Post-injury ex vivo model to investigate effects and toxicity of pharmacological treatment in rings of rabbit aortic vessels.

Animal experiments are widely accepted in arteriosclerosis research. The aim of the present study was to establish an organ culture model (rings of rabbit aortic vessels) to investigate inhibitory estrogen effects on post injury neointima formation in the vessel wall and to examine whether these effects are cytotoxic. Estrogens are used for secondary prevention of atherosclerosis in postmenopausal women (estrogen replacement therapy/ERT). Phytoestrogens as well as the ovarian 17 beta-estradiol have been demonstrated to inhibit proliferation and migration of vascular smooth muscle cells which are key events in atherogenesis and restenosis after coronary angioplasty. In situ endothelial denudation of the thoracic and abdominal aorta was performed in female rabbits by a 3F Fogarty catheter. Segments of 5 mm were randomized in groups of n = 12 and held in culture. 17 beta-estradiol, Genistein and Daidzein were applied in concentrations of 20 microM, 30 microM, and 40 microM. Groups without estrogen treatment served as controls. The segments were investigated after 21 days. Afterwards, 3 further groups (n = 12) were held with the lowest concentrations of 17 beta-estradiol or the two phytoestrogens having been evaluated to inhibit the neointima formation significantly. After 21 days of treatment these sections were held in medium only for another 7 days to proof whether these segments were still able to proliferate. A denuded control group was held in medium only over 28 days. Compared to controls, 30 microM 17 beta-estradiol, 20 microM Genistein, and 40 microM Daidzein inhibited neointima formation significantly over 21 days. After another 7 days of cultivation in medium only the amount of neointima formation was comparable to that of non-estrogen-treated controls after 21 days. We therefore suggest that the demonstrated inhibitory effect is not explained by toxicity. In conclusion, by the use of this organ culture model it was possible to demonstrate non-toxic post injury effects of different estrogens in the vasculature. Because 24 aortic segments could be taken from one aortic vessel, the number of animals that would have been necessary for an experiment (8 to 10 per group for statistical reasons) could be markedly reduced. The results are of clinical interest because phytoestrogens and 17 beta-estradiol may offer therapeutic options for patients after coronary angioplasty regarding the process of restenosis. Because phytoestrogens do not affect the reproductive system they can also be used in men.