Effects of agitation speed on the ex vivo expansion of cord blood hematopoietic stem/progenitor cells in stirred suspension culture.

The mononuclear cells were cultivated in stirred flasks at different agitation speeds of 30 rpm, 45 rpm, 60 rpm and 80 rpm. At the agitation speed of 30 rpm, total cells achieved higher expansion folds and the CFC density increased. When at higher agitation speed of 60 rpm or 80 rpm, the number of cells dropped rapidly and characteristics of hematopoietic stem/progenitor cells (HSPCs) were not maintained. Moreover, the culture duration of 6-9 days was better for HSPCs ex vivo expansion. These data indicated that HSPCs should be cultured at relatively low agitation speed and for a short-term period when cultured in stirred suspension system.