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Evaluation of Cardiac Contractility Modulation Therapy in 2D Human Stem Cell-Derived Cardiomyocytes
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cMyBP-C ablation in human engineered cardiac tissue causes progressive Ca2+-handling abnormalities
Willem J De Lange1, Emily T Farrell1, Jonathan J Hernandez1
1Departments of Pediatrics, School of Medicine and Public Health, University of Wisconsin-Madison , Madison, WI, USA.
The Journal of General Physiology
|March 9, 2023
Summary
Truncation mutations in cardiac myosin binding protein C (cMyBP-C) cause hypertrophic cardiomyopathy (HCM). This study shows cMyBP-C deficiency leads to progressive contractile dysfunction, initially hypercontractile then hypocontractile with impaired relaxation.
Area of Science:
- Cardiovascular Biology
- Genetics
- Biomedical Engineering
Background:
- Truncation mutations in cardiac myosin binding protein C (cMyBP-C) are a leading genetic cause of hypertrophic cardiomyopathy (HCM).
- Understanding the functional consequences of cMyBP-C mutations is crucial for developing targeted therapies for HCM.
- Existing models do not fully recapitulate the progressive nature of HCM phenotypes associated with cMyBP-C deficiency.
Purpose of the Study:
- To investigate the functional impact of heterozygous and homozygous cMyBP-C deficiency on cardiomyocyte contractility and Ca2+-handling.
- To model progressive hypertrophic cardiomyopathy using CRISPR-Cas9 gene editing in human induced pluripotent stem cells (iPSCs).
- To elucidate the molecular mechanisms underlying cMyBP-C related cardiac dysfunction.
Main Methods:
- CRISPR-Cas9 gene editing to create isogenic human iPSC lines with heterozygous (cMyBP-C+/-) and homozygous (cMyBP-C-/-) MYBPC3 frame-shift mutations.
- Generation of cardiac micropatterns and engineered cardiac tissue constructs (ECTs) from patient-derived cardiomyocytes.
- Comprehensive characterization of contractile function, Ca2+-handling, Ca2+-sensitivity, and gene expression (RNA-seq).
Main Results:
- Heterozygous cMyBP-C+/- ECTs exhibited haploinsufficiency and progressive hypocontractility with impaired relaxation.
- Homozygous cMyBP-C-/- micropatterns showed increased initial strain, while ECTs developed severe contractile depression and slower Ca2+-release over time.
- RNA-seq revealed differential expression of hypertrophic, sarcomeric, Ca2+-handling, and metabolic genes in cMyBP-C deficient models.
- Phenotype severity correlated with cMyBP-C levels, with homozygous deficiency showing more severe and earlier onset dysfunction.
Conclusions:
- cMyBP-C haploinsufficiency and ablation result in a progressive cardiac phenotype, transitioning from hypercontractility to hypocontractility with impaired relaxation.
- Calcium handling abnormalities are central to the observed contractile dysfunction in cMyBP-C deficient cardiomyocytes.
- These findings provide critical insights into the pathophysiology of HCM caused by MYBPC3 mutations and highlight the utility of engineered cardiac tissues for disease modeling.
