“…With this approach, the nitroreductase enzyme is expressed in the target tissue and its activity is used to convert an added nontoxic prodrug into a toxic agent that will kill cells. The principal limitation with this system is the issue of subsequent diffusion of the toxic metabolites into neighboring cells (Helsby et al, 2004), but this has apparently been solved using a new prodrug, metronidazole. The new studies have produced targeted cell-ablations within the pancreas, liver, and the heart (Curado et al, 2007;Pisharath et al, 2007), although their cardiac cell "damage" phenotype does not appear as extensive as we report here.…”