Marrow cells as progenitors of lung tissue

There is accumulating evidence showing that marrow-derived cells can engraft as differentiated epithelial cells of various tissues, including the lung. These findings challenge long-held views regarding the basic biology of stem cells. Elucidating the fundamental mechanisms controlling these processes is the major challenge of this field. Regardless, these experiments suggest new strategies for the treatment of chronic diseases. (C) 2003 Elsevier Inc. All rights reserved.