Bronchioalveolar stem cells: the crossroads of lung regeneration

Tyler T. Cooper, David A. Hess

Abstract

Mammalian lungs are encased in dense endothelial cell networks to support systemic delivery of oxygen to vital organs (1-3), and to provide host pathogen defense by physical or chemical removal of foreign bodies (3,4). The evolutionary-refined architecture of mammalian lungs is primarily comprised of endoderm-derived epithelial cell populations (5); however, the lungs also harbour mesoderm-derived cells which contribute to the renin-angiotensin axis (6), innate immunity (3,4), and platelet production (7). Oronasal to parenchymal, the respiratory system is organized from the trachea, bronchi, bronchioles to the alveoli; the primary site of gas exchange (1,2).