Lung regeneration is the major challenge of modern
medicine. In this issue, Ma et al. identified a previously
unknown population of adult human lung stem cells, which
locates at the basal layer of airway epithelium and could be
marked by SOX9 gene expression. Culture and orthotopic
transplantation of such cells generated functional human
alveoli and bronchioles in mouse model. In a pilot clinical trial,
after autologous transplantation of such cells, two patients with
chronic lung diseases demonstrated recovery of pulmonary
structure and function. This is the fi rst evidence showing that
human lung tissue could be regenerated by adult stem cell
transplantation. The cover picture illustrated the re-growth of
“respiratory tree”.