2.1 Patients and ethics
From 55 patients, a biopsy of the parietal pericardium (2x2 cm) was taken at the initiation of elective cardiothoracic surgery (coronary artery bypass grafting and/or cardiac valve replacement surgery) and stored in sterile physiological salt solution (PSS) at 4 °C as previously described(Leurgans et al., 2016). Informed written consent was obtained from all patients prior to surgery. The study was approved by the Regional Committees of Health Research Ethics for Southern Denmark (S-20140202) and experiments were conducted according to the principles expressed in the Declaration of Helsinki of the World Medical Association(World Medical, 2013). Characteristics of the patients are summarized in Table 1.