Evaluation of ex vivo expansion and engraftment in NOD-SCID mice of umbilical cord blood CD34+ cells using the DIDECO 'Pluricell System'

The Dideco 'Pluricell System' is a commercially available closed device composed of an expansion chamber and a kit of certified reagents that allow haematopoietic stem cell expansion. We have expanded seven umbilical cord blood (UCB) samples following the manufacturer's instructions; two groups of irradiated NOD-SCID mice have been transplanted with expanded and nonexpanded cells from the same UCB, and bone marrow was analysed for the presence of human cells. Average UCB volume was 61.6 +/- 8.8 ml; mean nucleated cell content was 1090.5 +/- 189.9 x 10(6). Percentage and number of CD34+ cells were 0.37 +/- 0.13% and 3.9 +/- 1.2 x 10(6). After separation, CD34+ cell purity was 82 +/- 11%. Mean number of inoculated cells was 760 000; mean NC and CD34+ fold expansion at 12 days was 230.4 +/- 91.5 and 21.0 +/- 11.9. Both groups of mice showed successful engraftment: the percentage of human cells was higher in the group receiving expanded cells (3.4 +/- 2.01%) compared to the group receiving nonexpanded cells (1.5 +/- 0.66%) (P<0.00018, Mann-Whitney test). The cell population obtained after 12 days expansion consisted mainly of myeloid and megakaryocytic progenitors. The CD34+ antigen reached the maximum expression level at day 12 (7.5 +/- 2.0%). Analysis of lineage-markers for human myelomonocytic, megakaryocytic, B, T, CD34 and erythroid cells, gave evidence that all the lineages were represented in the marrow of transplanted mice.