Hybrid hydrogel-extracellular matrix scaffolds identify distinct ligand and mechanical signatures in cardiac aging

Extracellular matrix (ECM) remodeling of cardiac tissue is a key contributor to age-related cardiovascular disease and dysfunction. Aberrant secretion, structural perturbations, and degradation of specific ECM components lead to significant alterations in ECM properties that disrupt healthy cell and tissue homeostasis. These changes in ECM are multifaceted, as alterations in ligand presentation, including both biochemical and architectural aspects, are often accompanied by stiffness changes, clouding our understanding of how and which ECM properties contribute to a dysfunctional state. To identify the specific roles of these interconnected ECM cues and elucidate their mechanistic regulation in cellular function, we developed a material system that can independently present these two distinct matrix properties, i.e., ligand presentation and stiffness, to cultured cells in vitro . We describe a decellularized ECM-synthetic hydrogel hybrid scaffold that maintains native matrix composition and organization of young or aged murine cardiac tissue with independently tunable scaffold mechanics that mimic young or aged tissue stiffness. Seeding these scaffolds with primary cardiac fibroblasts (CFs) from young or aged mice, we identify distinct age- and ECM-dependent mechanisms of CF activation. Importantly, we show that ligand presentation of young ECM can outweigh profibrotic stiffness cues typically present in aged ECM in maintaining or driving CF quiescence, thereby highlighting the unique roles of ECM in aging. Ultimately, these tunable scaffolds can enable the discovery of specific ECM targets to prevent aging dysfunction and promote rejuvenation. DECIPHER : DEC ellularized I n Situ P olyacrylamide H ydrogel- E CM hyb R id ### Competing Interest Statement The authors have declared no competing interest.