Bone marrow-derived cells contribute to lung regeneration after elastase-induced pulmonary emphysema.

All-trans retinoic acid (ATRA) is known to reverse the anatomic and physiologic signs of pulmonary emphysema. However, the origin of the progenitor cells involved in this lung regeneration remains unclear. Recently, it was shown that bone marrow could be the source of progenitor cells for several cell types. Mice with elastase-induced emphysema were treated with ATRA, granulocyte colony-stimulating factor (G-CSF), or a combination of both. ATRA or G-CSF promoted lung regeneration and increased bone marrow-derived cell (BMC) numbers in alveoli. Combined treatment of both had an additive effect, which indicated that BMC mobilization might be important in lung regeneration.