https://doi.org/10.1007/s00392-025-02625-4
1Klinikum rechts der Isar der Technischen Universität München Klinik und Poliklinik für Innere Medizin I München, Deutschland; 2LMU München Lehrstuhl für molekulare Tierzucht und Biotechnologie Oberschleissheim, Deutschland; 3Mass General Brigham Gene and cell therapy institute Boston, USA
Background:
Duchenne muscular dystrophy (DMD) represents the most frequent hereditary childhood myopathy, leading to premature death due to respiratory and cardiac failure. We have generated a pig model of DMD with a targeted deletion of DMD exon 52. Additionally, a porcine model of Becker muscular dystrophy (DMDΔ51–52), with shortened but functional dystrophin expression, was generated to benchmark possible outcomes of targeted therapies.
Application of AAV9 encoding intein split spCas9 and selected gRNAs targeting exon 51 (AAV9-Cas9-gE51) has successfully expressed DMDΔ51–52 in a therapeutic exon-skipping approach. High-resolution 3D electrophysiological mapping showed an increased area of low voltage (<1.3 mV) in DMD pigs compared to controls. Upon AAV9-Cas9-gE51 treatment, low-voltage areas are could be reduced in DMDΔ52 pigs.
Methods and Results:
AAV1 mediated delivery of the cardiac sarcoplasmic reticulum Ca2+ ATPase (SERCA2a) has also been applied to the DMDΔ52 pig model with the aim of improving electrical remodeling and contractile function. An intracoronary infusion method was employed utilizing an over-the-wire (OTW) balloon catheter to decelerate the transition time of fluid. AAV.SERCA2a was injected through the lumen of the OTW balloon. Upon AAV.SERCA2a treatment, ejection fraction measurements demonstrated improvement of contractile function comparable to BMD pigs. High-resolution 3D electrophysiological mapping reveals larger areas of vulnerable myocardium than after gene editing treatment.
Conclusions and Outlook:
Ubiquitous excision of exon 51 (DMDdelta51-52) and AAV.Cas9-gE51 treatment of a DMD pig improved EF and almost normalized action potential amplitudes. AAV.SERCA2a application sufficed to normalize left ventricular function, but did not ameliorate electrical vulnerability of the heart. Thus, AAV.SERCA2a combined with antitachycardic pacemaker protection may serve as a safe treatment option for DMD cardiomyopathy, whereas Cas9-mediated gene editing may provide additional therapy of electrical vulnerability.