Expansion of HPCs from cord blood in a novel 3D matrix.

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.