Cardiac allograft vasculopathy after cardiac transplantation and hormone therapy: Positive effects?

Background. There is a great deal of controversy surrounding the issue of hormone replacement therapy after transplantation. The question whether or not this therapy has effects in cardiac allograft vasculopathy (CAV), the Achilles heel of cardiac transplantation or other unique aspects of allograft function is still unknown. Methods. We investigated the long-term effect of 17 beta-estradiol as well as phytoestrogen Coumestrol, a synthetically produced phytoestrogen, on the development of CAV and the degree of fibrosis in an ovariectomized female heterotopic chronic allograft model (LEW-F344). Results. We found that, 150 days after transplantation, no significant effect of estrogen application on intimal thickening of coronary arteries was observed. 17 beta-estradiol and phytoestrogen Coumestrol did significantly reduce the perivascular immune reaction. However, the immune effect had no consequence on the intensity of CAV. Although neither 17 beta-estradiol nor phytoestrogen Coumestrol revealed a positive effect on CAV, the group of animals treated with 17 beta-estradiol showed the highest decline in heart function and the most distinct fibrosis. Conclusions. 17 beta-estradiol does not affect CAV positively, but worsens cardiac allograft function and leads to increased fibrosis. This is the first study showing a negative effect of 17-beta-estradiol after heart transplantation in the long term.