Exosomes as nanocarrier for Neurotherapy: Journey from application to challenges

Exosomes are nanosized extracellular vesicles that influence different facets of cell biology and mediate both short and long-range intercellular communication in health and illness. Exosomes also play important roles in the development of tumours, immunological responses, and neurological diseases. Therefore, it can be utilized as a potential biomarker for diagnosis and prognosis as well as for the treatment of various diseases. Exosomes are regarded as the safest and most selective vehicles for transporting therapeutic molecules to the brain. Exosomes assist in the aggregation, transmission, and efficient elimination of harmful proteins in neurodegenerative diseases. Exosomes are beneficial in the treatment of brain diseases due to their ability to cross the blood-brain barrier (BBB). However, its application to brain diseases as a diagnostic tool and treatment therapy is in the early stages of development. Here, we review recent efforts to deliver drugs via exosomes for the treatment of brain cancer and neurodegenerative diseases, as well as the challenges and potential ways for their clinical application. This article provides a comprehensive discussion of biogenesis, composition, and sources of exosomes as well as techniques for their isolation, purification, characterization, and cargo loading. Various challenges associated with exosomes in the form of scalability, stability, and regulation have been reviewed and the strategies to overcome these challenges are also discussed.