Hybrid hydrogel–extracellular matrix scaffolds identify biochemical and mechanical signatures of cardiac ageing

Extracellular matrix remodelling of cardiac tissue is a key contributor to age-related cardiovascular disease and dysfunction. Such remodelling is multifaceted including changes to the biochemical composition, architecture and mechanics, clouding our understanding of how and which extracellular matrix properties contribute to a dysfunctional state. Here we describe a decellularized extracellular matrix-synthetic hydrogel hybrid scaffold that independently confers two distinct matrix properties-ligand presentation and stiffness-to cultured cells in vitro, allowing for the identification of their specific roles in cardiac ageing. The hybrid scaffold maintains native matrix composition and organization of young or aged murine cardiac tissue, whereas its mechanical properties can be independently tuned to mimic young or aged tissue stiffness. Seeding these scaffolds with murine primary cardiac fibroblasts, we identify distinct age- and matrix-dependent mechanisms of cardiac fibroblast activation, matrix remodelling and senescence. Importantly, we show that the ligand presentation of a young extracellular matrix can outweigh the profibrotic stiffness cues typically present in an aged extracellular matrix in maintaining or driving cardiac fibroblast quiescence. Ultimately, these tunable scaffolds can enable the discovery of specific extracellular targets to prevent ageing dysfunction and promote rejuvenation. RNA-seq profiling of freshly isolated cardiac fibroblasts (CFs) from young or aged mice, as well as in vitro culture of these cells on DECIPHER ECM-hydrogel substrates after 48 hours.

心肌组织的细胞外基质（extracellular matrix）重塑是年龄相关心血管疾病与功能障碍的关键致病因素。此类重塑具有多维度特征，涵盖生化组成、结构架构与力学特性的改变，这使得我们难以厘清究竟哪些细胞外基质特性、以何种方式参与了功能障碍状态的形成。本研究报道了一种脱细胞细胞外基质-合成水凝胶复合支架（decellularized extracellular matrix-synthetic hydrogel hybrid scaffold），该支架可在体外环境中独立为培养细胞赋予两种截然不同的基质特性——配体呈递（ligand presentation）与基质刚度（stiffness），从而能够明确二者在心肌衰老中的具体作用。该复合支架可保留年轻或衰老小鼠心肌组织的天然基质组成与结构，同时其力学特性可被独立调控，以模拟年轻或衰老心肌组织的刚度水平。将原代小鼠心肌成纤维细胞接种至该支架后，本研究揭示了心肌成纤维细胞活化、基质重塑及细胞衰老的年龄与基质依赖性特异性机制。值得注意的是，本研究证实，在维持或诱导心肌成纤维细胞静息状态时，年轻细胞外基质的配体呈递效应可抵消衰老细胞外基质中常见的促纤维化刚度信号。最终，这种可定制调控的支架可助力发掘特异性细胞外靶点，以预防衰老相关功能障碍并促进组织年轻化。本数据集包含来自年轻及衰老小鼠的新鲜分离心肌成纤维细胞（cardiac fibroblasts, CFs）的RNA测序转录组分析数据，以及上述细胞在DECIPHER ECM-水凝胶底物上体外培养48小时后的转录组数据。