Bulk RNA-Seq on human IMR90-derived cardiomyocytes at baseline and after menadione-induced stress in the presence and absence of cMSC-conditioned media

Ischemic heart disease remains the foremost cause of death globally, with survivors at risk for subsequent heart failure. Paradoxically, cell therapies to offset cardiomyocyte loss after ischemic injury improve long-term cardiac function despite a lack of durable engraftment. An evolving consensus, inferred preponderantly from non-human models, is that transplanted cells benefit the heart via early paracrine signals. Here, we tested the impact of paracrine signals on human cardiomyocytes, using human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) as the target of mouse and human cardiac mesenchymal stromal cells (cMSC) with progenitor-like features. In co-culture and conditioned medium studies, cMSCs markedly inhibited human cardiomyocyte death. Little or no protection was conferred by mouse tail tip or human skin fibroblasts. Consistent with the results of transcriptomic profiling, functional analyses showed that the cMSC secretome suppressed apoptosis and and preserved cardiac mitochondrial transmembrane potential. Protection was independent of exosomes under the conditions tested. In mice, injecting cMSC-conditioned media into the infarct border zone reduced apoptotic cardiomyocytes >70% locally. Thus, hPSC-CMs provide an auspicious, relevant human platform to investigate extracellular signals for cardiac muscle survival, substantiating human cardioprotection by cMSCs, and suggesting the cMSC secretome or its components as potential cell-free therapeutic products.

缺血性心脏病仍是全球首要的致死性病因，其幸存者后续罹患心力衰竭的风险居高不下。颇具悖论性的是，尽管缺血损伤后移植的细胞无法实现持久植入，但用于抵消心肌细胞丢失的细胞疗法仍可改善心脏长期功能。目前学界日益达成的共识（主要基于非人动物模型推导得出）认为，移植细胞通过早期旁分泌信号对心脏发挥保护作用。本研究以人多能干细胞源性心肌细胞（human pluripotent stem cell-derived cardiomyocytes，hPSC-CMs）作为具备类祖细胞特性的小鼠及人源心脏间充质基质细胞（cardiac mesenchymal stromal cells，cMSCs）的作用靶点，探究了旁分泌信号对人心肌细胞的影响。在共培养与条件培养基实验中，cMSCs可显著抑制人心肌细胞死亡；而小鼠尾尖成纤维细胞或人皮肤成纤维细胞几乎未提供保护作用。转录组分析结果与之一致，功能分析显示cMSCs分泌组可抑制细胞凋亡并维持心脏线粒体跨膜电位。在本次实验条件下，该保护作用不依赖于外泌体。在小鼠模型中，向梗死边缘区注射cMSCs条件培养基可使局部凋亡心肌细胞比例降低70%以上。综上，hPSC-CMs可为研究调控心肌存活的细胞外信号提供一个前景良好且具有生理相关性的人源平台，证实了cMSCs对人体的心脏保护作用，并提示cMSCs分泌组及其组分有望成为无细胞治疗产品。