Allogeneic mesenchymal stem cell therapy for refractory cytopenias after hematopoietic stem cell transplantation.

Background: Posttransplant cytopenias are a severe complication after allogeneic stem cell transplantation (allo-SCT) and their origin is often multifactorial or unknown. They are frequently refractory to standard therapy, which may include steroids and/or immunoglobulins. Mesenchymal stem cells (MSCs) are an attractive therapeutic tool in the allo-SCT setting for the ability to enhance engraftment as well as acting as immunosuppressants for graft-versus-host disease. There is no prior experience in the literature of the use of MSCs to treat cytopenias after allo-SCT.

Case Reports: In this work we report for the first time four cases of refractory posttransplant cytopenias (three patients with thrombocytopenia and one with neutropenia) that were treated with MSCs from a third-party donor. MSCs were expanded from 100 mL of marrow obtained under standard good manufacturing practice conditions. Most patients received more than one cell dose, and median dose of MSCs administered was 1 × 10(6) /kg.

Results: All patients recovered normal blood counts, with a mean follow-up of 12.5 months. There were no adverse events related to MSC administration.

Conclusion: MSC therapy may contribute to the recovery of refractory posttransplant peripheral cytopenias in patients undergoing allo-SCT.