Cytokine effect on ex vivo expansion of haemopoietic stem cells from different human sources (vol 10, pg 291, 1998)

Human pluripotential stem cells (PSC) are currently the target for transpla ntation attempts and genetic manipulation. We have therefore investigated t he frequency and the expansion potential of PSC's in different types of blo od samples. CD 34(+) cells were thus obtained from human bone marrow (BM), as well as from peripheral blood (PB) and cord blood (CB) samples. After im mune-magnetic separation the highest yields of CD 34(+) cells were from BM (1.08-2.25%) and CB (0.42-1.32%) while PB samples gave much lower values. S uspension cultures of PSC's from the three sources were then set up, in the presence of combinations of haemopoietic growth factors. A remarkable ampl ification of the nucleated cell pool was observed reaching a maximum betwee n 10 and 15 days of culture; earliest and maximum expansion (up to 220-fold ) was achieved when Erythropoietin (Epo) was added to the culture medium, b ut this resulted in reduction of colony-forming cells and differentiation i nto erythroid progenitors. Clonogenic tests for BFU-E's derived colonies sh owed a peak value at 5 days of liquid culture. Further studies are advisabl e to establish the best cytokine combination for a valuable ex vivo expansi on, coupled with preservation of stem cell properties.