Because of their immunosuppressive abilities, mesenchymal stromal cells (MSCs) have been employed in clinical studies to treat steroid-refractory graft-versus-host disease (GVHD) after allogeneic hematopoietic cell transplantation. A number of studies have suggested that MSC infusion is safe and might be effective for treating acute GVHD. However, well-designed comparative studies are required to more precisely assess the impact of MSC infusion on GVHD treatment. Because MSCs form a bone marrow micro-environment and support hematopoiesis, they have been employed in clinical studies to facilitate hematopoietic recovery after cord blood transplantation and HLA-haploidentical donor transplantation. Some studies have demonstrated high engraftment rate and rapid neutrophil recovery. However, information is scarce. Further studies are required.
An allogeneic stem cell transplantation (allo-SCT) from a human leukocyte antigen (HLA) -identical sibling donor is the first treatment of choice for young patients with aplastic anemia (AA) while an allo-SCT from an alternative donors, such as an HLA-identical unrelated donor, and umbilical cord blood transplantation (CBT) need to be considered for AA patients whose disease is refractory to immunosuppressive therapy. The use of reduced-intensity conditioning regimens that ensure the engraftment of donor stem cells, and the development of more effective methods for preventing graft-versus-host disease (GVHD) would help to improve the outcomes of allo-SCT from alternative donors for AA. A reduced-dose cyclophosphamide (CY) regimen combined with fludarabine was developed to avoid cardiotoxicity due to CY and has since become the standard conditioning regimen for allo-SCT from alternative donors for AA. Recent reports have shown that alemtuzumab is more effective than anti-thymocyte globulin at preventing GVHD. Intensive immunosuppression based on strong conditioning regimens might be useful for reducing the risk of engraftment failure associated with CBT. The combined use of an HLA-haploidentical SCT from a related donor and the post-transplant administration of the CY regimen is currently attracting attention as a useful approach to SCT for AA due to its low transplant-related mortality rate and very low incidence of chronic GVHD.
To examine risk factors for cytomegalovirus (CMV) infection after allogeneic hematopoietic stem cell transplantation (allo-HCT), CMV infection was monitored weekly using both real-time quantitative polymerase chain reaction (RQ-PCR) and an antigenemia (Ag) assay in 81 patients who underwent allo-HCT. The relationship between clinical features and CMV status was analyzed retrospectively. Although the Ag assay could not be used until 2-3 weeks after allo-HCT because of a low white blood cell count, CMV DNA could be detected using RQ-PCR even in the early phase after allo-HCT. There was a significant correlation between viral load determined by the Ag assay and RQ-PCR. The detection rate with RQ-PCR was significantly higher than with the Ag assay 4 weeks after allo-HCT. Significantly more patients received pre-emptive therapy up until Day 100 after allo-HCT in the CMV-positive compared with CMV-negative groups, identified using RQ-PCR 3 and 4 weeks after allo-HCT. Compared with myeloid malignancy, patients with lymphoid malignancy had a significantly higher viral load 3 and 4 weeks after allo-HCT (RQ-PCR P=0.02 and P=0.014; Ag assay P=0.005 and P=0.002), and significantly more were undergoing pre-emptive therapy. Patients with low serum IgG levels before allo-HCT also had a significantly higher viral load than those with normal serum IgG concentrations 2 weeks after allo-HCT. Thus, it is recommended that these patients are monitored carefully for CMV after allo-HCT.