Hypertrophic cardiomyopathy-associated mutations drive stromal activation via EGFR-mediated paracrine signaling

Hypertrophic cardiomyopathy (HCM) is characterized by thickening of the
left ventricular wall, diastolic dysfunction, and fibrosis, and is
associated with mutations in genes encoding sarcomere proteins. While in
vitro studies have used human induced pluripotent stem cell-derived
cardiomyocytes (hiPSC-CMs) to study HCM, these models have not examined
the multicellular interactions involved in fibrosis. Using engineered
cardiac microtissues (CMTs) composed of HCM-causing MYH7-variant hiPSC-CMs
and wild-type fibroblasts, we observed cell-cell cross-talk leading to
increased collagen deposition, tissue stiffening, and decreased
contractility dependent on fibroblast proliferation. hiPSC-CM conditioned
media and single-nucleus RNA sequencing data suggested that fibroblast
proliferation is mediated by paracrine signals from MYH7-variant
cardiomyocytes. Furthermore, inhibiting epidermal growth factor receptor
tyrosine kinase with erlotinib hydrochloride attenuated stromal
activation. Last, HCM-causing MYBPC3-variant CMTs also demonstrated
increased stromal activation and reduced contractility, but with distinct
characteristics. Together, these findings establish a paracrine-mediated
cross-talk potentially responsible for fibrotic changes observed in HCM.

肥厚型心肌病（Hypertrophic cardiomyopathy, HCM）以左心室壁增厚、舒张功能障碍及纤维化为特征，与编码肌节蛋白的基因突变相关。既往体外研究已利用人类诱导多能干细胞衍生心肌细胞（human induced pluripotent stem cell-derived cardiomyocytes, hiPSC-CMs）开展HCM相关研究，但此类模型尚未探究纤维化过程中的多细胞相互作用。本研究构建了携带致病MYH7变异型hiPSC-CMs与野生型成纤维细胞的工程化心脏微组织（engineered cardiac microtissues, CMTs），观察到依赖成纤维细胞增殖的细胞间串扰可导致胶原沉积增加、组织硬化及收缩能力下降。hiPSC-CMs条件培养基与单细胞核RNA测序数据显示，成纤维细胞增殖由MYH7变异型心肌细胞的旁分泌信号介导。此外，采用盐酸厄洛替尼抑制表皮生长因子受体酪氨酸激酶可减轻基质激活。最后，携带致病MYBPC3变异型的CMTs同样表现出基质激活增强与收缩能力降低，但具备独特的表型特征。综上，本研究结果证实，旁分泌介导的细胞串扰或是HCM中纤维化改变的潜在诱因。