Exosomes

Exosomes are nanoscale extracellular vesicles, typically ranging in diameter from approximately 40 to 160 nm; originating from the endosomal pathway, they mediate intercellular communication by transferring proteins, lipids, DNA, mRNA, microRNA, and other bioactive substances between donor and recipient cells. Exosomes possess a unique combination of attributes-including natural targeting capabilities, low immunogenicity, biocompatibility, a long circulatory half-life, and the ability to traverse biological barriers (including the blood-brain barrier)-making them a highly attractive platform for applications in cancer therapy, regenerative medicine, disease diagnosis, and drug delivery. Mechanistically, tumor-derived exosomes regulate tumor progression through intercellular signaling; by delivering oncogenic miRNAs, proteins, and signaling mediators to stromal and immune cells, they promote angiogenesis, epithelial-mesenchymal transition (EMT), immune evasion, tumor metastasis, and the formation of a pre-metastatic niche. Furthermore, exosomes can induce and exacerbate chemotherapy resistance by shielding tumor cells from cytotoxic drugs and by transferring drug-resistance traits to neighboring cells.
In the field of drug development, engineered exosomes are being utilized as nanocarriers for the delivery of chemotherapeutic agents, siRNAs, miRNAs, lncRNAs, CRISPR payloads, and immunomodulators. In disease models involving breast cancer, lung cancer, glioma, colorectal cancer, and hepatocellular carcinoma, this strategy has effectively reduced systemic toxicity while simultaneously enhancing tumor-targeting specificity. Moreover, exosomes are being applied in tissue repair, the modulation of inflammatory diseases, the treatment of neurodegenerative disorders, and precision diagnostics based on "liquid biopsy" technologies; the biomarkers carried within circulating exosomes facilitate the early screening of diseases and the real-time monitoring of therapeutic efficacy.