Intratracheal therapy with autologous bone marrow-derived mononuclear cells reduces airway inflammation in horses with recurrent airway obstruction

•The cell therapy reduced the number of neutrophils in the BALF.•The cell therapy increased the number of macrophages in the BALF.•The cell therapy improved the clinical parameters of RAO horses.•The cell therapy increased the level of the anti-inflammatory interleukin-10.•Instillation of BMMCs can be a new treatment for horses with RAO.

This research evaluated the effects of bone marrow-derived mononuclear cells (BMMCs) on the inflammatory process in the equine recurrent airway obstruction (RAO). Eight horses in RAO clinical score were divided into cell therapy group (Gcel) treated with a single intratracheal dose of BMMCs, and dexamethasone group (Gdex) treated with 21 days of oral dexamethasone. The horses were clinically revaluated on days 7 and 21, together with cytological evaluation of the BALF, and detection of inflammatory markers (interleukins [IL]-10, -4, and -17, and interferon γ and α). There were decreases in respiratory effort and clinical score on days 7 and 21(p < 0.05) for both groups. The percentage of neutrophils decreased and macrophages increased on days 7 and 21 (p < 0.005) in both groups. IL-10 levels increased in the Gcel group on day 21 compared to days 0 and 7 (p < 0.05), but this was not observed in the Gdex group. The quantification of IL-4, IL-17, IFN-γ, and IFN-α did not change between evaluations in both groups. These preliminary results suggest that BMMCs may ameliorate the inflammatory response of RAO.