APOE and xanthoma: Using plasmid vectors expressing allelic human ApoE-2 or ApoE-3 isoforms, Athanasopoulos et al. [217] demonstrated that skeletal muscle was an effective secretory platform for ApoE gene augmentation and that muscle-based expression of ApoE-2 after intramuscular plasmid injection in ApoE−/− mice was able to reduce atherosclerotic lesions in proximal aorta by 20–30%, with total abolishment of gross dorsal xanthoma (>5 mm diameter) up to 9 months following a single ApoE-2 plasmid administration.