Short-term, serum-free, static culture of cord blood-derived CD34+cells: effects of FLT3-L and MIP-1 alpha on in vitro expansion of hematopoietic progenitor cells

Background and Objective., The use of ex vivo expanded cells has been sugge sted as a possible means to accelerate the speed of engraftment in cord blo od (CB) transplantation. The aim of this study was to fix the optimal condi tion for the generation of committed progenitors without affecting the stem cell compartment. Design and Methods. Analysis of the effects of FLT3-L and MIP-1 alpha when combined with SCF, IL-3 and IL-5, in short-term (6 days), serum-free expans ion cultures of CB-selected CD34(+) cells. Results. An important expansion was obtained that ranged between 8-15 times for CFU-GM, 21-51 times for the BFU-E/CFU-Mix population and 11 to 30 time s for CD34(+) cells assessed by Row cytometry, From the combinations tested , those in which FLT3-L was present had a significant increase in the expan sion of committed progenitors, while the presence of MIP-1 alpha had a detr imental effect on the generation of more differentiated cells, However, ste m cell candidates assessed by week 5 CAFC assay could be maintained in cult ure when both MIP-1 alpha and FLT3-L were present (up to 91% recovery). Thi s culture system was also able to expand megakaryocytic precursors as deter mined by the cc-expression of CD34 and CD61 antigens (45-70 times), in spit e of the use of cytokines non-specific for the megakaryocytic lineage. Interpretation and Conclusions, The results obtained point to the combinati on of SCF, IL-3, IL-6, FLT3-L and MIP-1 alpha as the best suited for a prec linical shortterm serum-free static ex vivo expansion protocol of CB CD34() cells, since it can generate large numbers of committed progenitor cells as well as maintaining week 5 CAFC. (C) 1999, Ferrata Storti Foundation.