bronchiolitis obliterans syndrome

Background: Mesenchymal stem cell (MSC) effects can shift immune responses toward anti-inflammatory and tolerogenic phenotypes, potentially helping patients with bronchiolitis obliterans syndrome (BOS). Methods: We evaluated the effect of infusing allogeneic MSC intravenously in 9 patients with moderate BOS refractory to standard therapy who were not candidates for retransplant, dividing them into 3 dosing groups: Group 1, 1×106 MSC/kg (n=3); Group 2, 2×106 MSC/kg (n=3); and Group 3, 4×106 MSC/kg (n=3). We recorded pulmonary function tests, laboratory variables, and serum biomarkers pre- and post-MSC infusion. Results: These patients had significant decline in forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) over 1 year pre-MSC infusion (mean ± SD) FVC, 3.11±0.98 L, and FEV1 1.99+0.64 L versus FVC 2.58±1.03 and FEV1 1.61±0.52 just before infusion (P<0.05); representing a mean loss of 530 mL in FVC and 374 mL in FEV1 over 12 months. One year post-MSC infusion, mean FVC and FEV1 increased to 2.66±1.01 L and 1.63±0.55 L, respectively (changes no longer significant compared to before MSC infusion). Patients in Group 1 showed elevation of tolerance-inducing T regulatory cells and increased levels of epidermal growth factor. Tolerance-inducing Th-2 cytokines increased in Groups 1 and 2. These changes were not significantly different in these small sub-groups. Conclusion: MSC infusion appears to slow down or reverse the progressive decline in lung function in some patients with moderate BOS, possibly by inducing anti-inflammatory effects and promoting cell proliferation and angiogenesis.