Engineering exosomal cargo loading via endogenous molecular pathways: Strategies to enhance therapeutic potential

Abstract Exosomes have emerged as highly promising drug delivery vehicles due to their intrinsic biocompatibility, low immunogenicity, and natural ability to traverse biological barriers. However, their clinical translation is hindered by several inherent limitations, including restricted loading efficiency for therapeutic proteins and nucleic acids, limited cargo specificity, and variability in delivery performance. To address these challenges, increasing attention has been directed toward exploiting the endogenous molecular pathways that naturally govern cargo selection and packaging within exosomes. Advances in this area have enabled the development of engineering strategies that emulate or amplify these intrinsic mechanisms to achieve more precise and efficient cargo loading while preserving vesicle structure and biological function. Such endogenous engineering approaches have shown superior reproducibility and are more compatible with large‐scale manufacturing compared with exogenous manipulation. Notably, most exosome therapeutics currently in phase II or III clinical evaluation rely on natural or endogenously modified vesicles, underscoring the translational promise of this direction. This review provides a systematic overview of the endogenous pathways involved in protein and RNA sorting, summarizes engineering strategies derived from these mechanisms, and highlights representative applications. Together, these insights aim to support the rational design of next‐generation exosome‐based therapeutics and accelerate their path toward clinical use.