Advancement of Radiolabeled Exosomes in Brain Disorders

A groundbreaking nanotechnology is promised by the exosome application in brain disorder treatments due to its phenomenal characteristic of being able to cross the blood-brain barrier (BBB), along with greater biocompatibility, low immunogenicity, and minimal side effects. Exosomes are involved in intracellular communication as they are noted to be heterogeneous group of nanoscale membrane-bound vesicles, typically 50–100 nm in diameter, secreted by both prokaryotic and eukaryotic cells. Their role seemed merely unimportant for years, until the last two decades, when their structure, role, and contents were studied and found that this paracrine cell-to-cell communication is achieved by substances carried in cargos, including interleukins and cytokines. Recent trend of investigations displayed how exosomes can come in handy in the pathogenesis, diagnosis, and treatment of several brain disorders, including Alzheimer’s disease, Parkinson’s disease, ischemic stroke, and many more, due to its natural ability to load both hydrophilic and hydrophobic compounds while crossing BBB. Currently, RMT (receptor-mediated transcytosis) of exosome is the prominent method of application, where ligands are expressed, such as LDLR-targeting apolipoprotein B, as engineered exosomes demonstrate much efficient drug uptake to the brain parenchyma. As comprehensive treatments of neurological disorders are currently in progress, it is crucial to comprehend the nature and potential of these exosomes; thus, radiolabeled exosomes can provide noninvasive tracking in understanding their activity in action, by imaging signal tissue penetration and accurate quantification. As per the recent studies, radiolabeled exosomes displayed higher sensitivity, specificity, and versatility while being noninvasive. This chapter will explore this nano-drug delivery system, exosome isolation by innovative means, and their physiochemical properties and will focus on the latest progression of radiolabeled exosomes technology underlying its BBB crossing ability, by summarizing natural, engineered, and radiolabeled assisted brain-targeted exosome-oriented drug treatment. We expect this chapter to also make our readers with major challenges in terms of exosome kinetics and clinical applications.