STM Article Repository

Neurodegenerative diseases (NDs; including Alzheimer Disease, Parkinson Disease, Amyotrophic lateral sclerosis, Huntington Disease, and others) are characterized by a progressive loss of neuronal cells and/or function that often leads to physical disabilities and in some cases progresses to death. Being localized to specific parts of the brain or showing systemic distribution, the progression of NDs is irreversible and often incurable as the progression mechanisms show variation and are not fully understood. Of the different risk factors associated with NDs, age along with prolonged processes of inflammation and oxidative stress are considered the major contributing factors. Considering the elusive nature of NDs, studies are currently directed at exploring and understanding disease development mechanisms, factors affecting disease progression, accurate diagnosis, timely interventions, and the development of suitable therapeutics that could combat the occurrence of the disease.

The recent trend in mechanistic foci for proper diagnosis and optimal treatment strategies includes studies oriented toward exploring the role of exosomes in disease progression and therapeutics of NDs. Extracellular vesicles (EVs) including exosomes are membrane-enclosed entities that display specific components on their surface and sequester molecules such as nucleic acids to shuttle as cargo intracellularly for communication purposes. It has been found that their production and transport via body fluids such as blood, breast milk, etc., influence the physiological and pathological parameters within the system. Studies performed with respect to their composition, biogenesis, and trafficking have provided deeper insights into the marked changes they undergo in the context of different human diseases.

The main goal of this Research Topic was an exploration of the latest outstanding discoveries pertinent to different aspects of NDs and insights into emerging diagnosis and treatment strategies. The present Research Topic includes six review articles that provide in-depth insight into different aspects of EVs in particular exosomes with respect to their composition, biogenesis and trafficking, their diagnostic utility, and target-specific delivery of therapeutic modules. The articles published in the issue are directed toward exploring the role of EVS in the improving cognitive function, in addition to covering various aspects of disease progression and therapeutic delivery in different NDs.

The review “Extracellular Vesicles: A New Paradigm in Understanding, Diagnosis and Treating Neurodegenerative Diseases” by Dar et al. illustrated how NDs are becoming one of the leading causes of disability and deaths internationally. The article highlighted an understanding of the role of exosomes in the pathogenesis and progression of NDs. With respect to the challenges posed by delivering drugs across the biological barriers, this review provided information about the utility of EVs in delivering therapeutic modules particularly non-coding RNAs across the blood-brain barrier to the central nervous system.

The review by Weng et al., “Role of Exosomes as Mediators of Neuroinflammation in the Pathogenesis and Treatment of Alzheimer's Disease,” summarized the role of neuroinflammation in the pathogenesis of Alzheimer's disease. Microglial cells play a significant role in the pathogenesis and secretion of tau in EVs in particular exosomes. As an inflammatory mediator, EVs carrying tau, Aβ, and other entities, induce neuroinflammation through diffusion at the interconnected neurons. The authors reported an association of neuroinflammation and EVs particularly exosomes with abnormal protein aggregates and neuronal death that proceeds with the development and severity in the pathogenesis of Alzheimer's disease.