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.