Neural stem cells for Parkinson’s disease management: Challenges, nanobased support, and prospects

Biodegradable, electroconductive self-healing hydrogel based on polydopamine-coated polyurethane nano-crosslinker for Parkinson's disease therapy

Parkinson's disease (PD) is a neurodegenerative disorder characterized by loss of dopaminergic neurons, causing motor and neurological impairments. Current treatments offer only temporary symptom relief without halting progression. Herein, a fully biodegradable, electroconductive self-healing hydrogel (CPUD gel) is developed, incorporating electroconductive polydopamine-coated polyurethane nanoparticles (PUD) as crosslinker. The core-shell PUD nanoparticles have a highly uniform size of ∼36 nm with a polydopamine shell of ∼4.8 nm thick on polyurethane core, revealed by small angle X-ray scattering, and own a conductivity of ∼0.82 mS/cm. As nano-crosslinker, the PUD can react with chitosan to form the dynamic CPUD hydrogel with shear modulus (∼280 Pa) and conductivity (∼4.34 mS/cm), mimicking brain tissue properties. In vitro, CPUD gel supports neural stem cell (NSC) proliferation (∼565 %) and differentiation, with elevated neuronal marker expression at 14 days, while exhibiting strong antioxidative and anti-inflammatory effects, rescuing ∼88 % inflamed NSCs. A therapeutic strategy combining injectable CPUD gel with acupuncture in a PD rat model, aiming to activate the innate regenerative mechanisms of body through mobilized endogenous stem cells, is further established. Using this approach, this hydrogel significantly elevates serum TGF-β1/SDF-1 levels, promotes dopaminergic neuron regeneration (>80 %), modulates neuroinflammation through M1-to M2-microglia transition (∼12.6-fold M2/M1 ratio), and improves motor function (from 8 % to 37 % forelimb contacts) in 14 days. Particularly, the electrophysiological spike rate is recovered from 66 to 19 spikes/s, close to the healthy rate 15 spikes/s. The synergistic immunomodulation and neuroprotection highlight the potential of CPUD gel as an advanced therapeutic tool for PD.

Network Meta-Analysis of Stem Cell Therapies for Parkinson's Disease: Exploring the Optimal Strategy Based on Animal Models

Stem cell therapy holds promise for Parkinson's disease (PD). To identify optimal stem cell regimens in PD mouse models and inform translational research, we conducted a network meta-analysis (NMA). Specifically, we systematically searched for studies on stem cell therapy in PD mouse models up to September 2024 in PubMed, Embase, Scopus, Web of Science, China National Knowledge Infrastructure, WANFANG, and VIP. Based on the data collected, we conducted an NMA using GeMTC-0.14.3 software. The results of traditional meta-analysis of 148 studies demonstrated superior efficacy of most interventions versus controls at biweekly intervals (2-8 weeks post-treatment), with neural stem cells engineered with neurotrophic factors (NSC-NFs) showing the lowest weighted mean difference, indicating optimal therapeutic effect. NMA demonstrated that NF-engineered NSC therapy ranked the highest at biweekly time points (2-8 weeks post-treatment). Doses of 105 cells showed optimal efficacy at 2, 4, and 6 weeks, peaking within this range, whereas doses of 103 cells showed the best efficacy at 8 weeks. Medial forebrain bundle (MFB) administration showed superior efficacy at weeks 2 and 8, while striatum (STR) infusion showed greater therapeutic effects at weeks 4 and 6, with both approaches significantly outperforming nasal and intravenous delivery at all evaluated time points (2, 4, 6, and 8 weeks). Taken together, these results suggest that NSC-NF (dosage of 105) delivered via MFB (at 2 and 8 weeks) or STR (at 4 and 6 weeks) may represent the optimal strategy. It provides important guidance for optimizing preclinical and clinical trial designs and offers valuable insights for clinical translation.

Exosome-Derived CDC42 From Hypoxia-Pretreated Neural Stem Cells Inhibits ACSL4-Related Ferroptosis to Alleviate Vascular Injury in Parkinson's Disease Mice Models

Parkinson's disease (PD) is a neurodegenerative disorder that gets exacerbated by vascular injury. Neural stem cell-derived exosomes (NSC-Exos) display effective neuroprotective properties in PD models. Cell division control protein 42 (CDC42) is connected to angiogenesis, but its effects in PD remain undefined. This research aims to reveal the role of CDC42 in PD. First, we applied 1-methyl-4-phenylpyridinium (MPP+) to induce the human cerebral microvascular endothelial cells (HCMECs) model and evaluated cell viability and ferroptosis. Then, we characterized NSC-Exos. Next, to appraise the effect of hypoxia-pretreated NSC-Exos (H-NSC-Exos) on the MPP+-induced cells model, we examined angiogenesis and ferroptosis in HCMECs. Moreover, we constructed the PD mice model using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and tested the behavioral experiments and vascular injury of mice. Furthermore, we examined cellular ferroptosis and angiogenesis after knockdown of CDC42. Additionally, we investigated the interaction of CDC42 with Acyl-CoA synthetase long-chain family member 4 (ACSL4) and detected cellular ferroptosis and angiogenesis after overexpression of ACSL4. We found that H-NSC-Exos reversed the MPP+-induced decrease in HCMECs viability and migration, lowered lipid-reactive oxygen species (lipid-ROS) levels, suppressed ferroptosis, and facilitated angiogenesis. Moreover, H-NSC-Exos attenuated MPTP-induced PD development, vascular injury, and ferroptosis in mice. H-NSC-Exos with the knockdown of CDC42 reduced cell viability and angiogenesis and raised ferroptosis and lipid-ROS levels, which were reversed by ferrostatin-1 and liproxstatin-1. CDC42 interacted with ACSL4. Furthermore, overexpression of ACSL4 aggravated the above effects of H-NSC-Exos in which CDC42 was knocked down. Our study reveals that H-NSC-Exos-derived CDC42 inhibited ACSL4-related ferroptosis to alleviate vascular injury in PD mice models. CDC42 may serve as a potent therapeutic target for PD treatment.

Drug repositioning for Parkinson's disease: An emphasis on artificial intelligence approaches

Parkinson's disease (PD) is one of the most incapacitating neurodegenerative diseases (NDDs). PD is the second most common NDD worldwide which affects approximately 1-2 percent of people over 65 years. It is an attractive pursuit for artificial intelligence (AI) to contribute to and evolve PD treatments through drug repositioning by repurposing existing drugs, shelved drugs, or even candidates that do not meet the criteria for clinical trials. A search was conducted in three databases Web of Science, Scopus, and PubMed. We reviewed the data related to the last years (1975-present) to identify those drugs currently being proposed for repositioning in PD. Moreover, we reviewed the present status of the computational approach, including AI/Machine Learning (AI/ML)-powered pharmaceutical discovery efforts and their implementation in PD treatment. It was found that the number of drug repositioning studies for PD has increased recently. Repositioning of drugs in PD is taking off, and scientific communities are increasingly interested in communicating its results and finding effective treatment alternatives for PD. A better chance of success in PD drug discovery has been made possible due to AI/ML algorithm advancements. In addition to the experimentation stage of drug discovery, it is also important to leverage AI in the planning stage of clinical trials to make them more effective. New AI-based models or solutions that increase the success rate of drug development are greatly needed.

Neuroprotection effects of kynurenic acid-loaded micelles for the Parkinson's disease models

Anti-glutamatergic agents may have neuroprotective effects against excitotoxicity that is known to be involved in the pathogenesis of Parkinson's disease (PD). One of these agents is kynurenic acid (KYNA), a tryptophan metabolite, which is an endogenous N-methyl-D-aspartic acid (NMDA) receptor antagonist. However, its pharmacological properties of poor water solubility and limited blood-brain barrier (BBB) permeability rules out its systemic administration in disorders affecting the central nervous system. Our aim in the present study was to investigate the neuroprotective effects of KYNA-loaded micelles (KYNA-MICs) against PD in vitro and in vivo. Lipid-based micelles (MICs) in conjunction with KYNA drug delivery have the potential to enhance the penetration of therapeutic drugs into a diseased brain without BBB obstacles. KYNA-MICs were characterized by particle size (105.8 ± 12.1 nm), loading efficiency (78.3 ± 4.23%), and in vitro drug release (approximately 30% at 24 h). The in vitro experiments showed that KYNA-MICs effectively reduced 2-fold protein aggregation. The in vivo studies revealed that KYNA was successfully delivered by 5-fold increase in neurotoxin-induced PD brains. The results showed significant enhancement of KYNA delivery into brain. We also found that the KYNA-MICs exhibited several therapeutic effects. The KYNA-MICs reduced protein aggregation of an in vitro PD model, ameliorated motor functions, and prevented loss of the striatal neurons in a PD animal model. The beneficial effects of KYNA-MICs are probably explained by the anti-excitotoxic activity of the treatment's complex. As the KYNA-MICs did not induce any appreciable side-effects at the protective dose applied to a chronic PD mouse model, our results demonstrate that KYNA provides neuroprotection and attenuates PD pathology.

In Vitro differentiation of hair-follicle bulge stem cells into synaptophysin-expressing neurons: a potential new approach for neuro-regeneration

Stem cells, particularly bulge hair follicle stem cells (HFSCs), have recently attracted significant interest due to their potential for tissue repair and regeneration. These cells, marked by their expression of Nestin (a neural stem cell marker), suggest the possibility of neural differentiation into neurons. This study investigated the use of retinoic acid (RA) and epidermal growth factor (EGF) to induce HFSC transformation into mature neurons, identified by synaptophysin expression. Rat whisker follicles were cultured in a medium suitable for HFSC survival and proliferation. Immunostaining techniques were used to identify HFSCs and assess their differentiation into neural cells. The addition of RA and EGF to the culture medium aimed to induce this differentiation. Findings demonstrate that HFSCs expressed Nestin, indicating their pluripotent nature. Treatment with RA and EGF resulted in synaptophysin expression, a marker of mature neurons, which was absent in the control group. However, this treatment group also displayed a decrease in the expression of other neural markers (βIII tubulin and NeuN). This study suggests that a combination of RA and EGF can accelerate HFSC differentiation into synaptophysin-positive cells in vitro. This research paves the way for further exploration of its potential application in neuro-regeneration.

Synergistic effects of curcumin and stem cells on spinal cord injury: a comprehensive review

Spinal cord injury (SCI) is damage to the spinal cord that permanently or temporarily disrupts its function, causing considerable autonomic, sensory, and motor disorders, and involves between 10 and 83 cases per million yearly. Traumatic SCI happens following primary acute mechanical damage, leading to injury to the spinal cord tissue and worsening clinical outcomes. The present therapeutic strategies for this complex disease fundamentally rely on surgical approaches and conservative remedies. However, these modalities are not effective enough for neurological recovery. Therefore, it is necessary to discover more efficient methods to treat patients with SCI. Today, considerable attention has been drawn to bioactive compounds-based remedies and stem cell therapy for curing various ailments and disorders, such as neurological diseases. Some researchers have recommended that harnessing curcumin, a polyphenol obtained from turmeric, in combination with stem cells, like mesenchymal stem cells, neural stem cells, and ependymal stem cells, can remarkably improve neurological recovery-related parameters more effective than the treatment with these two methods separately in experimental models. Hereby, this literature review delves into the functionality of curcumin combined with stem cells in treating SCI with a focus on cellular and molecular mechanisms.

Unveiling the Potential of Extracellular Vesicles as Biomarkers and Therapeutic Nanotools for Gastrointestinal Diseases

Extracellular vesicles (EVs), acting as inherent nanocarriers adept at transporting a range of different biological molecules such as proteins, lipids, and genetic material, exhibit diverse functions within the gastroenteric tract. In states of normal health, they participate in the upkeep of systemic and organ homeostasis. Conversely, in pathological conditions, they significantly contribute to the pathogenesis of gastrointestinal diseases (GIDs). Isolating EVs from patients' biofluids facilitates the discovery of new biomarkers that have the potential to offer a rapid, cost-effective, and non-invasive method for diagnosing and prognosing specific GIDs. Furthermore, EVs demonstrate considerable therapeutic potential as naturally targeted physiological carriers for the intercellular delivery of therapeutic cargo molecules or as nanoscale tools engineered specifically to regulate physio-pathological conditions or disease progression. Their attributes including safety, high permeability, stability, biocompatibility, low immunogenicity, and homing/tropism capabilities contribute to their promising clinical therapeutic applications. This review will delve into various examples of EVs serving as biomarkers or nanocarriers for therapeutic cargo in the context of GIDs, highlighting their clinical potential for both functional and structural gastrointestinal conditions. The versatile and advantageous properties of EVs position them as promising candidates for innovative therapeutic strategies in advancing personalized medicine approaches tailored to the gastroenteric tract, addressing both functional and structural GIDs.

Research progress of neural stem cells as a source of dopaminergic neurons for cell therapy in Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disease, the most characteristic pathological feature is the progressive loss of dopaminergic (DA) neurons in the substantia nigra pars compactus (SNpc) of the mesencephalon, along with reduced dopamine content in the striatum. Researchers have been searching for drugs and therapies to treat PD in decades. However, no approach could stop the progression of the disease, and even some of them caused adverse clinical side effects. PD has a well-defined lesion. Therefore, it is considered to be one of the most curable central nervous system diseases by cell replacement treatment. Fetal ventral mesencephalic tissue transplantation has been used to treat patients with PD and obtained positive treatment results. However, ethical issues, such as limited donor tissue, and side effects including graft-induced dyskinesias, limit its clinical applications. Neural stem cell (NSC) transplantation is a viable therapy choice because it possesses multipotency, self-renewal ability, and differentiation into DA neurons, which may substitute for lost DA neurons and slow down the neurodegenerative process in PD. Studies that investigated the delivery of NSCs by using animal models of PD revealed survival, migration, and even amelioration of behavioral deficits. Here, the research progress of NSCs or NSC-derived DA neurons in treating PD was reviewed, and the practicability of present manufacturing processes for clinical testing was considered. This review is expected to offer ideas for practical strategies to solve the present technical and biological problems related to the clinical application of NSCs in PD.

Designing and Formulation of Nanocarriers for "Alzheimer's and Parkinson's" Early Detection and Therapy

The potential of nanotechnology in advancing the diagnosis and treatment of neurodegenerative diseases is explored in this comprehensive literature review. The findings of these studies suggest that nanotechnology has the capacity to improve existing therapeutic approaches, create novel and safe compounds, and develop more precise imaging techniques and diagnostic methods for neurodegenerative diseases. With the emergence of the nanomedicine era, a new and innovative approach of diagnosing and treating these conditions has been introduced. Notably, the researchers' development of a nanocarrier drug delivery tool demonstrates immense potential compared to conventional therapy, as it maximizes therapeutic efficacy and minimizes undesirable as side effects.

The gut microbiome meets nanomaterials: exposure and interplay with graphene nanoparticles

Graphene-based nanoparticles are widely applied in many technology and science sectors, raising concerns about potential health risks. Emerging evidence suggests that graphene-based nanomaterials may interact with microorganisms, both pathogens and commensal bacteria, that dwell in the gut. This review aims to demonstrate the current state of knowledge on the interplay between graphene nanomaterials and the gut microbiome. In this study, we briefly overview nanomaterials, their usage and the characteristics of graphene-based nanoparticles. We present and discuss experimental data from in vitro studies, screening tests on small animals and rodent experiments related to exposure and the effects of graphene nanoparticles on gut microbiota. With this in mind, we highlight the reported crosstalk between graphene nanostructures, the gut microbial community and the host immune system in order to shed light on the perspective to bear on the biological interactions. The studies show that graphene-based material exposure is dosage and time-dependent, and different derivatives present various effects on host bacteria cells. Moreover, the route of graphene exposure might influence a shift in the gut microbiota composition, including the alteration of functions and diversity and abundance of specific phyla or genera. However, the mechanism of graphene-based nanomaterials' influence on gut microbiota is poorly understood. Accordingly, this review emphasises the importance of studies needed to establish the most desirable synthesis methods, types of derivatives, properties, and safety aspects mainly related to the routes of exposure and dosages of graphene-based nanomaterials.

Mastering the craft: Creating an insightful and widely-cited literature review

The art of constructing an insightful literature review manuscript has witnessed an exemplar in the work of Oz et al (2023), wherein concept progression harmoniously merges with figures and tables. Reflecting on retrospective data science, it is evident that well-cited articles can wield a transformative influence on the Journal Citation Reports Impact Factor score, as exemplified by Robert Weinberg's landmark on cancer (Hanahan and Weinberg, 2011). Here, we aim to spotlight a commendable contribution by Tuba Oz, Ajeet Kaushik, and Małgorzata Kujawska in this issue while pivoting towards identifying the hallmarks of a subpar literature review-elements that hinder rather than promote advancement. The hurdles and roadblocks encountered within subpar literature reviews are multifold. Anticipation of emerging trends, identification of challenges, and exploration of solutions remain conspicuously absent. Original Contributions fail to surface amidst the vast sea of pre-existing literature, with noticeable gaps amplified by the lack of illustrative figures and tables. The manuscript, at times, assumes a skeletal form, reflecting an attempt to accommodate an excess of references, leading to convoluted sentences laden with citations. In contrast, a potent solution lies in adopting a comprehensive approach. A nuanced and critical evaluation of sources can culminate in a robust discussion, surpassing the mere summarization of conclusions drawn by others. This approach, often dismissed, holds the potential to elevate clarity, coherence, and logical flow, ultimately inviting engaged readership and coveted citations. The critical necessity of integrating visionary insights is underscored and achieved through a rigorous analysis of pivotal concepts and innovative ideas. Examples can be harnessed to elucidate the application of these solutions. We advocate a paradigm shift, urging literature review writers to embrace the readers' perspective. A literature review's purpose extends beyond providing a comprehensive panorama; it should illuminate avenues for concept development within a specific field of interest. By achieving this balance, literature reviews stand to captivate a devoted readership, paving the way for manuscripts that are both widely read and frequently cited. The pathway forward requires a fusion of astute analysis and visionary insights, shaping the future of literature review composition.

Advances in graphene-based nanoplatforms and their application in Parkinson's disease

Graphene and GBNs offer diverse PD management modalities by targeting neurodegeneration, exerting regenerative properties and their use as carriers, biosensors, and imaging agents.