Despite decades of research, no specific pharmacological therapy to treat acute lung injury (ALI) has been identified. At present, the only effective therapies act by limiting iatrogenic injury associated with positive fluid balance1 or mechanical ventilation.2 3 As efforts to pharmacologically modulate the complex inflammatory process which leads to alveolar injury have been unsuccessful,4 focus has changed to cell based therapy, aimed at utilising stems cells which have pleiotropic effects and which respond appropriately to local signalling molecules.

Stem cells have the capacity for limitless self-renewal and differentiation. Mesenchymal stem cells (MSC) are multipotent adult stem cells with the capacity to differentiate into many different cell types, including alveolar cells. There are several mechanisms through which MSCs could potentially be used for attenuating lung injury and augmenting repair.5 On the basis of the currently available data, and supported by...