Abstract
Background aims
We have previously characterized the in vitro growth of two cord blood-derived hematopoietic 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
CD34+ CD38+ Lin− and CD34+ CD38− 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 CD34+ cells was fundamental for optimal growth, especially for CD34+ CD38− 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 CD34+ CD38− Lin− cells. The cytokine cocktail containing both early- and late-acting cytokines was significantly more potent at inducing hematopoietic 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 hematopoietic cells.
Conclusions
MSC seem to play a key role, particularly on more primitive (CD34+ CD38− 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 CFC and CD34+ cells.
Acknowledgments
This study was partially supported by grant number FP-2005/2/I/365 from the Mexican Institute of Social Security (IMSS, Mexico), and grant number 7204 from the National Council of Science and Technology (CONACYT, Mexico).