Neural Stem Cells Secretome Increased Neurogenesis and Behavioral Performance and the Activation of Wnt/β-Catenin Signaling Pathway in Mouse Model of Alzheimer’s Disease

Harmony of Wnt pathway in Alzheimer's: Navigating the multidimensional progression from preclinical to clinical stages

The Wnt pathway stands out as a pivotal signal transduction pathway, operating through two distinct modes of signaling: the canonical/β-catenin pathway and the non-canonical pathway. Among these, the canonical pathway assumes a paramount role in various physiological and pathological processes within the human body. Particularly in the brain, Wnt exhibits involvement in fundamental physiological events including neuronal differentiation/survival, axonogenesis, neural stem cell regulation, synaptic plasticity, and cell cycle modulation. Notably, scientific evidence underscores the critical role of the Wnt pathway in the pathogenesis of Alzheimer's disease (AD), correlating with its involvement in key pathological features such as tau tangles, Amyloid-β plaques, synaptic dysfunction, oxidative stress, mitochondrial dysfunction, cognitive impairments, and disruption of the blood-brain barrier integrity. This review aims to comprehensively explore the involvement and significance of Wnt signaling in Alzheimer's. Furthermore, it delves into recent advancements in research on Wnt signaling, spanning from preclinical investigations to clinical trials.

NSPCs-ES: mechanisms and functional impact on central nervous system diseases

Patients with central neuronal damage may suffer severe consequences, but effective therapies remain unclear. Previous research has established the transplantation of neural stem cells that generate new neurons to replace damaged ones. In a new field of scientific research, the extracellular secretion of NPSCs (NSPCs-ES) has been identified as an alternative to current chemical drugs. Many preclinical studies have shown that NSPCs-ES are effective in models of various central nervous system diseases (CNS) injuries, from maintaining functional structures at the cellular level to providing anti-inflammatory functions at the molecular level, as well as improving memory and motor functions, reducing apoptosis in neurons, and mediating multiple signaling pathways. The NSPC-ES can travel to the damaged tissue and exert a broad range of therapeutic effects by supporting and nourishing damaged neurons. However, gene editing and cell engineering techniques have recently improved therapeutic efficacy by modifying NSPCs-ES. Consequently, future research and application of NSPCs-ES may provide a novel strategy for the treatment of CNS diseases in the future. In this review, we summarize the current progress on these aspects.

Mechanistic insights and emerging therapeutic stratagems for Alzheimer's disease

Alzheimer's disease (AD), a multi-factorial neurodegenerative disorder has affected over 30 million individuals globally and these numbers are expected to increase in the coming decades. Current therapeutic interventions are largely ineffective as they focus on a single target. Development of an effective drug therapy requires a deep understanding of the various factors influencing the onset and progression of the disease. Aging and genetic factors exert a major influence on the development of AD. Other factors like post-viral infections, iron overload, gut dysbiosis, and vascular dysfunction also exacerbate the onset and progression of AD. Further, post-translational modifications in tau, DRP1, CREB, and p65 proteins increase the disease severity through triggering mitochondrial dysfunction, synaptic loss, and differential interaction of amyloid beta with different receptors leading to impaired intracellular signalling. With advancements in neuroscience tools, new inter-relations that aggravate AD are being discovered including pre-existing diseases and exposure to other pathogens. Simultaneously, new therapeutic strategies involving modulation of gene expression through targeted delivery or modulation with light, harnessing the immune response to promote clearance of amyloid deposits, introduction of stem cells and extracellular vesicles to replace the destroyed neurons, exploring new therapeutic molecules from plant, marine and biological sources delivered in the free state or through nanoparticles and use of non-pharmacological interventions like music, transcranial stimulation and yoga. Polypharmacology approaches involving combination of therapeutic agents are also under active investigation for superior therapeutic outcomes. This review elaborates on various disease-causing factors, their underlying mechanisms, the inter-play between different disease-causing players, and emerging therapeutic options including those under clinical trials, for treatment of AD. The challenges involved in AD therapy and the way forward have also been discussed.

Ultra-Low-Dose UV-C Photo-stimulation Promotes Neural Stem Cells Differentiation via Presenilin 1 Mediated Notch and β-Catenin Activation

Light-based photo-stimulation has demonstrated promising effects on stem cell behavior, particularly in optimizing neurogenesis. However, the precise parameters for achieving optimal results, including the wavelengths, light intensity, radiating energy, and underlying mechanisms, remain incompletely understood. In this study, we focused on utilizing ultraviolet-C (UV-C) at a specific wavelength of 254 nm, with an ultra-low dose at intensity of 330 μW/cm2 and a total energy of 594 mJ/cm2 per day over a period of seven days, to stimulate the proliferation and differentiation of mouse neural stem cells (NSCs). The results revealed that the application of ultra-low-dose UV-C yielded the most significant effect in promoting differentiation when compared to mixed ultraviolet (UV) and ultraviolet-A (UV-A) radiation at equivalent exposure levels. The mechanism exploration elucidated the role of Presenilin 1 in mediating the activation of β-catenin and Notch 1 by the UV-C treatment, both of which are key factors facilitating NSCs proliferation and differentiation. These findings introduce a novel approach employing ultra-low-dose UV-C for specifically enhancing NSC differentiation, as well as the underlying mechanism. It would contribute valuable insights into brain stimulation and neurogenesis modulation for various diseases, offering potential therapeutic avenues for further exploration.

Advanced molecular therapies for neurological diseases: focus on stroke, alzheimer's disease, and parkinson's disease

Neurological diseases (NDs) are one of the leading causes of disability and the second leading cause of death globally. Among these stroke, Alzheimer's disease (AD), and Parkinson's disease (PD) are the most common NDs. A rise in the absolute number of individuals affected with these diseases indicates that the current treatment strategies in management and prevention of these debilitating diseases are not effective sufficiently. Therefore, novel treatment strategies are being explored to cure these diseases by addressing the causative mechanisms at the molecular level. Advanced therapies like gene therapy (gene editing and gene silencing) and stem cell therapies aim to cure diseases by gene editing, gene silencing and tissue regeneration, respectively. Gene editing results in the deletion of the aberrant gene or insertion of the corrected gene which can be executed using the CRISPR/Cas gene editing tool a promising treatment strategy being explored for many other prevalent diseases. Gene silencing using siRNA silences the gene by inhibiting protein translation, thereby silencing its expression. Stem cell therapy aims to regenerate damaged cells or tissues because of their ability to divide into any type of cell in the human body. Among these approaches, gene editing and gene silencing have currently been applied in vitro and to animal models, while stem cell therapy has reached the clinical trial stage for the treatment of NDs. The current status of these strategies suggests a promising outcome in their clinical translation.

The Neural Multilineage Differentiation Capacity of Human Neural Precursors from the Umbilical Cord-Ready to Bench for Clinical Trials

Mesenchymal stem cells (MSC) are promising for regenerative medicine as they have a vast differentiation capacity, immunomodulatory properties and can be isolated from different tissues. Among them, the umbilical cord is considered a good source of MSC, as its collection poses no risk to donors and is unrelated to ethical issues. Furthermore, umbilical cord mesenchymal stem cells (UC-MSC) can differentiate into several cell lines, including neural lineages that, in the future, may become an alternative in the treatment of neurodegenerative diseases. This study used a natural functional biopolymer matrix (NFBX) as a membrane to differentiate UC-MSC into neurospheres and their Neural precursors without using neurogenic growth factors or gene transfection. Through the characterization of Neural precursors and differentiated cells, it was possible to demonstrate the broad potential for the differentiation of cells obtained through cultivation on this membrane. To demonstrate these Neural precursors' potential for future studies in neurodegenerative diseases, the Neural precursors from Wharton's jelly were differentiated into Schwann cells, oligodendrocytes, cholinergic-, dopaminergic- and GABAergic-like neurons.

Neurotrophic factor-secreting cells restored endogenous hippocampal neurogenesis through the Wnt/β-catenin signaling pathway in AD model mice

Background

Impairment in neurogenesis correlates with memory and  cognitive dysfunction in AD patients. In the recent decade, therapies with stem cell bases are growing and proved to be efficient. This study is a preliminary attempt to explore the impact of NTF-SCs on hippocampal neurogenesis mediated by the Wnt/β-catenin signaling cascade in AD-like mouse brain parenchyma.

Methods

The BALB/c mice were divided into four groups: Control, AD +Vehicle, AD+ TF-SCs-CM and AD+NTF-SCs (n = 10). For AD induction, 100 µM Aβ_1-42 was injected into lateral ventricles. The AD-like model was confirmed via passive avoidance test and Thioflavin-S staining 21 days following Aβ injection. Next, NTF-SCs were differentiated from ADMSCs, and both NTF-SCs and supernatant (NTF-SCs-CM) were injected into the hippocampus after AD confirmation. Endogenous neural stem cells (NSCs) proliferation capacity was assessed after 50 mg/kbW BrdU injection for 4 days using immunofluorescence (IF) staining. The percent of BrdU/Nestin and BrdU/NeuN positive NSCs were calculated. Real-time RT-PCR was used to detect genes related to the Wnt/β-catenin signaling cascade. The spatial learning and memory alternation was evaluated using the Morris water maze (MWM).

Results

Data showed the reduction in escape latency over 5 days in the AD mice compared to the control group. The administration of NTF-SCs and NTF-SCs-CM increased this value compared to the AD-Vehicle group. Both NTF-SCs and NTF-SCs-CM were the potential to reduce the cumulative distance to the platform in AD mice compared to the AD-Vehicle group. The time spent in target quadrants was ameliorated following NTF-SCs and NTF-SCs-CM transplantation followed by an improved MWM performance. IF imaging revealed the increase in BrdU/Nestin⁺ and BrdU/NeuN⁺ in AD mice that received NTF-SCs and NTF-SCs-CM, indicating enhanced neurogenesis. Based on real-time PCR analysis, the expression of PI3K, Akt, MAPK, ERK, Wnt, and β-catenin was upregulated and coincided with the suppression of GSK-3β after injection of NTF-SCs-CM and NTF-SCs. In this study, NTF-SCs had superior effects in AD mice that received NTF-SCs compared to NTF-SCs-CM.

Conclusions

The activation of Wnt/β-catenin pathway via NTF-SCs can be touted as a possible therapeutic approach to restore neurogenesis in AD mice.