Stem cells in airway smooth muscle: state of the art.

Very little is known regarding the function, origin, and turnover of airway smooth muscle (ASM). In this article, we discuss the embryological development of ASM, and provide information regarding candidate mesenchymal ASM progenitor cell populations specifically in relation to airway remodeling. This review also highlights the current limitations in studying ASM biology, and underscores the need for novel molecular tools and markers that will refine our understanding of this cell type in lung homeostasis and disease.