A co-culture system for expansion of nonenriched cord blood stem/progenitor cells
Many investigators have used xenogeneic, especially murine stromal cells and fetal calf serum to maintain and expand human stem cells. The proliferation and expansion of Human Hematopoietic Stem Cells (HSC) in ex vivo culture was examined with the goal of generating a suitable protocol for expanding HSC for patient transplantation. Using primary fetal liver cells, we established a serum- free culture system to expand human primitive stem/progenitors cells. Non enriched cord blood CD34 + cells were cultured on a monolayer of mouse primary fetal liver cells in the presence of trombopoietin, Flt3/Flk2 ligand and/or stem cell factor, IL-6 and IL-3 under serum-free conditions. After 1 or 2 weeks of culture, cells were examined for clonogenic progenitors and percentage of CD34 +, CD38 - cells. In the presence of trombopoietin, Flt3/Flk2 ligand and stem cell factor, fetal liver cells supported more than a 10- to 20-fold expansion of CD34 + cells. In addition, CFU-C assay were expanded more than 5 and 10 fold after 1 and 2 weeks of culture, respectively. These results strongly suggest that fetal liver cells may be a suitable feeder layer for expansion of hematopoietic progenitors from umbilical cord blood in vitro. © 2005 Asian Network for Scientific Information.