Sex-specific modification of progesterone receptor expression by 17β-oestradiol in human cardiac tissues

BACKGROUND: Although circulating levels of sexual hormones in elderly men and women are low and quite similar, the adaptation of the elderly heart to stress differs between the sexes. We have hypothesized that the effects of sexual hormones in the heart may differ in men and women. Here, we assessed whether 17β-oestradiol regulates gene expression in the human heart in a sex-dependent manner. We selected the progesterone receptor as a well studied 17β-oestradiol target that may be pathologically linked to cardiac remodelling. METHODS: In order to assess the ex vivo effects of 17β-oestradiol in intact human cardiac tissues, we developed a 24-h model for the culture of human atrial myocardium. We verified tissue viability after 24 h in culture with two standard assays to determine the degree of apoptosis and metabolic activity of cardiac tissues. Progesterone receptor mRNA and protein level were measured after 24-h treatment of tissues with 17β-oestradiol. Statistical analysis was performed by the Mann-Whitney U test and two-way ANOVA. RESULTS: We established a tissue culture model that allows for the study of viable human cardiac tissue over a 24-h period. After 24 h, cultured cardiac tissues revealed low apoptosis, retained their metabolic activity and, therefore, remained viable. Treatment with 17β-oestradiol led to an induction of the progesterone receptor mRNA level in female (P = 0.001) but not in male tissues. Similarly, there was an increase in the level of progesterone receptor protein in female tissues (P = 0.03), while a decreasing trend was observed in male tissues (P = 0.079) exposed to 17β-oestradiol. CONCLUSIONS: Our novel finding may offer a molecular explanation for the sex-specific differences observed in cardiac remodelling. The culture model we established for human cardiac tissue will facilitate the study of cellular processes in health and disease and will be of use for pharmacological testing.