytokines. Phenotype was determined using FACS. Colony-forming units (CFU) activity was evaluated. Engraftment capacity was evaluated by transplanting the expanded cells into non-obese diabetic (NOD)/SCID mice.

RESULTS

We describe the expansion of HPCs from UCB using the Cytomatrix system. When UCB-derived CD34(+) cells were cultured in the Cytomatrix system for 2 weeks we observed an increase in the number of nucleated cells (3-fold) and CFU (2.6-fold). The number of CD45(+) and CD34(+) cells both increased three-fold. Trends demonstrated an increase in the frequency of CD34(+)C38(-) cells, and an increase in both CD34(+)C33(+) cells and CD34(+)C61(+) cells. No expansion of T or B lymphocytes was observed. When expanded UCB cells from the Cytomatrix were injected into sub-lethally irradiated NOD/SCID mice, human cells were detected in the murine peripheral blood and BM 6 weeks post-transplantation.

DISCUSSION

This unique approach to the expansion of UCB cells in a serum-free, cytokine-free environment may provide expansion of HPCs with multi-lineage engraftment capability that could be used clinically.