Mesenchymal Stem Cells versus Mesenchymal Stem Cells Combined with Cord Blood for Engraftment Failure after Autologous Hematopoietic Stem Cell Transplantation: A Pilot Prospective,Open-Label,Randomized Trial

Engraftment failure (EF) after autologous hematopoietic stem cell transplantation is a serious complication. We prospectively evaluated the effects and safeties of mesenchymal stem cells (MSCs) alone and MSCs combined with cord blood (CB) for EF. Twenty-two patients were randomized to receive MSCs (MSC group; n = 11) or MSCs plus CB (CB group; n = 11). Patients with no response (NR) to MSCs received the therapeutic schedule in the CB group, and those patients with partial response (PR) in the MSC group and patients without complete remission (CR) in the CB group received another cycle of MSC treatment. Patients who did not achieve CR after 2 cycles of treatments received other treatments, including allogeneic HSCT. After the first treatment cycle, response was seen in 7 of 11 patients in the MSC group and in 9 of 11 in the CB group (P = .635), with a significant difference in neutrophil reconstruction between the 2 groups (P = .030). After 2 treatment cycles, 16 patients achieved CR, 3 achieved PR, and 3 had NR. No patient experienced graft-versus-host disease (GVHD). With a median follow-up of 345 d (range, 129 to 784 d) post-transplantation, 18 patients remained alive and 4 had died (3 from primary disease relapse and 1 from cytomegalovirus pneumonia). The 2-year overall survival, disease-free survival, and cumulative incidence of tumor relapse post-transplantation were 75.2% ± 12.0%, 79.5% ± 9.4%, and 20.5% ± 9.4%, respectively. Our data indicate that the 2 strategies are effective for EF and do not result in GVHD or increase the risk of tumor relapse, but the MSC plus CB regimen has a superior effect on neutrophil reconstruction.