Exosomes as Emerging Nanocarriers for Targeted Cancer Therapy.

Exosomes are nanoscale lipid bilayer vesicles secreted by eukaryotic cells into biological fluids. As an important subtype of extracellular vesicles, they can mediate intercellular material exchange and signal transmission by carrying bioactive substances such as proteins, nucleic acids, and lipids, and participate in the maintenance of physiological homeostasis and the regulation of pathophysiological processes in the body. These biological characteristics make exosomes less likely to be recognized and cleared by the immune system after entering the human body, nor do they cause obvious immune rejection reactions, laying the foundation for their use as delivery carriers. Through engineering techniques, they can be modified, and nucleic acids, small molecule drugs, and other substances can be precisely encapsulated inside exosomes through artificial intervention, forming "exosome-treatment payload" complexes. These complexes can take advantage of the properties of exosomes to significantly enhance their permeability in human tissues and cells, easily cross biological barriers, and promote the enrichment of treatment payloads in specific sites such as tumor tissues, thereby effectively optimizing treatment outcomes. However, the current application of exosomes is still limited by low separation and purification efficiency, high preparation costs, and easy damage to vesicle structure, and the clinical transformation process needs to be accelerated. This review focuses on the latest progress in the research of exosome-targeted delivery platforms, combines existing exosome drug loading technologies, and analyzes the clinical application potential and core challenges of this delivery system in cancer treatment, aiming to provide research directions for the development and clinical transformation of exosome-mediated anti-tumor targeted therapy strategies.