AAV-mediated cardiac gene transfer of wild-type desmin in mouse models for recessive desminopathies.

Mutations in the human desmin gene cause autosomal-dominant and recessive cardiomyopathies and myopathies with marked phenotypic variability. Here, we investigated the effects of adeno-associated virus (AAV)-mediated cardiac wild-type desmin expression in homozygous desmin knockout (DKO) and homozygous R349P desmin knockin (DKI) mice. These mice serve as disease models for two subforms of autosomal-recessive desminopathies, the former for the one with a complete lack of desmin protein and the latter for the one with solely mutant desmin protein expression in conjunction with protein aggregation pathology in striated muscle. Two-month-old mice were injected with either a single dose of 5 × 1012 AAV9-hTNT2-mDes (AAV-Des) vector genomes or NaCl as control. One week after injection, mice were subjected to a forced swimming exercise protocol for 4 weeks. Cardiac function was monitored over a period of 15 month after injection and before the mice were sacrificed for biochemical and morphological analysis. AAV-mediated cardiac expression of wild-type desmin in both the homozygous DKO and DKI backgrounds reached levels seen in wild-type mice. Notably, AAV-Des treated DKO mice showed a regular subcellular distribution of desmin as well as a normalization of functional and morphological cardiac parameters. Treated DKI mice, however, showed an aberrant subcellular localization of desmin, unchanged functional cardiac parameters, and a trend toward an increased cardiac fibrosis. In conclusion, the effect of a high-dose AAV9-based desmin gene therapy is highly beneficial for the heart in DKO animals, but not in DKI mice.

Identification of circular RNAs with host gene-independent expression in human model systems for cardiac differentiation and disease.

AIMS: Cardiovascular disease, one of the most common causes of death in western populations, is characterized by changes in RNA splicing and expression. Circular RNAs (circRNA) originate from back-splicing events, which link a downstream 5' splice site to an upstream 3' splice site. Several back-splicing junctions (BSJ) have been described in heart biopsies from human, rat and mouse hearts (Werfel et al., 2016; Jakobi et al., 2016 ). Here, we use human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs) to identify circRNA and host gene dynamics in cardiac development and disease. In parallel, we explore candidate interactions of selected homologs in mouse and rat via RIP-seq experiments. METHODS AND RESULTS: Deep RNA sequencing of cardiomyocyte development and ß-adrenergic stimulation uncovered 4518 circRNAs. The set of circular RNA host genes is enriched for chromatin modifiers and GTPase activity regulators. RNA-seq and qRT-PCR data showed that circular RNA expression is highly dynamic in the hiPSC-CM model with 320 circRNAs showing significant expression changes. Intriguingly, 82 circRNAs are independently regulated to their host genes. We validated the same circRNA dynamics for circRNAs from ATXN10, CHD7, DNAJC6 and SLC8A1 in biopsy material from human dilated cardiomyopathy (DCM) and control patients. Finally, we could show that rodent homologs of circMYOD, circSLC8A1, circATXN7 and circPHF21A interact with either the ribosome or Argonaute2 protein complexes. CONCLUSION: CircRNAs are dynamically expressed in a hiPSC-CM model of cardiac development and stress response. Some circRNAs show similar, host-gene independent expression dynamics in patient samples and may interact with the ribosome and RISC complex. In summary, the hiPSC-CM model uncovered a new signature of potentially disease relevant circRNAs which may serve as novel therapeutic targets.

AAV9-mediated gene transfer of desmin ameliorates cardiomyopathy in desmin-deficient mice.

Mutations of the human desmin (DES) gene cause autosomal dominant and recessive myopathies affecting skeletal and cardiac muscle tissue. Desmin knockout mice (DES-KO), which develop progressive myopathy and cardiomyopathy, mirror rare human recessive desminopathies in which mutations on both DES alleles lead to a complete ablation of desmin protein expression. Here, we investigated whether an adeno-associated virus-mediated gene transfer of wild-type desmin cDNA (AAV-DES) attenuates cardiomyopathy in these mice. Our approach leads to a partial reconstitution of desmin protein expression and the de novo formation of the extrasarcomeric desmin-syncoilin network in cardiomyocytes of treated animals. This finding was accompanied by reduced fibrosis and heart weights and improved systolic left-ventricular function when compared with control vector-treated DES-KO mice. Since the re-expression of desmin protein in cardiomyocytes of DES-KO mice restores the extrasarcomeric desmin-syncoilin cytoskeleton, attenuates the degree of cardiac hypertrophy and fibrosis, and improves contractile function, AAV-mediated desmin gene transfer may be a novel and promising therapeutic approach for patients with cardiomyopathy due to the complete lack of desmin protein expression.

Delivery of gelfoam-enabled cells and vectors into the pericardial space using a percutaneous approach in a porcine model.

Intrapericardial drug delivery is a promising procedure, with the ability to localize therapeutics with the heart. Gelfoam particles are nontoxic, inexpensive, nonimmunogenic and biodegradable compounds that can be used to deliver therapeutic agents. We developed a new percutaneous approach method for intrapericardial injection, puncturing the pericardial sac safely under fluoroscopy and intravascular ultrasound (IVUS) guidance. In a porcine model of myocardial infarction (MI), we deployed gelfoam particles carrying either (a) autologous mesenchymal stem cells (MSCs) or (b) an adenovirus encoding enhanced green fluorescent protein (eGFP) 48 h post-MI. The presence of MSCs and viral infection at the infarct zone was confirmed by immunoflourescence and PCR. Puncture was performed successfully in 16 animals. Using IVUS, we successfully determined the size of the pericardial space before the puncture, and safely accessed that space in setting of pericardial effusion and also adhesions induced by the MI. Intrapericardial injection of gelfoam was safe and reliable. Presence of the MSCs and eGFP expression from adenovirus in the myocardium were confirmed after delivery. Our novel percutaneous approach to deliver (stem-) cells or adenovirus was safe and efficient in this pre-clinical model. IVUS-guided delivery is a minimally invasive procedure that seems to be a promising new strategy to deliver therapeutic agents locally to the heart.