Work

Superior EX vivo cord blood TNC and hematopoietic progenitor cell expansion following co-culture with bone marrow-derived mesenchymal stem cells

Year: 2006

Type: article

Abstract: One factor limiting the therapeutic efficacy of cord blood (CB) hematopoietic progenitor cell (HPC) transplantation is the low cell dose of the graft. Low cell dose is associated with an increased incidence of delayed or failed engraftment. However, cell dose can be increased and the efficacy of CB transplantation potentially improved by ex vivo CB expansion prior to transplantation. Two ex vivo CB expansion techniques were compared and hematopoietic output followed by measuring total nucleated cell (TNC), CD133+ and CD34+, colony-forming unit (CFU) and cobblestone area-forming cell (CAFC) numbers. Technique 1: Ex vivo culture of CD133+-selected cells; and Technique 2: Co-culture of unmanipulated CB with allogeneic bone-marrow-derived mesenchymal stem cell (MSC) monolayers. In both cases, ex vivo culture was performed in medium supplemented with granulocyte colony-stimulating factor (G-CSF), stem cell factor (SCF) and either thrombopoietin (TPO) or megakaryocyte growth and differentiation factor (MDGF). When compared to ex vivo liquid culture, ex vivo CB-MSC co-culture (1) required less cell manipulation resulting in less initial HPC loss and (2) markedly improved TNC (>10-fold), CFU (>25-fold), CD133+ (>7-fold) CD34+ (>14-fold), CAFCwk2 (>200-fold), and CAFCwk6 (>44-fold) output. In addition, MSC have also been shown to promote hematopoietic engraftment in animal models and to possess immunomodulatory activities and have been shown to reduce the severity of graft versus host disease. One concern associated with any ex vivo expansion strategy is that short-term reconstituting, lower quality HPC will be expanded at the expense of long-term reconstituting, higher quality HPC, thereby significantly impacting the hematopoietic reserve of the graft. Here we demonstrate that although neither technique significantly expanded the more primitive CAFCwk6 population, they were better preserved in the CB-MSC co-culture system. Although the expansion of the more mature components of the hematopoietic system (TNC, CFU, CD133+, CD34+, and CAFCwk2) in both cases was at the expense of the more primitive HPC, in neither case was the CAFCwk6 compartment completely exhausted, thereby potentially preserving part of the hematopoietic reserve of the graft. In improving TNC and HPC expansion, ex vivo CB-MSC co-culture therefore holds promise for improving engraftment kinetics and post-transplant complications in CB transplant recipients.

Source: Transplantation and Cellular Therapy

DOI: 10.1016/j.bbmt.2005.11.406