Design and Validation of Liposomal ApoE2 Gene Delivery System to Evade Blood-Brain Barrier for Effective Treatment of Alzheimer's Disease

Liposomes as versatile agents for the management of traumatic and nontraumatic central nervous system disorders: drug stability, targeting efficiency, and safety

Various nanoparticle-based drug delivery systems for the treatment of neurological disorders have been widely studied. However, their inability to cross the blood-brain barrier hampers the clinical translation of these therapeutic strategies. Liposomes are nanoparticles composed of lipid bilayers, which can effectively encapsulate drugs and improve drug delivery across the blood-brain barrier and into brain tissue through their targeting and permeability. Therefore, they can potentially treat traumatic and nontraumatic central nervous system diseases. In this review, we outlined the common properties and preparation methods of liposomes, including thin-film hydration, reverse-phase evaporation, solvent injection techniques, detergent removal methods, and microfluidics techniques. Afterwards, we comprehensively discussed the current applications of liposomes in central nervous system diseases, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, traumatic brain injury, spinal cord injury, and brain tumors. Most studies related to liposomes are still in the laboratory stage and have not yet entered clinical trials. Additionally, their application as drug delivery systems in clinical practice faces challenges such as drug stability, targeting efficiency, and safety. Therefore, we proposed development strategies related to liposomes to further promote their development in neurological disease research.

The Different Cellular Entry Routes for Drug Delivery Using Cell Penetrating Peptides

The cell plasma membrane acts as a semi-permeable barrier essential for cellular protection and function, posing a challenge for therapeutic molecule delivery. Conventional techniques for crossing this barrier, including biophysical and biochemical methods, often exhibit limitations such as cytotoxicity and the risk of genomic integration when viral vectors are involved. In contrast, cell-penetrating peptides (CPPs) offer a promising non-invasive means to deliver a broad range of molecular cargoes, including proteins, nucleic acids and small molecules, into cells. CPPs, typically 5 to 30 amino acids long and rich in basic or non-polar residues, interact favourably with different cell membranes. These peptides have evolved since the discovery of the HIV-1 TAT peptide in the 1980s, expanding into various CPP families with diverse therapeutic applications. CPPs can form covalent or non-covalent complexes with their cargo, influencing their stability and efficacy. Based on their sequence properties and interactions, CPPs can be amphipathic or non-amphipathic, with distinct mechanisms of membrane penetration, such as direct penetration and endocytosis. While their uptake mechanisms are complex and not fully elucidated, ongoing optimization aims to enhance CPP specificity and efficacy. CPPs have demonstrated potential in drug delivery, gene therapy, cancer treatment and vaccine development, addressing key safety and efficiency concerns associated with viral vectors. This review explores the classification, mechanisms of action and therapeutic potential. It focuses on the intracellular vesicular trafficking of CPPs, highlighting their role as transformative tools in advancing cellular therapies and medical treatments.

From genetic roots to recent advancements in gene therapy targeting amyloid beta in Alzheimer's disease

Alzheimer's disease (AD) is one of the most prevalent neurodegenerative disorders. The pathological hallmarks of AD are amyloid-beta (Aβ) plaques and tau protein tangles, which cause neurodegeneration and lead to cognitive decline. The distinguished role of Aβ plaques in the onset of the disease, especially in familial AD, alongside the genetic complexity of AD, underscores the need for precise and targeted genetic interventions targeting Aβ. This review first highlights the amyloidogenic and non-amyloidogenic pathways and inflammatory mechanisms contributing to Aβ accumulation. It also introduces the role of genetic variants such as amyloid precursor protein (APP), presenilin (PSEN1), PSEN2, and Apolipoprotein E (APOE) alongside the molecular and cellular mechanisms involved in Aβ pathology. Then, gene therapy techniques are discussed for their potential to target Aβ either directly by inhibiting its production or enhancing its degradation or indirectly by targeting APOE, inflammatory pathways, and neurotrophic factors. While these approaches show significant preclinical promise, challenges such as timing, safety, and delivery across the blood-brain barrier persist and need further investigation.

Recent advances in nanomaterial-based brain-targeted delivery systems for glioblastoma therapy

Glioblastoma (GBM) poses a formidable challenge because of its high morbidity and mortality. The therapeutic efficacy of GBM is significantly hampered by the intricate blood-brain barrier (BBB) and blood-brain tumor barrier (BBTB). Nanomaterial-based brain-targeted delivery systems have shown great potential for effectively delivering therapeutic agents for GBM treatment by overcoming the limitations of conventional drugs, such as poor BBB penetration, a short half-life, and low bioavailability. This review focuses on an in-depth analysis of the interplay between the BBB/BBTB and drug transport kinetics while analyzing innovative nanoparticle-mediated strategies for enhanced GBM treatment. Moreover, the delivery strategies of nanoparticle-based brain-targeted systems are emphasized, with particular attention given to biomimetic nanoparticles (BMNPs), whose unique advantages. The current challenges, translational potential, and future research directions in this rapidly evolving field are comprehensively discussed, highlighting advances in nanomaterial applications. This review aims to stimulate further research into GBM delivery systems, offering promising avenues for maximizing the therapeutic effects of gene drugs or chemotherapeutic agents in practical applications.

Intranasal delivery of pApoE2 via penetratin-mannose multi-functionalized chitosan polymeric micelles to the brain: Reduced total tau and phosphorylated tau burden in transgenic Alzheimer's mouse model

The phosphorylated tau accumulation is a classical pathological hallmark of future cognitive decline and a cause of neuronal death in Alzheimer's disease (AD). In this study, we developed multi-functionalized chitosan (CS) based polymeric micelles to effectively deliver pApoE2 via intranasal administration to the brain. The CS was modified with caproic acid (CA), cell-penetrating peptide penetratin (PEN), and GLUT-1 transporter ligand mannose (MAN) for selective and enhanced delivery to the brain. The multi-functionalized Cap-g-CS-PEN-MAN polymeric micelles were ≤200 nm in size, cationic in charge, and uniformly distributed (PDI ≤ 0.3). The multi-functionalized polymeric micelles did not exhibit toxicity against bEnd.3 cells and erythrocytes up to polymer concentrations of 500 μg/mL. The Cap-g-CS-PEN-MAN /pDNA polyplex was stable against a DNase rich environment. The Cap-g-CS-PEN-MAN/pAPoE2 polyplex demonstrated elevated expression of ApoE in primary astrocytes and neurons, 9.47 ± 2.13 and 5.67 ± 2.69 ng/mg of protein, respectively. The therapeutic efficacy of the Cap-g-CS-PEN-MAN/pApoE2 polyplex was analyzed against the PS19 tauopathy mice model. Total tau burden was significantly (p ≤ 0.05) reduced by 4.09 ± 1.4 ng/mg of protein in Cap-g-CS-PEN-MAN/pApoE2 polyplex administered mice over the other groups. Phosphorylated tau pT181 level was also significantly (p ≤ 0.05) reduced in Cap-g-CS-PEN-MAN/pApoE2 polyplex administered mice over saline, pApoE2 and Cap-g-CS/pApoE2 treated groups.

Physicochemical and molecular docking studies of the single nucleotide polymorphisms (SNPs) of apolipoprotein E (APOE) gene associated with Alzheimer's disease: Interaction with Amiloride

The apolipoprotein E (APOE) gene's APOE4 variant is frequently associated with an elevated risk of Alzheimer's disease, while APOE3 isoform is found in normal individuals. Both the isoforms differ by only one base (Single nucleotide polymorphisms, SNPs). In this study, Amiloride hydrochloride (AM), a diuretic drug, was utilized to investigate its interaction with the DNA sequence of APOE isoforms, APOE3 and APOE4. Na+/H+ exchangers (NHEs) are inhibited by AM, thus making these transporters as amiloride-sensitive. Various physicochemical and molecular docking methods were employed to explore the AM binding site on the 22-mer apo3 and apo4 DNA sequences. Present study revealed that AM binds to the minor groove via vander Waals forces or H-bonding. The binding constants obtained from both the absorbance and fluorescence studies depict that AM strongly interacts with apo4 sequence. Competitive analysis with Acridine Orange and Hoechst supported the minor groove binding property of AM. Molecular docking results, including LigPlots, further supported the experimental analysis, revealing the interacting nitrogenous bases of the studied sequences. This study helps in facilitating our understanding regarding the DNA-drug binding interactions, which may further be utilized for designing a better and more target-specific drug for Alzheimer's disease treatment.

Molecular imaging-guided diagnosis and treatment integration for brain diseases

In practical clinical scenarios, improved diagnostic methods have been developed for the precise visualization of molecular targets using molecular imaging in brain diseases. Recently, the introduction of innovative molecular imaging modalities across both macroscopic and mesoscopic dimensions, with remarkable specificity and spatial resolution, has expanded the scope of applications beyond diagnostic testing, with the potential to guide therapeutic interventions, offering real-time feedback in the context of brain therapy. The molecular imaging-guided integration of diagnosis and treatment holds the potential to revolutionize disease management by enabling the real-time monitoring of treatment responses and therapy adjustments. Given the vibrant and ever-evolving nature of this field, this review provides an integrated picture on molecular image-guided diagnosis and treatment integration for brain diseases involving the basic concepts, significant breakthroughs, and recent trends. In addition, based on the current achievements, some critical challenges are also discussed.

Advancing Nanomaterial-Based Strategies for Alzheimer's Disease: A Perspective

Alzheimer's disease (AD) is a complex neurodegenerative disorder and the most common cause of dementia. By 2050, the number of AD cases is projected to exceed 131 million, placing significant strain on healthcare systems and economies worldwide. The pathogenesis of AD is multifactorial, involving hypotheses/mechanisms, such as amyloid-β (Aβ) plaques, tau protein hyperphosphorylation, cholinergic neuron damage, oxidative stress, and inflammation. Despite extensive research, the complexity of these potentially entangled mechanisms has hindered the development of treatments that can reverse disease progression. Nanotechnology, leveraging the unique physical, electrical, magnetic, and optical properties of nanomaterials, has emerged as a promising approach for AD treatment. In this Perspective, we first outlined the major current pathogenic hypotheses of AD and then reviewed recent advances in nanomaterials in addressing these hypotheses. We have also discussed the challenges in translating nanomaterials into clinical applications and proposed future directions, particularly the development of multifunctional and multitarget nanomaterials, to enhance their therapeutic efficacy and clinical applicability in AD treatment.

Utilization of nanotechnology to surmount the blood-brain barrier in disorders of the central nervous system

Central nervous system (CNS) diseases are a major cause of disability and death worldwide. Due to the blood-brain barrier (BBB), drug delivery for CNS diseases is extremely challenging. Nano-delivery systems can overcome the limitations of BBB to deliver drugs to the CNS, improve the ability of drugs to target the brain and provide potential therapeutic methods for CNS diseases. At the same time, the choice of different drug delivery methods (bypassing BBB or crossing BBB) can further optimize the therapeutic effect of the nano-drug delivery system. This article reviews the different methods of nano-delivery systems to overcome the way BBB enters the brain. Different kinds of nanoparticles to overcome BBB were discussed in depth.

Peptide-functionalized nanoparticles for brain-targeted therapeutics

Despite the rapid development of nanoparticle (NP)-based drug delivery systems, intravenous delivery of drugs to the brain remains a major challenge due to various biological barriers. To achieve therapeutic effects, NP-encapsulated drugs must avoid accumulation in off-target organs and selectively deliver to the brain, successfully cross the blood-brain barrier (BBB), and reach the target cells in the brain. Conjugating receptor-specific ligands to the surface of NPs is a promising technique for engineering NPs to overcome these barriers. Specifically, peptides as brain-targeting ligands have been of increasing interest given their ease of synthesis, low cytotoxicity, and strong affinity to target proteins. The success of peptides as targeting ligands is largely due to the diverse strategies of designing and modifying peptides with favorable properties, including membrane permeability and multi-receptor targeting. Here, we review the design and implementation of peptide-functionalized NP systems for neurological disease applications. We also explore advances in rational peptide design strategies for brain targeting, including using generative deep-learning models to computationally design new peptides.

Apolipoprotein E in Alzheimer's Disease: Focus on Synaptic Function and Therapeutic Strategy

Synaptic dysfunction is a critical pathological feature in the early phase of Alzheimer's disease (AD) that precedes typical hallmarks of AD, including beta-amyloid (Aβ) plaques and neurofibrillary tangles. However, the underlying mechanism of synaptic dysfunction remains incompletely defined. Apolipoprotein E (APOE) has been shown to play a key role in the pathogenesis of AD, and the ε4 allele of APOE remains the strongest genetic risk factor for sporadic AD. It is widely recognized that APOE4 accelerates the development of Aβ and tau pathology in AD. Recent studies have indicated that APOE affects synaptic function through a variety of pathways. Here, we summarize the mechanism of modulating synapses by various APOE isoforms and demonstrate the therapeutic potential by targeting APOE4 for AD treatment.

Drug delivery strategies with lipid-based nanoparticles for Alzheimer's disease treatment

Alzheimer's disease (AD) is a distinctive form of dementia characterized by age-related cognitive decline and memory impairment. A key hallmark of AD is the irreversible overaccumulation of beta-amyloid (Aβ) in the brain, associated with neuroinflammation and neuronal death. Although Aβ clearance and immunoregulation have been the major therapeutic strategies for AD, highly selective transport across the blood-brain barrier (BBB) negatively affects the delivery efficacy of the drugs without the ability to cross the BBB. In this review, we discuss the potential of lipid-based nanoparticles (LBNs) as promising vehicles for drug delivery in AD treatment. LBNs, composed of phospholipid mono- or bilayer, have attracted attention due to their exceptional cellular penetration capabilities and drug loading capabilities, which also facilitate cargo transcytosis across the BBB. Recent advances in the development and engineering of LBNs overcome the existing limitations of the current clinical approaches for AD treatment by addressing off-target effects and low therapeutic efficacy. Here, we review the transport pathways across the BBB, as well as various types of LBNs for AD therapy, including exosomes, liposomes, solid lipid nanoparticles (SLNs), and nanostructured lipid carriers (NLCs), to elucidate their distinctive properties, preparation methodologies, and therapeutic efficacy, thereby offering innovative avenues for novel drug development for clinical translation in AD therapy.

Synthesis and Characterization of Transferrin and Cell-Penetrating Peptide-Functionalized Liposomal Nanoparticles to Deliver Plasmid ApoE2 In Vitro and In Vivo in Mice

Alzheimer's disease (AD) is a prevalent neurodegenerative condition characterized by the aggregation of amyloid-β plaques and neurofibrillary tangles in the brain, leading to synaptic dysfunction and neuronal degeneration. Recently, new treatment approaches involving drugs such as donanemab and lecanemab have been introduced for AD. However, these drug regimens have been associated with adverse effects, leading to the exploration of gene therapy as a potential treatment option. The apolipoprotein E (ApoE) isoforms (ApoE2, ApoE3, and ApoE4) play pivotal roles in AD pathology, with ApoE2 known for its protective effects against AD, making it a promising candidate for gene therapy interventions. However, delivering therapeutics across the blood-brain barrier (BBB) remains a crucial challenge in treating neurological disorders. Liposomes, lipid-based vesicles, are effective nanocarriers due to their ability to shield therapeutics from degradation, though they often lack specificity for brain delivery. To address this issue, liposomes were functionalized with cell-penetrating peptides such as penetratin (Pen), cingulin (Cgn), and a targeting ligand transferrin (Tf). This modification strategy aimed to enhance the delivery of therapeutic ApoE2 plasmids across the BBB to neurons, thereby increasing the level of ApoE2 protein expression. Experimental findings demonstrated that dual-functionalized liposomes (CgnTf and PenTf) exhibited higher cellular uptake, biodistribution, and transfection efficiency than single-functionalized (Pen, Cgn, or Tf) and nonfunctionalized liposomes. In vitro studies using primary neuronal cells, bEnd.3 cells, and primary astrocytes consistently supported these findings. Following a single dose treatment via tail vein administration in C57BL6/J mice, in vivo biodistribution results showed significantly higher biodistribution levels in the brain (∼12% ID/gram of tissue) for dual-functionalized liposomes. Notably, treatment with dual-functionalized liposomes resulted in a 2-fold increase in ApoE2 expression levels compared to baseline levels. These findings highlight the potential of dual-functionalized liposomes as an efficacious delivery system for ApoE2 gene therapy in AD, highlighting a promising strategy to address the disease's underlying mechanisms.

Penetratin and Mannose-Functionalized Cannabidiol Lipid Nanoparticles Encapsulating the BDNF Gene Reduce Amyloid-Induced Inflammation

Inflammation is emerging as a critical player in the disease progression of Alzheimer's disease (AD) by its interaction with amyloid beta plaques in a feed-forward loop. There is also a decline in the nourishment and enriching neurotrophic factor, brain-derived neurotrophic factor (BDNF), in the brain. Therefore, supplementing the brain with BDNF by gene delivery and delivering the anti-inflammatory agent, cannabidiol (CBD) in this case, to mitigate inflammation-induced disease cascade offers an attractive treatment strategy. To achieve the brain localization of CBD and pBDNF, lipid nanoparticles (LNPs) functionalized with mannose and penetratin were utilized. CBD and pBDNF were successfully encapsulated in the LNPs (more than 80%) with a size less than 180 nm, polydispersity index less than 0.25, and zeta potential of 23 mV. CBD was released from the formulation over a period of a week. The dual-functionalized LNPs demonstrated higher cellular uptake of CBD and expressed a significantly higher amount of BDNF (p-value <0.05) after transfection than their nonmodified counterparts in four brain cell lines, i.e., brain endothelial cells (b.END3), immortalized microglia cells (IMGs), primary astrocytes, and primary neurons. Similarly, the permeation of CBD through the dual-modified LNPs across the in vitro coculture blood-brain barrier model was significantly higher (p-value <0.05) compared to free CBD or nonfunctionalized nanoparticles. The LNPs demonstrated anti-inflammatory activity against lipopolysaccharides and human amyloid beta1-42 oligomer induction as they reduced the protein and mRNA expression of pro-inflammatory cytokines TNF-α (p < 0.05) and IL-1β (p < 0.05) in IMG cells. In summary, the penetratin and mannose-functionalized LNPs encapsulating CBD and pBDNF could serve as a promising therapy in AD, requiring further validation in animal models.

Lipid-based Non-viral Vector: Promising Approach for Gene Delivery

OBJECTIVES

The present review aims to discuss various strategies to overcome intracellular and extracellular barriers involved in gene delivery as well as the advantages, challenges, and mechanisms of gene delivery using non-viral vectors. Additionally, patents, clinical studies, and various formulation approaches related to lipid-based carrier systems are discussed.

METHODS

Data were searched and collected from Google Scholar, ScienceDirect, PubMed, and Springer.

RESULTS

In this review, we have investigated the advantages of non-viral vectors over viral vectors. The advantage of using non-viral vectors are that they seek more attention in different fields. They play an important role in delivering the genetic materials. However, few non-viral vector-based carrier systems have been found in clinical settings. Challenges are developing more stable, site-specific gene delivery and conducting thorough safety assessments to minimize the undesired effects.

CONCLUSION

In comparison to viral vectors, non-viral vector-based lipid nanocarriers have more advantages for gene delivery. Gene therapy research shows promise in addressing health concerns. Lipid-based nanocarriers can overcome intracellular and extracellular barriers, allowing efficient delivery of genetic materials. Nonviral vectors are more attractive due to their biocompatibility, ease of synthesis, and cost-effectiveness. They can deliver various nucleic acids and have improved gene delivery efficacy by avoiding degradation steps. Despite limited clinical use, many patents have been filed for mRNA vaccine delivery using non-viral vectors.

Intranasal administration of angiotensin receptor shRNA to brain lowers blood pressure in spontaneously hypertensive rats

Neurogenic hypertension (NH) is characterized by heightened sympathetic activity mediated by angiotensin II in specific brain areas including the paraventricular nucleus and circumventricular organs. While strategies targeting sympathetic activity have shown effectiveness in managing NH, their invasive nature hinders their widespread clinical adoption. Conversely, nose-to-brain drug delivery is emerging as a promising approach to access the brain with reduced invasiveness. We hypothesize that the intranasal delivery of plasmid DNA encoding angiotensin receptor shRNA (PEAS) can effectively lower blood pressure (BP). PEAS was administered encapsulated within transferrin and Tetanus Toxin Fragment C-functionalized liposomes. Equal number of both male and female spontaneously hypertensive rats (SHR) were used to determine the effect of PEAS delivery to brain. Blood pressure was measured by the tail cuff measurement. Synthesized liposomes were found to be cationic, < 200 nm, entrapped over 88 % of the plasmid and protected PEAS from DNase degradation. In vitro, formulations caused a significant (p < 0.05) decrease (>70 %) in angiotensin receptor expression in brain endothelial cell lines, primary astrocytes and primary neurons. Intranasal administration of PEAS to SHR resulted in a significant (p < 0.05) reduction of angiotensin receptor gene expression in the brain. In the hypothalamus of SHR, intranasal administration resulted in > 70 % reduction in gene expression, ∼15 % greater than intravenous administration. Both routes were associated with an over 25 mmHg significant (p < 0.05) reduction in BP following administration of PEAS. Intranasal administration of PEAS effectively lowered BP in SHR, offering a promising non-invasive approach for managing NH.

Gene Therapy: Towards a New Era of Medicine

Over the past years, many significant advances have been made in the field of gene therapy and shown promising results in clinical trials conducted. Gene therapy aims at modifying or replacing a defective, inefficient, or nonfunctional gene with a healthy, functional gene by administration of genome material into the cell to cure genetic diseases. Various methods have been devised to do this by using several viral and non-viral vectors which are either administered by in vivo or ex vivo technique. Viral vectors are best suitable for this therapy due to their potential to invade cells and deliver their genetic material whereas non-viral vectors are less efficient than viral vectors but possess some advantages such as less immunogenic response and large gene carrying capacity. Recent advances in biotechnology such as CRISPR-Cas9 mediated genome engineering and Cancer treatment with Chimeric antigen receptor (CAR) T-cell therapy are addressed in this review. This review article also delves into some recent research studies, gene therapy trials, and its applications, laying out future hopes for gene therapy in the treatment of various diseases namely haemophilia, Muscular dystrophy, SCID, Sickle cell disease, Familial Hypercholesterolemia, Cystic Fibrosis. Additionally, it also includes various nanoformulations and clinical trial data related to gene therapy.

Recent Progress in Nanomedicine for the Diagnosis and Treatment of Alzheimer's Diseases

Alzheimer's disease (AD) is a neurodegenerative disease that causes memory loss and progressive and permanent deterioration of cognitive function. The most challenging issue in combating AD is its complicated pathogenesis, which includes the deposition of amyloid β (Aβ) plaques, intracellular hyperphosphorylated tau protein, neurofibrillary tangles (NFT), etc. Despite rapid advancements in mechanistic research and drug development for AD, the currently developed drugs only improve cognitive ability and temporarily relieve symptoms but cannot prevent the development of AD. Moreover, the blood-brain barrier (BBB) creates a huge barrier to drug delivery in the brain. Therefore, effective diagnostic tools and treatments are urgently needed. In recent years, nanomedicine has provided opportunities to overcome the challenges and limitations associated with traditional diagnostics or treatments. Various types of nanoparticles (NPs) play an essential role in nanomedicine for the diagnosis and treatment of AD, acting as drug carriers to improve targeting and bioavailability across/bypass the BBB or acting as drugs directly on AD lesions. This review categorizes different types of NPs and summarizes their applications in nanomedicine for the diagnosis and treatment of AD. It also discusses the challenges associated with clinical applications and explores the latest developments and prospects of nanomedicine for AD.

Surface engineered nano architectonics: An evolving paradigm for tackling Alzheimer's disease

As per the World Health Organization (WHO) estimation, Alzheimer's disease (AD) will affect 100 million population across the globe by 2050. AD is an incurable neurodegenerative disease that remains a mystery for neurologists owing to its complex pathophysiology. Currently, available therapeutic regimens will only cause symptomatic relief by improving the cognitive and behavioral functions of AD. However, the major pitfalls in managing AD include tight junctions in the endothelial cells of the blood-brain barrier (BBB), diminished neuronal bioavailability, enzymatic degradation and reduced stability of the therapeutic moiety. In an effort to surmount the drawbacks mentioned above, researchers shifted their focus toward nanocarriers (NCs). Nevertheless, non-specific targeting of NCs imparts toxicity to the peripheral organs, thereby reducing the bioavailability of therapeutic moiety at the target site. To unravel this unmet clinical need, scientists came up with the idea of a novel intriguing strategy of surface engineering by targeting ligands. Surface-decorated NCs provide targeted drug delivery, controlled drug release, enhanced penetration and bioavailability. In this state-of-the-art review, we have highlighted in detail various molecular signalling pathways involved in AD pathogenesis. The significance of surface functionalization and its application in AD management have been deliberated. We have elaborated on the regulatory bottlenecks and clinical hurdles faced during lab-to-industrial scale translation along with possible solutions.

Controlled Drug Release Systems for Cerebrovascular Diseases

This review offers a comprehensive exploration of optimized drug delivery systems tailored for controlled release and their crucial role in addressing cerebrovascular diseases. Through an in‐depth analysis, various controlled release methods, including nanoparticles, liposomes, hydrogels, and other emerging technologies are examined. Highlighting the importance of precise drug targeting, it is delved into the underlying mechanisms of these delivery systems and their potential to improve therapeutic outcomes while minimizing adverse effects. Additionally, the specific applications of these optimized drug delivery systems in treating cerebrovascular disorders such as ischemic stroke, cerebral aneurysms, and intracranial hemorrhage are discussed. By shedding light on the advancements in drug delivery techniques and their implications in cerebrovascular medicine, this review offers valuable insights into the future of therapeutic interventions in neurology.

Nanomedicine in Neuroprotection, Neuroregeneration, and Blood-Brain Barrier Modulation: A Narrative Review

Nanomedicine is a newer, promising approach to promote neuroprotection, neuroregeneration, and modulation of the blood-brain barrier. This review includes the integration of various nanomaterials in neurological disorders. In addition, gelatin-based hydrogels, which have huge potential due to biocompatibility, maintenance of porosity, and enhanced neural process outgrowth, are reviewed. Chemical modification of these hydrogels, especially with guanidine moieties, has shown improved neuron viability and underscores tailored biomaterial design in neural applications. This review further discusses strategies to modulate the blood-brain barrier-a factor critically associated with the effective delivery of drugs to the central nervous system. These advances bring supportive solutions to the solving of neurological conditions and innovative therapies for their treatment. Nanomedicine, as applied to neuroscience, presents a significant leap forward in new therapeutic strategies that might help raise the treatment and management of neurological disorders to much better levels. Our aim was to summarize the current state-of-knowledge in this field.

A Comprehensive Review of Nanoparticles: From Classification to Application and Toxicity

Nanoparticles are structures that possess unique properties with high surface area-to-volume ratio. Their small size, up to 100 nm, and potential for surface modifications have enabled their use in a wide range of applications. Various factors influence the properties and applications of NPs, including the synthesis method and physical attributes such as size and shape. Additionally, the materials used in the synthesis of NPs are primary determinants of their application. Based on the chosen material, NPs are generally classified into three categories: organic, inorganic, and carbon-based. These categories include a variety of materials, such as proteins, polymers, metal ions, lipids and derivatives, magnetic minerals, and so on. Each material possesses unique attributes that influence the activity and application of the NPs. Consequently, certain NPs are typically used in particular areas because they possess higher efficiency along with tenable toxicity. Therefore, the classification and the base material in the NP synthesis hold significant importance in both NP research and application. In this paper, we discuss these classifications, exemplify most of the major materials, and categorize them according to their preferred area of application. This review provides an overall review of the materials, including their application, and toxicity.

Bio-Nano Toolbox for Precision Alzheimer's Disease Gene Therapy

Alzheimer's disease (AD) is the most burdensome aging-associated neurodegenerative disorder, and its treatment encounters numerous failures during drug development. Although there are newly approved in-market β-amyloid targeting antibody solutions, pathological heterogeneity among patient populations still challenges the treatment outcome. Emerging advances in gene therapies offer opportunities for more precise personalized medicine; while, major obstacles including the pathological heterogeneity among patient populations, the puzzled mechanism for druggable target development, and the precision delivery of functional therapeutic elements across the blood-brain barrier remain and limit the use of gene therapy for central neuronal diseases. Aiming for "precision delivery" challenges, nanomedicine provides versatile platforms that may overcome the targeted delivery challenges for AD gene therapy. In this perspective, to picture a toolbox for AD gene therapy strategy development, the most recent advances from benchtop to clinics are highlighted, possibly available gene therapy targets, tools, and delivery platforms are outlined, their challenges as well as rational design elements are addressed, and perspectives in this promising research field are discussed.

Nanoliposomes as nonviral vectors in cancer gene therapy

Nonviral vectors, such as liposomes, offer potential for targeted gene delivery in cancer therapy. Liposomes, composed of phospholipid vesicles, have demonstrated efficacy as nanocarriers for genetic tools, addressing the limitations of off-targeting and degradation commonly associated with traditional gene therapy approaches. Due to their biocompatibility, stability, and tunable physicochemical properties, they offer potential in overcoming the challenges associated with gene therapy, such as low transfection efficiency and poor stability in biological fluids. Despite these advancements, there remains a gap in understanding the optimal utilization of nanoliposomes for enhanced gene delivery in cancer treatment. This review delves into the present state of nanoliposomes as carriers for genetic tools in cancer therapy, sheds light on their potential to safeguard genetic payloads and facilitate cell internalization alongside the evolution of smart nanocarriers for targeted delivery. The challenges linked to their biocompatibility and the factors that restrict their effectiveness in gene delivery are also discussed along with exploring the potential of nanoliposomes in cancer gene therapy strategies by analyzing recent advancements and offering future directions.

An Overview on the Physiopathology of the Blood-Brain Barrier and the Lipid-Based Nanocarriers for Central Nervous System Delivery

The state of well-being and health of our body is regulated by the fine osmotic and biochemical balance established between the cells of the different tissues, organs, and systems. Specific districts of the human body are defined, kept in the correct state of functioning, and, therefore, protected from exogenous or endogenous insults of both mechanical, physical, and biological nature by the presence of different barrier systems. In addition to the placental barrier, which even acts as a linker between two different organisms, the mother and the fetus, all human body barriers, including the blood-brain barrier (BBB), blood-retinal barrier, blood-nerve barrier, blood-lymph barrier, and blood-cerebrospinal fluid barrier, operate to maintain the physiological homeostasis within tissues and organs. From a pharmaceutical point of view, the most challenging is undoubtedly the BBB, since its presence notably complicates the treatment of brain disorders. BBB action can impair the delivery of chemical drugs and biopharmaceuticals into the brain, reducing their therapeutic efficacy and/or increasing their unwanted bioaccumulation in the surrounding healthy tissues. Recent nanotechnological innovation provides advanced biomaterials and ad hoc customized engineering and functionalization methods able to assist in brain-targeted drug delivery. In this context, lipid nanocarriers, including both synthetic (liposomes, solid lipid nanoparticles, nanoemulsions, nanostructured lipid carriers, niosomes, proniosomes, and cubosomes) and cell-derived ones (extracellular vesicles and cell membrane-derived nanocarriers), are considered one of the most successful brain delivery systems due to their reasonable biocompatibility and ability to cross the BBB. This review aims to provide a complete and up-to-date point of view on the efficacy of the most varied lipid carriers, whether FDA-approved, involved in clinical trials, or used in in vitro or in vivo studies, for the treatment of inflammatory, cancerous, or infectious brain diseases.

Blood pressure reduction through brain delivery of nanoparticles loaded with plasmid DNA encoding angiotensin receptor shRNA

Elevated brain angiotensin II activity plays a key role in the development of neurogenic hypertension. While blood pressure (BP) control in neurogenic hypertension has been successfully demonstrated by regulating central angiotensin II activity, current techniques involving cerebrovascular injections of potential therapeutic agents are not suitable for clinical translation. To address this gap, we present the synthesis of dual-functionalized liposomes functionalized with targeting ligand and cell-penetrating peptide. Functionalized liposomes were synthesized using the thin film hydration technique and loaded with plasmid DNA encoding short hairpin RNA targeted toward angiotensin II receptors (PEAS), via the post-insertion method. The synthesized liposomes had a cationic surface charge, an average size of 150 nm, and effectively entrapped more than 89% of loaded PEAS. These liposomes loaded with PEAS demonstrated biocompatibility and efficient delivery to brain-derived cell lines, resulting in a remarkable reduction of more than 70% in receptor expression within 7 days. To assess the therapeutic potential, spontaneously hypertensive rats were administered intravenous injections of functionalized liposomes loaded with PEAS, and the changes in mean arterial pressure were monitored for 45 days. Remarkably, this treatment led to a significant (p < 0.001) decrease in BP of more than 30 mm Hg compared with saline-treated rats.

Mechanistic insights and emerging therapeutic stratagems for Alzheimer's disease

Alzheimer's disease (AD), a multi-factorial neurodegenerative disorder has affected over 30 million individuals globally and these numbers are expected to increase in the coming decades. Current therapeutic interventions are largely ineffective as they focus on a single target. Development of an effective drug therapy requires a deep understanding of the various factors influencing the onset and progression of the disease. Aging and genetic factors exert a major influence on the development of AD. Other factors like post-viral infections, iron overload, gut dysbiosis, and vascular dysfunction also exacerbate the onset and progression of AD. Further, post-translational modifications in tau, DRP1, CREB, and p65 proteins increase the disease severity through triggering mitochondrial dysfunction, synaptic loss, and differential interaction of amyloid beta with different receptors leading to impaired intracellular signalling. With advancements in neuroscience tools, new inter-relations that aggravate AD are being discovered including pre-existing diseases and exposure to other pathogens. Simultaneously, new therapeutic strategies involving modulation of gene expression through targeted delivery or modulation with light, harnessing the immune response to promote clearance of amyloid deposits, introduction of stem cells and extracellular vesicles to replace the destroyed neurons, exploring new therapeutic molecules from plant, marine and biological sources delivered in the free state or through nanoparticles and use of non-pharmacological interventions like music, transcranial stimulation and yoga. Polypharmacology approaches involving combination of therapeutic agents are also under active investigation for superior therapeutic outcomes. This review elaborates on various disease-causing factors, their underlying mechanisms, the inter-play between different disease-causing players, and emerging therapeutic options including those under clinical trials, for treatment of AD. The challenges involved in AD therapy and the way forward have also been discussed.

Brain Targeting Nanomedicines: Pitfalls and Promise

Brain diseases are the most devastating problem among the world's increasingly aging population, and the number of patients with neurological diseases is expected to increase in the future. Although methods for delivering drugs to the brain have advanced significantly, none of these approaches provide satisfactory results for the treatment of brain diseases. This remains a challenge due to the unique anatomy and physiology of the brain, including tight regulation and limited access of substances across the blood-brain barrier. Nanoparticles are considered an ideal drug delivery system to hard-to-reach organs such as the brain. The development of new drugs and new nanomaterial-based brain treatments has opened various opportunities for scientists to develop brain-specific delivery systems that could improve treatment outcomes for patients with brain disorders such as Alzheimer's disease, Parkinson's disease, stroke and brain tumors. In this review, we discuss noteworthy literature that examines recent developments in brain-targeted nanomedicines used in the treatment of neurological diseases.

Functionalized nanoparticles to deliver nucleic acids to the brain for the treatment of Alzheimer's disease

Brain-targeted gene delivery across the blood-brain barrier (BBB) is a significant challenge in the 21st century for the healthcare sector, particularly in developing an effective treatment strategy against Alzheimer's disease (AD). The Internal architecture of the brain capillary endothelium restricts bio-actives entry into the brain. Additionally, therapy with nucleic acids faces challenges like vulnerability to degradation by nucleases and potential immune responses. Functionalized nanocarrier-based gene delivery approaches have resulted in safe and effective platforms. These nanoparticles (NPs) have demonstrated efficacy in protecting nucleic acids from degradation, enhancing transport across the BBB, increasing bioavailability, prolonging circulation time, and regulating gene expression of key proteins involved in AD pathology. We provided a detailed review of several nanocarriers and targeting ligands such as cell-penetrating peptides (CPPs), endogenous proteins, and antibodies. The utilization of functionalized NPs extends beyond a singular system, serving as a versatile platform for customization in related neurodegenerative diseases. Only a few numbers of bioactive regimens can go through the BBB. Thus, exploring functionalized NPs for brain-targeted gene delivery is of utmost necessity. Currently, genes are considered high therapeutic potential molecules for altering any disease-causing gene. Through surface modification, nanoparticulate systems can be tailored to address various diseases by replacing the target-specific molecule on their surface. This review article presents several nanoparticulate delivery systems, such as lipid NPs, polymeric micelles, exosomes, and polymeric NPs, for nucleic acids delivery to the brain and the functionalization strategies explored in AD research.

Cell-Penetrating Peptides: Promising Therapeutics and Drug-Delivery Systems for Neurodegenerative Diseases

Currently, one of the most significant and rapidly growing unmet medical challenges is the treatment of neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD). This challenge encompasses the imperative development of efficacious therapeutic agents and overcoming the intricacies of the blood-brain barrier for successful drug delivery. Here we focus on the delivery aspect with particular emphasis on cell-penetrating peptides (CPPs), widely used in basic and translational research as they enhance drug delivery to challenging targets such as tissue and cellular compartments and thus increase therapeutic efficacy. The combination of CPPs with nanomaterials such as nanoparticles (NPs) improves the performance, accuracy, and stability of drug delivery and enables higher drug loads. Our review presents and discusses research that utilizes CPPs, either alone or in conjugation with NPs, to mitigate the pathogenic effects of neurodegenerative diseases with particular reference to AD and PD.

How Precise are Nanomedicines in Overcoming the Blood-Brain Barrier? A Comprehensive Review of the Literature

New nanotechnology strategies for enhancing drug delivery in brain disorders have recently received increasing attention from drug designers. The treatment of neurological conditions, including brain tumors, stroke, Parkinson's Disease (PD), and Alzheimer's disease (AD), may be greatly influenced by nanotechnology. Numerous studies on neurodegeneration have demonstrated the effective application of nanomaterials in the treatment of brain illnesses. Nanocarriers (NCs) have made it easier to deliver drugs precisely to where they are needed. Thus, the most effective use of nanomaterials is in the treatment of various brain diseases, as this amplifies the overall impact of medication and emphasizes the significance of nanotherapeutics through gene therapy, enzyme replacement therapy, and blood-barrier mechanisms. Recent advances in nanotechnology have led to the development of multifunctional nanotherapeutic agents, a promising treatment for brain disorders. This novel method reduces the side effects and improves treatment outcomes. This review critically assesses efficient nano-based systems in light of obstacles and outstanding achievements. Nanocarriers that transfer medications across the blood-brain barrier and nano-assisted therapies, including nano-immunotherapy, nano-gene therapy, nano enzyme replacement therapy, scaffolds, and 3D to 6D printing, have been widely explored for the treatment of brain disorders. This study aimed to evaluate existing literature regarding the use of nanotechnology in the development of drug delivery systems that can penetrate the blood-brain barrier (BBB) and deliver therapeutic agents to treat various brain disorders.

Extending dual-targeting upper-limit in liposomal delivery of lithospermic acid B for Alzheimer's mitochondrial revitalization

Mitochondrial dysfunction is a pivotal event in Alzheimer's disease (AD) pathogenesis. Lithospermic acid B (LA) has shown promise in safeguarding mitochondria, yet the underlying mechanism remains elusive. Here, we present evidence that LA rejuvenated AD-related mitochondrial pool by co-activating mitophagy and mitochondria biogenesis via PINK1/LC3B/P62 and PGC-1α/Nrf2. To advance in vivo application, hydrophilic LA was encapsulated in liposome (MT-LIP@LA) composed of D-mannosamine-cholesterol/DSPE-PEG2000-Tet1/lecithin (molar ratio, 3:0.3:10) for cascaded brain-neuron targeting. MT-LIP demonstrated 4.3-fold enhanced brain accumulation (2.57%dose/g-brain) than LIP (0.60%dose/g-brain) and precisely targeted neurons at AD lesion sites. Mechanism studies unraveled factors contributing to the preeminent brain targeting ability of MT-LIP: (1) high-density modified mannose efficiently binds to glucose transporter 1 (GLUT1) on blood-brain barrier (BBB); (2) prone to trafficking towards caveolin-Golgi pathway during transcytosis. This augmented therapeutic platform efficiently restored mitochondrial health, prevented neurodegeneration, and ameliorated memory deficits in 3 × Tg-AD transgenic mice. Our studies revealed the underlying pharmacological mechanism of LA and provided a concise but efficient platform for neuronal mitochondria quality control in vivo.

Innovative Genoceuticals in Human Gene Therapy Solutions: Challenges and Safe Clinical Trials of Orphan Gene Therapy Products

The success of gene therapy attempts is controversial and inconclusive. Currently, it is popular among the public, the scientific community, and manufacturers of Gene Therapy Medical Products. In the absence of any remedy or treatment options available for untreatable inborn metabolic orphan or genetic diseases, cancer, or brain diseases, gene therapy treatment by genoceuticals and T-cells for gene editing and recovery remains the preferred choice as the last hope. A new concept of "Genoceutical Gene Therapy" by using orphan 'nucleic acid-based therapy' aims to introduce scientific principles of treating acquired tissue damage and rare diseases. These Orphan Genoceuticals provide new scope for the 'genodrug' development and evaluation of genoceuticals and gene products for ideal 'gene therapy' use in humans with marketing authorization application (MAA). This perspective study focuses on the quality control, safety, and efficacy requirements of using 'nucleic acid-based and human cell-based new gene therapy' genoceutical products to set scientific advice on genoceutical-based 'orphan genodrug' design for clinical trials as per Western and European guidelines. The ethical Western FDA and European EMA guidelines suggest stringent legal and technical requirements on genoceutical medical products or orphan genodrug use for other countries to frame their own guidelines. The introduction section proposes lessknown 'orphan drug-like' properties of modified RNA/DNA, human cell origin gene therapy medical products, and their transgene products. The clinical trial section explores the genoceutical sources, FDA/EMA approvals for genoceutical efficacy criteria with challenges, and ethical guidelines relating to gene therapy of specific rare metabolic, cancer and neurological diseases. The safety evaluation of approved genoceuticals or orphan drugs is highlighted with basic principles and 'genovigilance' requirements (to observe any adverse effects, side effects, developed signs/symptoms) to establish their therapeutic use. Current European Union and Food and Drug Administration guidelines continuously administer fast-track regulatory legal framework from time to time, and they monitor the success of gene therapy medical product efficacy and safety. Moreover, new ethical guidelines on 'orphan drug-like genoceuticals' are updated for biodistribution of the vector, genokinetics studies of the transgene product, requirements for efficacy studies in industries for market authorization, and clinical safety endpoints with their specific concerns in clinical trials or public use.

Single and Multitarget Systems for Drug Delivery and Detection: Up-to-Date Strategies for Brain Disorders

This review summarizes the recent findings on the development of different types of single and multitarget nanoparticles for disease detection and drug delivery to the brain, focusing on promising active principles encapsulated and nanoparticle surface modification and functionalization. Functionalized nanoparticles have emerged as promising tools for the diagnosis and treatment of brain disorders, offering a novel approach to addressing complex neurological challenges. They can act as drug delivery vehicles, transporting one or multiple therapeutic agents across the blood-brain barrier and precisely releasing them at the site of action. In diagnostics, functionalized nanoparticles can serve as highly sensitive contrast agents for imaging techniques such as magnetic resonance imaging and computed tomography scans. By attaching targeting ligands to the nanoparticles, they can selectively accumulate in the affected areas of the brain, enhancing the accuracy of disease detection. This enables early diagnosis and monitoring of conditions like Alzheimer's or Parkinson's diseases. While the field is still evolving, functionalized nanoparticles represent a promising path for advancing our ability to diagnose and treat brain disorders with greater precision, reduced invasiveness, and improved therapeutic outcomes.

A Promising Approach: Magnetic Nanosystems for Alzheimer's Disease Theranostics

Among central nervous system (CNS) disorders, Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder and a major cause of dementia worldwide. The yet unclear etiology of AD and the high impenetrability of the blood-brain barrier (BBB) limit most therapeutic compounds from reaching the brain. Although many efforts have been made to effectively deliver drugs to the CNS, both invasive and noninvasive strategies employed often come with associated side effects. Nanotechnology-based approaches such as nanoparticles (NPs), which can act as multifunctional platforms in a single system, emerged as a potential solution for current AD theranostics. Among these, magnetic nanoparticles (MNPs) are an appealing strategy since they can act as contrast agents for magnetic resonance imaging (MRI) and as drug delivery systems. The nanocarrier functionalization with specific moieties, such as peptides, proteins, and antibodies, influences the particles' interaction with brain endothelial cell constituents, facilitating transport across the BBB and possibly increasing brain penetration. In this review, we introduce MNP-based systems, combining surface modifications with the particles' physical properties for molecular imaging, as a novel neuro-targeted strategy for AD theranostics. The main goal is to highlight the potential of multifunctional MNPs and their advances as a dual nanotechnological diagnosis and treatment platform for neurodegenerative disorders.

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.

Non-Invasive Intranasal Delivery of pApoE2: Effect of Multiple Dosing on the ApoE2 Expression in Mice Brain

Chitosan-based polymeric micelles are promising non-viral nanocarriers for safe and targeted gene delivery. Multi-functionalized chitosan polymeric micelles were prepared by grafting fatty acid, cell-penetrating peptide, and mannose on the chitosan backbone. The polymeric micelles were subjected to surface morphology and surface topography using scanning electron microscopy and atomic force microscopy, respectively. The hemotoxic profile of the prepared polymeric micelles was established against erythrocytes and was found to be <5% hemotoxic up to the concentration of 600 µg/mL. In vitro ApoE2 expression in primary astrocytes and neurons was analyzed. Multi-functionalized polymeric micelles produced greater (p < 0.05) transfection in astrocytes and neurons in comparison to mono-functionalized micelles. Intranasal administration of polymeric micelles/pApoE2 polyplex led to significantly higher (p < 0.05) in vivo pApoE2 expression than chitosan and unfunctionalized polymeric micelles-treated mice groups. The outcomes of this study predict that the developed multi-functionalized polymeric micelles could be an effective and safe gene delivery platform to the brain through the intranasal route.

Nanomedicine strategies for central nervous system (CNS) diseases

The blood-brain barrier (BBB) is a crucial part of brain anatomy as it is a specialized, protective barrier that ensures proper nutrient transport to the brain, ultimately leading to regulating proper brain function. However, it presents a major challenge in delivering pharmaceuticals to treat central nervous system (CNS) diseases due to this selectivity. A variety of different vehicles have been designed to deliver drugs across this barrier to treat neurodegenerative diseases, greatly impacting the patient's quality of life. The two main types of vehicles used to cross the BBB are polymers and liposomes, which both encapsulate pharmaceuticals to allow them to transcytose the cells of the BBB. For Alzheimer's disease, Parkinson's disease, multiple sclerosis, and glioblastoma brain cancer, there are a variety of different nanoparticle treatments in development that increase the bioavailability and targeting ability of existing drugs or new drug targets to decrease symptoms of these diseases. Through these systems, nanomedicine offers a new way to target specific tissues, especially for the CNS, and treat diseases without the systemic toxicity that often comes with medications used currently.

Levodopa-loaded nanoparticles for the treatment of Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disorder characterized by degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNpc) resulting in dopamine (DA) deficiency, which manifests itself in motor symptoms including tremors, rigidity and bradykinesia. Current PD treatments aim at symptom reduction through oral delivery of levodopa (L-DOPA), a precursor of DA. However, L-DOPA delivery to the brain is inefficient and increased dosages are required as the disease progresses, resulting in serious side effects like dyskinesias. To improve PD treatment efficacy and to reduce side effects, recent research focuses on the encapsulation of L-DOPA into polymeric- and lipid-based nanoparticles (NPs). These formulations can protect L-DOPA from systemic decarboxylation into DA and improve L-DOPA delivery to the central nervous system. Additionally, NPs can be modified with proteins, peptides and antibodies specifically targeting the blood-brain barrier (BBB), thereby reducing required dosages and free systemic DA. Alternative delivery approaches for NP-encapsulated L-DOPA include intravenous (IV) administration, transdermal delivery using adhesive patches and direct intranasal administration, facilitating increased therapeutic DA concentrations in the brain. This review provides an overview of the recent advances for NP-mediated L-DOPA delivery to the brain, and debates challenges and future perspectives on the field.

Non-viral approaches for gene therapy and therapeutic genome editing across the blood-brain barrier

The success of brain-targeted gene therapy and therapeutic genome editing hinges on the efficient delivery of biologics bypassing the blood-brain barrier (BBB), which presents a significant challenge in the development of treatments for central nervous system disorders. This is particularly the case for nucleic acids and genome editors that are naturally excluded by the BBB and have poor chemical stability in the bloodstream and poor cellular uptake capability, thereby requiring judiciously designed nanovectors administered systemically for intracellular delivery to brain cells such as neurons. To overcome this obstacle, various strategies for bypassing the BBB have been developed in recent years to deliver biologics to the brain via intravenous administration using non-viral vectors. This review summarizes various brain targeting strategies and recent representative reports on brain-targeted non-viral delivery systems that allow gene therapy and therapeutic genome editing via intravenous administration, and highlights ongoing challenges and future perspectives for systemic delivery of biologics to the brain via non-viral vectors.

Nanoparticle-Based Drug Delivery Systems: An Inspiring Therapeutic Strategy for Neurodegenerative Diseases

Neurodegenerative diseases are common, incurable neurological disorders with high prevalence, and lead to memory, movement, language, and intelligence impairments, threatening the lives and health of patients worldwide. The blood-brain barrier (BBB), a physiological barrier between the central nervous system and peripheral blood circulation, plays an important role in maintaining the homeostasis of the intracerebral environment by strictly regulating the transport of substances between the blood and brain. Therefore, it is difficult for therapeutic drugs to penetrate the BBB and reach the brain, and this affects their efficacy. Nanoparticles (NPs) can be used as drug transport carriers and are also known as nanoparticle-based drug delivery systems (NDDSs). These systems not only increase the stability of drugs but also facilitate the crossing of drugs through the BBB and improve their efficacy. In this article, we provided an overview of the types and administration routes of NPs, highlighted the preclinical and clinical studies of NDDSs in neurodegenerative diseases, and summarized the combined therapeutic strategies in the management of neurodegenerative diseases. Finally, the prospects and challenges of NDDSs in recent basic and clinical research were also discussed. Above all, NDDSs provide an inspiring therapeutic strategy for the treatment of neurodegenerative diseases.

Extracellular vesicle-based delivery of silencing sequences for the treatment of Machado-Joseph disease/spinocerebellar ataxia type 3

Machado-Joseph disease (MJD)/spinocerebellar ataxia type 3 (SCA3) is the most common autosomal dominantly inherited ataxia worldwide. It is caused by an over-repetition of the trinucleotide CAG within the ATXN3 gene, which confers toxic properties to ataxin-3 (ATXN3) species. RNA interference technology has shown promising therapeutic outcomes but still lacks a non-invasive delivery method to the brain. Extracellular vesicles (EVs) emerged as promising delivery vehicles due to their capacity to deliver small nucleic acids, such as microRNAs (miRNAs). miRNAs were found to be enriched into EVs due to specific signal motifs designated as ExoMotifs. In this study, we aimed at investigating whether ExoMotifs would promote the packaging of artificial miRNAs into EVs to be used as non-invasive therapeutic delivery vehicles to treat MJD/SCA3. We found that miRNA-based silencing sequences, associated with ExoMotif GGAG and ribonucleoprotein A2B1 (hnRNPA2B1), retained the capacity to silence mutant ATXN3 (mutATXN3) and were 3-fold enriched into EVs. Bioengineered EVs containing the neuronal targeting peptide RVG on the surface significantly decreased mutATXN3 mRNA in primary cerebellar neurons from MJD YAC 84.2 and in a novel dual-luciferase MJD mouse model upon daily intranasal administration. Altogether, these findings indicate that bioengineered EVs carrying miRNA-based silencing sequences are a promising delivery vehicle for brain therapy.

Selective neurodegeneration generated by intravenous α-synuclein pre-formed fibril administration is not associated with endogenous α-synuclein levels in the rat brain

Selective loss of discrete neuronal populations is a prominent feature of many neurodegenerative conditions, but the molecular basis of this is poorly understood. A central role of α-synuclein in the selective neurodegeneration of Parkinson's disease has been speculated, as its level of expression critically determines the propensity of this protein to misfold. To investigate whether the propensity of neuronal cell loss is associated with the level of endogenous α-synuclein expression, non-transgenic rats were given a single intravenous administration of α-synuclein pre-formed fibrils (PFFs) reversibly complexed with the rabies virus glycoprotein peptide (RVG9R). The number of surviving cells in different neuronal populations was systematically quantified using unbiased stereology. Our data demonstrated that a non-selective, transvascular delivery of α-synuclein PFFs led to a time-dependent loss of specific populations of midbrain (but not olfactory) dopaminergic neurons, medullary (but not pontine) cholinergic neurons, and brainstem serotonergic neurons. Contrary to the central role of endogenous α-synuclein expression in determining the seeding and aggregation propensity of pathological α-synuclein, we did not observe an association between the levels of α-synuclein expression in different regions of the rodent brain (although did not ascertain this at the individual cell level) and neurodegenerative propensity. The results from our study highlight the complexity of the neurodegenerative process generated by α-synuclein seeding. Further investigations are therefore required to elucidate the molecular basis of neurodegeneration driven by exogenous pathogenic α-synuclein spread.

Multifunctionalized Cationic Chitosan Polymeric Micelles Polyplexed with pVGF for Noninvasive Delivery to the Mouse Brain through the Intranasal Route for Developing Therapeutics for Alzheimer's Disease

Multifunctionalized Chitosan-based polymeric micelles were used to deliver pVGF to the brain. VGF (non-acronymic) plays significant roles in neurogenesis and learning as well as synaptic and cognitive functions. Therefore, VGF gene therapy could be a better approach in developing effective therapeutics against Alzheimer's disease. Multifunctionalized chitosan polymeric micelles were developed by grafting oleic acid (OA) on the chitosan (CS) skeleton followed by penetratin (PEN) and mannose (MAN) conjugation. The OA-g-CS-PEN-MAN graft polymer formed cationic nanomicelles in an aqueous medium and polyplexed with pVGF. The polymeric micelles were nontoxic and cationic in charge and had an average hydrodynamic diameter of 199.8 ± 15.73 nm. Qualitative in vitro transfection efficiency of OA-g-CS-PEN-MAN/pGFP polyplex was investigated in bEnd.3, primary neurons, and astrocyte cells. In vivo transfection efficiency of OA-g-CS-PEN-MAN/pVGF polyplexes was analyzed in C57BL6/J mice after intranasal administration for 7 days. The VGF expression levels in primary astrocytes and neurons after OA-g-CS-PEN-MAN/pVGF treatment were 2.4 ± 0.24 and 1.49 ± 0.02 pg/μg of protein, respectively. The VGF expression in the OA-g-CS-PEN-MAN/pVGF polyplex-treated animal group was 64.9 ± 12.7 pg/mg of protein, significantly higher (p < 0.01) than that of the unmodified polymeric micelles. The in vivo transfection outcomes revealed that the developed multifunctionalized OA-g-CS-PEN-MAN polymeric micelles could effectively deliver pVGF to the brain, transfect brain cells, and express VGF in the brain after noninvasive intranasal administration.

A New Strategy for Nucleic Acid Delivery and Protein Expression Using Biocompatible Nanohydrogels of Predefined Sizes

We have developed new formulations of nanohydrogels (NHGs) complexed with DNA devoid of cell toxicity, which, together with their tuned sizes, makes them of great interest for delivering DNA/RNA for foreign protein expression. Transfection results demonstrate that, unlike classical lipo/polyplexes, the new NHGs can be incubated indefinitely with cells without apparent cellular toxicity, resulting in the high expression of foreign proteins for long periods of time. Although protein expression starts with a delay as compared to classical systems, it is sustained for a long period of time, even after passing cells without observation of toxicity. A fluorescently labelled NHG used for gene delivery was detected inside cells very early after incubation, but the protein expression was delayed by many days, demonstrating that there is a time-dependent release of genes from the NHGs. We suggest that this delay is due to the slow but continuous release of DNA from the particles concomitantly with slow but continuous protein expression. Additionally, results obtained after the in vivo administration of m-Cherry/NHG complexes indicated a delayed but prolonged expression of the marker gene in the tissue of administration. Overall, we have demonstrated gene delivery and foreign protein expression using GFP and m-Cherry marker genes complexed with biocompatible nanohydrogels.

Brain-targeted delivery of losartan through functionalized liposomal nanoparticles for management of neurogenic hypertension

There is mounting experimental evidence that blocking angiotensin receptor type 1 activity can prevent the occurrence of hypertension in spontaneously hypertensive rats. Studies have proved this strategy via evasive means, such as intracerebrovascular injections, making clinical translation difficult. This study aimed to develop penetratin and transferrin functionalized liposomes as a delivery tool to safely deliver losartan potassium (an angiotensin receptor blocker) to the brain. Penetratin and transferrin functionalized losartan-loaded liposomes were prepared via the post-insertion technique. Losartan-loaded liposomes were cationic, approximately 150 nm in size, entrapping 66.8 ± 1.5% of losartan. All formulations were well tolerated and internalized by primary and cultured cells in 4 hours. Further, the ability to deliver losartan potassium across the blood-brain barrier was evaluated in vivo in Wistar Kyoto rats either in solution or when encapsulated within liposomal nanoparticles. Upon intravenous administration, we did not find a detectable amount of losartan in the brain tissue of rats that received free losartan solution. Contrary, liposome formulations could deliver losartan to the brain, with a brain AUC and mean resident time of 163.304 ± 13.09 and 8.623 h ± 0.66, respectively. In addition, no toxicity was observed in the animals that received the losartan-loaded liposomes.

Endothelial Dysfunction in Neurodegenerative Diseases

The cerebral vascular system stringently regulates cerebral blood flow (CBF). The components of the blood-brain barrier (BBB) protect the brain from pathogenic infections and harmful substances, efflux waste, and exchange substances; however, diseases develop in cases of blood vessel injuries and BBB dysregulation. Vascular pathology is concurrent with the mechanisms underlying aging, Alzheimer's disease (AD), and vascular dementia (VaD), which suggests its involvement in these mechanisms. Therefore, in the present study, we reviewed the role of vascular dysfunction in aging and neurodegenerative diseases, particularly AD and VaD. During the development of the aforementioned diseases, changes occur in the cerebral blood vessel morphology and local cells, which, in turn, alter CBF, fluid dynamics, and vascular integrity. Chronic vascular inflammation and blood vessel dysregulation further exacerbate vascular dysfunction. Multitudinous pathogenic processes affect the cerebrovascular system, whose dysfunction causes cognitive impairment. Knowledge regarding the pathophysiology of vascular dysfunction in neurodegenerative diseases and the underlying molecular mechanisms may lead to the discovery of clinically relevant vascular biomarkers, which may facilitate vascular imaging for disease prevention and treatment.

Neurogenic Hypertension, the Blood-Brain Barrier, and the Potential Role of Targeted Nanotherapeutics

Hypertension is a major health concern globally. Elevated blood pressure, initiated and maintained by the brain, is defined as neurogenic hypertension (NH), which accounts for nearly half of all hypertension cases. A significant increase in angiotensin II-mediated sympathetic nervous system activity within the brain is known to be the key driving force behind NH. Blood pressure control in NH has been demonstrated through intracerebrovascular injection of agents that reduce the sympathetic influence on cardiac functions. However, traditional antihypertensive agents lack effective brain permeation, making NH management extremely challenging. Therefore, developing strategies that allow brain-targeted delivery of antihypertensives at the therapeutic level is crucial. Targeting nanotherapeutics have become popular in delivering therapeutics to hard-to-reach regions of the body, including the brain. Despite the frequent use of nanotherapeutics in other pathological conditions such as cancer, their use in hypertension has received very little attention. This review discusses the underlying pathophysiology and current management strategies for NH, as well as the potential role of targeted therapeutics in improving current treatment strategies.