Familial hypertrophic cardiomyopathy (HCM) is the leading cause of sudden cardiac death in young people, including trained athletes, and is the most common
inherited heart defect. In this proposal, we will generate human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) from patients with HCM. The
specific aims are as follow:
Specific Aim 1: Generate iPSCs from patients with HCM and healthy controls.
Specific Aim 2: Determine the extent of disease by performing molecular and functional analyses of hiPSC-CMs.
Specific Aim 3: Rescue the molecular and functional phenotypes using zinc finger nuclease (ZFN) technology.
Over the past year, we have characterized iPSC-CMs from a 10-patient family cohort with the MYH7 mutation using standard 3D EB differentiation protocols.
We found normal and hypertrophic iPSC-CMs were predictive as in vitro model for arrhythmia screening using microelectroarrays and single cell patch-clamping
analysis. For example, we found that administration of catecholamine drug norepinephrine causes the formation of torsade de point which is a lethan arrhythmia.
This recapitulates the phenotype in patients with HCM receiving catecholamine drugs. We also found increase in torsade formation when the iPSC-CMs are treated
with hERG blockers that are also known to cause increases in arrhythmia in HCM patients. We believe the use of hiPSC-CM from healthy individuals and patients with
genetic heart disease can help predict the potential arrhythmic risk in existing or new drug agents that are undergoing FDA evaluation.
We have also generated HCM mutations in lines of normal iPSC to determine whether these mutant lines will exhibit HCM phenotype. This would satisfy the Koch’s postulate
with regards to the role of the mutant DNA sequence on HCM manifestation. We found, using TALEN and piggyBac transposon technologies that genome edited can be generated
to carry R663H mutation in the MYH7 gene and that these genome edited iPSC-CM recapitulated the HCM phenotype associated with the R663H mutation such as sarcomere
disassembly and intracellular calcium abnormalities as well as contractile arrhythmias. We have also corrected mutant HCM human iPSC from patients with MYH7 R663H mutation
and show that these corrected iPSC-CM exhibit normal sarcomeric phenotype with smaller cell size and reduced calcium transient irregularities.