Neuroprotective Effect of Nerve Growth Factor Loaded in Porous Silicon Nanostructures in an Alzheimer's Disease Model and Potential Delivery to the Brain

Multifunctional mesoporous silica nanoparticles for biomedical applications

Mesoporous silica nanoparticles (MSNs) are recognized as a prime example of nanotechnology applied in the biomedical field, due to their easily tunable structure and composition, diverse surface functionalization properties, and excellent biocompatibility. Over the past two decades, researchers have developed a wide variety of MSNs-based nanoplatforms through careful design and controlled preparation techniques, demonstrating their adaptability to various biomedical application scenarios. With the continuous breakthroughs of MSNs in the fields of biosensing, disease diagnosis and treatment, tissue engineering, etc., MSNs are gradually moving from basic research to clinical trials. In this review, we provide a detailed summary of MSNs in the biomedical field, beginning with a comprehensive overview of their development history. We then discuss the types of MSNs-based nanostructured architectures, as well as the classification of MSNs-based nanocomposites according to the elements existed in various inorganic functional components. Subsequently, we summarize the primary purposes of surface-functionalized modifications of MSNs. In the following, we discuss the biomedical applications of MSNs, and highlight the MSNs-based targeted therapeutic modalities currently developed. Given the importance of clinical translation, we also summarize the progress of MSNs in clinical trials. Finally, we take a perspective on the future direction and remaining challenges of MSNs in the biomedical field.

Mouse nerve growth factor suppresses neuronal apoptosis in valproic acid-induced autism spectrum disorder rats by regulating the phosphoinositide-3-kinase/serine/threonine kinase signaling pathway

BACKGROUND

Autism spectrum disorder (ASD) is a group of neurodevelopmental disorders characterized by deficits in social communication and restrictive behaviors. Mouse nerve growth factor (mNGF), a neurotrophic factor, is critical for neuronal growth and survival, and the mNGF treatment is considered a promising therapy for neurodegeneration. In light of this, we aimed to evaluate the effect of mNGF on neurological function in ASD.

METHODS

An ASD rat model was established by intraperitoneal injection of valproic acid (VPA). Social behavior, learning, and memory of the rats were measured. TdT-mediated dUTP Nick-end labeling and Nissl assays were performed to detect neuronal apoptosis and survival in the hippocampus and prefrontal cortex. Apoptosis-related proteins and oxidative stress markers were detected.

RESULTS

mNGF improved locomotor activity, exploratory behavior, social interaction, and spatial learning and memory in VPA-induced ASD rats. In the hippocampus and prefrontal cortex, mNGF suppressed neuronal apoptosis, increased the number of neurons, superoxide dismutase, and glutathione levels, and decreased reactive oxygen species, nitric oxide, TNF-α, and IL-1β levels compared with the VPA group. In addition, mNGF increased the levels of Bcl-2, p-phosphoinositide-3-kinase (PI3K), and p-serine/threonine kinase (Akt), and decreased the levels of Bax and cleaved caspase-3, while the PI3K inhibitor LY294002 reversed these effects.

CONCLUSION

These data suggest that mNGF suppressed neuronal apoptosis and ameliorated the abnormal behaviors in VPA-induced ASD rats, in part, by activating the PI3K/Akt signaling pathway.

The Molecular Effects of Environmental Enrichment on Alzheimer's Disease

Environmental enrichment (EE) is an environmental paradigm encompassing sensory, cognitive, and physical stimulation at a heightened level. Previous studies have reported the beneficial effects of EE in the brain, particularly in the hippocampus. EE improves cognitive function as well as ameliorates depressive and anxiety-like behaviors, making it a potentially effective neuroprotective strategy against neurodegenerative diseases such as Alzheimer's disease (AD). Here, we summarize the current evidence for EE as a neuroprotective strategy as well as the potential molecular pathways that can explain the effects of EE from a biochemical perspective using animal models. The effectiveness of EE in enhancing brain activity against neurodegeneration is explored with a view to differences present in early and late life EE exposure, with its potential application in human being discussed. We discuss EE as one of the non pharmacological approaches in preventing or delaying the onset of AD for future research.

Protein and Gene Delivery Systems for Neurodegenerative Disorders: Where Do We Stand Today?

It has been estimated that every year, millions of people are affected by neurodegenerative disorders, which complicate their lives and their caregivers' lives. To date, there has not been an approved pharmacological approach to provide the complete treatment of neurodegenerative disorders. The only available drugs may only relieve the symptoms or slow down the progression of the disease. The absence of any treatment is quite rational given that neurodegeneration occurs by the progressive loss of the function or structure of the nerve cells of the brain or the peripheral nervous system, which eventually leads to their death either by apoptosis or necrotic cell death. According to a recent study, even though adult brain cells are injured, they can revert to an embryonic state, which may help to restore their function. These interesting findings might open a new path for the development of more efficient therapeutic strategies to combat devastating neurodegenerative disorders. Gene and protein therapies have emerged as a rapidly growing field for various disorders, especially neurodegenerative diseases. Despite these promising therapies, the complete treatment of neurodegenerative disorders has not yet been achieved. Therefore, the aim of this review is to address the most up-to-date data for neurodegenerative diseases, but most importantly, to summarize the available delivery systems incorporating proteins, peptides, and genes that can potentially target such diseases and pass into the blood-brain barrier. The authors highlight the advancements, at present, on delivery based on the carrier, i.e., lipid, polymeric, and inorganic, as well as the recent studies on radiopharmaceutical theranostics.

Porous Silicon Nanoparticles Targeted to the Extracellular Matrix for Therapeutic Protein Delivery in Traumatic Brain Injury

Traumatic brain injury (TBI) is a major cause of disability and death among children and young adults in the United States, yet there are currently no treatments that improve the long-term brain health of patients. One promising therapeutic for TBI is brain-derived neurotrophic factor (BDNF), a protein that promotes neurogenesis and neuron survival. However, outstanding challenges to the systemic delivery of BDNF are its instability in blood, poor transport into the brain, and short half-life in circulation and brain tissue. Here, BDNF is encapsulated into an engineered, biodegradable porous silicon nanoparticle (pSiNP) in order to deliver bioactive BDNF to injured brain tissue after TBI. The pSiNP carrier is modified with the targeting ligand CAQK, a peptide that binds to extracellular matrix components upregulated after TBI. The protein cargo retains bioactivity after release from the pSiNP carrier, and systemic administration of the CAQK-modified pSiNPs results in effective delivery of the protein cargo to injured brain regions in a mouse model of TBI. When administered after injury, the CAQK-targeted pSiNP delivery system for BDNF reduces lesion volumes compared to free BDNF, supporting the hypothesis that pSiNPs mediate therapeutic protein delivery after systemic administration to improve outcomes in TBI.

Role of micronutrients in Alzheimer's disease: Review of available evidence

Alzheimer's disease (AD) is one of the most common age-related neurodegenerative disorders that have been studied for more than 100 years. Although an increased level of amyloid precursor protein is considered a key contributor to the development of AD, the exact pathogenic mechanism remains known. Multiple factors are related to AD, such as genetic factors, aging, lifestyle, and nutrients. Both epidemiological and clinical evidence has shown that the levels of micronutrients, such as copper, zinc, and iron, are closely related to the development of AD. In this review, we summarize the roles of eight micronutrients, including copper, zinc, iron, selenium, silicon, manganese, arsenic, and vitamin D in AD based on recently published studies.

Porous Silicon Nanocarriers with Stimulus-Cleavable Linkers for Effective Cancer Therapy

Porous silicon nanoparticles (pSiNPs) are widely utilized as drug carriers due to their excellent biocompatibility, large surface area, and versatile surface chemistry. However, the dispersion in pore size and biodegradability of pSiNPs arguably have hindered the application of pSiNPs for controlled drug release. Here, a step-changing solution to this problem is described involving the design, synthesis, and application of three different linker-drug conjugates comprising anticancer drug doxorubicin (DOX) and different stimulus-cleavable linkers (SCLs) including the photocleavable linker (ortho-nitrobenzyl), pH-cleavable linker (hydrazone), and enzyme-cleavable linker (β-glucuronide). These SCL-DOX conjugates are covalently attached to the surface of pSiNP via copper (I)-catalyzed alkyne-azide cycloaddition (CuAAC, i.e., click reaction) to afford pSiNP-SCL-DOXs. The mass loading of the covalent conjugation approach for pSiNP-SCL-DOX reaches over 250 µg of DOX per mg of pSiNPs, which is notably twice the mass loading achieved by noncovalent loading. Moreover, the covalent conjugation between SCL-DOX and pSiNPs endows the pSiNPs with excellent stability and highly controlled release behavior. When tested in both in vitro and in vivo tumor models, the pSiNP-SCL-DOXs induces excellent tumor growth inhibition.

Using a Hand-Held Gene Gun for Genetic Transformation of Tetrahymena thermophila

Biolistic bombardment is widely used as a means of delivering vector-coated microparticles into microorganisms, cultured cells, and tissues. The first particle delivery system contained a helium propulsion unit (the gun) mounted in a vacuum-controlled chamber. In contrast, the hand-held gene gun does not operate within a chamber. It is completely hand-held, easy, and efficient to use, and it requires minimal space on the laboratory bench top. This chapter describes protocols for using a hand-held gene gun to deliver transformation vectors for overexpression of genes or gene replacement into the macronucleus of Tetrahymena thermophila. The protocols provide helpful information for preparing Tetrahymena for biolistic bombardment, preparation of vector-coated microcarriers, and basic gene gun operating procedures.

A Review of Techniques for Biodelivery of Nerve Growth Factor (NGF) to the Brain in Relation to Alzheimer's Disease

Age-dependent progressive neurodegeneration and associated cognitive dysfunction represent a serious concern worldwide. Currently, dementia accounts for the fifth highest cause of death, among which Alzheimer's disease (AD) represents more than 60% of the cases. AD is associated with progressive cognitive dysfunction which affects daily life of the affected individual and associated family. The cognitive dysfunctions are at least partially due to the degeneration of a specific set of neurons (cholinergic neurons) whose cell bodies are situated in the basal forebrain region (basal forebrain cholinergic neurons, BFCNs) but innervate wide areas of the brain. It has been explicitly shown that the delivery of the neurotrophic protein nerve growth factor (NGF) can rescue BFCNs and restore cognitive dysfunction, making NGF interesting as a potential therapeutic substance for AD. Unfortunately, NGF cannot pass through the blood-brain barrier (BBB) and thus peripheral administration of NGF protein is not viable therapeutically. NGF must be delivered in a way which will allow its brain penetration and availability to the BFCNs to modulate BFCN activity and viability. Over the past few decades, various methodologies have been developed to deliver NGF to the brain tissue. In this chapter, NGF delivery methods are discussed in the context of AD.

Glioblastoma: What can we do for these patients today and what will we be able to do in the future?

Glioblastoma multiforme (GBM) is an extremely aggressive primary human brain tumor. The median survival of GBM patients is 15 months in case of completing the modern complex treatment protocol. Chemotherapy can help to extend the life expectancy of patients. GBM treatment resistance is associated with cancer stem cells (CSCs). The present paper analyses the main reasons for ineffectiveness of the existing GBM treatment methods and suggests treating CSCs as a complex phenomenon, resulting from the coordinated interaction of normal stem cells and cancer cells (CCs) in immunosuppressive microsurroundings. The GBM treatment strategy is suggested not for only suppressing strategically important signaling pathways in CCs, but also for regulating interaction between normal stem cells and cancer cells. The paper considers the issue of controlling penetrability of the blood-brain barrier that is one of the main challenges in neuro-oncology. Also, the paper suggests the ways of extending life expectancy of GBM patients today and prospects for the near future.

Advances in Laser Ablation Synthesized Silicon-Based Nanomaterials for the Prevention of Bacterial Infection

Nanomaterials have unique properties and characteristics derived from their shape and small size that are not present in bulk materials. If size and shape are decisive, the synthesis method used, which determines the above parameters, is equally important. Among the different nanomaterial’s synthesis methods, we can find chemical methods (microemulsion, sol-gel, hydrothermal treatments, etc.), physical methods (evaporation-condensation, laser treatment, etc.) and biosynthesis. Among all of them, the use of laser ablation that allows obtaining non-toxic nanomaterials (absence of foreign compounds) with a controlled 3D size, has emerged in recent years as a simple and versatile alternative for the synthesis of a wide variety of nanomaterials with numerous applications. This manuscript reviews the latest advances in the use of laser ablation for the synthesis of silicon-based nanomaterials, highlighting its usefulness in the prevention of bacterial infection.

Expression Profiling and Cell Type Classification Analysis in Periodontitis Reveal Dysregulation of Multiple lncRNAs in Plasma Cells

Objective

Periodontitis is a chronic inflammatory disease with a downregulated immune response. The mechanisms of the immune response, especially regarding immune-related long non-coding RNAs (lncRNAs), in periodontitis remain unclear. This study aimed to analyze the immune cell landscapes and immune-related transcriptome expression in periodontitis.

Materials and Methods

The periodontitis-related microarray data set GSE16134 was downloaded from the Gene Expression Omnibus database. Then, the proportions of the infiltrated immune cell subpopulations were evaluated by Cell-type Identification By Estimating Relative Subsets Of RNA Transcripts (CIBERSORT). Differentially expressed immune-related genes (DEMGs) and lncRNAs were analyzed by the “limma” package in R software. Co-expression of DEMGs and lncRNAs in immune cell subpopulations was evaluated. Gene set enrichment analysis (GSEA) was performed to identify alterations in immune function through potential pathways.

Results

Increased numbers of plasma cells were observed in periodontitis-affected tissues versus those of healthy tissues, while T cells were downregulated. A total of 51 DEMGs were identified, and 12 immune-related signaling pathways were enriched by GSEA, most of which were related to the stimulation and function of B cells and T cells. Only 3 differentially upregulated lncRNAs (FAM30A, GUSBP11, and LINC00525) were screened for the regulation of the immune response. Besides, the level of lncRNAs (FAM30A, GUSBP11, and LINC00525) expression were positively correlated with the fraction of plasma cells in periodontitis.

Conclusion

The discovery of differentially expressed immune-related transcriptomes in periodontitis lesions helps to explain the regulation of the immune mechanism in the development of periodontitis.

Neuroprotective effects of notoginsenoside R1 by upregulating Trx-1 on acrylamide-induced neurotoxicity in PC12

Acrylamide (ACR) is a water-soluble chemical that is commonly used in chemical and cosmetic manufacture. Many studies have been carried out to investigate the neurotoxicity mechanisms of ACR, resulting in oxidative stress and nerve damages. One of the commonly used traditional Chinese medicines is notoginsenoside R1 (NR1). However, its mitochondrial-mediated apoptotic effect caused in ACR-induced neurotoxicity has not been reported. Our results have shown that NR1 resisted the neurotoxicity induced by ACR by upregulating the levels of thioredoxin-1 (Trx-1) in Rat adrenal chromaffin cell tumor (PC12) cells. NR1 inhibited the increase in levels of Bax, caspase-9, and caspase-3, which was instigated by ACR. Moreover, NR1 inhibited the decrease in levels of B-cell lymphoma 2 and Trx-1 induced by ACR. The downregulation of Trx-1 aggravated the mitochondrial-mediated apoptosis and increased the expression of the above molecules, which was induced by ACR. In contrast, overexpression of Trx-1 attenuated the mitochondrial-mediated apoptosis and inhibited the expression of the mentioned molecules induced by ACR. Our results suggested that NR1 protected ACR-induced mitochondrial apoptosis by upregulating Trx-1.

β-Asarone Inhibits Amyloid-β by Promoting Autophagy in a Cell Model of Alzheimer's Disease

Alzheimer's disease (AD) is one of the most common types of dementia that causes memory, thinking, and behavior problems. The most important feature of AD is the gradual irreversible loss of cognitive ability through the formation of amyloid β (Aβ) plaques and neurofibrillary tangles composed of tau protein. The metabolism of Aβ and tau proteins is closely related to and is affected by autophagy. Current research speculates that autophagy dysfunction leads to an increase in harmful proteins in AD. β-Asarone is the main constituent of Acorus tatarinowii Schott and has important effects on the central nervous system. In this paper, we primarily explored the effects of β-asarone on the clearance of noxious proteins and the associated potential mechanisms via autophagy in a PC12 cell AD model. A CCK-8 assay and LDH experiments were used to assess cell viability/toxicity, and SPiDER-βGal was used to detect cellular senescence. The important proteins associated with the pathogenesis of AD including APP, PS1, Aβ, BACE1, and SYN1 were analyzed by immunofluorescence (IF) and Western blot analysis. Antimycin A (A3) and cyclosporine A (CSA) were selected as the activators and inhibitors of autophagy, respectively. LC3, BECN, P62, PINK1, and Parkin protein expression were also examined by IF and Western blot analysis. The data showed that β-asarone administration significantly dose-dependently increased cell proliferation and decreased cytotoxicity; moreover, β-asarone inhibited SA-βGal and improved cell senescence. The results further showed that, compared to the model, APP, PS1, Aβ, BACE1, and p62 were reduced, while SYN1, BECN1, and LC3 were increased after treatment with β-asarone. The results of Canonical Correlation Analysis (CCA) showed a highly significant relationship between the pathological factors of AD and the protein expression of autophagy. In conclusion, our study demonstrated that β-asarone can inhibit Aβ, and this effect may occur by promoting autophagy in a cell model of AD.

Alzheimer's Disease Pharmacotherapy in Relation to Cholinergic System Involvement

Alzheimer’s disease, a major and increasing global health challenge, is an irreversible, progressive form of dementia, associated with an ongoing decline of brain functioning. The etiology of this disease is not completely understood, and no safe and effective anti-Alzheimer’s disease drug to prevent, stop, or reverse its evolution is currently available. Current pharmacotherapy concentrated on drugs that aimed to improve the cerebral acetylcholine levels by facilitating cholinergic neurotransmission through inhibiting cholinesterase. These compounds, recognized as cholinesterase inhibitors, offer a viable target across key sign domains of Alzheimer’s disease, but have a modest influence on improving the progression of this condition. In this paper, we sought to highlight the current understanding of the cholinergic system involvement in Alzheimer’s disease progression in relation to the recent status of the available cholinesterase inhibitors as effective therapeutics.

Bone Morphogenic Protein 2-Loaded Porous Silicon Carriers for Osteoinductive Implants

Bone morphogenetic proteins (BMPs) are probably the most important growth factors in bone formation and healing. However, the utilization of BMPs in clinical applications is mainly limited due to the protein poor solubility at physiological pH, rapid clearance and relatively short biological half-life. Herein, we develop degradable porous silicon (PSi)-based carriers for sustained delivery of BMP-2. Two different loading approaches are examined, physical adsorption and covalent conjugation, and their effect on the protein loading and release rate is thoroughly studied. The entrapment of the protein within the PSi nanostructures preserved its bioactivity for inducing osteogenic differentiation of rabbit bone marrow mesenchymal stems cells (BM-MSCs). BM-MSCs cultured with the BMP-2 loaded PSi carriers exhibit a relatively high alkaline phosphatase (ALP) activity. We also demonstrate that exposure of MSCs to empty PSi (no protein) carriers generates some extent of differentiation due to the ability of the carrier's degradation products to induce osteoblast differentiation. Finally, we demonstrate the integration of these promising BMP-2 carriers within a 3D-printed patient-specific implant, constructed of poly(caprolactone) (PCL), as a potential bone graft for critical size bone defects.