Impact of Cotransplantation of Mesenchymal Stem Cells on Lung Function After Unrelated Allogeneic Hematopoietic Stem Cell Transplantation Following Non-Myeloablative Conditioning

Background. In the context of hematopoietic stem cell transplantation (HSCT), mesenchymal stem cells (MSC) have been used to promote engraftment and prevent graft-versus-host disease. However, in animal models, MSC were shown to cause pulmonary alterations after systemic administration. The impact of MSC infusion on lung function has not been studied in humans. The objective of the study was to investigate the impact of MSC co-infusion on lung function and airway inflammation as well as on the incidence of pulmonary infections and cytomegalovirus (CMV) reactivation after HSCT. Methods. We have prospectively followed 30 patients who underwent unrelated HSCT with MSC co-infusion after non-myeloablative conditioning (NMA). Each patient underwent detailed lung function testing (FEV1, FVC, FEV1/FVC, RV, TLC, DLCO, and KCO) and measurement of exhaled nitric oxide before HSCT and 3, 6, and 12 months posttransplant. The incidence of pulmonary infections and CMV reactivation were also monitored. This group was compared with another group of 28 patients who underwent the same type of transplantation but without MSC co-infusion. Results. Lung function tests did not show important modifications over time and did not differ between the MSC and control groups. There was a higher 1-year incidence of infection, particularly of fungal infections, in patients having received a MSC co-infusion. There was no difference between groups regarding the 1-year incidence of CMV reactivation. Conclusions. MSC co-infusion does not induce pulmonary deterioration 1 year after HSCT with NMA conditioning. MSC appear to be safe for the lung, but close monitoring of pulmonary infections remains essential.