Clearance of p16-positive cardiac cells improves age-related cardiac remodeling in mice.

Senescent cells are characterized by expression of markers like p16 and secretion of profibrotic and proinflammatory factors. The role of cellular senescence in age-related cardiac remodeling and dysfunction is incompletely understood. This study aimed to: (i) evaluate the effect of p16- positive cell clearance on cardiac function and structure in aging mice, and (ii) assess the role of different cardiac cell-types in the response. Hypertrophy markers, ion channels and calcium handling protein gene expression. Statistical analysis for all panels: one-way ANOVA followed by Tukey's test, significance level P<0.05 (N=6 for each group). Each point represents results from one mouse; bars and horizontal lines are means and SD. NK-ATTAC mice, permitting targeted clearance of p16-positive cells upon exposure to the dimerizing agent AP20187 (AP), were treated with AP or vehicle from 12 to 18 months of age. Cardiac function and structure were assessed with echocardiography, hemodynamics with a Millar catheter. p16-positive cells in various cardiac cell populations were analyzed with Fluorescence-Activated Cell Sorting (FACS) and immunofluorescence imaging. Echocardiography revealed significant attenuation of aging-associated increases in left ventricular mass to diameter at end-diastole (LVDd) and anterior wall thickness at end diastole (LVAWTd) in Aged-AP mice versus Aged-Vehicle. Diastolic dysfunction in vehicle mice normalized with AP treatment. FACS results indicated clearance of p16-positive fibroblasts with AP. Immunofluorescence imaging indicated reduced p16-positive fibroblasts and cardiomyocytes with AP, implicating them in the effects of p16-positive cell clearance on age-related cardiac remodeling. Exposure of cardiomyocytes to senescent fibroblast products led to upregulation of hypertrophy markers, pointing to paracrine effects on cardiomyocytes. This study highlights the potential contribution of senescent fibroblasts and cardiomyocytes to age-related cardiac remodeling. Modulating senescence might provide a new approach to age-related cardiac diseases like heart failure.