Valproic acid-labeled chitosan nanoparticles promote recovery of neuronal injury after spinal cord injury

Exploring the Therapeutic Potential of N-Methyl-D-Aspartate Receptor Antagonists in Neuropathic Pain Management

Neuropathic pain (NeP) is a complex and debilitating condition that impacts millions of people globally. Although various treatment options exist, their effectiveness is often limited, and they can be accompanied by significant side effects. In recent years, there has been increasing interest in targeting the N-methyl-D-aspartate receptor (NMDAR) as a potential therapeutic approach to alleviate different types of neuropathic pain. This narrative review aims to provide a comprehensive examination of NMDAR antagonists, specifically ketamine, memantine, methadone, amantadine, carbamazepine, valproic acid, phenytoin, dextromethorphan, riluzole, and levorphanol, in the management of NeP. By analyzing and summarizing current preclinical and clinical studies, this review seeks to evaluate the efficacy of these pharmacologic agents in providing adequate relief for NeP.

A review: oligodendrocytes in neuronal axonal conduction and methods for enhancing their performance

OBJECTIVES

This review explores the vital role of oligodendrocytes in axon myelination and efficient neuronal transmission and the impact of dysfunction resulting from neurotransmitter deficiencies related disorders. Furthermore, the review also provides insight into the potential of bionanotechnology for addressing neurodegenerative diseases by targeting oligodendrocytes.

METHODS

A review of literature in the field was conducted using Google scholar. Systematic searches were performed to identify relevant studies and reviews addressing the role of oligodendrocytes in neural function, the influence of neurotransmitters on oligodendrocyte differentiation, and the potential of nanotechnology-based strategies for targeted therapy of oligodendrocytes.

RESULTS

This review indicates the mechanisms underlying oligodendrocyte differentiation and the influence of neurotransmitters on this process. The importance of action potentials and neurotransmission in neural function and the susceptibility of damaged nerve axons to ischemic or toxic damage is provided in detail. The potential of bionanotechnology for targeting neurodegenerative diseases using nanotechnology-based strategies, including polymeric, lipid-based, inorganic, organic, and biomimetic nanoparticles, suggests better management of neurodegenerative disorders.

CONCLUSION

While nanotechnology-based biomaterials show promise for targeted oligodendrocyte therapy in addressing neurodegenerative disorders linked to oligodendrocyte dysfunction, encapsulating neuroprotective agents within nanoparticles offers additional advantages. Nano-based delivery systems effectively protect drugs from degradation and prolong their therapeutic effects, holding promise in overcoming the blood-brain barrier by facilitating drug transport. However, a multifaceted approach is essential to enhance oligodendrocyte differentiation, promote myelin repair, and facilitate myelin dynamics with reduced toxicity. Further research is needed to elucidate the optimal therapeutic approaches and enhance patient outcomes.

Schiff-Base Cross-Linked Poly(2-oxazoline) Micelle Drug Conjugates Possess Antiferroptosis Activity in Numerous In Vitro Cell Models

A great deal of nanocarriers have been applied to induce ferroptosis in cancer research, yet there are limited examples of nanocarrier formulations to rescue ferroptosis, which can be applied to neurodegeneration, inflammation, liver damage, kidney disease, and more. Here, we present the synthesis, characterization, and in vitro evaluation of pH-responsive, core-cross-linked micelle (CCM) ferrostatin-1 (Fer-1) conjugates with amine, valproic acid, and biotin surface chemistries. Fer-1 release from stable and defined CCM Fer-1 conjugates was quantified, highlighting the sustained release for 24 h. CCM Fer-1 conjugates demonstrated excellent ferroptosis rescue by their antilipid peroxidation activity in a diverse set of cell lines in vitro. Additionally, CCMs showed tunable cell association in SH-SY5Y and translocation across an in vitro blood-brain barrier (BBB) model, highlighting potential brain disease applications. Overall, here, we present a polymeric Fer-1 delivery system to enhance Fer-1 action, which could help in improving Fer-1 action in the treatment of ferroptosis-related diseases.

Effects of Valproic Acid Therapy on Rats with Spinal Cord Injury: A Systematic Review and Meta-Analysis

OBJECTIVE

To systematically evaluate the efficacy of valproic acid (VPA) in rats with spinal cord injury (SCI) to reduce the risk of clinical conversion and provide a valuable reference for future animal and clinical studies.

METHODS

We searched scientific databases, including PubMed, Ovid-Embase, Web of Science, and Scopus databases. The relevant literature was searched from the establishment date of the database to June 28, 2023. The search results were screened, data were extracted, and the quality of the literature was evaluated independently by 2 reviewers.

RESULTS

Among 656 nonduplicated references, 14 articles were included for meta-analysis. The summary results showed that the overall Basso, Beattie and Bresnahan scores of the VPA intervention group were significantly higher than those in the control group at 1-6 weeks after VPA intervention. Subgroup analysis showed that the injury model, administration dose, rat strain, country of study, or follow-up duration had no significant effect on the efficacy of VPA on rats with SCI. In addition, mesh analysis showed that high doses of the VPA group had a better effect on SCI rats, compared with the low dose group and the medium dose group.

CONCLUSIONS

To date, this is the first systematic evaluation of the potential effects of VPA on motor recovery in rats with SCI. We concluded that VPA can promote motor recovery in rats with SCI, and higher doses of VPA seem to be more effective in rats with SCI. However, the limited quality and sample of included studies reduced the application of this meta-analysis. In the future, more high-quality, direct comparative studies are needed to explore this issue in depth.

Chitosan Nanoparticles Loaded with Quercetin and Valproic Acid: A Novel Approach for Enhancing Antioxidant Activity against Oxidative Stress in the SH-SY5Y Human Neuroblastoma Cell Line

BACKGROUND

Multiple drug-delivery systems obtained by loading nanoparticles (NPs) with different drugs that have different physicochemical properties present a promising strategy to achieve synergistic effects between drugs or overcome undesired effects. This study aims to develop a new NP by loading quercetin (Que) and valproic acid (VPA) into chitosan. In this context, our study investigated the antioxidant activities of chitosan NPs loaded with single and dual drugs containing Que against oxidative stress.

METHOD

The synthesis of chitosan NPs loaded with a single (Que or VPA) and dual drug (Que and VPA), the characterization of the NPs, the conducting of in vitro antioxidant activity studies, and the analysis of the cytotoxicity and antioxidant activity of the NPs in human neuroblastoma SH-SY5Y cell lines were performed.

RESULT

The NP applications that protected cell viability to the greatest extent against H2O2-induced cell damage were, in order, 96 µg/mL of Que-loaded chitosan NP (77.30%, 48 h), 2 µg/mL of VPA-loaded chitosan NP (70.06%, 24 h), 96 µg/mL of blank chitosan NP (68.31%, 48 h), and 2 µg/mL of Que- and VPA-loaded chitosan NP (66.03%, 24 h).

CONCLUSION

Our study establishes a successful paradigm for developing drug-loaded NPs with a uniform and homogeneous distribution of drugs into NPs. Chitosan NPs loaded with both single and dual drugs possessing antioxidant activity were successfully developed. The capability of chitosan NPs developed at the nanometer scale to sustain cell viability in SH-SY5Y cell lines implies the potential of intranasal administration of chitosan NPs for future studies, offering protective effects in central nervous system diseases.

Hydrogel and Nanomedicine-Based Multimodal Therapeutic Strategies for Spinal Cord Injury

Spinal cord injury (SCI) is a severe neurodegenerative disease caused by mechanical and biological factors, manifesting as a loss of motor and sensory functions. Inhibition of injury expansion and even reversal of injury in the acute damage stage of SCI are important strategies for treating this disease. Hydrogels and nanoparticle (NP)-based drugs are the most effective, widely studied, and clinically valuable therapeutic strategies in the field of repair and regeneration. Hydrogels are 3D flow structures that fill the pathological gaps in SCI and provide a microenvironment similar to that of the spinal cord extracellular matrix for nerve cell regeneration. NP-based drugs can easily penetrate the blood-spinal cord barrier, target SCI lesions, and are noninvasive. Hydrogels and NPs as drug carriers can be loaded with various drugs and biological therapeutic factors for slow release in SCI lesions. They help drugs function more efficiently by exerting anti-inflammatory, antioxidant, and nerve regeneration effects to promote the recovery of neurological function. In this review, the use of hydrogels and NPs as drug carriers and the role of both in the repair of SCI are discussed to provide a multimodal strategic reference for nerve repair and regeneration after SCI.

Nanomaterial payload delivery to central nervous system glia for neural protection and repair

Central nervous system (CNS) glia, including astrocytes, microglia, and oligodendrocytes, play prominent roles in traumatic injury and degenerative disorders. Due to their importance, active pharmaceutical ingredients (APIs) are being developed to modulate CNS glia in order to improve outcomes in traumatic injury and disease. While many of these APIs show promise in vitro, the majority of APIs that are systemically delivered show little penetration through the blood-brain barrier (BBB) or blood-spinal cord barrier (BSCB) and into the CNS, rendering them ineffective. Novel nanomaterials are being developed to deliver APIs into the CNS to modulate glial responses and improve outcomes in injury and disease. Nanomaterials are attractive options as therapies for central nervous system protection and repair in degenerative disorders and traumatic injury due to their intrinsic capabilities in API delivery. Nanomaterials can improve API accumulation in the CNS by increasing permeation through the BBB of systemically delivered APIs, extending the timeline of API release, and interacting biophysically with CNS cell populations due to their mechanical properties and nanoscale architectures. In this review, we present the recent advances in the fields of both locally implanted nanomaterials and systemically administered nanoparticles developed for the delivery of APIs to the CNS that modulate glial activity as a strategy to improve outcomes in traumatic injury and disease. We identify current research gaps and discuss potential developments in the field that will continue to translate the use of glia-targeting nanomaterials to the clinic.

Ferroptosis and mitochondrial dysfunction in acute central nervous system injury

Acute central nervous system injuries (ACNSI), encompassing traumatic brain injury (TBI), non-traumatic brain injury like stroke and encephalomeningitis, as well as spinal cord injuries, are linked to significant rates of disability and mortality globally. Nevertheless, effective and feasible treatment plans are still to be formulated. There are primary and secondary injuries occurred after ACNSI. Most ACNSIs exhibit comparable secondary injuries, which offer numerous potential therapeutic targets for enhancing clinical outcomes. Ferroptosis, a newly discovered form of cell death, is characterized as a lipid peroxidation process that is dependent on iron and oxidative conditions, which is also indispensable to mitochondria. Ferroptosis play a vital role in many neuropathological pathways, and ACNSIs may induce mitochondrial dysfunction, thereby indicating the essentiality of the mitochondrial connection to ferroptosis in ACNSIs. Nevertheless, there remains a lack of clarity regarding the involvement of mitochondria in the occurrence of ferroptosis as a secondary injuries of ACNSIs. In recent studies, anti-ferroptosis agents such as the ferroptosis inhibitor Ferrostain-1 and iron chelation therapy have shown potential in ameliorating the deleterious effects of ferroptosis in cases of traumatic ACNSI. The importance of this evidence is extremely significant in relation to the research and control of ACNSIs. Therefore, our review aims to provide researchers focusing on enhancing the therapeutic outcomes of ACNSIs with valuable insights by summarizing the physiopathological mechanisms of ACNSIs and exploring the correlation between ferroptosis, mitochondrial dysfunction, and ACNSIs.

Applications of chitosan-based biomaterials: From preparation to spinal cord injury neuroprosthetic treatment

Spinal cord injury (SCI)-related disabilities are a serious problem in the modern society. Further, the treatment of SCI is highly challenging and is urgently required in clinical practice. Research on nerve tissue engineering is an emerging approach for improving the treatment outcomes of SCI. Chitosan (CS) is a cationic polysaccharide derived from natural biomaterials. Chitosan has been found to exhibit excellent biological properties, such as nontoxicity, biocompatibility, biodegradation, and antibacterial activity. Recently, chitosan-based biomaterials have attracted significant attention for SCI repair in nerve tissue engineering applications. These studies revealed that chitosan-based biomaterials have various functions and mechanisms to promote SCI repair, such as promoting neural cell growth, guiding nerve tissue regeneration, delivering nerve growth factors, and as a vector for gene therapy. Chitosan-based biomaterials have proven to have excellent potential for the treatment of SCI. This review aims to introduce the recent advances in chitosan-based biomaterials for SCI treatment and to highlight the prospects for further application.

Current Status of Polysaccharides-Based Drug Delivery Systems for Nervous Tissue Injuries Repair

Neurological disorders affecting both CNS and PNS still represent one of the most critical and challenging pathologies, therefore many researchers have been focusing on this field in recent decades. Spinal cord injury (SCI) and peripheral nerve injury (PNI) are severely disabling diseases leading to dramatic and, in most cases, irreversible sensory, motor, and autonomic impairments. The challenging pathophysiologic consequences involved in SCI and PNI are demanding the development of more effective therapeutic strategies since, as yet, a therapeutic strategy that can effectively lead to a complete recovery from such pathologies is not available. Drug delivery systems (DDSs) based on polysaccharides have been receiving more and more attention for a wide range of applications, due to their outstanding physical-chemical properties. This review aims at providing an overview of the most studied polysaccharides used for the development of DDSs intended for the repair and regeneration of a damaged nervous system, with particular attention to spinal cord and peripheral nerve injury treatments. In particular, DDSs based on chitosan and their association with alginate, dextran, agarose, cellulose, and gellan were thoroughly revised.

Sustained release of valproic acid loaded on chitosan nanoparticles within hybrid of alginate/chitosan hydrogel with/without stem cells in regeneration of spinal cord injury

Hydrogels have been increasingly applied in tissue regeneration and drug delivery systems (DDS). In this study, the capacity of valproic acid (Val) encapsulated within hybrid of alginate (Alg)-chitosan (Cs) (Alg-Cs) hydrogel containing Cs nanoparticle (Npch) with/without human endometrial stem cells (hEnSC) was initially examined for regeneration of spinal cord injury (SCI). To evaluate the stability of the synthesized hydrogels zeta potential necessary measurements were made. Physicochemically, the developed hydrogels were evaluated using Fourier-transform infrared (FTIR) spectroscopy. The physical properties including degradation rate, swelling ability, and tunability of the synthesized hydrogels were studied. To evaluate the nerve regeneration ability of the synthesized hydrogels, 35 Sprague-Dawley rats were undergone SCI. The spinal cords were exposed using laminectomy in T9-T10 area and the hemi-section SCI model was made. The rats were then randomly divided into 5 groups (n = 7) including, Alg-Cs/Npch, Alg-Cs/Npch/hEnSCs, Alg-Cs/Npch/Val, and Alg-Cs/Npch/hEnScs/Val, and the control groups without any intervention. The FTIR spectra showed band frequencies and assignments of Val, Alg-Cs, and alginate. Nanoparticles were formulated with a mean diameter of 187 and 210 nm, for Val/Alg-Cs and Alg-Cs, respectively. The loading of Val into Alg-Cs led to its reduced size by about 40 nm. The Cs-Npch/Val hydrogels degraded faster than the Alg-Cs-/Npch/Val hydrogel specifically in extended time of incubation. A higher swelling capacity of Alg-Cs/Npch hydrogel, compared to Cs/Npch/Val and Alg-Cs/Npch/Val hydrogels, was found. The Cs-Npch/Val hydrogels degraded faster than Alg-Cs-/Npch/Val hydrogel. The Alg-Cs/Npch/hEnSCs/Val could regenerate the damaged nerve fibers and histologically prevent the SCI-induced vacuolization spaces. The prepared Alg-Cs/Npch/Val could be a suitable polymeric carrier for taurine drugs as bioactive substrate in nerve tissue engineering (NTE) and DDS.

Experimental treatments to attenuate blood spinal cord barrier rupture in rats with traumatic spinal cord injury: A meta-analysis and systematic review

Background: Traumatic spinal cord injury (t-SCI) is a severe injury that has a devastating impact on neurological function. Blood spinal cord barrier (BSCB) destruction following SCI aggravates the primary injury, resulting in a secondary injury. A series of experimental treatments have been proven to alleviate BSCB destruction after t-SCI.

Methods: From a screen of 1,189 papers, which were retrieved from Pubmed, Embase, and Web of science, we identified 28 papers which adhered to strict inclusion and exclusion criteria. Evans blue (EB) leakage on the first day post-SCI was selected as the primary result. Secondary outcomes included the expression of tight junction (TJ) proteins and adhesion junction (AJ) proteins in protein immunoblotting. In addition, we measured functional recovery using the Basso, Beattie, Besnahan (BBB) score and we analyzed the relevant mechanisms to explore the similarities between different studies.

Result: The forest plot of Evans blue leakage (EB leakage) reduction rate: the pooled effect size of the 28 studies was 0.54, 95% CI: 0.47–0.61, p < 0.01. This indicates that measures to mitigate BSCB damage significantly improved in reducing overall EB leakage. In addition TJ proteins (Occludin, Claudin-5, and ZO-1), AJ proteins (P120 and β-catenin) were significantly upregulated after treatment in all publications. Moreover, BBB scores were significantly improved. Comprehensive studies have shown that in t-SCI, inhibition of matrix metalloproteinases (MMPs) is the most commonly used mechanism to mitigate BSCB damage, followed by endoplasmic reticulum (ER) stress and the Akt pathway. In addition, we found that bone marrow mesenchymal stem cell-derived exosomes (BMSC-Exos), which inhibit the TIMP2/MMP signaling pathway, may be the most effective way to alleviate BSCB injury.

Conclusion: This study systematically analyzes the experimental treatments and their mechanisms for reducing BSCB injury in the early stage of t-SCI. BMSC-Exos, which inhibit MMP expression, are currently the most effective therapeutic modality for alleviating BSCB damage. In addition, the regulation of MMPs in particular as well as the Akt pathway and the ER stress pathway play important roles in alleviating BSCB injury.

Systematic Review Registration:https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022324794.

Combination Therapy Using Nanomaterials and Stem Cells to Treat Spinal Cord Injuries

As a part of the central nervous system, the spinal cord (SC) provides most of the communications between the brain and other parts of the body. Any damage to SC interrupts this communication, leading to serious problems, which may remain for the rest of their life. Due to its significant impact on patients' quality of life and its exorbitant medical costs, SC injury (SCI) is known as one of the most challengeable diseases in the world. Thus, it is critical to introduce highly translatable therapeutic platforms for SCI treatment. So far, different strategies have been introduced, among which utilizing various types of stem cells is one of the most interesting ones. The capability of stem cells to differentiate into several types of cell lines makes them promising candidates for the regeneration of injured tissues. One of the other interesting and novel strategies for SCI treatment is the application of nanomaterials, which could appear as a carrier for therapeutic agents or as a platform for culturing the cells. Combining these two approaches, stem cells and nanomaterials, could provide promising therapeutic strategies for SCI management. Accordingly, in this review we have summarized some of the recent advancements in which the applications of different types of stem cells and nanomaterials, alone and in combination forms, were evaluated for SCI treatment.

Applications of Chitosan in Surgical and Post-Surgical Materials

The continuous advances in surgical procedures require continuous research regarding materials with surgical applications. Biopolymers are widely studied since they usually provide a biocompatible, biodegradable, and non-toxic material. Among them, chitosan is a promising material for the development of formulations and devices with surgical applications due to its intrinsic bacteriostatic, fungistatic, hemostatic, and analgesic properties. A wide range of products has been manufactured with this polymer, including scaffolds, sponges, hydrogels, meshes, membranes, sutures, fibers, and nanoparticles. The growing interest of researchers in the use of chitosan-based materials for tissue regeneration is obvious due to extensive research in the application of chitosan for the regeneration of bone, nervous tissue, cartilage, and soft tissues. Chitosan can serve as a substance for the administration of cell-growth promoters, as well as a support for cellular growth. Another interesting application of chitosan is hemostasis control, with remarkable results in studies comparing the use of chitosan-based dressings with traditional cotton gauzes. In addition, chitosan-based or chitosan-coated surgical materials provide the formulation with antimicrobial activity that has been highly appreciated not only in dressings but also for surgical sutures or meshes.

Functional resveratrol-biodegradable manganese doped silica nanoparticles for the spinal cord injury treatment

Spinal cord injury (SCI) causes secondary injury, accompanied by pathological changes such as oxidative stress, inflammation and neuronal apoptosis. This leads to permanent disabilities such as paralysis and loss of movement or sensation. Due to the ineffectiveness of drugs passing through the blood spinal cord barrier (BSCB), there is currently no effective treatment for SCI. The aim of this experiment was to design plasma complex component functionalized manganese-doped silica nanoparticles (PMMSN) with a redox response as a targeted drug carrier for resveratrol (RES), which effectively transports insoluble drugs to cross the BSCB. RES was adsorbed into PMMSN with a particle size of approximately 110 ​nm by the adsorption method, and the drug loading reached 32.61 ​± ​3.38%. The RES release results for the loaded sample (PMMSN-RES) showed that the PMMSN-RES exhibited a release slowly effect. In vitro and vivo experiments demonstrated that PMMSN-RES decreased reactive oxygen species (ROS) and malondialdehyde (MDA), increased superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities, reduced the expression of inflammatory (TNF-α, IL-1β and IL-6) and apoptotic cytokines (cleaved caspase-3) in spinal cord tissue after SCI. In summary, PMMSN-RES may be a potential pharmaceutical preparation for the treatment of SCI by reducing neuronal apoptosis and inhibiting inflammation caused by reducing oxidative stress to promote the recovery of mouse motor function.

Nanoparticles in traumatic spinal cord injury: therapy and diagnosis

Nanotechnology has been previously employed for constructing drug delivery vehicles, biosensors, solar cells, lubricants and as antimicrobial agents. The advancement in synthesis procedure makes it possible to formulate nanoparticles (NPs) with precise control over physico-chemical and optical properties that are desired for specific clinical or biological applications. The surface modification technology has further added impetus to the specific applications of NPs by providing them with desirable characteristics. Hence, nanotechnology is of paramount importance in numerous biomedical and industrial applications due to their biocompatibility and stability even in harsh environments. Traumatic spinal cord injuries (TSCIs) are one of the major traumatic injuries that are commonly associated with severe consequences to the patient that may reach to the point of paralysis. Several processes occurring at a biochemical level which exacerbate the injury may be targeted using nanotechnology. This review discusses possible nanotechnology-based approaches for the diagnosis and therapy of TSCI, which have a bright future in clinical practice.

Trends of Chitosan Based Delivery Systems in Neuroregeneration and Functional Recovery in Spinal Cord Injuries

Spinal cord injury (SCI) is one of the most complicated nervous system injuries with challenging treatment and recovery. Regenerative biomaterials such as chitosan are being reported for their wide use in filling the cavities, deliver curative drugs, and also provide adsorption sites for transplanted stem cells. Biomaterial scaffolds utilizing chitosan have shown certain therapeutic effects on spinal cord injury repair with some limitations. Chitosan-based delivery in stem cell transplantation is another strategy that has shown decent success. Stem cells can be directed to differentiate into neurons or glia in vitro. Stem cell-based therapy, biopolymer chitosan delivery strategies, and scaffold-based therapeutic strategies have been advancing as a combinatorial approach for spinal cord injury repair. In this review, we summarize the recent progress in the treatment strategies of SCI due to the use of bioactivity of chitosan-based drug delivery systems. An emphasis on the role of chitosan in neural regeneration has also been highlighted.

Biocompatible valproic acid-coupled nanoparticles attenuate lipopolysaccharide-induced inflammation

Inflammatory diseases like sepsis are associated with dysregulated gene expression, often caused by an imbalance of epigenetic regulators, such as histone acetyltransferases (HATs) and histone deacetylases (HDACs), and consequently, altered epigenetic chromatin signatures or aberrant posttranslational modifications of signalling proteins and transcription factors. Thus, HDAC inhibitors (HDACi) are a promising class of anti-inflammatory drugs. Recently, an efficient drug delivery system carrying the class I/IIa selective HDACi valproic acid (VPA) was developed to circumvent common disadvantages of free drug administration, e.g. short half-life and side effects. The cellulose-based sulphated VPA-coupled (CV-S) nanoparticles (NPs) are rapidly taken up by cells, do not cause any toxic effects and are fully biocompatible. Importantly, VPA is intracellularly cleaved from the NPs and HDACi activity could be proven. Here, we demonstrate that CV-S NPs exhibit overall anti-inflammatory effects in primary human macrophages and are able to attenuate the lipopolysaccharide-induced inflammatory response. CV-S NPs show superior potential to free VPA to suppress the TLR-MyD88-NF-κB signalling axis, leading to decreased TNF-α expression and secretion.

Valproic Acid Labeled Chitosan Nanoparticles Promote the Proliferation and Differentiation of Neural Stem Cells After Spinal Cord Injury

Chitosan nanoparticles and valproic acid are demonstrated as the protective agents in the treatment of spinal cord injury (SCI). However, the effects of valproic acid-labeled chitosan nanoparticles (VA-CN) on endogenous spinal cord neural stem cells (NSCs) following SCI and the underlying mechanisms involved remain to be elucidated. In this study, the VA-CN was constructed and the effects of VA-CN on NSCs were assessed in a rat model of SCI. We found VA-CN treatment promoted recovery of the tissue and locomotive function following SCI. Moreover, administration of VA-CN significantly enhanced neural stem cell proliferation and the expression levels of neurotrophic factors following SCI. Furthermore, administration of VA-CN led to a decrease in the number of microglia following SCI. In addition, VA-CN treatment significantly increased the Tuj 1- positive cells in the spinal cord of the SCI rats, suggesting that VA-CN could enhance the differentiation of NSCs following SCI. In conclusion, these results demonstrated that VA-CN could improve the functional and histological recovery through promoting the proliferation and differentiation of NSCs following SCI, which would provide a newly potential therapeutic manner for the treatment of SCI.

Astrocyte responses to nanomaterials: Functional changes, pathological changes and potential applications

Astrocytes are responsible for regulating and optimizing the functional environment of neurons in the brain and can reduce the adverse impacts of external factors by protecting neurons. However, excessive astrocyte activation upon stimulation may alter their initial protective effect and actually lead to aggravation of injury. Similar to the dual effects of astrocytes in the response to injury within the central nervous system (CNS), nanomaterials (NMs) can have either toxic or beneficial effects on astrocytes, serving to promote injury or inhibit tumors. As the important physiological functions of astrocytes have been gradually revealed, the effects of NMs on astrocytes and the underlying mechanisms have become a new frontier in nanomedicine and neuroscience. This review summarizes the in vitro and in vivo findings regarding the effects of various NMs on astrocytes, focusing on functional alterations and pathological processes in astrocytes, as well as the possible underlying mechanisms. We also emphasize the importance of co-culture models in studying the interaction between NMs and cells of the CNS. Finally, we discuss NMs that have shown promise for application in astrocyte-related diseases and propose some challenges and suggestions for further investigations, with the aim of providing guidance for the widespread application of NMs in the CNS.

Rea regulates microglial polarization and attenuates neuronal apoptosis via inhibition of the NF-κB and MAPK signalings for spinal cord injury repair

Inflammation and neuronal apoptosis aggravate the secondary damage after spinal cord injury (SCI). Rehmannioside A (Rea) is a bioactive herbal extract isolated from Rehmanniae radix with low toxicity and neuroprotection effects. Rea treatment inhibited the release of pro-inflammatory mediators from microglial cells, and promoted M2 polarization in vitro, which in turn protected the co-cultured neurons from apoptosis via suppression of the NF-κB and MAPK signalling pathways. Furthermore, daily intraperitoneal injections of 80 mg/kg Rea into a rat model of SCI significantly improved the behavioural and histological indices, promoted M2 microglial polarization, alleviated neuronal apoptosis, and increased motor function recovery. Therefore, Rea is a promising therapeutic option for SCI and should be clinically explored.