Targeted delivery of therapeutic agents to the heart

Abstract

For therapeutic materials to be successfully delivered to the heart, several barriers need to be overcome, including the anatomical challenges of access, the mechanical force of the blood flow, the endothelial barrier, the cellular barrier and the immune response. Various vectors and delivery methods have been proposed to improve the cardiac-specific uptake of materials to modify gene expression. Viral and non-viral vectors are widely used to deliver genetic materials, but each has its respective advantages and shortcomings. Adeno-associated viruses have emerged as one of the best tools for heart-targeted gene delivery. In addition, extracellular vesicles, including exosomes, which are secreted by most cell types, have gained popularity for drug delivery to several organs, including the heart. Accumulating evidence suggests that extracellular vesicles can carry and transfer functional proteins and genetic materials into target cells and might be an attractive option for heart-targeted delivery. Extracellular vesicles or artificial carriers of non-viral and viral vectors can be bioengineered with immune-evasive and cardiotropic properties. In this Review, we discuss the latest strategies for targeting and delivering therapeutic materials to the heart and how the knowledge of different vectors and delivery methods could successfully translate cardiac gene therapy into the clinical setting. For therapeutic materials to be delivered to the heart, several barriers need to be overcome. In this Review, Ishikawa and colleagues discuss strategies for targeted delivery of therapeutic materials to the heart, including the use of adeno-associated viruses and exosomes, with a focus on agents directed at modifying gene expression. Therapies directed at modifying gene expression are emerging and have shown positive results for non-cardiac diseases in clinical trials; clinical translation of these therapies for cardiac diseases remains slow. Currently, cardiac-specific delivery of therapeutic materials in large mammals requires invasive approaches, and the patterns of distribution depend on the delivery method used. Vector options for gene delivery are increasing; adeno-associated viruses provide safe gene delivery but their gene-transduction efficacy in the human heart remains suboptimal. Extracellular vesicles hold immense potential for the delivery of therapeutic agents; their clinical applications depend on their efficient isolation, scalability, drug loading, biodistribution and tissue targeting. Next-generation cardiovascular therapeutics might include bioengineered macromolecules, viruses, nanobiologics and extracellular vesicles. Therapies directed at modifying gene expression are emerging and have shown positive results for non-cardiac diseases in clinical trials; clinical translation of these therapies for cardiac diseases remains slow. Currently, cardiac-specific delivery of therapeutic materials in large mammals requires invasive approaches, and the patterns of distribution depend on the delivery method used. Vector options for gene delivery are increasing; adeno-associated viruses provide safe gene delivery but their gene-transduction efficacy in the human heart remains suboptimal. Extracellular vesicles hold immense potential for the delivery of therapeutic agents; their clinical applications depend on their efficient isolation, scalability, drug loading, biodistribution and tissue targeting. Next-generation cardiovascular therapeutics might include bioengineered macromolecules, viruses, nanobiologics and extracellular vesicles.