Chimerism and use of mesenchymal stem cells in umbilical cord blood transplantation.

We performed a retrospective single-center analysis of 50 umbilical cord blood transplantations (UCBTs), focusing on chimerism development. Complete donor chimerism (DC) was associated with acute graft-vs.-host disease (aGVHD) grades II-IV for the CD3 (+) cell lineage (p = 0.01) and, in multivariate analysis, with total body irradiation (TBI) for all lineages (p < 0.01). Overall survival (OS) was negatively associated with patient age, (p < 0.001); aGVHD grades III-IV, (p < 0.001); and treatment with mesenchymal stem cells (MSCs) (p = 0.027). In conclusion, though multiple factors may have contributed, the association of TBI and DC might be worthy of consideration in the treatment of patients with malignant disease in the UCBT setting. The negative influence of MSCs on OS may be a reason for more careful usage of this treatment modality in combination with UCBT.