Individual and combined effects of mesenchymal stromal cells and recombinant stimulatory cytokines on the in vitro growth of primitive XXXX cells from human umbilical cord blood.

@entity2280 @entity25938 @entity3053 @entity1583
BACKGROUND AIMS: We have previously characterized the in vitro growth of two cord blood-derived @entity1583 cell populations in liquid cultures supplemented with recombinant cytokines. In the present study, we assessed the effects of bone marrow-derived mesenchymal stromal cells (MSC) on the growth of such cells. METHODS: @entity2280 (+) @entity3053 (+) Lin(-) and @entity2280 (+) @entity3053 (-) Lin(-) cells were obtained by negative selection, and cultured in the presence of marrow-derived MSC and/or early- and late-acting cytokines. Hematopoietic cell growth was assessed throughout a 30-day culture period. RESULTS: In the presence of MSC alone, both populations showed significant proliferation. Direct contact between MSC and @entity2280 (+) cells was fundamental for optimal growth, especially for @entity2280 (+) @entity3053 (-) Lin(-) cells. In the presence of early-acting cytokines alone, cell growth was significantly higher than in cultures established with MSC but no cytokines. In cultures containing both MSC and early-acting cytokines, a further stimulation was observed only for @entity2280 (+) @entity3053 (-) Lin(-) cells. The cytokine cocktail containing both early- and late-acting cytokines was significantly more potent at inducing @entity1583 cell growth than the early-acting cytokine cocktail. When cultures were supplemented with early- and late-acting cytokines, MSC had no further effect on the growth of @entity1583 cells. CONCLUSIONS: MSC seem to play a key role, particularly on more primitive ( @entity2280 (+) @entity3053 (-) Lin(-)) cells, only in the absence of cytokines or the presence of early-acting cytokines. When both early- and late-acting cytokines are present in culture, MSC seem to be unnecessary for optimal development of @entity25938 and @entity2280 (+) cells.
