Progenitor cells in acute lung injury

Aim. Acute lung injury (ALI) and the acute respiratory distress syndrome (ARDS) are common and serious pulmonary illnesses associated with a high morbidity and mortality. A specific therapy that improves outcomes in these disorders has not been forthcoming. There is growing interest to explore novel therapies, namely stem cells, to repair damage to the lung that is observed in these disorders. In this manuscript, stem cell investigations in the field of pulmonary medicine are delineated, with a focus on endothelial progenitor cells (EPCs) in the setting of ALI. Methods. A review of the pertinent literature in this field is presented, including recent investigations in animal models. Work related to the assessment of EPCs in human subjects after transplantation and in patients with pneumonia is described. The measurement of circulating EPCs in those with ALI is presented in detail. Results. Patients with ALI have an increased number of circulating EPCs than do healthy controls. Further, a greater number of circulating EPCs is associated with improved outcomes in a multivariable analysis correcting for the effects of age, gender, and severity of illness scores. Conclusion. EPCs represent a rapidly expanding interest in critical care medicine. However, their specific properties and utilities with regards to lung injury need to be further delineated prior to their use in the therapy of ALI.