Mesenchymal stem cell-derived exosomes altered neuron cholesterol metabolism via Wnt5a-LRP1 axis and alleviated cognitive impairment in a progressive Parkinson's disease model

Potential biofluid markers for cognitive impairment in Parkinson's disease

Cognitive impairment is a particularly severe non-motor symptom of Parkinson's disease that significantly diminishes the quality of life of affected individuals. Identifying reliable biomarkers for cognitive impairment in Parkinson's disease is essential for early diagnosis, prognostic assessments, and the development of targeted therapies. This review aims to summarize recent advancements in biofluid biomarkers for cognitive impairment in Parkinson's disease, focusing on the detection of specific proteins, metabolites, and other biomarkers in blood, cerebrospinal fluid, and saliva. These biomarkers can shed light on the multifaceted etiology of cognitive impairment in Parkinson's disease, which includes protein misfolding, neurodegeneration, inflammation, and oxidative stress. The integration of biofluid biomarkers with neuroimaging and clinical data can facilitate the development of predictive models to enhance early diagnosis and monitor the progression of cognitive impairment in patients with Parkinson's disease. This comprehensive approach can improve the existing understanding of the mechanisms driving cognitive decline and support the development of targeted therapeutic strategies aimed at modifying the course of cognitive impairment in Parkinson's disease. Despite the promise of these biomarkers in characterizing the mechanisms underlying cognitive decline in Parkinson's disease, further research is necessary to validate their clinical utility and establish a standardized framework for early detection and monitoring of cognitive impairment in Parkinson's disease.

Effectiveness of mesenchymal stem cell-derived extracellular vesicles therapy for Parkinson's disease: A systematic review of preclinical studies

BACKGROUND

Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) can traverse the blood-brain barrier due to their small size. This characteristic makes them a research hotspot for the treatment of Parkinson's disease (PD) and is expected to be a potentially revolutionary strategy for treating PD. Despite this, no summary of clinical trial results has been reported.

AIM

To assess the efficacy and durability of MSC-EVs in treating PD.

METHODS

Systematic searches were conducted in four electronic databases until June 2024 to collect studies on the use of MSC-EVs for this purpose. Thirteen relevant randomized controlled trials, encompassing 16 experiments, were selected for inclusion.

RESULTS

Behavioral assessments, including the rotarod and apomorphine turning behavior tests, indicated improvements in motor coordination (P < 0.00001); the Pole test and the Wire-hang test showed enhanced limb motor agility and synchronization (P = 0.003 and P < 0.00001, respectively). Histopathologically, there was a reduction in inflammatory markers such as tumor necrosis factor-α and interleukin-6 (P = 0.03 and P = 0.01, respectively) and an increase in tyrosine hydroxylase-positive cells in the lesion areas (P < 0.00001).

CONCLUSION

MSC-EV therapy for PD is a gradual process, with significant improvements observable more than 2 weeks after administration and lasting at least 8 weeks. This study is the first to demonstrate the efficacy and durability of MSC-EV treatment in PD.

A Review of the Neuroprotective Properties of Exosomes Derived from Stem Cells and Exosome-Coated Nanoparticles for Treating Neurodegenerative Diseases and Stroke

Neurological diseases, including neurodegenerative disorders and stroke, represent significant medical challenges due to their complexity and the limitations of current treatment approaches. This review explores the potential of stem cell (SC)-derived exosomes (Exos) as a transformative therapeutic strategy for these diseases. Exos, especially those derived from SCs, exhibit natural targeting ability, biocompatibility, and the capacity to cross the blood-brain barrier (BBB), making them ideal vehicles for drug delivery. This review provides an in-depth discussion of the properties and advantages of SC-Exos. It highlights their potential synergistic benefits in therapeutic approaches to treat neurological diseases. This article discusses the mechanisms of action of SC-Exos, highlighting their ability to target specific cells, modulate disease pathways, and provide controlled release of therapeutic agents. Applications in specific neurological disorders have been investigated, demonstrating the potential to improve outcomes in conditions such as Alzheimer's Disease (AD), Parkinson's Disease (PD), and stroke. Moreover, Exos-coated nanoparticles (NPs) combine the natural properties of Exos with the multifunctionality of NPs. This integration takes advantage of exosome membrane biocompatibility and targeting capabilities while preserving NPs' beneficial features, such as drug loading and controlled release. As a result, Exos-coated NPs may enhance the precision, efficacy, and safety of therapeutic interventions. In conclusion, SC-Exos represent a promising and innovative approach to treating neurological diseases.

Therapeutic Potential of Mesenchymal Stem Cell-Derived Extracellular Vesicles in the Treatment of Parkinson's Disease

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by the gradual loss of dopamine-producing neurons. Oxidative stress, mitochondrial dysfunction, detrimental immune response, and neuroinflammation are mainly responsible for the injury and degeneration of dopaminergic neurons in the brains of patients suffering from PD. Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) have emerged as a promising therapeutic approach for treating PD due to their ability to suppress the activation of inflammatory immune cells and enhance the viability and function of dopamine-producing neurons. MSC-EVs can easily bypass the blood-brain barrier and deliver their cargo (neuroprotective factors, immunosuppressive proteins, and microRNAs) to injured dopamine-producing neurons and brain-infiltrated inflammatory immune cells. A large number of recently published experimental studies demonstrated that MSC-EVs efficiently alleviated PD-related motor and behavioral deficits in animal models, indicating that MSC-EVs should be considered as potentially new therapeutic agents for the treatment of PD. Accordingly, in this review article, we summarized current knowledge about the therapeutic potential of MSCs-EVs in the treatment of PD, paving the way for their future clinical use in the treatment of neurodegenerative and neuroinflammatory disorders.

Whispers in the Brain: Extracellular Vesicles in Neuropathology and the Diagnostic Alchemy of Neurological Diseases

Extracellular vesicles (EVs) have emerged as pivotal mediators in neurological diseases, showcasing multifaceted potential roles ranging from pathogenesis to diagnosis. These nano-sized membranous structures, released by various cell types including neurons, astrocytes, and microglia, encapsulate a diverse cargo of proteins, lipids, RNA species, and even DNA fragments. In neuropathology, EVs contribute significantly to intercellular communication within the central nervous system (CNS), influencing physiological or pathological cascades. Through the transfer of bioactive molecules, EVs modulate neuroinflammation, neuronal survival, synaptic plasticity, and the propagation of protein aggregates characteristic of neurodegenerative disorders. Moreover, their presence in biofluids such as cerebrospinal fluid (CSF), blood, and urine reflects the pathophysiological state of the CNS, offering a window into the diagnosis, monitoring and treatment of neurological diseases. Recent advancements in EV isolation techniques, coupled with high-throughput omics technologies, have facilitated the profiling of EV cargo, enabling the identification of disease-specific biomarkers with high sensitivity and specificity. This review explores the intricate roles of EVs in neuropathology, highlighting their involvement in Alzheimer's disease, Parkinson's disease, multiple sclerosis, and other neurological disorders. Furthermore, it delves into the diagnostic potential of EVs, discussing current challenges and prospects in harnessing EV-derived biomarkers for precision medicine in neurology. Ultimately, understanding the biology of EVs in neurological contexts promises transformative insights into disease mechanisms and therapeutic strategies, paving the way for innovative diagnostic tools and targeted interventions in clinical practice.

Exosome-based drug delivery systems for enhanced neurological therapeutics

Exosomes are small extracellular vesicles naturally secreted by cells into body fluids, enriched with bioactive molecules such as RNAs, proteins, and lipids. These nanosized vesicles play a crucial role in physiological and pathological processes by facilitating intercellular communication and modulating cellular responses, particularly within the central nervous system (CNS). Their ability to cross the blood-brain barrier and reflect the characteristics of their parent cells makes exosomal cargo a promising candidate for biomarkers in the early diagnosis and clinical assessment of neurological conditions. This review offers a comprehensive overview of current knowledge on the characterization of mammalian-derived exosomes, their application as drug delivery systems for neurological disorders, and ongoing clinical trials involving exosome-loaded cargo. Despite their promising attributes, a significant challenge remains the lack of standardized isolation methods, as current techniques are often complex, costly, and require sophisticated equipment, affecting the scalability and affordability of exosome-based therapies. The review highlights the engineering potential of exosomes, emphasizing their ability to be customized for targeted therapeutic delivery through surface modification or conjugation. Future advancements in addressing these challenges and leveraging the unique properties of exosomes could lead to innovative and effective therapeutic strategies in neurology.

Roles, Functions, and Pathological Implications of Exosomes in the Central Nervous System

Exosomes are a subset of extracellular vesicles (EVs) secreted by nearly all cell types and have emerged as a novel mechanism for intercellular communication within the central nervous system (CNS). These vesicles facilitate the transport of proteins, nucleic acids, lipids, and metabolites between neurons and glial cells, playing a pivotal role in CNS development and the maintenance of homeostasis. Current evidence indicates that exosomes from CNS cells may function as either inhibitors or enhancers in the onset and progression of neurological disorders. Furthermore, exosomes have been found to transport disease-related molecules across the blood-brain barrier, enabling their detection in peripheral blood. This distinctive property positions exosomes as promising diagnostic biomarkers for neurological conditions. Additionally, a growing body of research suggests that exosomes derived from mesenchymal stem cells exhibit reparative effects in the context of neurological disorders. This review provides a concise overview of the functions of exosomes in both physiological and pathological states, with particular emphasis on their emerging roles as potential diagnostic biomarkers and therapeutic agents in the treatment of neurological diseases.

Therapeutic potential of mesenchymal stem cell-derived exosomes and miRNAs in neuronal regeneration and rejuvenation in neurological disorders: a mini review

Mesenchymal stem cells (MSCs) have gained considerable attention in the field of regenerative medicine due to their ability to secrete small extracellular vesicles (EVs) known as exosomes. This review delves into the various biological activities of MSCs and the cell interactions enabled by these exosomes, with a focus on their potential for neuronal regeneration and the treatment of neurological disorders. We scrutinize findings from multiple studies that underscore the neuroprotective and neuro-regenerative effects of exosomes derived from MSCs, illuminating their mechanisms of action and therapeutic applications. This review thoroughly investigates all related pathways, miRNAs, and factors to suggest potential strategies for enhancing therapy for neurological disorders using exosomes and miRNAs, and for boosting neuronal regeneration.

Exosomes as therapeutic and drug delivery vehicle for neurodegenerative diseases

Neurodegenerative disorders are complex, progressive, and life-threatening. They cause mortality and disability for millions of people worldwide. Appropriate treatment for neurodegenerative diseases (NDs) is still clinically lacking due to the presence of the blood-brain barrier (BBB). Developing an effective transport system that can cross the BBB and enhance the therapeutic effect of neuroprotective agents has been a major challenge for NDs. Exosomes are endogenous nano-sized vesicles that naturally carry biomolecular cargoes. Many studies have indicated that exosome content, particularly microRNAs (miRNAs), possess biological activities by targeting several signaling pathways involved in apoptosis, inflammation, autophagy, and oxidative stress. Exosome content can influence cellular function in healthy or pathological ways. Furthermore, since exosomes reflect the features of the parental cells, their cargoes offer opportunities for early diagnosis and therapeutic intervention of diseases. Exosomes have unique characteristics that make them ideal for delivering drugs directly to the brain. These characteristics include the ability to pass through the BBB, biocompatibility, stability, and innate targeting properties. This review emphasizes the role of exosomes in alleviating NDs and discusses the associated signaling pathways and molecular mechanisms. Furthermore, the unique biological features of exosomes, making them a promising natural transporter for delivering various medications to the brain to combat several NDs, are also discussed.

Novel combination of Olesoxime/Resveratrol-encapsulated exosomes to improve cognitive function by targeting amyloid β-induced Alzheimer's disease: investigation on in vitro and in vivo model

Alzheimer's disease (AD) is a fatal neurological illness that worsens with time. Preventing the aggregate formation of amyloid beta protein is a promising approach to treat Alzheimer's disease. This article describes an amiable procedure for the synthesis of Olesoxime-Resveratrol (OLX-RSV) encapsulated in exosomes. By suppressing Aβ1-42 aggregation and crossing the blood-brain barrier also known as BBB after intravenous treatment without resulting in any discernible damage, the nanocomposite demonstrated good biocompatibility. A variety of characterization technique including particle size, TEM, and in vitro drug release experiments, were used to characterize the exosomes. Human Neuroblastoma (SHSY5Y) cells were used to test the cytotoxicity and viability of cells of the formulation using the Cell Counting Kit-8 assay. The prepared OLX-RSV-loaded exosomes were tested for their ability to suppress Aβ1-42 in SHSY5Y Cells by analyzing the amyloid samples using CD spectra. The effects of apoptosis on Human neuroblastoma cells were studied using cytofluorometry. The parameters of SOD, caspase-3 and the ability to scavenge reactive oxygen species (ROS) were also evaluated. The behavioral outcomes of Morris water maze test demonstrated that OLX-RSV-loaded exosomes significantly enhanced the APP/PS1 mice's capacity to learn and remember spatial cues. Therefore, we hypothesized that OLX-RSV-loaded exosomes could be a useful and efficient method in the treatment of AD.

The rising roles of exosomes in the tumor microenvironment reprogramming and cancer immunotherapy

Exosomes are indispensable for intercellular communications. Tumor microenvironment (TME) is the living environment of tumor cells, which is composed of various components, including immune cells. Based on TME, immunotherapy has been recently developed for eradicating cancer cells by reactivating antitumor effect of immune cells. The communications between tumor cells and TME are crucial for tumor development, metastasis, and drug resistance. Exosomes play an important role in mediating these communications and regulating the reprogramming of TME, which affects the sensitivity of immunotherapy. Therefore, it is imperative to investigate the role of exosomes in TME reprogramming and the impact of exosomes on immunotherapy. Here, we review the communication role of exosomes in regulating TME remodeling and the efficacy of immunotherapy, as well as summarize the underlying mechanisms. Furthermore, we also introduce the potential application of the artificially modified exosomes as the delivery systems of antitumor drugs. Further efforts in this field will provide new insights on the roles of exosomes in intercellular communications of TME and cancer progression, thus helping us to uncover effective strategies for cancer treatment.

The role of exosomes in adult neurogenesis: implications for neurodegenerative diseases

Exosomes are cup-shaped extracellular vesicles with a lipid bilayer that is approximately 30 to 200 nm in thickness. Exosomes are widely distributed in a range of body fluids, including urine, blood, milk, and saliva. Exosomes exert biological function by transporting factors between different cells and by regulating biological pathways in recipient cells. As an important form of intercellular communication, exosomes are increasingly being investigated due to their ability to transfer bioactive molecules such as lipids, proteins, mRNAs, and microRNAs between cells, and because they can regulate physiological and pathological processes in the central nervous system. Adult neurogenesis is a multistage process by which new neurons are generated and migrate to be integrated into existing neuronal circuits. In the adult brain, neurogenesis is mainly localized in two specialized niches: the subventricular zone adjacent to the lateral ventricles and the subgranular zone of the dentate gyrus. An increasing body of evidence indicates that adult neurogenesis is tightly controlled by environmental conditions with the niches. In recent studies, exosomes released from different sources of cells were shown to play an active role in regulating neurogenesis both in vitro and in vivo, thereby participating in the progression of neurodegenerative disorders in patients and in various disease models. Here, we provide a state-of-the-art synopsis of existing research that aimed to identify the diverse components of exosome cargoes and elucidate the therapeutic potential of exosomal contents in the regulation of neurogenesis in several neurodegenerative diseases. We emphasize that exosomal cargoes could serve as a potential biomarker to monitor functional neurogenesis in adults. In addition, exosomes can also be considered as a novel therapeutic approach to treat various neurodegenerative disorders by improving endogenous neurogenesis to mitigate neuronal loss in the central nervous system.

Current progression in application of extracellular vesicles in central nervous system diseases

Early diagnosis and pharmacological treatment of central nervous system (CNS) diseases has been a long-standing challenge for clinical research due to the presence of the blood-brain barrier. Specific proteins and RNAs in brain-derived extracellular vesicles (EVs) usually reflect the corresponding state of brain disease, and therefore, EVs can be used as diagnostic biomarkers for CNS diseases. In addition, EVs can be engineered and fused to target cells for delivery of cargo, demonstrating the great potential of EVs as a nanocarrier platform. We review the progress of EVs as markers and drug carriers in the diagnosis and treatment of neurological diseases. The main areas include visual imaging, biomarker diagnosis and drug loading therapy for different types of CNS diseases. It is hoped that increased knowledge of EVs will facilitate their clinical translation in CNS diseases.

Pathogenic and therapeutic role of exosomes in neurodegenerative disorders

Neurodegenerative disorders affect millions of people worldwide, and the prevalence of these disorders is only projected to rise as the number of people over 65 will drastically increase in the coming years. While therapies exist to aid in symptomatic relief, effective treatments that can stop or reverse the progress of each neurodegenerative disease are lacking. Recently, research on the role of extracellular vesicles as disease markers and therapeutics has been intensively studied. Exosomes, 30-150 nm in diameter, are one type of extracellular vesicles facilitating cell-to-cell communication. Exosomes are thought to play a role in disease propagation in a variety of neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. Accordingly, the exosomes derived from the patients are an invaluable source of disease biomarkers. On the other hand, exosomes, especially those derived from stem cells, could serve as a therapeutic for these disorders, as seen by a rapid increase in clinical trials investigating the therapeutic efficacy of exosomes in different neurological diseases. This review summarizes the pathological burden and therapeutic approach of exosomes in neurodegenerative disorders. We also highlight how heat shock increases the yield of exosomes while still maintaining their therapeutic efficacy. Finally, this review concludes with outstanding questions that remain to be addressed in exosomal research.

Pathological mechanisms of neuroimmune response and multitarget disease-modifying therapies of mesenchymal stem cells in Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disease characterized by the degeneration of dopaminergic neurons in the substantia nigra (SN); the etiology and pathological mechanism of the disease are still unclear. Recent studies have shown that the activation of a neuroimmune response plays a key role in the development of PD. Alpha-synuclein (α-Syn), the primary pathological marker of PD, can gather in the SN and trigger a neuroinflammatory response by activating microglia which can further activate the dopaminergic neuron's neuroimmune response mediated by reactive T cells through antigen presentation. It has been shown that adaptive immunity and antigen presentation processes are involved in the process of PD and further research on the neuroimmune response mechanism may open new methods for its prevention and therapy. While current therapeutic regimens are still focused on controlling clinical symptoms, applications such as immunoregulatory strategies can delay the symptoms and the process of neurodegeneration. In this review, we summarized the progression of the neuroimmune response in PD based on recent studies and focused on the use of mesenchymal stem cell (MSC) therapy and challenges as a strategy of disease-modifying therapy with multiple targets.

Exosomes rich in Wnt5 improved circadian rhythm dysfunction via enhanced PPARγ activity in the 6-hydroxydopamine model of Parkinson's disease

Sleep disorder is one of the most common non-motor symptoms in Parkinson's disease (PD) and even appear as early symptoms. Here we investigated the therapeutic potential of mesenchymal stem cell-derived exosomes (MSC-EXOs) on sleep disorder in PD rats. 6-hydroxydopa (6-OHDA) was used to establish the PD rat model. BMSC^quiescent-EXO and BMSC^induced-EXO groups were given intravenous injection 100 µg/g per day for 4 weeks, while control groups were given intravenous injection of the same volume of normal saline. The total sleep time, slow-wave sleep time and fast-wave sleep time in the BMSC^quiescent-EXO and BMSC^induced-EXO groups were significantly prolonged (P < 0.05) compared with PD group, while the awakening time was significantly shortened (P < 0.05). In addition, increased levels of dopamine (P < 0.05) and 5-hydroxytryptamine (P < 0.05) levels were observed in the striatum of BMSC^quiescent-EXO and BMSC^induced-EXO groups. Further, qPCR and western blot revealed that the mRNA levels of CLOCK, BMAL1 and PER2 in suprachiasmatic nucleus (SCN) were notably increased in BMSC^quiescent-EXO and BMSC^induced-EXO groups compared to those from PD rats. More importantly, peroxisome proliferation-activated receptor γ (PPARγ) activities were significantly enhanced after treatment with BMSC^quiescent-EXO and BMSC^induced-EXO. JC-1 fluorescence staining showed that mitochondrial membrane potential imbalance was repaired after inoculation of BMSC^induced-EXO. In summary, MSC-EXOs showed the improvement of sleep disorder in PD rats through recovering circadian rhythm associated gene expression. The potential mechanisms may be related with increased PPARγ activities and rescued mitochondrial membrane potential imbalance in Parkinson striatum.

Exosomes for the diagnosis and treatment of dementia

PURPOSE OF REVIEW

Dementia is a syndrome with several possible pathologies. To date, definitive methods for diagnosis and treatment of sub-types of dementia have not been established. Emerging evidence suggests that exosomes can provide important information for the diagnosis and treatment of several subtypes of dementia. This article reviews recent studies on the application of exosomes in dementia.

RECENT FINDINGS

Exosomes are involved in the pathogenesis of Alzheimer's disease (AD) and Parkinson's disease (PD) through transporting toxic proteins such as amyloid beta (Aβ), tau, and α-synuclein. Exosomal microRNAs (miR) and proteins reflect the disease state, and therefore, exosomes can be used as diagnostic markers for diseases such as AD, PD, Huntington's disease (HD), vascular dementia (VaD), dementia with Lewy bodies (DLB), and frontotemporal dementia (FTD). Mesenchymal stem cell (MSC)-derived exosomes have been shown to ameliorate disease pathology, and improve cognitive function in AD, PD, and VAD.

SUMMARY

Recent studies have shown that exosomes could be novel diagnostic agents for dementia because they contain molecules that could be potential biomarker candidates indicative of the type and stage of dementia. Therapeutic application of exosomes in dementia has revealed that exosomes only, or exosomes loaded with an active pharmaceutical ingredient (API), ameliorate disease phenotype of dementia. Further work is needed to exploit this potential.

ERVWE1 Reduces Hippocampal Neuron Density and Impairs Dendritic Spine Morphology through Inhibiting Wnt/JNK Non-Canonical Pathway via miR-141-3p in Schizophrenia

Human endogenous retroviruses (HERVs) are remnants of ancestral germline infections by exogenous retroviruses. Human endogenous retroviruses W family envelope gene (HERV-W env, also called ERVWE1), located on chromosome 7q21-22, encodes an envelope glycoprotein from the HERV-W family. Mounting evidence suggests that aberrant expression of ERVWE1 involves the etiology of schizophrenia. Moreover, the genetic and morphological studies indicate that dendritic spine deficits may contribute to the onset of schizophrenia. Here, we reported that ERVWE1 changed the density and morphology of the dendritic spine through inhibiting Wingless-type (Wnt)/c-Jun N-terminal kinases (JNK) non-canonical pathway via miR-141-3p in schizophrenia. In this paper, we found elevated levels of miR-141-3p and a significant positive correlation with ERVWE1 in schizophrenia. Moreover, serum Wnt5a and actin-related protein 2 (Arp2) levels decreased and demonstrated a significant negative correlation with ERVWE1 in schizophrenia. In vitro experiments disclosed that ERVWE1 up-regulated miR-141-3p expression by interacting with transcription factor (TF) Yin Yang 1 (YY1). YY1 modulated miR-141-3p expression by binding to its promoter. The luciferase assay revealed that YY1 enhanced the promoter activity of miR-141-3p. Using the miRNA target prediction databases and luciferase reporter assays, we demonstrated that miR-141-3p targeted Wnt5a at its 3' untranslated region (3' UTR). Furthermore, ERVWE1 suppressed the expression of Arp2 through non-canonical pathway, Wnt5a/JNK signaling pathway. In addition, ERVWE1 inhibited Wnt5a/JNK/Arp2 signal pathway through miR-141-3p. Finally, functional assays showed that ERVWE1 induced the abnormalities in hippocampal neuron morphology and spine density through inhibiting Wnt/JNK non-canonical pathway via miR-141-3p in schizophrenia. Our findings indicated that miR-141-3p, Wnt5a, and Arp2 might be potential clinical blood-based biomarkers or therapeutic targets for schizophrenia. Our work also provided new insight into the role of ERVWE1 in schizophrenia pathogenesis.