Cotransplantation of Haploidentical Hematopoietic and Umbilical Cord Mesenchymal Stem Cells with a Myeloablative Regimen for Refractory/relapsed Hematologic Malignancy

Human leukocyte antigen haploidentical hematopoietic stem-cell transplantation (haplo-HSCT) is associated with an increased risk of graft failure and severe graft-versus-host disease (GVHD). Mesenchymal stromal cells (MSCs) have been shown to support in vivo normal hematopoiesis and to display potent immunesuppressive effects. We cotransplanted the culture-expanded third-party donor-derived umbilical cord MSCs (UC-MSCs) in 50 people with refractory/relapsed hematologic malignancy undergoing haplo-HSCT with myeloablative conditioning. We observed that all patients given MSCs showed sustained hematopoietic engraftment without any adverse UC-MSC infusion-related reaction. The median times to neutrophil >0.50 × 10(9)/L and platelet >20 × 10(9)/L engraftment were 12.0 and 15.0 days, respectively. We did not observe an increase in severe acute GVHD (aGVHD) and extensive chronic GVHD (cGVHD), too. Grade II-IV aGVHD was observed in 12 of 50 (24.0 %) patients. cGVHD was observed in 17 of 45 (37.7 %) patients and was extensive in 3 patients. Additionally, only five patients (10.0 %) experienced relapse at a median time to progression of 192 days. The probability that patients would attain progression-free survival at 2 years was 66.0 %. The results indicate that this new strategy is effective in improving donor engraftment and reducing severe GVHD, which will provide a feasible option for the therapy of high-risk hematologic malignancy.