Ex Vivo Expansion of Cord Blood Hematopoietic Stem and Progenitor Cells in a Wharton’s Jelly and Bone Marrow Stromal Cell Based Co-Culture System

Umbilical cord blood (UCB) is of great value by providing transplantable hematopoietic stem and progenitor cells (HSPCs). Compared with HSPCs from adult bone marrow and periferial blood, UCB cells are more primitive with higher proliferation ability, and UCB HSPC transplantation requires less HLA matching. The major problems in UCB transplantation is the limited number of transplantable cells in each unit which are often insufficient for transplantation in adults

In order to elucidate the effects of the main components of bone marrow on cord blood CD34+ expansion, freshly enriched cord blood CD34+ cells were cultured in contact with bone marrow stromal cell (BM-MSC) monolayer, BM-MSCs pre-seeded in decellularized Wharton's jelly matrix (DWJM), and in DWJM alone, as well as separated by a transwell preventing the physical contact between CD34+ cells and BM-MSCs in a medium supplemented with a cytokine cocktail including Flt-3 igand, stem cell factor, and thrombopoietin. Expansion patterns were analyzed by CD34+ and CD45+ expansion, as well as colony-forming unit (CFU) assay. We found that the number of CFU increases significantly in cord blood CD34+ cells co-cultured with BM-MSCs in DWJM compared to that of control. Particularly, the increase in CFU-GEMM, BFU-E and CFU-GM number is more significant compared to other colonies. Importantly, DWJM alone is not able to increase CFU numbers compared to that of the control indicating there is a synergistic effect between DWJM and BM-MSCs on cell stemness. Surprisingly, BM-MSCs in DWJM also increses CD34+ cell expansion by 2 to 3 fold after one week culture, presumably from enhanced ablilty of self-renewal from CD34+ cells. Therefore, our data suggest DWJM synergizes with BM-MSCs to increase CD34 cell stemness, which can potentially be used in the clinic therapy.