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Microdystrophins Partially Rescue Duchenne Muscular Dystrophy Deficits in iPSC-Cardiomyocytes

ABSTRACT: Duchenne muscular dystrophy (DMD) is a severe muscle wasting disease caused by the lack of dystrophin. Dilated cardiomyopathy is the leading cause of death in DMD patients. Smaller variants of dystrophin, called microdystrophins, amenable to packaging into adeno-associated virus (AAV), have shown to be effective in improving skeletal muscle function in animal models; however, the functional benefit of these microdystrophins in the DMD heart remains unclear. To determine the efficacy of microdystrophin gene therapy, we compared three microdystrophin variants in DMD cardiomyocytes differentiated from human induced pluripotent stem cells (iPSCs). We used three DMD lines of different genetic backgrounds and benchmarked against healthy isogenic controls expressing full-length dystrophin. DMD iPSC-cardiomyocytes exhibit hallmarks of disease, including arrhythmia and poor viability compared to healthy isogenic controls. In parallel, we tested a dystrophin variant, called minidystrophin, which is larger than the microdystrophins. We validated dystrophin expression and compared transcriptional profiles by bulk RNA sequencing. For morphological analysis, we performed immunohistochemistry of cardiac troponin on fixed cells. To test the functional benefit of the transgenes, we performed calcium imaging with a ratiometric calcium indicator as well as viability assays. Our results show that the microdystrophins partially rescue disease phenotypes; however, the results are variable among genetic backgrounds. None of the gene therapies altered the global transcriptional profile of the DMD iPSC-CMs to resemble a healthy profile. Minidystrophin significantly improved cell viability of DMD iPSC-CMs in two of three lines of different genetic backgrounds. Our findings suggest that microdystrophins may have limited efficacy in DMD cardiomyocytes and that the delivery of larger dystrophin variants may be necessary to delay the onset of cardiac complications.

ORGANISM(S): Homo sapiens

PROVIDER: GSE310327 | GEO | 2026/06/30

REPOSITORIES: GEO

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Project description:Absence of the dystrophin gene in Duchenne muscular dystrophy (DMD) results in the degeneration of skeletal and cardiac muscles. Owing to advances in respiratory medicine, cardiomyopathy has become a significant aspect of the disease. While CRISPR/Cas9 genome editing technology holds great potential as a novel therapeutic avenue for DMD, little is known about the efficacy of correction of DMD using the CRISPR/Cas9 system in mitigating the cardiomyopathy phenotype in DMD. To define the effects of CRISPR/Cas9 genome editing on structural, functional and transcriptional dysregulation in DMD-associated cardiomyopathy. We generated induced pluripotent stem cells (iPSCs) from a patient with a deletion of exon 44 of the DMD gene (ΔEx44) and his healthy brother. Here, we targeted exon 45 of the DMD gene by CRISPR/Cas9 genome editing to generate corrected DMD (cDMD) iPSC lines, wherein the DMD open reading frame was restored via reframing (RF) or exon skipping (ES). While DMD cardiomyocytes (CMs) demonstrated morphologic, structural and functional deficits compared to control CMs, CMs from both cDMD lines were similar to control CMs. Bulk RNA-sequencing of DMD CMs showed transcriptional dysregulation consistent with dilated cardiomyopathy, which was mitigated in cDMD CMs. We then corrected DMD CMs by adenoviral delivery of Cas9/gRNA and showed that postnatal correction of DMD CMs reduces their arrhythmogenic potential. Single-nucleus RNA-sequencing of hearts showed reduced transcriptional dysregulation in CMs and fibroblasts in corrected mice compared with DMD mice, consistent with reduced histopathologic changes.We show that CRISPR/Cas9-mediated correction of DMD ΔEx44 mitigates structural, functional and transcriptional dysregulation consistent with dilated cardiomyopathy irrespective of how the protein reading frame is restored. We show that these effects extend to postnatal editing in iPSC-CMs and mice. These findings provide key insights into the utility of genome editing as a novel therapeutic for DMD-associated cardiomyopathy.

Project description:Rationale – Absence of the dystrophin gene in Duchenne muscular dystrophy (DMD) results in the degeneration of skeletal and cardiac muscles. Owing to advances in respiratory medicine, cardiomyopathy has become a significant aspect of the disease. While CRISPR/Cas9 genome editing technology holds great potential as a novel therapeutic avenue for DMD, little is known about the efficacy of correction of DMD using the CRISPR/Cas9 system in mitigating the cardiomyopathy phenotype in DMD. Objective – To define the effects of CRISPR/Cas9 genome editing on structural, functional and transcriptional dysregulation in DMD-associated cardiomyopathy. Methods and Results – We generated induced pluripotent stem cells (iPSCs) from a patient with a deletion of exon 44 of the DMD gene (ΔEx44) and his healthy brother. Here, we targeted exon 45 of the DMD gene by CRISPR/Cas9 genome editing to generate corrected DMD (cDMD) iPSC lines, wherein the DMD open reading frame was restored via reframing (RF) or exon skipping (ES). While DMD cardiomyocytes (CMs) demonstrated morphologic, structural and functional deficits compared to control CMs, CMs from both cDMD lines were similar to control CMs. Bulk RNA-sequencing of DMD CMs showed transcriptional dysregulation consistent with dilated cardiomyopathy, which was mitigated in cDMD CMs. We then corrected DMD CMs by adenoviral delivery of Cas9/gRNA and showed that postnatal correction of DMD CMs reduces their arrhythmogenic potential. Single-nucleus RNA-sequencing of hearts showed reduced transcriptional dysregulation in CMs and fibroblasts in corrected mice compared with DMD mice, consistent with reduced histopathologic changes. Conclusions – We show that CRISPR/Cas9-mediated correction of DMD ΔEx44 mitigates structural, functional and transcriptional dysregulation consistent with dilated cardiomyopathy irrespective of how the protein reading frame is restored. We show that these effects extend to postnatal editing in iPSC-CMs and mice. These findings provide key insights into the utility of genome editing as a novel therapeutic for DMD-associated cardiomyopathy.

Project description:Many oncology drugs have been found to induce cardiotoxicity in a subset of patients, which significantly limits their clinical use and impedes the benefit of lifesaving anti-cancer treatments. Human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) carry donor-specific genetic information and have been proposed for explore the inter-individual difference in oncology drug-induced cardiotoxicity. Herein, we evaluated the inter- and intra- individual variability of iPSC-CM-related assays and presented a practical approach for using donor-specific iPSC-CMs to predict personalized doxorubicin (DOX)-induced cardiotoxicity (DIC) prior to chemotherapy. Our findings demonstrated that donor-specific iPSC-CMs exhibited greater line-to-line variability than the intra-individual variability in impedance cytotoxicity and transcriptome assays. The variable and dose-dependent cytotoxic responses of iPSC-CMs resembled those observed in clinical practice, and largely replicated the reported mechanisms of DIC. By categorizing iPSC-CMs into DOX-resistant and DOX-sensitive cell lines based on their phenotypic reactions to DOX, we found that the sensitivity of donor-specific iPSC-CMs to DOX may predict in vivo DIC risk. Furthermore, we assessed the limitations of the model for identification of potential genetic/molecular biomarker and pinpointed a differentially expressed gene, DND microRNA-mediated repression inhibitor 1 (DND1), between the DOX-resistant and DOX-sensitive iPSC-CMs. We also discussed the selection of DOX dose and exposure duration for inter-individual variability of DIC assessment. Our results support the utility of donor-specific iPSC-CMs in assessing inter-individual difference and enabling personalized cardiotoxicity prediction. Further studies will encompass a large panel of donor-specific iPSC-CMs to investigate the role of the DND1 and known DIC genetic variants, and to identify potential novel molecular and genetic biomarkers for predicting DOX and other oncology drug-induced cardiotoxicity.

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Microdystrophins Partially Rescue Duchenne Muscular Dystrophy Deficits in iPSC-Cardiomyocytes

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