Cotransplantation of umbilical cord-derived mesenchymal stem cells promote hematopoietic engraftment in cord blood transplantation

Background. Delayed hematopoietic reconstitution after cord blood transplantation (CBT) may lead to increased risk of complications and longer hospitalization. Bone marrowYderived mesenchymal stem cells (MSCs) have been found to promote engraftment after hematopoietic stem cell transplantation. However, harvesting MSCs from bone marrow involves an invasive procedure. Then again, MSCs can be easily obtained from umbilical cords without harm to the donors. Methods. Umbilical cordYderived MSCs (UCMSCs) were isolated from Wharton's jelly and then ex vivo cultured. After showing normal karyotype and negative for infectious contamination, culture-expanded UCMSCs were intravenously infused into the recipients on the day of CBT. The control patients were those receiving CBT alone. Adverse effects and efficacy of intravenous UCMSCs were evaluated. Results. A total of five patients received cotransplantation of UCMSCs at the time of CBT. No serious adverse events were observed. The time to achieve neutrophil engraftment ranged from 7 to 13 days (median, 11 days) and platelet engraftment ranged from 22 to 41 days (median, 32 days). Compared with the nine patients receiving CBT alone, patients receiving cotransplantation of UCMSCs had significantly faster hematopoietic recovery of neutrophils and platelets (P=0.02 and 0.01, respectively). Conclusions. This pilot study is the first report of cotransplantation of UCMSCs in CBT. Intravenous infusion of UCMSCs appeared to be a feasible and safe modality to enhance hematopoietic engraftment in patients receiving CBT. Further studies were warranted.