Allogeneic Compact Bone-Derived Mesenchymal Stem Cell Transplantation Attenuates the Severity of Idiopathic Pneumonia Syndrome in a Murine Bone Marrow Transplantation Model.

Background/aims: Idiopathic pneumonia syndrome (IPS) is a serious and life-threatening lung complication following allogeneic hematopoietic stem cell transplantation (allo-HSCT) and currently no effective therapies exist. This study was designed to determine whether transplantation of allogeneic murine compact bone derived- mesenchymal stem cells (CB-MSCs) could prevent the development of IPS.

Methods: We tested the effects of CB-MSCs transplantation on IPS using an established murine model of C57BL/6 (H-2b)→BALB/c (H-2d). Survival rates, body weight change, clinical GVHD scores, lung histological changes were assessed after IPS induction. Mechanistically, concentrations of cytokines (TNF-α, IFN-γ and IL-4) and chemokines (CCL5, CXCL9 and CXCL10) in bronchoalveolar lavage fluid (BALF) from the recipient mice were measured at different time point post-transplantation. CD4+CD25+Foxp3+ regulatory T cell (Treg) percentage, CCR5, CXCR3 and CCR7 expression on CD3+ T cells, and lung CXCR3, CCR5, CCR7, T-bet and GATA-3 mRNA levels were also evaluated at different time point post-transplantation.

Results: Co-transplantation of CB-MSCs significantly attenuated the severity of lung injuries and increased survival rate of mice compared to non-cotransplanted mice. A higher Treg percentage, reduction of TNF-α, IFN-γ, CCL5, CXCL9 and CXCL10 levels, down-regulation of CXCR3 and CCR5, as well as up-regulation of CCR7, were observed in MSCs co-transplantation mice. Also, the prophylactic effect of CB-MSCs was associated with a shift of Th1/Th2 balance toward anti-inflammatory Th2 polarization.

Conclusions: Allogeneic CB-MSCs effectively controlled the occurrence of IPS due to its profound immunomodulatory capacity. This may offer a novel prophylactic approach for IPS after allo-HSCT.