Lombardi, L. M. | Search bioRxiv

bioRxiv2026

In Vivo Cardiac Prime Editing Corrects the Pathogenic Mutation and Rescues Cardiomyopathy Phenotypes in a Novel Humanized RBM20 Mouse Model

Heart disease affects millions of individuals and prime editing (PE) may enable curative therapies that address the underlying drivers of heart disease. Here we describe the establishment and optimization of an in vivo cardiac PE platform which mediates efficient editing in the heart with no detectable editing in the liver. We performed a proof-of-concept test on RNA binding motif protein 20 (RBM20), which if mutated, can cause dilated cardiomyopathy (DCM) in humans. Our dual-AAV based PE therapeutic rescued cardiomyopathy phenotypes in the heterozygous Rbm20R636Q mouse model. To further develop PE targeting human RBM20, we introduced a novel humanized mouse model carrying human RBM20 wildtype (WT) or R634Q mutant sequences and displaying RBM20 cardiomyopathy phenotypes. Our human RBM20 PE therapeutic efficiently corrected the pathogenic mutation and rescued phenotypes in the humanized RBM20 mouse model. Our findings demonstrate the potential of in vivo cardiac PE in treating heart disease, offer a valuable humanized DCM mouse model for developing various therapies, and present an optimized in vivo PE platform that can be adopted for targeting other organs and tissues.

bioengineering↗

bioRxiv2024

Gene Therapy Mediates Therapeutic Improvement in Cardiac Hypertrophy and Survival in a Murine Model of MYBPC3-Associated Cardiomyopathy

BackgroundHypertrophic cardiomyopathy (HCM) affects an estimated 600,000 people in the U.S. and is the leading cause of sudden cardiac arrest in those under 18. Loss-of-function mutations in Myosin Binding Protein C3, MYBPC3, are the most common genetic cause of HCM. The majority of MYBPC3 mutations causative for HCM result in truncations. The sarcomeric pathophysiology of the majority of HCM patients with MYBPC3 mutations appears to be due to haploinsufficiency, as the total amount of MYBPC3 protein incorporated into sarcomeres falls significantly below normal. MethodsA clear path for the treatment of haploinsufficiency is the restoration of the insufficient gene product; in this case wild-type MYBPC3. To achieve this, we engineered an AAV vector (TN-201) with superior properties for mediating cardiomyocyte-selective expression of MYBPC3 after systemic delivery. ResultsWe have demonstrated for the first time with AAV gene therapy the ability of both a mouse surrogate and TN-201, which encodes human MYBPC3 to reverse cardiac hypertrophy and systolic dysfunction and to improve diastolic dysfunction and survival in a symptomatic MYBPC3-deficient murine model of disease. Dose-ranging efficacy studies exhibited restoration of wild-type MYBPC3 protein levels and saturation of cardiac improvement at the clinically relevant dose of 3E13 vg/kg, outperforming a previously published construct. Further, we have established stable cardiac benefit for greater than one year post-injection, as well as reversal of cardiac dysfunction even in late-stage models of disease. ConclusionsOur data suggest that by restoring MYBPC3 to the sarcomere, TN-201 has the potential to slow and even reverse the course of the disease in patients with MYBPC3-associated HCM.

genetics↗