Modeling incomplete penetrance in arrhythmogenic cardiomyopathy by human induced pluripotent stem cell derived cardiomyocytes
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ABSTRACT: Human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs) are commonly used to model arrhythmogenic cardiomyopathy (ACM), a heritable cardiac disease characterized by severe ventricular arrhythmias, fibrofatty myocardial replacement and progressive ventricular dysfunction. Although ACM is inherited as an autosomal dominant disease, incomplete penetrance and variable expressivity are extremely common, resulting in different clinical manifestations. Here, we propose hiPSC-CMs as a powerful in vitro model to study incomplete penetrance in ACM. Six hiPSC lines were generated from blood samples of three ACM patients carrying a heterozygous deletion of exon 4 in the PKP2 gene, two asymptomatic (ASY) carriers of the same mutation and one healthy control (CTR), all belonging to the same family. Whole exome sequencing was performed in all family members and hiPSC-CMs were examined by ddPCR, western blot, Wes™ immunoassay system, patch clamp, immunofluorescence and RNASeq. Our results show molecular and functional differences between ACM and ASY hiPSC_x0002_CMs, including a higher amount of mutated PKP2 mRNA, a lower expression of the connexin-43 protein, a lower overall density of sodium current, a higher intracellular lipid accumulation and sarcomere disorganization in ACM compared to ASY hiPSC_x0002_CMs. Differentially expressed genes were also found, supporting a predisposition for a fatty phenotype in ACM hiPSC-CMs. These data indicate that hiPSC-CMs are a suitable model to study incomplete penetrance in ACM.
Project description:Arrhythmogenic cardiomyopathy (ACM) is an inherited progressive cardiomyopathy. The pathophysiological events are well understood, yet the underlying molecular mechanisms remain undefined. Here, we created a novel research platform comprising of patient originated hiPSC-derived cardiomyocytes bearing a pathological PKP2 mutation (PKP2 c.2013delC/WT), a novel knock-in murine model carrying the equivalent mutation (Pkp2 c.1755delA/WT), and human explanted ACM hearts, to identify disease driving mechanisms. Pkp2 c.1755delA/WT mice displayed reduced desmosomal and adherens junctions protein levels and protein disarray of the intercalated discs in areas of active fibrotic remodeling. These findings were validated in hiPSC-derived cardiomyocytes and human explanted ACM hearts. Led by proteomics data, we demonstrated that the ubiquitin-proteasome system was responsible for the observed desmosomal protein degradation. The research platform presented here provides a strong scientific basis to identify bona fide pathological processes and will aid in the development of potential therapies for the prevention of ACM disease progression.
Project description:Arrhythmogenic cardiomyopathy (ACM) is an inherited progressive cardiomyopathy. The pathophysiological events are well understood, yet the underlying molecular mechanisms remain undefined. Here we use patient originated hiPSC-derived cardiomyocytes bearing a pathogenic PKP2 mutation (PKP2 c.2013delC/WT), a corresponding knock-in mouse model carrying the equivalent murine mutation (Pkp2 c.1755delA/WT), and human explanted ACM hearts, to identify disease driving mechanisms. Pkp2 c.1755delA/WT mice over time displayed signs of ACM as observed by cardiac dysfunction and pathological remodeling. At a molecular level these mice showed a reduction in desmosomal and adherens junction proteins as well as disarray of the intercalated discs in areas of active fibrotic remodeling. These findings were validated in the mutant hiPSC-derived cardiomyocytes as well as human explanted ACM hearts, indicating both the conservation and relevance of protein degradation in the pathogenesis of the disease. Led by proteomics data, we demonstrated that the ubiquitin-proteasome system was responsible for the observed desmosomal protein degradation. These findings show the importance of appropriate disease modeling and provide means for therapeutic intervention for the prevention of ACM disease progression.
Project description:Arrhythmogenic cardiomyopathy (ACM) is an inherited progressive cardiomyopathy. The pathophysiological events are well understood, yet the underlying molecular mechanisms remain undefined. Here we use patient originated hiPSC-derived cardiomyocytes bearing a pathogenic PKP2 mutation (PKP2 c.2013delC/WT), a corresponding knock-in mouse model carrying the equivalent murine mutation (Pkp2 c.1755delA/WT), and human explanted ACM hearts, to identify disease driving mechanisms. Pkp2 c.1755delA/WT mice over time displayed signs of ACM as observed by cardiac dysfunction and pathological remodeling. At a molecular level these mice showed a reduction in desmosomal and adherens junction proteins as well as disarray of the intercalated discs in areas of active fibrotic remodeling. These findings were validated in the mutant hiPSC-derived cardiomyocytes as well as human explanted ACM hearts, indicating both the conservation and relevance of protein degradation in the pathogenesis of the disease. Led by proteomics data, we demonstrated that the ubiquitin-proteasome system was responsible for the observed desmosomal protein degradation. These findings show the importance of appropriate disease modeling and provide means for therapeutic intervention for the prevention of ACM disease progression.
Project description:Current differentiation protocols for human pluripotent stem cells produce a heterogeneous population of cardiomyocytes (CMs). Here, we identified CD151 as a marker of ventricular CMs (VCMs) and atrial CMs (ACMs) from 212 different cell surface markers. In the VCM induction, CD151high CMs were a homogeneous population of mature VCMs, including binuclear VCMs, and showed enriched cell cycle-related genes based on RNA-seq analysis. As for the ACM induction, CD151low CMs expressed high levels of atrial-related genes and exhibited atrial-type electrophysiological properties. According to RNA-seq analysis, CD151high CMs from the ACM induction had molecular signatures for cell-cell interactions and NOTCH signaling. When treated with a NOTCH signal inhibitor, the same cells showed mature electrophysiological properties consistent of ACMs with an increasing expression of atrial-related genes. Altogether, we found that CD151 is an indicator of subtype specification with distinct mechanisms between VCM and ACM differentiation and that NOTCH signaling inhibition enhances atrial specification.
Project description:Background: Cardiomyocytes (CMs) induced from human induced pluripotent stem cells (hiPSCs) by traditional methods are a mix of atrial and ventricular CMs and many other non-cardiomyocytes. Retinoic acid (RA) plays an important role in regulation of the spatiotemporal development of the embryonic heart and high concentrations of RA have been shown to steer differentiation towards atrial CMs, whereas lower concentrations of RA promote a more ventricular-like CM profile. Aim: Create engineered heart tissue (EHT) with left and right ventricular phenotype from hiPSCs by intervening with specific concentrations of retinoic acid (RA) during hiPSC differentiation towards CM. Methods: hiPSC were derived by reprogramming skin fibroblasts. Different concentrations of RA (Control group without RA, LRA group with 0.05 µM and HRA group with 0.1 µM) were administered during third to sixth days of the differentiation process. Engineered heart tissues (EHTs) were generated by assembling CMs derived from hiPSC (hiPSC-CM) at high cell density in a low collagen hydrogel. The maturation and growth of EHTs were induced in a customized biomimetic tissue culture system, that provides continuous electrical stimulation, medium agitation and stretch. The function of CMs and EHTs was analyzed under different conditions. Finally, RNA extraction and tissue fixation were performed on CMs and EHTs for RT-qPRC and immunofluorescence staining analysis. RNA sequencing was conducted on EHTs to examine how RA affects both the function and structure of EHT. Results: In the HRA group, hiPSC-CMs exhibited the first onset of beating and showed the highest expression of maturity genes MYH7 and cTnT. The expression of TBX5, NKX2.5 and CORIN, which are the marker genes for left ventricular CMs, was also the highest in the HRA group. The transcription factor MEF2C associated with RA and ventricular development genes, NPPA and MYH7, were highly expressed in the HRA group, while GATA4 was less expressed in the HRA group. In terms of EHT, the HRA group displayed the highest contraction force, the lowest beating frequency, and the highest sensitivity to hypoxia and isoprenaline, which means it was more functionally similar to the left ventricle. The expression of TBX5 and NKX2.5 was found to be the highest expression in the HRA group of EHT, while expression of TBX20 and ISL1 was found to be the highest expression in control group. When the electrical stimulation frequency of EHT in the HRA group was raised, it correspondingly increased its contractile force. The heightened contractility of EHT within the HRA group can be attributed to the promotion of augmented extracellular matrix strength by RA. Conclusion: By interfering with the differentiation process of hiPSC with a specific concentration of RA at a specific time, we were able to successfully induce CMs and EHT with a phenotype similar to that of the left ventricle or right ventricle. Our research paved the way for future studies on in vitro left ventricular or right ventricular function, personalized drug screening, and precision medicine.
Project description:ABSTRACT Background: Viral myocarditis is a life-threatening illness that may lead to heart failure or cardiac arrhythmias. This study examined whether human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) could be used to model the pathogenic processes of coxsackievirus-induced viral myocarditis and to screen antiviral therapeutics for efficacy. Methods and Results: Human iPSC-CMs were infected with a luciferase-expressing mutant of the coxsackievirus B3 strain (CVB3-Luc). Brightfield microscopy, immunofluorescence, and calcium imaging were used to characterize virally infected hiPSC-CMs. Viral proliferation on hiPSC-CMs was subsequently quantified using bioluminescence imaging. For drug screening, select antiviral compounds including interferon beta 1 (IFNβ1), ribavirin, pyrrolidine dithiocarbamate (PDTC), and fluoxetine were tested for their capacity to abrogate CVB3-Luc proliferation in hiPSC-CMs in vitro. The ability of some of these compounds to reduce CVB3-Luc proliferation in hiPSC-CMs was consistent with the reported drug effects in previous studies. Finally, mechanistic analyses via gene expression profiling of hiPSC-CMs infected with CVB3-Luc revealed an activation of viral RNA and protein clearance pathways within these hiPSC-CMs after IFNβ1 treatment. Conclusions: This study demonstrates that hiPSC-CMs express the coxsackievirus and adenovirus receptor, are susceptible to coxsackievirus infection, and can be used to confirm antiviral drug efficacy. Our results suggest that the hiPSC-CM/CVB3-Luc assay is a sensitive platform that could be used to screen novel antiviral therapeutics for their effectiveness in a high-throughput fashion. For this experiment, human induced pluripotent stem cell derived cardiomyocytes were infected with coxsackievirus at multiplicity of infection (MOI) of 5 for 8 hours. Cells were treated with and without interferon beta 1 in order to determine if treatment activates antiviral response genes and/or viral clearance pathways. 4 total samples (2 for each condition) were analyzed
Project description:Background: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a familial cardiac disease associated with ventricular arrhythmias and an increased risk of sudden cardiac death. Currently, there are no approved treatments that address the underlying genetic cause of this disease, representing a significant unmet need. Mutations in Plakophilin-2 (PKP2), encoding a desmosomal protein, account for approximately 40% of ARVC cases and result in reduced gene expression. Methods: Our goal is to examine the feasibility and the efficacy of adeno-associated virus 9 (AAV9)-mediated restoration of PKP2 expression in a cardiac specific knock-out mouse model of Pkp2. Results: We show that a single dose of AAV9:PKP2 gene delivery prevents disease development before the onset of cardiomyopathy and attenuates disease progression after overt cardiomyopathy. Restoration of PKP2 expression leads to a significant extension of lifespan by restoring cellular structures of desmosomes and gap junctions, preventing or halting decline in left ventricular ejection fraction, preventing or reversing dilation of the right ventricle, ameliorating ventricular arrhythmia event frequency and severity, and preventing adverse fibrotic remodeling. RNA sequencing analyses show that restoration of PKP2 expression leads to highly coordinated and durable correction of PKP2-associated transcriptional networks beyond desmosomes, revealing a broad spectrum of biological perturbances behind ARVC disease etiology. Conclusions: We identify fundamental mechanisms of PKP2-associated ARVC beyond disruption of desmosome function. The observed PKP2 dose-function relationship indicates that cardiac-selective AAV9:PKP2 gene therapy may be a promising therapeutic approach to treat ARVC patients with PKP2 mutations.
Project description:Background: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a familial cardiac disease associated with ventricular arrhythmias and an increased risk of sudden cardiac death. Currently, there are no approved treatments that address the underlying genetic cause of this disease, representing a significant unmet need. Mutations in Plakophilin-2 (PKP2), encoding a desmosomal protein, account for approximately 40% of ARVC cases and result in reduced gene expression. Methods: Our goal is to examine the feasibility and the efficacy of adeno-associated virus 9 (AAV9)-mediated restoration of PKP2 expression in a cardiac specific knock-out mouse model of Pkp2. Results: We show that a single dose of AAV9:PKP2 gene delivery prevents disease development before the onset of cardiomyopathy and attenuates disease progression after overt cardiomyopathy. Restoration of PKP2 expression leads to a significant extension of lifespan by restoring cellular structures of desmosomes and gap junctions, preventing or halting decline in left ventricular ejection fraction, preventing or reversing dilation of the right ventricle, ameliorating ventricular arrhythmia event frequency and severity, and preventing adverse fibrotic remodeling. RNA sequencing analyses show that restoration of PKP2 expression leads to highly coordinated and durable correction of PKP2-associated transcriptional networks beyond desmosomes, revealing a broad spectrum of biological perturbances behind ARVC disease etiology. Conclusions: We identify fundamental mechanisms of PKP2-associated ARVC beyond disruption of desmosome function. The observed PKP2 dose-function relationship indicates that cardiac-selective AAV9:PKP2 gene therapy may be a promising therapeutic approach to treat ARVC patients with PKP2 mutations.
Project description:Background: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a familial cardiac disease associated with ventricular arrhythmias and an increased risk of sudden cardiac death. Currently, there are no approved treatments that address the underlying genetic cause of this disease, representing a significant unmet need. Mutations in Plakophilin-2 (PKP2), encoding a desmosomal protein, account for approximately 40% of ARVC cases and result in reduced gene expression. Methods: Our goal is to examine the feasibility and the efficacy of adeno-associated virus 9 (AAV9)-mediated restoration of PKP2 expression in a cardiac specific knock-out mouse model of Pkp2. Results: We show that a single dose of AAV9:PKP2 gene delivery prevents disease development before the onset of cardiomyopathy and attenuates disease progression after overt cardiomyopathy. Restoration of PKP2 expression leads to a significant extension of lifespan by restoring cellular structures of desmosomes and gap junctions, preventing or halting decline in left ventricular ejection fraction, preventing or reversing dilation of the right ventricle, ameliorating ventricular arrhythmia event frequency and severity, and preventing adverse fibrotic remodeling. RNA sequencing analyses show that restoration of PKP2 expression leads to highly coordinated and durable correction of PKP2-associated transcriptional networks beyond desmosomes, revealing a broad spectrum of biological perturbances behind ARVC disease etiology. Conclusions: We identify fundamental mechanisms of PKP2-associated ARVC beyond disruption of desmosome function. The observed PKP2 dose-function relationship indicates that cardiac-selective AAV9:PKP2 gene therapy may be a promising therapeutic approach to treat ARVC patients with PKP2 mutations.
Project description:Human iPSC-derived cardiomyocytes (hiPSC-CMs) have proven invaluable for cardiac disease modeling and cardiac regeneration. Challenges with quality, inter-batch consistency, cryopreservation and scale remain, reducing experimental reproducibility and clinical translation. Here, we report a robust stirred suspension cardiac differentiation protocol with careful functional characterization of the resulting hiPSC-CMs. In a bioreactor, the protocol produced 1.2E6/mL hiPSC-CMs with ~94% purity from 14 iPSC lines. Bioreactor-differentiated CMs (bCMs) showed high viability after cryo-recovery (>90%) and predominantly ventricular identity. Compared to standard monolayer-differentiated CMs (mCMs), bCMs had greater reproducibility and more mature functional properties, including pacing capture to 4 Hz and greater force production in 3D engineered heart tissues. In more readily available magnetically stirred spinner flasks, the protocol yielded 1.8E6/mL spinner-differentiated CMs (sCMs) with 94% purity. Differentiation scaled readily in spinner flasks, as a 3.8-fold increase in cultured volume yielded 3.4E6/ml sCMs. sCMs had intermediate functional properties between mCMs and bCMs. Minor protocol modifications generated the first bioreactor-derived cardiac organoids (bCOs) fully generated in suspension. These reproducible, scalable, and resource efficient approaches to generate cardiac cells and organoids with well-characterized properties will expand the applications of hiPSC-CMs.