Key result
Modeled PKP2 gene therapy requires at least ~60% transduction efficiency to restore half-normal conduction velocity.
Why the study?
Patients with PKP2 arrhythmogenic cardiomyopathy are entering gene therapy trials, but AAV trials generally transduce <50% of myocytes, leaving conduction effects unclear.
Does varying levels of PKP2 gene therapy transduction improve conduction velocity and prevent conduction block in computational models of arrhythmogenic cardiomyopathy?
Does varying levels of PKP2 gene therapy transduction improve conduction velocity and prevent conduction block in computational models of arrhythmogenic cardiomyopathy?
Answers are grounded in this paper and cite their sources.
Computational modeling suggests that PKP2 gene therapy requires 60-80% transduction efficiency to meaningfully restore conduction velocity, indicating that anticipated transduction levels may not sufficiently decrease reentrant arrhythmia risk.
BACKGROUND: Patients with arrhythmogenic cardiomyopathy due to pathogenic variants in PKP2 , the gene for the desmosomal protein plakophilin-2, are being enrolled in gene therapy trials designed to replace the defective allele via adeno-associated viral transduction of cardiac myocytes. Evidence from experimental systems and patients indicates that ventricular myocytes in PKP2 arrhythmogenic cardiomyopathy have greatly reduced electrical coupling at gap junctions and reduced Na + current density. In previous adeno-associated viral gene therapy trials, <50% of ventricular myocytes have generally been transduced. METHODS: We used established computational models of ventricular cell electrophysiology to define the effects of varying levels of successful gene therapy on conduction in patients with PKP2 arrhythmogenic cardiomyopathy. Conduction velocity and development of conduction block were analyzed in tissue constructs composed of cells with levels of electrical coupling and Na + current density observed in experimental studies. RESULTS: We observed a nonlinear relationship between conduction velocity and the proportion of transduced cells. Conduction velocity increased only modestly when up to 40% of myocytes were transduced. Conduction block did not occur in tissue constructs with moderate levels of uncoupling (0.10 or 0.15 of normal) as this degree of coupling was sufficient to allow electrotonic current to pass through diseased cells. Thus, low levels of transduction, likely to occur in phase 1 clinical trials, do not seem to pose a major safety concern. However, our models did not incorporate the potential effects of fibrosis and inflammation, both of which are presumably present in PKP2 arrhythmogenic cardiomyopathy patients undergoing gene therapy and could impact arrhythmogenesis. CONCLUSIONS: The extent of successful ventricular myocyte transduction anticipated to be achieved in PKP2 adeno-associated viral gene therapy trials will likely not restore conduction velocity to levels sufficient to decrease the risk of reentrant arrhythmias. Transduction efficiency of 60% to 80% would be required to restore conduction velocity to 50% of normal.
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Ostini et al. (2025) studied PKP2 arrhythmogenic cardiomyopathy. PKP2 gene therapy (varying levels of transduction) was evaluated on Conduction velocity and development of conduction block. Computational modeling of PKP2 gene therapy indicates that a transduction efficiency of 60% to 80% is required to restore conduction velocity to 50% of normal.
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