Cytokine-free Expansion of Hematopoietic Stem Cells with Mixed Mesenchymal Stem Cells Isolated from Bone Marrow and Periosteum

Most hematopoietic stem cells are located in bone marrow(BM) architecture in close proximity to the endosteal surface of bone. We investigated the synergistic effects of mesenchymal stem cells(MSCs) from BM and periosteum-derived progenitor cells(PDPCs) as mixed feeder cells on the ex vivo expansion of CD34+ cells from umbilical cord blood. Enriched CD34+ cells were cultured in a cytokine- and serum-free medium for 2 weeks with the respective mitomycin C-treated each or mixed feeder layers. Total cell expansion, immunophenotypes, and clonogenic ability were analyzed. In mixed feeder cultures, total nucleated cells were expanded by 26.4-fold at day 10. Furthermore, fold increase of CD34+/CD38(-)cells was found to be 67-fold. These results indicate that the PDPCs can be used as efficient feeder cells for the ex vivo expansion of CD34+ cells.