Defining cardiac functional recovery in end-stage heart failure at single-cell resolution

Recovery of cardiac function is the holy grail of heart failure therapy yet is infrequently observed and remains poorly understood. In this study, we performed single-nucleus RNA sequencing from patients with heart failure who recovered left ventricular systolic function after left ventricular assist device implantation, patients who did not recover and non-diseased donors. We identified cell-specific transcriptional signatures of recovery, most prominently in macrophages and fibroblasts. Within these cell types, inflammatory signatures were negative predictors of recovery, and downregulation of RUNX1 was associated with recovery. In silico perturbation of RUNX1 in macrophages and fibroblasts recapitulated the transcriptional state of recovery. Cardiac recovery mediated by BET inhibition in mice led to decreased macrophage and fibroblast Runx1 expression and diminished chromatin accessibility within a Runx1 intronic peak and acquisition of human recovery signatures. These findings suggest that cardiac recovery is a unique biological state and identify RUNX1 as a possible therapeutic target to facilitate cardiac recovery. Amrute, Lai et al. performed single-nucleus RNA sequencing and compared the cellular and transcriptomic features of hearts from non-diseased donors, from patients with heart failure who recovered systolic function after left ventricular assist device implantation and from patients who did not recover. The analyses identified cell-type-specific signatures of recovery and revealed the downregulation of RUNX1 expression in macrophages and fibroblasts as a predictor of recovery, as confirmed by in silico simulations and re-analysis of data from a mouse model of cardiac functional recovery.