Exosomes as Emerging Therapeutic and Diagnostic Platforms: Biological Functions, Clinical Applications, and Translational Challenges

Exosomes are small membrane-bound extracellular vesicles of endosomal origin that play pivotal roles in intercellular communication by transferring proteins, lipids, metabolites, and nucleic acids. Increasing evidence indicates that these vesicles participate in diverse physiological and pathological processes, including immune regulation, tissue repair, tumor progression, neurodegeneration, and cardiovascular homeostasis. Their distinctive biological properties have consequently generated considerable interest in their development as diagnostic tools, therapeutic agents, and drug-delivery platforms. Recent progress in exosome biology and biogenesis, together with technological advances in vesicle isolation, characterization, engineering, and large-scale production, has accelerated their preclinical development and early clinical translation. Nevertheless, substantial challenges—including donor-cell heterogeneity, low production yields, insufficiently standardized protocols, and regulatory uncertainty—must be addressed before widespread clinical implementation can be achieved. This narrative review integrates current knowledge of exosome biology, diagnostic and therapeutic applications, and engineering strategies. It further examines major translational barriers and outlines future priorities for advancing exosome-based technologies toward precision medicine.