Effects of the cyclophosphamide metabolite acrolein in mammalian limb bud cultures

Cyclophosphamide must be metabolized by drug-oxidating systems in order to become biologically active. Up to now, it is not known exactly which metabolite is responsible for the teratogenic effects of the drug. Besides aldophosphamide and phosphoramide mustard, the metabolite acrolein must be considered as a possible candidate. We tested this unsaturated aldehyde in a mouse limb bud culture system, since results from in vivo studies are controversial and inconclusive. The following results were obtained: Concentrations of acrolein between 3 and 10 mg/l induce a significant impairment of limb bud differentiation with explants from 12-day-old mouse embryos. Scapula and paw skeleton were more affected than ulna and radius. With limbs from 11-day-old embryos we found similar effects, even at lower concentrations. A contact time of 20-40 min is sufficient to induce abnormal development. It is possible to antagonize the teratogenic effect of acrolein by addition of mesna (300 mg/l) to the culture medium. The abnormalities observed with acrolein under these experimental conditions are clearly different from those seen with hydroperoxy-cyclophosphamide.