Recent advances in induced pluripotent stem cell (iPSC) technology and directed differentiation of iPSCs into cardiomyocytes (iPSC-CMs) make it possible to model genetic heart disease in vitro. We apply CRISPR/Cas9 genome editing technology to introduce three RBM20 mutations in iPSCs and differentiate them into iPSC-CMs to establish an in vitro model of RBM20 mutant dilated cardiomyopathy (DCM). In iPSC-CMs harboring a known causal RBM20 variant, the splicing of RBM20 target genes, calcium handling, and contractility are impaired consistent with the disease manifestation in patients. A variant (Pro633Leu) identified by exome sequencing of patient genomes displays the same disease phenotypes, thus establishing this variant as disease causing. We find that all-trans retinoic acid upregulates RBM20 expression and reverts the splicing, calcium handling, and contractility defects in iPSC-CMs with different causal RBM20 mutations. These results suggest that pharmacological upregulation of RBM20 expression is a promising therapeutic strategy for DCM patients with a heterozygous mutation in RBM20.

诱导多能干细胞（iPSC）技术的最新进展以及将iPSC定向分化为心肌细胞（iPSC-CMs）使得在体外模拟遗传性心脏病成为可能。我们应用CRISPR / Cas9基因组编辑技术在iPSC中引入三个RBM20突变，并将它们分化为iPSC-CM，以建立RBM20突变型扩张型心肌病（DCM）的体外模型。在具有已知因果关系的RPS20的iPSC-CM中RBM20靶基因的剪接，钙处理和收缩力受损，与患者的疾病表现相符。通过患者基因组外显子组测序鉴定的变体（Pro633Leu）显示相同的疾病表型，因此将该变体确定为引起疾病的原因。我们发现全反式维甲酸可上调RBM20的表达，并恢复具有不同因果关系的RBM20突变的iPSC-CM中的剪接，钙处理和可收缩性缺陷。这些结果表明，RBM20表达的药理上调是DCM患者的杂合突变有希望的治疗策略RBM20。