The cellular and molecular elements involved in the turnover and regeneration of the lung alveolar epithelium remain largely unknown (Kim, Am J Physiol Lung Cell Mol Physiol 293:L1092-1098, 2007). Isolation and characterization of putative stem cells with limited and nonspecific markers have made necessary the use, in parallel, of culture restrictive conditions and optimized reagents to allow selection and long-term expansion of this population.