In a recent proteomics study, Johnson et al.71 studied the human cardiac ECM from cadaveric donor hearts. Decellularization was achieved after perfusion with high SDS concentration (i.e. 10 times greater than that used in our protocol) for more than 3 days. This yields a simplified ECM, but the ECM proteins will be denatured and ECM-associated proteins will be lost during prolonged incubation with such a high concentration of detergents. The study of ECM using MS approaches described below, requires a gentler extraction method from snap-frozen tissues that strikes a balance between removal of cellular components while preserving ECM-associated proteins.