Neuroprotective effects of carboxymethylated chitosan on hydrogen peroxide induced apoptosis in Schwann cells

Schwann cell-encapsulated chitosan-collagen hydrogel nerve conduit promotes peripheral nerve regeneration in rodent sciatic nerve defect models

Chitosan has various tissue regeneration effects. This study was designed to investigate the nerve regeneration effect of Schwann cell (SC)-encapsulated chitosan-collagen hydrogel nerve conduit (CCN) transplanted into a rat model of sciatic nerve defect. We prepared a CCN consisting of an outer layer of chitosan hydrogel and an inner layer of collagen hydrogel to encapsulate the intended cells. Rats with a 10-mm sciatic nerve defect were treated with SCs encapsulated in CCN (CCN+), CCN without SCs (CCN-), SC-encapsulated silicone tube (silicone+), and autologous nerve transplanting (auto). Behavioral and histological analyses indicated that motor functional recovery, axonal regrowth, and myelination of the CCN+ group were superior to those of the CCN- and silicone+ groups. Meanwhile, the CCN- and silicone+ groups showed no significant differences in the recovery of motor function and nerve histological restoration. In conclusion, SC-encapsulated CCN has a synergistic effect on peripheral nerve regeneration, especially axonal regrowth and remyelination of host SCs. In the early phase after transplantation, SC-encapsulated CCNs have a positive effect on recovery. Therefore, using SC-encapsulated CCNs may be a promising approach for massive peripheral nerve defects.

Traumatic neuromas of peripheral nerves: Diagnosis, management and future perspectives

Traumatic neuromas are infrequent in clinical settings but are prevalent following trauma or surgery. A traumatic neuroma is not a true malignancy, rather, it is a hyperplastic, reparative nerve reaction after injury and typically manifests as a nodular mass. The most common clinical manifestations include painful hypersensitivity and the presence of a trigger point that causes neuralgic pain, which could seriously decrease the living standards of patients. While various studies are conducted aiming to improve current diagnosis and management strategies via the induction of emerging imaging tools and surgical or conservative treatment. However, researchers and clinicians have yet to reach a consensus regarding traumatic neuromas. In this review, we aim to start with the possible underlying mechanisms of traumatic neuromas, elaborate on the diagnosis, treatment, and prevention schemes, and discuss the current experiment models and advances in research for the future management of traumatic neuromas.

Nerve Regeneration Effect of a Composite Bioactive Carboxymethyl Chitosan-Based Nerve Conduit with a Radial Texture

Chitosan (CTS) has been used as a nerve guidance conduit (NGC) material for bridging peripheral nerve defects due to its biocompatible, biodegradable, and non-toxic properties. However, the nerve regeneration effect of chitosan alone is restricted due to its inadequate biological activity. Herein, a composite, bioactive chitosan based nerve conduit, consisting of outer warp-knitted tube scaffold made from medical-grade chitosan fiber, and inner porous cross linked carboxymethyl chitosan (C-CM-CTS) sponge with radial texture was developed. The inner wall of the scaffold was coated with C-CM-CTS solution. CM-CTS provided favorable bioactivities in the composite chitosan-based nerve conduit. An in vitro study of CM-CTS revealed its satisfying biocompatibility with fibroblast and its inhibition of oxidative damage to Schwann cells. As the internal filler of the NGC, the lyophilized sponge of C-CM-CTS showed a longitudinal guidance effect for nerve reconstruction. After 10 mm defect in rat sciatic nerve was bridged with the composite bioactive chitosan-based nerve conduit, the nerve conduit was able to effectively promote axonal regeneration and played a positive role in inducing nerve regeneration and functional recovery. In addition to the functional advantages, which are equal to those of an autograft; the technology for the preparation of this conduit can be put into mass production.

Chitosan attenuated the neurotoxicity-induced titanium dioxide nanoparticles in brain of adult rats

In the current study, we aimed to investigate the neurotoxic effect of oral titanium dioxide nanoparticles (TiO₂ NPs) as well as the possible neuroprotective effect of carboxymethyl chitosan in adult rats for 14 days. The results revealed that TiO₂ NPs inhibited the activity of the acetylcholine esterase enzyme and the levels of serotonin, dopamine, and norepinephrine neurotransmitters. Additionally, it induced neuro-oxidative stress and neuroinflammation via an elevation in MDA levels and IL-6, while GSH concentration, as well as GPx and GST activities, were decreased. TiO₂ NPs induced neuronal apoptosis through upregulation of the expression of caspase-8 and -9 that was further confirmed by increasing caspases-3 and -8 proteins in the hippocampus, cerebral cortex, and cerebellum. The expression of the immediate-early gene BDNF was increased in response to TiO₂ NPs, while that of Arc was reduced. Chitosan significantly attenuated the TiO₂ NPs-induced neurotoxicity regarding AChE, serotonin, MDA, GSH, GPx, GST, IL-6, caspases-8, -9, and -3. Chitosan inhibited the expression of Arc and alleviated the effect of TiO₂ NPs on BDNF expression. Collectively, TiO₂ NPs induced neurotoxicity via their action on vital neuronal biomarkers that might in turn cause brain dysfunction. Despite the neuroprotection of chitosan, its inhibitory effect on Arc expression should be considered.

Carboxymethylated chitosan alleviated oxidative stress injury in retinal ganglion cells via IncRNA-THOR/IGF2BP1 axis

BACKGROUND

Glaucoma is an advanced nerve disorder described by the deterioration of axon and RGCs. CMCS has been previously used as an anti-apoptotic and anti-oxidant agent.

OBJECTIVE

The current study aimed to explore the protective impact of CMCS against H2O2-induced injury in glaucoma in vitro.

METHODS

The relative expression of lncRNA THOR and the protein expression of IGF2BP1 in H2O2-induced RGC-5 cells were detected by RT-PCR and western blot methods respectively. The cell viability was measured using MTT assay while apoptosis rate was measured by flow cytometry. Moreover, ROS level was measured using ROS assay kit. Furthermore, the relations between THOR and IGF2BP1 were determined by using RNA pull-down.

RESULTS

The expression of THOR was reduced in H2O2-induced RGCs. Also, RGCs viability was inhibited while the level of ROS and cell apoptosis were enhanced. CMCS treatment considerably enhanced the expression of THOR and IGF2BP1 protein and cell viability but reduced ROS level and cell apoptosis. Moreover, IGF2BP1 protein was positively regulated by lncRNA THOR. CMCS protected the RGCs from oxidative stress via regulating lncRNA THOR/IGF2BP1.

CONCLUSION

CMCS enhanced the cell viability and reduced the cell apoptosis and ROS level and protected RGCs from oxidative stress via lncRNATHOR/IGF2BP1 pathway, potentially suggesting a new therapeutic strategy for the treatment of glaucoma.

Chitosan nanoparticles as a promising candidate for liver injury induced by 2-nitropropane: Implications of P53, iNOS, VEGF, PCNA, and CD68 pathways

The current article was designed to assess the role of chitosan nanoparticles (CNPs) in the management of hepatic injury induced by the hepatocarcinogen 2-nitropropane (2-NP). Rats were divided into three groups. The first group served as a control, the second group was injected with 2-NP, while the third group was treated with CNPs 1 h before 2-NP injection every other day for 4 weeks. The 2-NP injection upregulated serum AST and ALT activities, as well as hepatic TNF- α, IL-6, and MDA levels and the expression of vascular endothelial growth factor (VEGF) and caspase-3, whereas GSH contents and SOD activity were decreased. Immunohistochemistry investigations revealed that the hepatic protein expression of collagen I, inducible nitric oxide synthetase, proliferating cell nuclear antigen, cluster of differentiation, and p53 were upregulated. hematoxylin and eosin (H&E) and Masson's trichrome stains supported the previous parameters, and CNPs ameliorated most of the previous biochemical parameters. CNPs achieved promising results in the limitation of 2-NP hepatotoxicity.

Benefits under the Sea: The Role of Marine Compounds in Neurodegenerative Disorders

Marine habitats offer a rich reservoir of new bioactive compounds with great pharmaceutical potential; the variety of these molecules is unique, and its production is favored by the chemical and physical conditions of the sea. It is known that marine organisms can synthesize bioactive molecules to survive from atypical environmental conditions, such as oxidative stress, photodynamic damage, and extreme temperature. Recent evidence proposed a beneficial role of these compounds for human health. In particular, xanthines, bryostatin, and 11-dehydrosinulariolide displayed encouraging neuroprotective effects in neurodegenerative disorders. This review will focus on the most promising marine drugs' neuroprotective potential for neurodegenerative disorders, such as Parkinson's and Alzheimer's diseases. We will describe these marine compounds' potential as adjuvant therapies for neurodegenerative diseases, based on their antioxidant, anti-inflammatory, and anti-apoptotic properties.

Development prospects of curable osteoplastic materials in dentistry and maxillofacial surgery

The article presents classification of the thermosetting materials for bone augmentation. The physical, mechanical, biological, and clinical properties of such materials are reviewed. There are two main types of curable osteoplastic materials: bone cements and hydrogels. Compared to hydrogels, bone cements have high strength features, but their biological properties are not ideal and must be improved. Hydrogels are biocompatible and closely mimic the extracellular matrix. They can be used as cytocompatible scaffolds for tissue engineering, as can protein- and nucleic acid-activated structures. Hydrogels may be impregnated with osteoinductors such as proteins and genetic vectors without conformational changes. However, the mechanical properties of hydrogels limit their use for load-bearing bone defects. Thus, improving the strength properties of hydrogels is one of the possible strategies to achieve the basis for an ideal osteoplastic material.

Mitochondrial dependent pathway is involved in the protective effects of carboxymethylated chitosan on nitric oxide-induced apoptosis in chondrocytes

Background

Chondrocyte apoptosis activated by the mitochondrial dependent pathway serves a crucial role in cartilage degeneration of osteoarthritis (OA). In the present study, the protective effects of CMCS against sodium nitroprusside (SNP)-induced chondrocyte apoptosis were evaluated and the underlying molecular mechanisms were elucidated.

Methods

Chondrocytes were isolated from articular cartilage of SD rats and identified by type II collagen immunohistochemistry. The chondrocytes stimulated with or without SNP to induce apoptosis, were treated by CMCS for various concentrations. The cell viability were determined by MTT and LDH assays. Cell apoptotic ratio was determined by Annexin V-FITC/PI staining. Mitochondrial membrane potential (ΔΨm) was detected by using Rhodamine123 (Rho123) staining. To understand the mechanism, the mRNA expression levels of Bcl-2, Bax, cytochrome c (Cyt c) and cleaved caspase-3 were detected by real-time PCR and western blot analysis, respectively.

Results

It was shown using the MTT and LDH assays that CMCS protected the viability of chondrocyte against SNP damage. Annexin V-FITC/PI and Rho123 staining showed that CMCS not only inhibited the cell apoptosis but also restored the reduction of the ΔΨm in chondrocytes. In SNP-induced chondrocytes, CMCS down-regulated the expression of Bax, Cyt c and cleaved caspase-3 but upregulated the expression of Bcl-2, as shown by real-time PCR and western blot.

Conclusions

Taken together, these results indicated that CMCS has the protective effect on chondrocytes against SNP-induced apoptosis, at least partly, via inhibiting the mitochondrial dependent apoptotic pathway. Thus, CMCS may be potentially used as a biological agent for prevention and treatment of OA.

Synthesis, Bioapplications, and Toxicity Evaluation of Chitosan-Based Nanoparticles

The development of advanced nanomaterials and technologies is essential in biomedical engineering to improve the quality of life. Chitosan-based nanomaterials are on the forefront and attract wide interest due to their versatile physicochemical characteristics such as biodegradability, biocompatibility, and non-toxicity, which play a promising role in biological applications. Chitosan and its derivatives are employed in several applications including pharmaceuticals and biomedical engineering. This article presents a comprehensive overview of recent advances in chitosan derivatives and nanoparticle synthesis, as well as emerging applications in medicine, tissue engineering, drug delivery, gene therapy, and cancer therapy. In addition to the applications, we critically review the main concerns and mitigation strategies related to chitosan bactericidal properties, toxicity/safety using tissue cultures and animal models, and also their potential environmental impact. At the end of this review, we also provide some of future directions and conclusions that are important for expanding the field of biomedical applications of the chitosan nanoparticles.

Relevance and Recent Developments of Chitosan in Peripheral Nerve Surgery

Developments in tissue engineering yield biomaterials with different supporting strategies to promote nerve regeneration. One promising material is the naturally occurring chitin derivate chitosan. Chitosan has become increasingly important in various tissue engineering approaches for peripheral nerve reconstruction, as it has demonstrated its potential to interact with regeneration associated cells and the neural microenvironment, leading to improved axonal regeneration and less neuroma formation. Moreover, the physiological properties of its polysaccharide structure provide safe biodegradation behavior in the absence of negative side effects or toxic metabolites. Beneficial interactions with Schwann cells (SC), inducing differentiation of mesenchymal stromal cells to SC-like cells or creating supportive conditions during axonal recovery are only a small part of the effects of chitosan. As a result, an extensive body of literature addresses a variety of experimental strategies for the different types of nerve lesions. The different concepts include chitosan nanofibers, hydrogels, hollow nerve tubes, nerve conduits with an inner chitosan layer as well as hybrid architectures containing collagen or polyglycolic acid nerve conduits. Furthermore, various cell seeding concepts have been introduced in the preclinical setting. First translational concepts with hollow tubes following nerve surgery already transferred the promising experimental approach into clinical practice. However, conclusive analyses of the available data and the proposed impact on the recovery process following nerve surgery are currently lacking. This review aims to give an overview on the physiologic properties of chitosan, to evaluate its effect on peripheral nerve regeneration and discuss the future translation into clinical practice.

Protection of carboxymethylated chitosan on chondrocytes from nitric oxide-induced apoptosis by regulating phosphatidylinositol 3-kinase/Akt signaling pathway

Chondrocyte apoptosis is the most important element of development and progression of osteoarthritis (OA). Nitric oxide (NO) was used as the agent to induce chondrocyte apoptosis. Carboxymethylated chitosan (CMCS) has anti-apoptosis effect on many cell types in vitro. This study was designed to investigate the protective effect of CMCS on NO-induced chondrocyte apoptosis and the probable molecular mechanisms. The newborn Sprague-Dawley (SD) rats were used in this study for isolation of chondrocytes. The cell viability was determined by cell counting kit (CCK-8), cell apoptosis was detected by Annexin-V/PI double staining assay kit. The levels of phosphorylated-PI3K (p-PI3K), phosphorylated-Akt (p-Akt), Bcl-2 and Bax were determined by Western blot analysis. The caspase-3 activity was determined by a quantitative colorimetric assay. Results showed that pretreatment with CMCS could inhibit the apoptosis induced by NO. CMCS could decrease the activity of NO and decrease the expression of Bcl-2, p-PI3K and p-Akt, increase the expression of Bax, cytochrome c and caspase-3. CMCS also could reverse the effect of NO that prompted matrix metalloproteinase-13 (MMP-13) and inhibited tissue inhibitor of metalloproteinase-1 (TIMP-1) activity. All the present results indicated that CMCS can protect NO induced chondrocytes apoptosis by activate PI3K/Akt signaling pathway.

Schwann cell proliferation and differentiation that is induced by ferulic acid through MEK1/ERK1/2 signalling promotes peripheral nerve remyelination following crush injury in rats

Schwann cell proliferation and differentiation is critical for the remyelination of injured peripheral nerves. Ferulic acid (FA) is a widely used antioxidant agent with neuroprotective properties. However, the potentially beneficial effects of FA on Schwann cells are unknown. Therefore, the present study was designed to examine the effects of FA on Schwann cell proliferation and differentiation. By using the cultured primary Schwann cells and proliferation assay, the results identified that FA was capable of increasing Schwann cell proliferation and expression of myelin-associated glycoprotein (MAG) and myelin basic protein (MBP) in vitro. It was also observed that the beneficial effect of FA treatment on Schwann cells was mainly dependent on the activation of MEK1/ERK1/2 signalling. Furthermore, FA was intraperitoneally administered to rats with sciatic nerve crush injury, and the results revealed an increase in Schwann cell proliferation and differentiation, while the MAG and MBP expression levels in sciatic nerves were markedly upregulated following FA administration. In conclusion, the current results demonstrate that Schwann cell proliferation and differentiation is induced by FA through MEK1/ERK1/2 signalling and that FA may accelerate injured peripheral nerve remyelination.

Protective effect of reduced glutathione C60 derivative against hydrogen peroxide-induced apoptosis in HEK 293T cells

Hydrogen peroxide (H2O2) and free radicals cause oxidative stress, which induces cellular injuries, metabolic dysfunction, and even cell death in various clinical abnormalities. Fullerene (C60) is critical for scavenging oxygen free radicals originated from cell metabolism, and reduced glutathione (GSH) is another important endogenous antioxidant. In this study, a novel water-soluble reduced glutathione fullerene derivative (C60-GSH) was successfully synthesized, and its beneficial roles in protecting against H2O2-induced oxidative stress and apoptosis in cultured HEK 293T cells were investigated. Fourier Transform infrared spectroscopy and (1)H nuclear magnetic resonance were used to confirm the chemical structure of C60-GSH. Our results demonstrated that C60-GSH prevented the reactive oxygen species (ROS)-mediated cell damage. Additionally, C60-GSH pretreatment significantly attenuated H2O2-induced superoxide dismutase (SOD) consumption and malondialdehyde (MDA) elevation. Furthermore, C60-GSH inhibited intracellular calcium mobilization, and subsequent cell apoptosis via bcl-2/bax-caspase-3 signaling pathway induced by H2O2 stimulation in HEK 293T cells. Importantly, these protective effects of C60-GSH were superior to those of GSH. In conclusion, these results suggested that C60-GSH has potential to protect against H2O2-induced cell apoptosis by scavenging free radicals and maintaining intracellular calcium homeostasis without evident toxicity.

Abalone Protein Hydrolysates: Preparation, Angiotensin I Converting Enzyme Inhibition and Cellular Antioxidant Activity

Abalone protein was hydrolyzed by enzymatic hydrolysis and the optimal enzyme/substrate (E/S) ratios were determined. Abalone protein hydrolysates (APH) produced by Protamex at E/S ratio of 1:100 showed angiotensin I converting enzyme inhibitory activity with IC50 of 0.46 mg/mL, and APH obtained by Flavourzyme at E/S ratio of 1:100 possessed the oxygen radical absorbance capacity value of 457.6 μM trolox equivalent/mg sample. Flavourzyme abalone protein hydrolysates (FAPH) also exhibited H2O2 scavenging activity with IC50 of 0.48 mg/mL and Fe(2+) chelating activity with IC50 of 2.26 mg/mL as well as high reducing power. FAPH significantly (P<0.05) protected H2O2-induced hepatic cell damage in cultured hepatocytes, and the cell viability was restored to 90.27% in the presence of FAPH. FAPH exhibited 46.20% intracellular ROS scavenging activity and 57.89% lipid peroxidation inhibition activity in cultured hepatocytes. Overall, APH may be useful as an ingredient for functional foods.

Improvement in antiproliferative activity of Angelica gigas Nakai by solid dispersion formation via hot-melt extrusion and induction of cell cycle arrest and apoptosis in HeLa cells

Angelica gigas Nakai (AGN) is one of the most popular herbal medicines and widely used as a functional food product. In this study, AGN was firstly processed by a low-temperature turbo mill and a hot melting extruder to reduce particle size and form solid dispersion (SD). Anticancer activity against HeLa cells was then examined. AGN-SD based on Soluplus was formed via hot-melt extrusion (HME) and showed the strongest cytotoxic effect on HeLa cells. In addition, the possible mechanism of cell death induced by AGN-SD on HeLa cells was also investigated. AGN-SD decreased cell viability, induced apoptosis, increased the production of reactive oxygen species, regulated the expression of Bcl-2 and Bax, and induced G2/M phase arrest in HeLa cells. This study suggested that AGN-SD based on Soluplus and the method to improve antiproliferative effect by SD formation via HME may be suitable for application in the pharmaceutical industry.

Chitosan: An Update on Potential Biomedical and Pharmaceutical Applications

Chitosan is a natural polycationic linear polysaccharide derived from chitin. The low solubility of chitosan in neutral and alkaline solution limits its application. Nevertheless, chemical modification into composites or hydrogels brings to it new functional properties for different applications. Chitosans are recognized as versatile biomaterials because of their non-toxicity, low allergenicity, biocompatibility and biodegradability. This review presents the recent research, trends and prospects in chitosan. Some special pharmaceutical and biomedical applications are also highlighted.