The acute respiratory distress syndrome (ARDS) and its less severe form, acute lung injury (ALI), are among the leading causes of morbidity and mortality in critically ill patients. Commonly induced by conditions associated with severe pulmonary inflammation, ALI results in disruption of the lung alveolar-capillary membrane barrier and resultant pulmonary edema associated with a proteinaceous alveolar exudate. Sepsis is another frequent and often fatal clinical condition for patients in the intensive care unit. It is characterized by a combination of infection and systemic inflammatory response syndrome (SIRS). Current effective treatment strategies for both ALI/ARDS and sepsis are lacking. We first examined the potential therapeutic role of mesenchymal stromal cells (MSCs) alone or together with the vasculoprotective factor, angiopoietin-1 (ANGPT1), for treatment of experimental ALI in mice. MSCs significantly reduced LPS (lipopolysaccharide)-induced pulmonary inflammation, as reflected by cell counts in bronchoalveolar lavage (BAL) fluid and pro-inflammatory cytokine levels in both BAL fluid and lung parenchymal homogenates. More importantly, administration of MSCs transfected with human ANGPT1 plasmid (MSCs-pANGPT1) completely reversed LPS-induced permeability in the lung (i.e., ALI). A follow-up study showed that MSCs remained effective in rescuing mice with LPS-induced ALI; however, the additional benefit from ANGPT1 was no longer observed. To further evaluate MSC-based therapy in a more clinically relevant model of acute injury, the cecal-ligation-and-puncture (CLP) model for sepsis was employed. Our results demonstrated that MSCs can reduce both systemic and pulmonary inflammation, as well as renal and liver dysfunction/injury, as reflected by plasma urea and bilirubin levels, in septic mice. Most notably, MSCs reduced sepsis-associated mortality from 45% to 24%. Our data demonstrate the feasibility and effectiveness of MSC- and MSC-based gene therapy for experimental ALI and sepsis, and provide the basis for the development of an innovative approach for the prevention and treatment of clinical ALI/ARDS and sepsis.

The acute respiratory distress syndrome (ARDS) and its less severe form, acute lung injury (ALI), are among the leading causes of morbidity and mortality in critically ill patients. Commonly induced by conditions associated with severe pulmonary inflammation, ALI results in disruption of the lung alveolar-capillary membrane barrier and resultant pulmonary edema associated with a proteinaceous alveolar exudate. Sepsis is another frequent and often fatal clinical condition for patients in the intensive care unit. It is characterized by a combination of infection and systemic inflammatory response syndrome (SIRS). Current effective treatment strategies for both ALI/ARDS and sepsis are lacking. We first examined the potential therapeutic role of mesenchymal stromal cells (MSCs) alone or together with the vasculoprotective factor, angiopoietin-1 (ANGPT1), for treatment of experimental ALI in mice. MSCs significantly reduced LPS (lipopolysaccharide)-induced pulmonary inflammation, as reflected by cell counts in bronchoalveolar lavage (BAL) fluid and pro-inflammatory cytokine levels in both BAL fluid and lung parenchymal homogenates. More importantly, administration of MSCs transfected with human ANGPT1 plasmid (MSCs-pANGPT1) completely reversed LPS-induced permeability in the lung (i.e., ALI). A follow-up study showed that MSCs remained effective in rescuing mice with LPS-induced ALI; however, the additional benefit from ANGPT1 was no longer observed. To further evaluate MSC-based therapy in a more clinically relevant model of acute injury, the cecal-ligation-and-puncture (CLP) model for sepsis was employed. Our results demonstrated that MSCs can reduce both systemic and pulmonary inflammation, as well as renal and liver dysfunction/injury, as reflected by plasma urea and bilirubin levels, in septic mice. Most notably, MSCs reduced sepsis-associated mortality from 45% to 24%. Our data demonstrate the feasibility and effectiveness of MSC- and MSC-based gene therapy for experimental ALI and sepsis, and provide the basis for the development of an innovative approach for the prevention and treatment of clinical ALI/ARDS and sepsis.