Sex-related differences in myocardial microvasculature – an experimental study on explanted healthy human hearts

The aim of this study is to provide insights regarding sex differences in the coronary microvasculature by studying myocardial capillary density and distribution using confocal microscopy on uniquely available pristine female and male hearts from healthy donors, not used for heart transplant. In order to describe potential sex differences in human myocardial microvasculature, a histological study will be performed in collaboration with The Sydney Heart Bank. Sydney Heart Bank is world-unique in that it contains pristine heart-transplant-grade preservation of >100 healthy hearts from transplant donors (~50% male). These hearts were not used for transplant for different reasons, mostly due to lack of compatible recipient. The myocardium in these hearts can uniquely be stained using antibodies for confocal microscopy, which is otherwise impossible following conventional autopsy due to tissue degradation. A total of 40 healthy donor hearts (20 age-matched hearts of each sex) will be studied. Capillary density per area, per cardiomyocyte, and average cardiomyocyte size will be quantified. Thus, sex-differences in both over-all capillary density and capillary distribution throughout the left ventricular myocardium will be assessed. Furthermore, myocardial extracellular volume and amount of interstitial fibrosis will be determined.