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

Abstract

Animal experiments are widely accepted in arteriosclerosis research. The aim of the present study was to establish an organ culture model (rabbit aorta) to investigate inhibitory estrogen effects on post injury neointima formation in the vessel wall and to examine whether these effects are cytotoxic. Phytoestrogens as well as 17ß-estradiol have been demonstrated to inhibit proliferation and migration of vascular smooth muscle cells. They are able to reduce neointima proliferation in certain concentrations. 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 randomised in groups of n = 12 and held in culture. 17ß-estradiol, Genistein and Daidzein were applicated in concentrations of 20 µM, 30 µM, and 40 µM. 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 concentration of 17ß-estradiol or the two phytoestrogens having been evaluated to inhibit the neointima formation. 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 µM 17ß-estradiol, 20 µM Genistein, and 40 µM Daidzein significantly inhibited neointima formation over 21 days. After another 7 days of cultivation in medium only the amount of neointima formation was comparable to that of not estrogen-treated controls after 21 days. We therefore concluded 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 in vivo experiment could be markedly reduced. The results are of clinical interest because phytoestrogens and 17ß-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.