Neural stem cell-derived extracellular vesicles: mini players with key roles in neurogenesis, immunomodulation, neuroprotection and aging

Extracellular vesicles from hiPSC-derived NSCs protect human neurons against Aβ-42 oligomers induced neurodegeneration, mitochondrial dysfunction and tau phosphorylation

BACKGROUND

Alzheimer's disease (AD) is characterized by the accumulation of amyloid beta-42 (Aβ-42) in the brain, causing various adverse effects. Thus, therapies that reduce Aβ-42 toxicity in AD are of great interest. One promising approach is to use extracellular vesicles from human induced pluripotent stem cell-derived neural stem cells (hiPSC-NSC-EVs) because they carry multiple therapeutic miRNAs and proteins capable of protecting neurons against Aβ-42-induced toxicity. Therefore, this in vitro study investigated the proficiency of hiPSC-NSC-EVs to protect human neurons from Aβ-42 oligomers (Aβ-42o) induced neurodegeneration.

METHODS

We isolated hiPSC-NSC-EVs using chromatographic methods and characterized their size, ultrastructure, expression of EV-specific markers and proficiency in getting incorporated into mature human neurons. Next, mature human neurons differentiated from two different hiPSC lines were exposed to 1 µM Aβ-42o alone or with varying concentrations of hiPSC-NSC-EVs. The protective effects of hiPSC-NSC-EVs against Aβ-42o-induced neurodegeneration, oxidative stress, mitochondrial dysfunction, impaired autophagy, and tau phosphorylation were ascertained using multiple measures and one-way ANOVA with Newman-Keuls multiple comparisons post hoc tests.

RESULTS

A significant neurodegeneration was observed when human neurons were exposed to Aβ-42o alone. Neurodegeneration was associated with (1) elevated levels of reactive oxygen species (ROS), mitochondrial superoxide, malondialdehyde (MDA) and protein carbonyls (PCs), (2) increased expression of proapoptotic Bax and Bad genes and proteins, and genes encoding mitochondrial complex proteins, (3) diminished mitochondrial membrane potential and mitochondria, (4) reduced expression of the antiapoptotic gene and protein Bcl-2, and autophagy-related proteins, and (5) increased phosphorylation of tau. However, the addition of an optimal dose of hiPSC-NSC-EVs (6 × 109 EVs) to human neuronal cultures exposed to Aβ-42o significantly reduced the extent of neurodegeneration, along with diminished levels of ROS, superoxide, MDA and PCs, normalized expressions of Bax, Bad, and Bcl-2, and autophagy-related proteins, higher mitochondrial membrane potential and mitochondria, enhanced expression of genes linked to mitochondrial complex proteins, and reduced tau phosphorylation.

CONCLUSIONS

An optimal dose of hiPSC-NSC-EVs could significantly decrease the degeneration of human neurons induced by Aβ-42o. The results support further research into the effectiveness of hiPSC-NSC-EVs in AD, particularly their proficiency in preserving neurons and slowing disease progression.

Impact of Microglia-Derived Extracellular Vesicles on Resident Central Nervous System Cell Populations After Acute Brain Injury Under Various External Stimuli Conditions

Acute brain injuries (ABI) caused by various emergencies can lead to structural and functional damage to brain tissue. Common causes include traumatic brain injury, cerebral hemorrhage, ischemic stroke, and heat stroke. Globally, ABI represent a significant portion of neurosurgical cases. Previous studies have emphasized the significant therapeutic potential of stem cell-derived extracellular vesicles (EVs). Recent research indicates that EVs extracted from resident cells in the central nervous system (CNS) also show therapeutic potential following brain injury. Microglia, as innate immune cells of the CNS, respond to changes in the internal environment by altering their phenotype and secreting EVs that impact various CNS cells, including neurons, astrocytes, oligodendrocytes, endothelial cells, neural stem cells (NSCs), and microglia themselves. Notably, under different external stimuli, microglia can either promote neuronal survival, angiogenesis, and myelin regeneration while reducing glial scarring and inflammation, or they can exert opposite effects. This review summarizes and evaluates the current research findings on how microglia-derived EVs influence various CNS cells after ABI under different external stimuli. It analyzes the interaction mechanisms between EVs and resident CNS cells and discusses potential future research directions and clinical applications.

Resveratrol-Enhanced Human Neural Stem Cell-Derived Exosomes Mitigate MPP+-Induced Neurotoxicity Through Activation of AMPK and Nrf2 Pathways and Inhibition of the NLRP3 Inflammasome in SH-SY5Y Cells

Parkinson's disease (PD) is a progressive neurodegenerative disorder primarily characterized by the loss of dopaminergic neurons in the substantia nigra. Mitochondrial dysfunction, oxidative stress, and neuroinflammation are recognized as critical pathological mechanisms driving neurodegeneration in PD. Exosome (Exo)-based therapies, particularly those derived from human neural stem cells (hNSCs), offer promising neuroprotective effects due to their ability to transfer bioactive molecules that modulate cellular processes. Resveratrol (RES), a polyphenolic compound with potent antioxidant and anti-inflammatory properties, has been shown to enhance the therapeutic potential of stem cell (SC)-derived Exos. This study investigated the neuroprotective effects of RES-treated hNSCs-derived Exos (RES-hNSCs-Exos) on SH-SY5Y cells exposed to 1-methyl-4-phenylpyridinium (MPP+), a neurotoxin commonly used to model Parkinsonian neurotoxicity. Treating SH-SY5Y cells with MPP+ led to significant reductions in cell viability, mitochondrial dysfunction, increased oxidative stress, and the activation of inflammatory pathways. Treatment with RES-hNSCs-Exos rescued SH-SY5Y cells from MPP+-induced toxicity by improving cell viability, enhancing ATP production, increasing mitochondrial biogenesis, and reducing reactive oxygen species (ROS) generation. The findings also demonstrated the increased expression of essential genes involved in mitochondrial biogenesis, such as PGC1α, NRF1, and Tfam, indicating improved mitochondrial function in the presence of RES-hNSCs-Exos. Further analysis revealed that these protective effects were mediated by activating the AMP-activated protein kinase (AMPK) and Nrf2 signaling pathways, which promoted mitochondrial health and reduced oxidative stress. Moreover, RES-hNSCs-Exos treatment suppressed neuroinflammation by downregulating NLRP3 inflammasome activation and reducing the secretion of pro-inflammatory cytokines IL-1β and IL-18. In conclusion, the results suggest that RES-hNSCs-Exos exhibit potent neuroprotective effects against MPP+-induced neurotoxicity by enhancing mitochondrial function, reducing oxidative stress, and inhibiting neuroinflammation. These findings highlight the potential of hNSCs-Exos as a novel therapeutic strategy for neurodegenerative diseases like PD, with RES as a valuable enhancer of Exos efficacy.

Emerging strategies for nerve repair and regeneration in ischemic stroke: neural stem cell therapy

Ischemic stroke is a major cause of mortality and disability worldwide, with limited treatment options available in clinical practice. The emergence of stem cell therapy has provided new hope to the field of stroke treatment via the restoration of brain neuron function. Exogenous neural stem cells are beneficial not only in cell replacement but also through the bystander effect. Neural stem cells regulate multiple physiological responses, including nerve repair, endogenous regeneration, immune function, and blood-brain barrier permeability, through the secretion of bioactive substances, including extracellular vesicles/exosomes. However, due to the complex microenvironment of ischemic cerebrovascular events and the low survival rate of neural stem cells following transplantation, limitations in the treatment effect remain unresolved. In this paper, we provide a detailed summary of the potential mechanisms of neural stem cell therapy for the treatment of ischemic stroke, review current neural stem cell therapeutic strategies and clinical trial results, and summarize the latest advancements in neural stem cell engineering to improve the survival rate of neural stem cells. We hope that this review could help provide insight into the therapeutic potential of neural stem cells and guide future scientific endeavors on neural stem cells.

Promise of mesenchymal stem cell-derived extracellular vesicles for alleviating subarachnoid hemorrhage-induced brain dysfunction by neuroprotective and antiinflammatory effects

Subarachnoid hemorrhage (SAH), accounting for ∼5% of all strokes, represents a catastrophic subtype of cerebrovascular accident. SAH predominantly results from intracranial aneurysm ruptures and affects ∼30,000 individuals annually in the United States and ∼6 individuals per 100,000 people worldwide. Recent studies have implicated that administering mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) may be beneficial in inducing neuroprotective and antiinflammatory effects following SAH. EVs are nanosized particles bound by a lipid bilayer. MSC-EVs comprise a therapeutic cargo of nucleic acids, lipids, and proteins, having the promise to ease SAH-induced long-term brain impairments. This review evaluated the findings of published studies on the therapeutic efficacy of MSC-EVs in the context of SAH. A growing body of evidence points out the therapeutic potential of MSC-EVs for improving brain function in animal models of SAH. Specifically, studies demonstrated their ability to reduce neuronal apoptosis and neuroinflammation and enhance neurological recovery through neuroprotective and antiinflammatory mechanisms. Such outcomes reported in various studies suggest that MSC-EVs hold great potential as a novel and minimally invasive approach to ameliorate SAH-induced neurological damage and improve patient outcomes. The review also discusses the limitations of EV therapy and the required future research efforts toward harnessing the full potential of MSC-EVs in treating SAH.

Integrating Mitochondrial Biology into Innovative Cell Therapies for Neurodegenerative Diseases

The role of mitochondria in neurodegenerative diseases is crucial, and recent developments have highlighted its significance in cell therapy. Mitochondrial dysfunction has been implicated in various neurodegenerative disorders, including Alzheimer's, Parkinson's, amyotrophic lateral sclerosis, and Huntington's diseases. Understanding the impact of mitochondrial biology on these conditions can provide valuable insights for developing targeted cell therapies. This mini-review refocuses on mitochondria and emphasizes the potential of therapies leveraging mesenchymal stem cells, embryonic stem cells, induced pluripotent stem cells, stem cell-derived secretions, and extracellular vesicles. Mesenchymal stem cell-mediated mitochondria transfer is highlighted for restoring mitochondrial health in cells with dysfunctional mitochondria. Additionally, attention is paid to gene-editing techniques such as mito-CRISPR, mitoTALENs, mito-ZNFs, and DdCBEs to ensure the safety and efficacy of stem cell treatments. Challenges and future directions are also discussed, including the possible tumorigenic effects of stem cells, off-target effects, disease targeting, immune rejection, and ethical issues.

Extracellular Vesicles from hiPSC-derived NSCs Protect Human Neurons against Aβ-42 Oligomers Induced Neurodegeneration, Mitochondrial Dysfunction and Tau Phosphorylation

Background

One of the hallmarks of Alzheimer's disease (AD) is the buildup of amyloid beta-42 (Aβ-42) in the brain, which leads to various adverse effects. Therefore, therapeutic interventions proficient in reducing Aβ-42-induced toxicity in AD are of great interest. One promising approach is to use extracellular vesicles from human induced pluripotent stem cell-derived neural stem cells (hiPSC-NSC-EVs) because they carry multiple therapeutic miRNAs and proteins capable of protecting neurons against Aβ-42-induced pathological changes. Therefore, this in vitro study investigated the proficiency of hiPSC-NSC-EVs to protect human neurons derived from two distinct hiPSC lines from Aβ-42o-induced neurodegeneration.

Methods

We isolated hiPSC-NSC-EVs using chromatographic methods and characterized their size, ultrastructure, expression of EV-specific markers and proficiency in getting incorporated into mature human neurons. Next, mature human neurons differentiated from two different hiPSC lines were exposed to 1 µM Aβ-42 oligomers (Aβ-42o) alone or with varying concentrations of hiPSC-NSC-EVs. The protective effects of hiPSC-NSC-EVs against Aβ-42o-induced neurodegeneration, increased oxidative stress, mitochondrial dysfunction, impaired autophagy, and tau phosphorylation were ascertained using multiple measures and one-way ANOVA with Newman-Keuls multiple comparisons post hoc tests.

Results

Significant neurodegeneration was observed when human neurons were exposed to Aβ-42o alone. Notably, neurodegeneration was associated with elevated levels of oxidative stress markers malondialdehyde (MDA) and protein carbonyls (PCs), increased expression of proapoptotic Bax and Bad genes and proteins, reduced expression of the antiapoptotic gene and protein Bcl-2, increased expression of genes encoding mitochondrial complex proteins, decreased expression of autophagy-related proteins Beclin-1 and microtubule-associated protein 1 light chain 3B, and increased phosphorylation of tau. However, the addition of an optimal dose of hiPSC-NSC-EVs (6 x 10 9 EVs) to human neuronal cultures exposed to Aβ-42o significantly reduced the extent of neurodegeneration, along with diminished levels of MDA and PCs, normalized expressions of Bax, Bad, and Bcl-2, and genes linked to mitochondrial complex proteins, and reduced tau phosphorylation.

Conclusions

The findings demonstrate that an optimal dose of hiPSC-NSC-EVs could significantly decrease the degeneration of human neurons induced by Aβ-42o. The results also support further research into the effectiveness of hiPSC-NSC-EVs in AD, particularly their proficiency in preserving neurons and slowing disease progression.

Exosomes: The endogenous nanomaterials packed with potential for diagnosis and treatment of neurologic disorders

Neurologic disorders (NDs) are serious diseases that threaten public health. However, due to the complex pathogenesis and significant individual differences in traditional treatments, specific treatment methods for NDs are still lacking. Exosomes, the smallest extracellular vesicles secreted by eukaryotic cells, are receiving increasing attention in the field of NDs. They contain misfolded proteins related to various NDs, including amyloid-beta, Tau proteins, and α-synuclein, indicating their promising roles in the diagnosis and treatment of NDs. In this review, an overview of the biogenesis, composition, and biological functions of exosomes is provided. Moreover, we summarize their potential roles in the pathogenesis of three prevalent NDs (including Alzheimer's disease, Ischemic stroke, and Parkinson's disease). On this basis, the diagnostic potential and therapeutic value of exosomes carrying various bioactive molecules are discussed in detail. Also, the concerns and perspectives of exosome-based diagnosis and therapy are discussed.

Unraveling the Multifaceted Roles of Extracellular Vesicles: Insights into Biology, Pharmacology, and Pharmaceutical Applications for Drug Delivery

Extracellular vesicles (EVs) are nanoparticles released from various cell types that have emerged as powerful new therapeutic option for a variety of diseases. EVs are involved in the transmission of biological signals between cells and in the regulation of a variety of biological processes, highlighting them as potential novel targets/platforms for therapeutics intervention and/or delivery. Therefore, it is necessary to investigate new aspects of EVs' biogenesis, biodistribution, metabolism, and excretion as well as safety/compatibility of both unmodified and engineered EVs upon administration in different pharmaceutical dosage forms and delivery systems. In this review, we summarize the current knowledge of essential physiological and pathological roles of EVs in different organs and organ systems. We provide an overview regarding application of EVs as therapeutic targets, therapeutics, and drug delivery platforms. We also explore various approaches implemented over the years to improve the dosage of specific EV products for different administration routes.