StemSpan™-ACF has been developed for the in vitro culture and expansion of human hematopoietic cells. This medium contains recombinant proteins and synthetic components; it does not contain serum or other human- or animal-derived components. Recombinant hematopoietic growth factors, required for the optimal growth and expansion of hematopoietic cells, have not been added to StemSpan-ACF. This allows users to prepare medium that meets their requirements.