Poison gas protects transplanted organs

Carbon monoxide is produced in most cell types through the catabolism of heme by enzymes of the heme oxygenase (HO) family. HO genes are also considered to offer protection against rejection in transplanted organs, but a direct role for carbon monoxide (CO) in such protection has been difficult to prove. In the January 20 online Nature Medicine, Leo E. Otterbein and colleagues at the University of Pittsburgh School of Medicine, USA, show CO that blocks development of arteriosclerotic lesions associated with chronic graft rejection and balloon-angioplasty–induced vessel injury (Nature Medicine, DOI:10.1038/nm817, January 20, 2003).

Otterbein et al. examined aortic segments transplanted into rats and mice and observed that graft exposure to CO prevented the arteriosclerotic lesions and suppressed stenosis after carotid balloon injury. The effect of CO was associated with a profound inhibition of graft leukocyte infiltration as well as with inhibition of smooth muscle cell proliferation. In addition, they ...