Rationale: There are controversial reports on applications of mesenchymal stromal cells (MSCs) in patients with
acute respiratory distress syndrome (ARDS). Objectives: We hypothesized that lung microenvironment was the main determinant of beneficial versus detrimental effects of MSCs during ARDS. Methods: Lung
proteome was profiled in three models of injury induced by
acid instillation and/or
mechanical ventilation in mice. Human gene of
glutathione peroxidase-1 was delivered before MSC administration; or MSCs carrying human gene of
IL-10 or
hepatocyte growth factor were administered after
lung injury. An inhibitory cocktail against
IL-6,
fibronectin, and oxidative stress was used in in vitro studies using human small airway epithelial cells and human MSCs after exposure to plasma of patients with ARDS. Measurements and Main Results: Distinct proteomic profiles were observed in three
lung injury models. Administration of MSCs protected lung from
ventilator-induced injury, whereas it worsened
acid-primed
lung injuries associated with fibrotic development in lung environment that had high levels of
IL-6 and
fibronectin along with low
antioxidant capacity. Correction of microenvironment with
glutathione peroxidase-1, or treatment with MSCs carrying human gene of
IL-10 or
hepatocyte growth factor after
acid-primed injury, reversed the detrimental effects of native MSCs. Proteomic profiles obtained in the mouse models were also similarly observed in
human ARDS. Treatment with the inhibitory cocktail in samples of patients with ARDS retained protective effects of MSCs in small airway epithelial cells. Conclusions: MSCs can be beneficial or detrimental depending on microenvironment at the time of administration. Identification of potential beneficiaries seems to be crucial to guide MSC
therapy in ARDS.