Nitrogen mustard (Chlorambucil) has a negative influence on early vascular development

The sulphur and nitrogen mustards are strong alkylating agents, which induces inflammations of the skin including blistering right up to ulcerations. Depending on the severity, the wounds may need weeks to heal. In the past it was shown that sulphur mustard has a destructive effect on endothelial precursor cells, which have been shown to play a pivotal role in the wound healing reaction by inducing neovascularisation. However, for these alkylating agents as well as for sulphur mustard nothing is known about their effects on endothelial precursors. Therefore, we investigated and compared the influence of Chlorambucil on proliferation, apoptosis and differentiation of endothelial cells in intact mouse embryoid bodies (EB). EBs were treated at different developmental stages and with different periods of Chlorambucil treatment.It was found that in each developmental stage and under each treatment period's Chlorambucil has an extremely negative effect on the vascularisation with a vessel reduction of around 99%. Of particular importance was the negative effect of treatment around day 3 of the development. On this day we found 377 vessels under control conditions but only 1.6 vessels under 24 h treatment of Chlorambucil. At this point in time many endothelial precursors can be found in the EB. Moreover, a negative effect on all stem cells was evident at this point in time, shown by an extreme reduction in EB size with 17.9 mm2 for the control and only 1.55 mm2 under Chlorambucil treatment. This negative effect on the vascularisation, on endothelial precursors but also on stem cells in general is of possible importance for impaired wound healing.