Increased length-dependent activation of human engineered heart tissue after chronic a1A-adrenergic agonist treatment: testing a novel heart failure therapy

Chronic stimulation of cardiac a1A-adrenergic receptors (a1A-ARs) improves symptoms in multiple preclinical models of heart failure. However, the translational significance remains unclear. This study tested the effects of chronic a1A-AR stimulation on human engineered heart tissue (EHT). EHTs were created from thin slices of decellularized pig myocardium seeded with human induced pluripotent stem cell (iPSC)-derived cardiomyocytes and fibroblasts. Using a paired experimental design, EHTs were cultured for 3 wk., mechanically tested, cultured again for 2 wk. with a1A-AR agonist A61603 (10 nM) or vehicle control, and retested after drug washout for 24-hr. Separate control experiments determined the effects of EHT age (3-5 wk.) or repeat mechanical testing. We found that chronic A61603 treatment caused a 25% increase of length-dependent activation (LDA) of contraction compared to vehicle treatment (n=7/group, P=0.035). EHT force was not increased after chronic A61603 treatment. However, after vehicle treatment, EHT force was increased 35% relative to baseline testing (n=7/group, P=0.022), suggesting EHT maturation. Control experiments showed increased EHT force resulted from repeat mechanical testing, not from EHT aging. RNA-seq analysis confirmed the a1A-AR is expressed in human EHTs and found chronic A61603 treatment affected gene expression in biological pathways which are known to be activated by a1A-ARs, including the MAP kinase signaling pathway. In conclusion, chronic stimulation of the a1A-AR, a promising preclinical target for treating heart failure, gave mixed results in human EHTs. Chronic a1A-AR stimulation had a positive effect (increased LDA) but potentially, a negative effect (lower EHT force). The translational significance of these findings requires further study. Overall design: Comparative gene expression profiling analysis of RNA-seq data for EHT cells under either chronic A61603 treatment or vehicle treatment (control).

慢性刺激心脏α1A肾上腺素能受体（α1A-ARs）可改善多种心力衰竭临床前模型的症状，但其转化应用价值仍不明确。本研究探究了慢性α1A-AR刺激对人类工程化心脏组织（EHT）的影响。研究人员将人类诱导多能干细胞（iPSC）分化得到的心肌细胞与成纤维细胞接种于脱细胞猪心肌薄片中，构建EHT。采用配对实验设计，将EHT培养3周后进行力学性能测试；随后更换培养体系，分别加入α1A-AR激动剂A61603（10 nM）或溶剂对照，继续培养2周；药物洗脱24小时后再次进行力学测试。此外，通过独立对照实验明确了EHT培养时长（3~5周）与重复力学测试对实验结果的影响。研究结果显示，与溶剂对照组相比，慢性A61603处理可使收缩的长度依赖性激活（LDA）升高25%（每组n=7，P=0.035）。慢性A61603处理并未提升EHT的收缩力，但溶剂对照组的EHT收缩力较基线测试升高了35%（每组n=7，P=0.022），提示EHT发生了成熟化。对照实验证实，EHT收缩力的提升源于重复力学测试，而非培养时长增加。RNA测序（RNA-seq）分析证实，人类EHT中表达α1A-AR，且慢性A61603处理可调控已知由α1A-AR激活的生物学通路的基因表达，其中包括丝裂原活化蛋白激酶（MAP kinase）信号通路。综上，作为治疗心力衰竭的极具潜力的临床前靶点，慢性刺激α1A-AR在人类EHT中得到了双向性结果：慢性α1A-AR刺激可产生正向效应（提升LDA），但也可能存在负向效应（降低EHT收缩力）。上述发现的转化应用价值仍需进一步研究。总体实验设计：对慢性A61603处理组与溶剂对照组（对照组）的EHT细胞进行RNA-seq数据的比较基因表达谱分析。