Neurotherapeutic applications of nanomedicine for treating Alzheimer's disease

Melatonin Inhibits Hypoxia-Induced Alzheimer's Disease Pathogenesis by Regulating the Amyloidogenic Pathway in Human Neuroblastoma Cells

Stroke and Alzheimer's disease (AD) are prevalent age-related diseases; however, the relationship between these two diseases remains unclear. In this study, we aimed to investigate the ability of melatonin, a hormone produced by the pineal gland, to alleviate the effects of ischemic stroke leading to AD by observing the pathogenesis of AD hallmarks. We utilized SH-SY5Y cells under the conditions of oxygen-glucose deprivation (OGD) and oxygen-glucose deprivation and reoxygenation (OGD/R) to establish ischemic stroke conditions. We detected that hypoxia-inducible factor-1α (HIF-1α), an indicator of ischemic stroke, was highly upregulated at both the protein and mRNA levels under OGD conditions. Melatonin significantly downregulated both HIF-1α mRNA and protein expression under OGD/R conditions. We detected the upregulation of β-site APP-cleaving enzyme 1 (BACE1) mRNA and protein expression under both OGD and OGD/R conditions, while 10 µM of melatonin attenuated these effects and inhibited beta amyloid (Aβ) production. Furthermore, we demonstrated that OGD/R conditions were able to activate the BACE1 promoter, while melatonin inhibited this effect. The present results indicate that melatonin has a significant impact on preventing the aberrant development of ischemic stroke, which can lead to the development of AD, providing new insight into the prevention of AD and potential stroke treatments.

Alzheimer's disease current therapies, novel drug delivery systems and future directions for better disease management

Alzheimer's disease (AD), is a neurodegenerative disorder that escalates with time, exerting a significant impact on physical and mental health and leading to death. The prevalence of AD is progressively rising along with its associated economic burden and necessitates effective therapeutic approaches in the near future. This review paper aims to offer an insightful overview of disease pathogenesis, current FDA-approved drugs, and drugs in different clinical phases. It also explores innovative formulations and drug delivery strategies, focusing on nanocarriers and long-acting medications (LAMs) to enhance treatment efficacy and patient adherence. The review also emphasizes preclinical evidence related to nanocarriers and their potential to improve drug bioavailability, pharmacokinetics, and pharmacodynamics parameters, while also highlighting their ability to minimize systemic side effects. By providing a comprehensive analysis, this review furnishes valuable insights into different pathophysiological mechanisms for future drug development. It aims to inform the development of treatment strategies and innovative formulation approaches for delivering existing molecules in Alzheimer's disease, ultimately striving to improve patient compliance.

Epigenetic Alterations in Alzheimer's Disease: Impact on Insulin Signaling and Advanced Drug Delivery Systems

Alzheimer's disease (AD) is a neurodegenerative condition that predominantly affects the hippocampus and the entorhinal complex, leading to memory lapse and cognitive impairment. This can have a negative impact on an individual's behavior, speech, and ability to navigate their surroundings. AD is one of the principal causes of dementia. One of the most accepted theories in AD, the amyloid β (Aβ) hypothesis, assumes that the buildup of the peptide Aβ is the root cause of AD. Impaired insulin signaling in the periphery and central nervous system has been considered to have an effect on the pathophysiology of AD. Further, researchers have shifted their focus to epigenetic mechanisms that are responsible for dysregulating major biochemical pathways and intracellular signaling processes responsible for directly or indirectly causing AD. The prime epigenetic mechanisms encompass DNA methylation, histone modifications, and non-coding RNA, and are majorly responsible for impairing insulin signaling both centrally and peripherally, thus leading to AD. In this review, we provide insights into the major epigenetic mechanisms involved in causing AD, such as DNA methylation and histone deacetylation. We decipher how the mechanisms alter peripheral insulin signaling and brain insulin signaling, leading to AD pathophysiology. In addition, this review also discusses the need for newer drug delivery systems for the targeted delivery of epigenetic drugs and explores targeted drug delivery systems such as nanoparticles, vesicular systems, networks, and other nano formulations in AD. Further, this review also sheds light on the future approaches used for epigenetic drug delivery.

Use of Albumin for Drug Delivery as a Diagnostic and Therapeutic Tool

Drug delivery is an important topic that has attracted the attention of researchers in recent years. Albumin nanoparticles play a significant role in drug delivery as a carrier due to their unique characteristics. Albumin is non-toxic, biocompatible, and biodegradable. Its structure is such that it can interact with different drugs, which makes the treatment of the disease faster and also reduces the side effects of the drug. Albumin nanoparticles can be used in the diagnosis and treatment of many diseases, including cancer, diabetes, Alzheimer's, etc. These nanoparticles can connect to some compounds, such as metal nanoparticles, antibodies, folate, etc. and create a powerful nanostructure for drug delivery. In this paper, we aim to investigate albumin nanoparticles in carrier format for drug delivery application. In the beginning, different types of albumin and their preparation methods were discussed, and then albumin nanoparticles were discussed in detail in diagnosing and treating various diseases.

Nanoparticles loaded with natural medicines for the treatment of Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease that disrupts cognitive function and severely affects the quality of life. Existing drugs only improve cognitive function and provide temporary relief of symptoms but do not stop or delay disease progression. Recently, natural medicines, especially Chinese herbal medicines, have gained attention in the treatment of AD due to their antioxidant, anti-inflammatory, and neuroprotective effects. However, conventional oral dosage forms lack brain specificity and have side effects that lead to poor patient compliance. Utilizing nanomedicine is a promising approach to improve brain specificity, bioavailability, and patient compliance. This review evaluates recent advances in the treatment of AD with nanoparticles containing various natural medicines. This review highlights that nanoparticles containing natural medicines are a promising strategy for the treatment of AD. It is believed that this technology can be translated into the clinic, thereby providing opportunities for AD patients to participate in social activities.

The behavioral, pathological and therapeutic features of the triple transgenic Alzheimer's disease (3 × Tg-AD) mouse model strain

As a classic animal model of Alzheimer's disease (AD), the 3 × Tg-AD mouse not only recapitulates most of anatomical hallmarks observed in AD pathology but also displays cognitive alterations in memory and learning tasks. The 3 × Tg-AD can better show the two characteristics of AD, amyloid β (Aβ) and neurofibrillary tangles (NFT). Therefore, 3 × Tg-AD strain is widely used in AD pathogenesis research and new drug development of AD. In this paper, the construction methods, pathological changes, and treatment characteristics of 3 × Tg-AD mouse models commonly used in AD research are summarized and commented, hoping to provide reference for researchers to choose and establish experimental patterns.

Advancements in the Application of Nanomedicine in Alzheimer's Disease: A Therapeutic Perspective

Alzheimer's disease (AD) is a progressive neurodegenerative disease that affects most people worldwide. AD is a complex central nervous system disorder. Several drugs have been designed to cure AD, but with low success rates. Because the blood-brain and blood-cerebrospinal fluid barriers are two barriers that protect the central nervous system, their presence has severely restricted the efficacy of many treatments that have been studied for AD diagnosis and/or therapy. The use of nanoparticles for the diagnosis and treatment of AD is the focus of an established and rapidly developing field of nanomedicine. Recent developments in nanomedicine have made it possible to effectively transport drugs to the brain. However, numerous obstacles remain to the successful use of nanomedicines in clinical settings for AD treatment. Furthermore, given the rapid advancement in nanomedicine therapeutics, better outcomes for patients with AD can be anticipated. This article provides an overview of recent developments in nanomedicine using different types of nanoparticles for the management and treatment of AD.

Phytochemicals: A Promising Alternative for the Prevention of Alzheimer's Disease

Alzheimer's disease (AD) is a neurological condition that worsens with ageing and affects memory and cognitive function. Presently more than 55 million individuals are affected by AD all over the world, and it is a leading cause of death in old age. The main purpose of this paper is to review the phytochemical constituents of different plants that are used for the treatment of AD. A thorough and organized review of the existing literature was conducted, and the data under the different sections were found using a computerized bibliographic search through the use of databases such as PubMed, Web of Science, Google Scholar, Scopus, CAB Abstracts, MEDLINE, EMBASE, INMEDPLAN, NATTS, and numerous other websites. Around 360 papers were screened, and, out of that, 258 papers were selected on the basis of keywords and relevant information that needed to be included in this review. A total of 55 plants belonging to different families have been reported to possess different bioactive compounds (galantamine, curcumin, silymarin, and many more) that play a significant role in the treatment of AD. These plants possess anti-inflammatory, antioxidant, anticholinesterase, and anti-amyloid properties and are safe for consumption. This paper focuses on the taxonomic details of the plants, the mode of action of their phytochemicals, their safety, future prospects, limitations, and sustainability criteria for the effective treatment of AD.

Preparation and evaluation of injectable microsphere formulation for longer sustained release of donepezil

In this study, donepezil-loaded PLGA and PLA microspheres (Dp-PLGA-M/Dp-PLA-M) and Dp-PLA-M wrapped in a polyethylene glycol-b-polycaprolactone (PC) hydrogel (Dp-PLA-M/PC) were prepared to reduce the dosing frequency of injections to treat Alzheimer's disease patients. Dp-PLGA-M and Dp-PLA-M with a uniform particle size distribution were repeatably fabricated in nearly quantitative yield and with high encapsulated Dp yields using an ultrasonic atomizer. The injectability and in vitro and in vivo Dp release, biodegradation, and inflammatory response elicited by the Dp-PLGA-M, Dp-PLA-M, and Dp-PLA-M/PC formulations were then compared. All injectable formulations showed good injectability with ease of injection, even flow, and no clogging using a syringe needle under 21-G. The injections required a force of <1 N. According to the biodegradation rate of micro-CT, GPC and NMR analyses, the biodegradation of Dp-PLA-M was slower than that of Dp-PLGA-M, and the biodegradation rate of Dp-PLA-M/PC was also slower. In the Dp release experiment, Dp-PLA-M sustained Dp for longer compared with Dp-PLGA-M. Dp-PLA-M/PC exhibited a longer sustained release pattern of two months. In vivo bioavailability of Dp-PLA-M/PC was almost 1.4 times higher than that of Dp-PLA-M and 1.9 times higher than that of Dp-PLGA-M. The variations in the Dp release patterns of Dp-PLGA-M and Dp-PLA-M were explained by differences in the degradation rates of PLGA and PLA. The sustained release of Dp by Dp-PLA-M/PC was attributed to the fact that the PC hydrogel served as a wrapping matrix for Dp-PLA-M, which could slow down the biodegradation of PLA-M, thus delaying the release of Dp from Dp-PLA-M. Dp-PLGA-M induced a higher inflammatory response compared to Dp-PLA-M/PC, suggesting that the rapid degradation of PLGA triggered a strong inflammatory response. In conclusion, Dp-PLA-M/PC is a promising injectable Dp formulation that could be used to reduce the dosing frequency of Dp injections.

Photobiomodulation in Alzheimer's Disease-A Complementary Method to State-of-the-Art Pharmaceutical Formulations and Nanomedicine?

Alzheimer's disease (AD), as a neurodegenerative disorder, usually develops slowly but gradually worsens. It accounts for approximately 70% of dementia cases worldwide, and is recognized by WHO as a public health priority. Being a multifactorial disease, the origins of AD are not satisfactorily understood. Despite huge medical expenditures and attempts to discover new pharmaceuticals or nanomedicines in recent years, there is no cure for AD and not many successful treatments are available. The current review supports introspection on the latest scientific results from the specialized literature regarding the molecular and cellular mechanisms of brain photobiomodulation, as a complementary method with implications in AD. State-of-the-art pharmaceutical formulations, development of new nanoscale materials, bionanoformulations in current applications and perspectives in AD are highlighted. Another goal of this review was to discover and to speed transition to completely new paradigms for the multi-target management of AD, to facilitate brain remodeling through new therapeutic models and high-tech medical applications with light or lasers in the integrative nanomedicine of the future. In conclusion, new insights from this interdisciplinary approach, including the latest results from photobiomodulation (PBM) applied in human clinical trials, combined with the latest nanoscale drug delivery systems to easily overcome protective brain barriers, could open new avenues to rejuvenate our central nervous system, the most fascinating and complex organ. Picosecond transcranial laser stimulation could be successfully used to cross the blood-brain barrier together with the latest nanotechnologies, nanomedicines and drug delivery systems in AD therapy. Original, smart and targeted multifunctional solutions and new nanodrugs may soon be developed to treat AD.

Polysorbate 80-coated albumin nanoparticles to deliver paclitaxel into the brain to treat glioma

Aim: To develop stable paclitaxel (PTX)-loaded bovine serum albumin (BSA) nanoparticles (BSA-NPs-PTX) as drug-delivery vehicles for delivering paclitaxel into the brain to treat glioma. Methods: This study used PTX-loaded BSA NPs coated with polysorbate 80 (Ps 80) to enhance PTX concentration in the brain. Results: The low IC50 indicated that the fabricated BSA-NPs-PTX and BSA-NPs-PTX-Ps 80 showed significantly enhanced cytotoxicity. The pharmacokinetic and biodistribution analysis of BSA-NPs-PTX and BSA-NPs-PTX 80 showed comparable pharmacokinetic profiles but were significantly different compared with free PTX. Conclusion: BSA-NPs-PTX-Ps 80 exhibited higher plasma concentration-time curves, as compared with BSA-NPs-PTX and PTX. BSA-NPs-PTX and BSA-NPs-PTX-Ps 80 showed significantly improved PTX distribution in the frontal cortex, posterior brain and cerebellum.

AdipoRon mitigates tau pathology and restores mitochondrial dynamics via AMPK-related pathway in a mouse model of Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) is a complicated and refractory neurodegenerative disease that is typically characterized by memory loss and multiple cognitive impairments. Multiple neuropathology including hyperphosphorylated tau formation and accumulation, dysregulated mitochondrial dynamics, and synaptic damage have been well implicated in the progression of AD. So far, there are few valid and effective therapeutic modalities for treatment. AdipoRon, a specific adiponectin (APN) receptor agonist, is reported to be associated with cognitive deficits improvement. In the present study, we attempt to explore the potential therapeutic effects of AdipoRon on tauopathy and related molecular mechanisms.

METHODS

In this study, P301S tau transgenic mice were used. The plasma level of APN was detected by ELISA. The level of APN receptors was qualified by western blot and immunofluorescence. 6-month-old mice were treated with AdipoRon or vehicle by oral administration daily for 4 months. The benefits of AdipoRon on tau hyperphosphorylation, mitochondrial dynamics, and synaptic function were detected by western blot, immunohistochemistry, immunofluorescence, Golgi staining and transmission electron microscopy. Morris water maze test and novel object recognition test were conducted to explore memory impairments.

RESULTS

Compared with wild-type mice, the expression of APN in plasma in 10-month-old P301S mice was obviously decreased. APN receptors in the hippocampus were increased in the hippocampus. AdipoRon treatment significantly rescued memory deficits in P301S mice. Besides, AdipoRon treatment was also detected to improve synaptic function, enhance mitochondrial fusion, and mitigate hyperphosphorylated tau accumulation in P301S mice and SY5Y cells. Mechanistically, AMPK/SIRT3 and AMPK/GSK3β signaling pathways are demonstrated to be involved in AdipoRon-mediated benefits on mitochondrial dynamics and tau accumulation, respectively, and inhibition of AMPK related pathways showed counteracted effects.

CONCLUSION

Our results demonstrated that AdipoRon treatment could significantly mitigate tau pathology, improve synaptic damage, and restore mitochondrial dynamics via the AMPK-related pathway, which provides a novel potential therapeutic approach to retard the progression of AD and other tauopathies diseases.

Donepezil accelerates the release of PLGA microparticles via catalyzing the polymer degradation regardless of the end groups and molecular weights

Poly (lactic-co-glycolic acid) (PLGA) is one of the most successful polymers for sustained parenteral drug products in the market. However, rational selection of PLGA in the formulations is still challenging due to the lack of fundamental studies. The present study aimed to investigate the influence of donepezil (DP) on the in-vitro and in-vivo performance of PLGA sustained microspheres. Three kinds of PLGAs with different end groups and molecular weights were selected. Then DP-loaded PLGA microspheres (DP-MSs) with similar particle size, drug loading, and encapsulation efficiency were prepared using an o/w emulsion-solvent evaporation method. Laser diffraction and scanning electron microscopy showed that the prepared DP-MSs were about 35 μm and spherical in shape. Differential scanning calorimetry and X-ray diffraction indicated that DP was in an amorphous state inside the microspheres. Unexpectedly, the molecular weight and end group of PLGAs did not significantly influence the in-vitro and in-vivo performance of the DP-MSs. The gel permeation chromatography indicated that the degradation rates of PLGAs were accelerated with the incorporation of DP into the microspheres, and the molecular weight of all three kinds of PLGAs sharply dropped to about 11,000 Da within the initial three days. The basic catalysis effect induced by DP might be responsible for the accelerated degradation of PLGAs, which led to similar in-vitro release profiles of DP from different PLGA matrices. A point-to-point level A correlation between the in-vitro release and the in-vivo absorption was observed, which confirmed the accelerated release of DP from the DP-MSs in-vivo. The results indicated that the influence of DP on the degradation of PLGA should be considered when developing DP-sustained microspheres.

Intelligent polymeric hydrogen sulfide delivery systems for therapeutic applications

Hydrogen sulfide (H₂S) plays an important role in regulating various pathological processes such as protecting mammalian cell from harmful injuries, promoting tissue regeneration, and regulating the process of various diseases caused by physiological disorders. Studies have revealed that the physiological effects of H₂S are highly associated with its concentrations. At relatively low concentration, H₂S shows beneficial functions. However, long-time and high-dose donation of H₂S would inhibit regular biological process, resulting in cell dysfunction and apoptosis. To regulate the dosage of H₂S delivery for precision medicine, H₂S delivery systems with intelligent characteristics were developed and a variety of biocompatibility polymers have been utilized to establish intelligent polymeric H₂S delivery systems, with the abilities to specifically target the lesions, smartly respond to pathological microenvironments, as well as real-timely monitor H₂S delivery and lesion conditions by incorporating imaging-capable moieties. In this review, we focus on the design, preparation, and therapeutic applications of intelligent polymeric H₂S delivery systems in cardiovascular therapy, inflammatory therapy, tissue regenerative therapy, cancer therapy and bacteria-associated therapy. Strategies for precise H₂S therapies especially imaging-guided H₂S theranostics are highlighted. Since H₂S donors with stimuli-responsive characters are vital components for establishing intelligent H₂S delivery systems, the development of H₂S donors is also briefly introduced.

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H₂S is an endogenous gasotransmitter that plays important role in regulating various physiological and pathological pathways.

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Controlled H₂S delivery is vital since the therapeutic effects of H₂S are highly associated with its concentrations.

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Intelligent polymeric H₂S delivery systems possess specific targeting, stimuli responsive and imaging guided capabilities, representing a strategic option for next generation of therapies.

Metformin inhibits cardiometabolic syndrome associated cognitive deficits in high fat diet rats

Objectives

Glucose intolerance and insulin resistance are hallmarks of metabolic syndrome and lead to Alzheimer's disease (AD). The purpose of this study is to elucidate the neuroprotective effect of metformin through insulin regulation with cardiometabolic and neurotransmitter metabolic enzyme regulation in high-fat, high-sucrose diet and streptozotocin (HFHS-STZ)-induced rats.

Methods

Male Wistar rats were treated with metformin (180 mg/kg and 360 mg/kg). STZ (35 mg/kg i.p.) injection was performed on the 14th day of 42 days of HFHS diet treatment. Brain neurotransmitter metabolic enzymes (acetylcholinesterase and monoamine oxidase) were determined along with sodium-potassium ATPase (Na+K+-ATPase). Plasma lipids and homeostasis model assessment of insulin resistance (HOMA-IR) was performed. Mean arterial blood pressure, heart rate and electrocardiogram (QT, QTc and RR intervals) were analysed with PowerLab.

Results

Metformin treatment significantly (p < 0.001) reduced the HOMA-IR index and decreased neurotransmitter metabolic enzymes such as AChE and MAO (p < 0.01 and p < 0.05). The lipid profile was significantly (p < 0.001) controlled with cardiometabolic functions.

Conclusions

Our investigation revealed that metformin has a remarkable role in regulating brain insulin, vascular system with monoaminergic metabolic enzymes and enhancing synaptic plasticity. Metformin may be a selective early therapeutic agent in metabolic syndrome associated with cognitive decline.

Progress and Challenges in Targeted Protein Degradation for Neurodegenerative Disease Therapy

Neurodegenerative diseases (NDs) are currently incurable diseases that cause progressive degeneration of nerve cells. Many of the disease-causing proteins of NDs are "undruggable" for traditional small-molecule inhibitors (SMIs). None of the compounds that attenuated the amyloid-β (Aβ) accumulation process have entered clinical practice, and many phase III clinical trials of SMIs for Alzheimer's disease (AD) have failed. In recent years, emerging targeted protein degradation (TPD) technologies such as proteolysis-targeting chimeras (PROTACs), lysosome-targeting chimaeras (LYTACs), and autophagy-targeting chimeras (AUTACs) with TPD-assistive technologies such as click-formed proteolysis-targeting chimeras (CLIPTACs) and deubiquitinase-targeting chimera (DUBTAC) have developed rapidly. In vitro and in vivo experiments have also confirmed that TPD technology can target the degradation of ND pathogenic proteins, bringing hope for the treatment of NDs. Herein, we review the latest TPD technologies, introduce their targets and technical characteristics, and discuss the emerging TPD technologies with potential in ND research, with the hope of providing a new perspective for the development of TPD technology in the NDs field.

Lipid nanoparticles in the development of mRNA vaccines for COVID-19

Coronavirus disease (COVID-19) was first reported in December 2019, Hubei Province, China. As on 9th December 2021, severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) has affected 266018810 people worldwide with 5265092 deaths. The outbreak of COVID-19 pandemic has caused severe public health crisis across the world. Nucleic acids have been emerging as potential drugs to treat a variety of diseases. Lipid nanoparticles (LNPs) have great potential to deliver nucleic acids including mRNAs. The two mRNA-based vaccines namely the BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna) have been given emergency use authorization (EUA) by the US-FDA to prevent SARS-CoV-2 caused COVID-19 and the vaccines were developed using LNPs. This article focuses on the potential application of LNPs in the development and delivery of mRNA vaccines for COVID-19.

Inorganic Nanomaterials Versus Polymer-Based Nanoparticles for Overcoming Neurodegeneration

Neurodegenerative disorders (NDs) affect a great number of people worldwide and also have a significant socio-economic impact on the aging population. In this context, nanomedicine applied to neurological disorders provides several biotechnological strategies and nanoformulations that improve life expectancy and the quality of life of patients affected by brain disorders. However, available treatments are limited by the presence of the blood–brain barrier (BBB) and the blood–cerebrospinal fluid barrier (B–CSFB). In this regard, nanotechnological approaches could overcome these obstacles by updating various aspects (e.g., enhanced drug-delivery efficiency and bioavailability, BBB permeation and targeting the brain parenchyma, minimizing side effects). The aim of this review is to carefully explore the key elements of different neurological disorders and summarize the available nanomaterials applied for neurodegeneration therapy looking at several types of nanocarriers. Moreover, nutraceutical-loaded nanoparticles (NPs) and synthesized NPs using green approaches are also discussed underling the need to adopt eco-friendly procedures with a low environmental impact. The proven antioxidant properties related to several natural products provide an interesting starting point for developing efficient and green nanotools useful for neuroprotection.

Nanomedicine to deliver biological macromolecules for treating COVID-19

Coronavirus disease (COVID-19) was first reported in December 2019, China and later it was found that the causative microorganism is severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). As on 3rd June 2021, SARS-CoV-2 has affected 171049741 people worldwide with 3549710 deaths. Nanomedicine such as nanoparticles, liposomes, lipid nanoparticles, virus-like nanoparticles offer tremendous hopes to treat viral infections including COVID-19. Most importantly target specific ligands can be attached on the surface of them and this makes them more target specific and the loaded drug can be delivered to cellular and molecular level. These properties of nanomedicines can be utilized to deliver drugs or vaccines to treat viral diseases including SARS-CoV-2 infection. This review discusses about SARS-CoV-2 and the potential application of nanomedicines for delivering biological macromolecules like vaccines and drugs for treating COVID-19.

Application of curcumin nanoformulations in Alzheimer's disease: prevention, diagnosis and treatment

Objectives: Alzheimer's disease (AD) is a serious neurodegenerative disease. Although many therapeutic strategies have been studied, their clinical applications are immature. Moreover, these methods can only alleviate symptoms rather than cure it, posing a challenge to brain health in older adults worldwide. Curcumin (CUR) is a very promising natural compound for nerve protection and treatment. It can prevent and treat AD, and on the other hand, its fluorescence properties can be used in the diagnosis of AD. However, CUR is characterized by very low water solubility, fluid instability, rapid metabolism, low bioavailability and difficulty in penetrating the biological barriers, which limit its application. Nanocarriers are a potential material to improve the biocompatibility of CUR and its ability to cross biological barriers. Therefore, delivering CUR by nanocarriers is an effective method to achieve better efficacy. Methods: In this review, the preventive, therapeutic and diagnostic effects of CUR nanoformulations on AD, as well as various patents, clinical trials and experimental research progress in this field are discussed. The aim is to provide detailed reference and practical suggestions for future research. Results: CUR has a variety of pharmacological activities in the prevention and treatment of AD, and its nanoformulation can effectively improve solubility, bioavailability and the ability to penetrate the blood-brain barrier. Significant benefits have been observed in the current study. Discussion: CUR formulations have a good prospect in the prevention, diagnosis and treatment of AD, but the safety and principle of its administration need more detailed study in the future.

2D materials-based nanomedicine: From discovery to applications

Due to their unique physicochemical characteristics, 2D materials have attracted more and more attention in the biomedicine field. Currently, 2D materials-based nanomedicines have been extensively applied in various diseases including cancer, bacterial infection, tissue engineering, biological protection, neurodegenerative diseases, and cardiovascular disease. Depending on their various characteristics, these 2D nanomedicines exert their therapeutic effect in different ways, showing great clinical application prospects. Herein, we focus on the various biomedical applications of 2D materials-based nanomedicine. The structures and characteristics of several typical 2D nanomaterials with different configurations and their corresponding biomedical applications are first introduced. Then, the potential of 2D nanomedicines on therapeutic and imaging and their biological functionalization are discussed. Furthermore, the therapeutic potentials of 2D nanomedicines in various diseases are also comprehensively summarized. At last, the challenges and perspectives for the advancement of 2D nanomedicines in clinical transformation are outlooks.

Turning the structure of the Aβ42 peptide by different functionalized carbon nanotubes: a molecular dynamics simulation study

Functionalized carbon nanotubes (CNTs) can inhibit the self-assembly of amyloid-beta (Aβ) peptides. Under abnormal conditions, the structure of the Aβ peptides undergoes a fundamental transformation, and this transformation will induce conformational conversions of other polymerized Aβ peptides. Here, we explore the interactions between different functionalized CNTs and Aβ₄₂ peptides by molecular dynamics simulations. Our results show that compared to the original CNTs, the highly functionalized CNTs induce different adsorption patterns of the peptides. This adsorption pattern destroys the α-helix structure and increases the β-turn and random coil content significantly. The hydrogen bonds formed by the peptide and water molecules or CNTs further reveal the reasons for the structural transformation of the peptide. Due to electrostatic interactions and π-π stacking interactions, some amino acids (such as Phe4, Lys16, Phe20, and Lys28) are tightly fixed on the surfaces, and other amino acids move around these amino acids to accelerate the unfolding and denaturation of the peptide. Our research shows that functionalized CNTs have excellent potential to inhibit the abnormal aggregation of Aβ₄₂ peptides. Our research also provides theoretical guidance in the design and synthesis of carbon nanomedicines for protein conformation diseases.

Nanoparticles in Combating Neuronal Dysregulated Signaling Pathways: Recent Approaches to the Nanoformulations of Phytochemicals and Synthetic Drugs Against Neurodegenerative Diseases

As the worldwide average life expectancy has grown, the prevalence of age-related neurodegenerative diseases (NDDs) has risen dramatically. A progressive loss of neuronal function characterizes NDDs, usually followed by neuronal death. Inflammation, apoptosis, oxidative stress, and protein misfolding are critical dysregulated signaling pathways that mainly orchestrate neuronal damage from a mechanistic point. Furthermore, in afflicted families with genetic anomalies, mutations and multiplications of α-synuclein and amyloid-related genes produce some kinds of NDDs. Overproduction of such proteins, and their excessive aggregation, have been proven in various models of neuronal malfunction and death. In this line, providing multi-target therapies carried by novel delivery systems would pave the road to control NDDs through simultaneous modulation of such dysregulated pathways. Phytochemicals are multi-target therapeutic agents, which employ several mechanisms towards neuroprotection. Besides, the blood-brain barrier (BBB) is a critical issue in managing NDDs since it inhibits the accessibility of drugs to the brain in sufficient concentration. Besides, discovering novel delivery systems is vital to improving the efficacy, bioavailability, and pharmacokinetic of therapeutic agents. Such novel formulations are also employed to improve the drug's biodistribution, allow for the co-delivery of several medicines, and offer targeted intracellular delivery against NDDs. The present review proposes nanoformulations of phytochemicals and synthetic agents to combat NDDs by modulating neuroinflammation, neuroapoptosis, neuronal oxidative stress pathways and protein misfolding.

Quercetin Exhibits α7nAChR/Nrf2/HO-1-Mediated Neuroprotection Against STZ-Induced Mitochondrial Toxicity and Cognitive Impairments in Experimental Rodents

The objective of the present study was to investigate the α7nAChR-mediated Nrf2-dependant protective activity against streptozotocin (STZ)-induced brain mitochondrial toxicity in Alzheimer's disease (AD)-like rats. STZ (3 mg/kg) was injected through an intracerebroventricular route to induce AD-like dementia. Repeated Quercetin (50 mg/kg, i.p.) administration attenuated cognitive impairments in the STZ-challenged animals during Morris water-maze and Y-maze tests. Quercetin significantly mitigated the STZ-induced increase in cholinergic dysfunction, such as the increase in acetylcholinesterase activity, decrease in acetylcholine level, and activity of choline acetyltransferase, and increase in amyloid-beta aggregation and mitochondrial toxicity in respect of mitochondrial bioenergetics, integrity, and oxidative stress in memory-challenged rat hippocampus, prefrontal cortex and, amygdala. Further, Quercetin significantly attenuated STZ-induced reduction in the α7nAChRs and HO-1 expression levels in the selected rat brain regions. On the contrary, trigonelline (10 mg/kg, i.p.) and methyllycaconitine (2 mg/kg; i.p.) abolished the neuroprotective effects of Quercetin against STZ-induced behavioral, molecular, and biochemical alterations in the AD-like animals. Hence, Quercetin exhibits α7nAChR/Nrf2/HO-1-mediated neuroprotection against STZ-challenged AD-like animals. Thus, Quercetin could be considered as a potential therapeutic option in the management of AD.

Nano-lipidic formulation and therapeutic strategies for Alzheimer's disease via intranasal route

AIM

The inability of drug molecules to cross the 'Blood-Brain Barrier' restrict the effective treatment of Alzheimer's disease. Lipid nanocarriers have proven to be a novel paradigm in brain targeting of bioactive by facilitating suitable therapeutic concentrations to be attained in the brain.

METHODS

The relevant information regarding the title of this review article was collected from the peer-reviewed published articles. Also, the physicochemical properties, and their in vitro and in vivo evaluations were presented in this review article.

RESULTS

Administration of lipid-based nano-carriers have abilities to target the brain, improve the pharmacokinetic and pharmacodynamics properties of drugs, and mitigate the side effects of encapsulated therapeutic active agents.

CONCLUSION

Unlike oral and other routes, the Intranasal route promises high bioavailability, low first-pass effect, better pharmacokinetic properties, bypass of the systemic circulation, fewer incidences of unwanted side effects, and direct delivery of anti-AD drugs to the brain via circumventing 'Blood-Brain Barrier'.

Nanotherapeutics for Alzheimer's Disease with Preclinical Evaluation and Clinical Trials: Challenges, Promises and Limitations

Alzheimer's disease (AD), a progressive and irreversible neurodegenerative disorder, is the most common form of dementia worldwide. Currently, there is no disease-modifying AD drug, and the development of effective treatments is made even harder by the highly selective nature of the blood-brain barrier (BBB) that allows the passage only of molecules with specific chemical-physical properties. In this context, nanomedicine and its nanoparticles (NPs) offer potential solutions to the challenge of AD therapy, in particular, the requirements for i) BBB crossing, ii) multitarget therapy iii) enhancement of pharmacokinetics; and iv) more precise delivery. In addition, the possibility to optimize NP biophysical and biological (i.e. target-specific ligands) properties allows for highly tailored delivery platforms. Preclinical studies have demonstrated that nanotherapeutics provide superior pharmacokinetics and brain uptake than free drugs and, on the other hand, these are also able to mitigate the side-effects of the symptomatic treatments approved by the FDA. Among the plethora of potential AD nanodrugs, multitarget nanotherapeutics are considered the most promising strategy due to their ability to hit simultaneously multiple pathogenic factors, while nano-nutraceuticals are emerging as interesting tools in the treatment/prevention of AD. This review provides a comprehensive overview of nanomedicine in AD therapy, focusing on key optimization of NPs properties, most promising nanotherapeutics in preclinical studies and difficulties that are limiting the efficient translation from bench to bedside.

A novel small-molecule PROTAC selectively promotes tau clearance to improve cognitive functions in Alzheimer-like models

Intracellular accumulation of tau is a hallmark pathology in Alzheimer disease (AD) and the related tauopathies, thus targeting tau could be promising for drug development. Proteolysis Targeting Chimera (PROTAC) is a novel drug discovery strategy for selective protein degradation from within cells. Methods: A novel small-molecule PROTAC, named as C004019 with a molecular mass of 1,035.29 dalton, was designed to simultaneously recruite tau and E3-ligase (Vhl) and thus to selectively enhance ubiquitination and proteolysis of tau proteins. Western blotting, immunofluoresence and immunohistochemical staining were employed to verify the effects of C004019 in cell models (HEK293 and SH-SY5Y) and mouse models (hTau-transgenic and 3xTg-AD), respectively. The cognitive capacity of the mice was assessed by a suite of behavior experiments. Electrophysiology and Golgi staining were used to evaluate the synaptic plasticity. Results: C004019 induced a robust tau clearance via promoting its ubiquitination-proteasome-dependent proteolysis in HEK293 cells with stable or transient overexpression of human tau (hTau), and in SH-SY5Y that constitutively overexpress hTau. Furthermore, intracerebral ventricular infusion of C004019 induced a robust tau clearance in vivo. Most importantly, both single-dose and multiple-doses (once per 6 days for a total 5 times) subcutaneous administration of C004019 remarkably decreased tau levels in the brains of wild-type, hTau-transgenic and 3xTg-AD mice with improvement of synaptic and cognitive functions. Conclusions: The PROTAC (C004019) created in the current study can selectively and efficiently promote tau clearance both in vitro and in vivo, which provides a promising drug candidate for AD and the related tauopathies.

Quercetin-Conjugated Superparamagnetic Iron Oxide Nanoparticles Protect AlCl3-Induced Neurotoxicity in a Rat Model of Alzheimer's Disease via Antioxidant Genes, APP Gene, and miRNA-101

Alzheimer's disease (AD) is a neurodegenerative disease with cognitive impairment. Oxidative stress in neurons is considered as a reason for development of AD. Antioxidant agents such as quercetin slow down AD progression, but the usage of this flavonoid has limitations because of its low bioavailability. We hypothesized that quercetin-conjugated superparamagnetic iron oxide nanoparticles (QT-SPIONs) have a better neuroprotective effect on AD than free quercetin and regulates the antioxidant, apoptotic, and APP gene, and miRNA-101. In this study, male Wistar rats were subjected to AlCl3, AlCl3 + QT, AlCl3 + SPION, and AlCl3 + QT-SPION for 42 consecutive days. Behavioral tests and qPCR were used to evaluate the efficiency of treatments. Results of behavioral tests revealed that the intensity of cognitive impairment was decelerated at both the middle and end of the treatment period. The effect of QT-SPIONs on learning and memory deficits were closely similar to the control group. The increase in expression levels of APP gene and the decrease in mir101 led to the development of AD symptoms in rats treated with AlCl3 while these results were reversed in the AlCl3 + QT-SPIONs group. This group showed similar results with the control group. QT-SPION also decreased the expression levels of antioxidant enzymes along with increases in expression levels of anti-apoptotic genes. Accordingly, the antioxidant effect of QT-SPION inhibited progression of cognitive impairment via sustaining the balance of antioxidant enzymes in the hippocampus of AD model rats.

Albumin nanoparticles coated with polysorbate 80 for the targeted delivery of antiepileptic drug levetiracetam into the brain

The aim of the study was to target levetiracetam (LEV) into the brain by albumin nanoparticles. The levetiracetam-loaded albumin nanoparticles (LEV-NPs) were formulated by desolvation. The particle size of LEV-NPs was 153.7 ± 44.8 nm and the zeta potential was - 10.8 mV. The in vitro LEV release, in pH 6.8 phosphate buffer, was determined by dialysis and showed a biphasic pattern of drug release and ranged in between 40.42 ± 2.6% w/w and 63.61 ± 2.12% w/w. The biodistribution study was conducted on male Wistar rats. The LEV was given as i.v. injection in tail vein, and the formulations were the free drug, LEV-NPs, and levetiracetam-loaded albumin nanoparticles further coated with 1% polysorbate 80 (LEV-NPs-PS 80). A significant increase in LEV concentration was achieved in the brain for LEV-NPs-PS 80 when compared with LEV free drug. The LEV concentration achieved in the brain after administering free drug and LEV-NPs-PS 80 was 5.28 ± 1.79 and 18.54 ± 2.38 μg/gm respectively. The LEV-NPs-PS 80 enhanced LEV concentration in the brain by 3.51-fold when compared with the free drug. Graphical abstract.