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.

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.

Treatment of multifocal breast cancer by systemic delivery of dual-targeted adeno-associated viral vectors.

Adeno-associated viral (AAV) vectors yield high potential for clinical gene therapy but, like for other vectors systems, they frequently do not sufficiently transduce the target tissue and their unspecific tropism prevents their application for multifocal diseases such as disseminated cancer. Targeted AAV vectors have been obtained from random AAV display peptide libraries but so far, all vector variants selected from AAV libraries upon systemic administration in vivo retained some collateral tropism, frequently the heart. Here we explored, if this impediment can be overcome by microRNA-regulated transgene cassettes as the combination of library-derived capsid targeting and micro-RNA control has not been evaluated so far. We used a tumor-targeted AAV capsid variant (ESGLSQS) selected from random AAV-display peptide libraries in vivo with remaining off-target tropism toward the heart and regulated targeted transgene expression in vivo by complementary target elements for heart-specific microRNA (miRT-1d). Although this vector still maintained its strong transduction capacity for tumor target tissue after intravenous injection, transgene expression in the heart was almost completely abrogated. This strong and completely tumor-specific transgene expression was used for therapeutic gene transfer in an aggressive multifocal, transgenic, polyoma middle T-induced, murine breast cancer model. A therapeutic suicide gene, delivered systemically by this dual-targeted AAV vector to multifocal breast cancer, significantly inhibited tumor growth after one single vector administration while avoiding side effects compared with untargeted vectors.