LTBP4 and heart failure: Levels of cytokines such as TGF-β3, LTBP4, and IGFBP7, which were expressed from senescent failing cardiomyocytes, were high in patients with heart failure (depending on the severity) and low after transplantation, similar to NT-proBNP, a well-established biomarker of heart failure35 (Fig. 7n, Supplementary Fig. 7g).