GLUT-1: An Effective Target To Deliver Brain-Derived Neurotrophic Factor Gene Across the Blood Brain Barrier

Insights into 2D and 3D cell culture models for nanoparticle-based drug delivery to glioblastoma

Glioblastoma (GBM) remains a formidable challenge due to its aggressive nature, protected location within the brain, and resistance to conventional treatments. Its complex tumor microenvironment (TME), coupled with the blood-brain barrier (BBB), hinders drug delivery leading to poor treatment outcomes. Nanoparticles (NPs) offer a promising solution, as they can improve the pharmacokinetic properties of anticancer agents. By functionalizing NPs with targeting molecules, researchers aim to enhance drug concentration in the brain. However, developing effective NP-based therapies requires robust in vitro models that accurately capture the complexities of GBM. Two-dimensional (2D) and three-dimensional (3D) cell culture models provide a versatile platform for studying NP-cell interactions. By customizing cell types, incorporating TME components, and adjusting flow conditions, researchers can tailor these models to specific research questions. While 2D models offer a simpler starting point, 3D models, such as multicellular spheroids and organoids, can more accurately replicate the complex TME, including the BBB and tumor heterogeneity. These models enable a more comprehensive evaluation of NP efficacy and safety, ultimately accelerating drug development and reducing reliance on animal testing.

Intravenous Nanoemulsions Loaded with Phospholipid Complex of a Novel Pyrazoloquinolinone Ligand for Enhanced Brain Delivery

Background/Objectives: The novel pyrazoloquinolinone ligand CW-02-79 shows a unique profile of selective binding to σ2 receptors, but its poor solubility in both water and lipids makes its research and development a burdensome task. We aimed to develop a phospholipid-complex-based nanoemulsion formulation containing CW-02-79 suitable for intravenous administration in preclinical research. Methods: The decorated and undecorated nanoemulsions were formulated and subjected to detailed physiochemical characterization. The delivery and exposure to CW-02-79 from selected nanoemulsions were examined in the in vitro blood-brain barrier model based on human-induced pluripotent stem-cell-derived microvascular endothelial cells, astrocytes, and pericytes, and in vivo neuropharmacokinetic study in rats, respectively. Results: The developed biocompatible nanoemulsions loaded with a CW-02-79-phospholipid complex at a mass ratio of 1:10 exhibited a small droplet size and narrow size distribution, with satisfactory physicochemical stability during steam sterilization and short-term storage at 25 °C. The analysis of protein binding interactions revealed that the PEGylated nanoemulsions had fewer observable interactions compared to the undecorated nanoemulsions, especially when 0.2% DSPE-PEG2000 and 0.1% DSPE-PEG2000-mannose were combined. An in vitro BBB study demonstrated that a substantial part of CW-02-79 present in the applied nanoemulsion is able to permeate the barrier. The quantification of CW-02-79 in plasma/brain homogenate and calculated pharmacokinetic parameters confirmed good systemic and brain availability after intravenous administration. There were subtle differences in the pharmacokinetic parameters in favor of a dual surface-functionalized nanoemulson containing the glucose transporter-1-targeting ligand (mannose). Conclusions: The developed and characterized nanoemulsions enable substantial brain exposure to CW-02-79 as a prerequisite for a pharmacologically and clinically relevant selective modulation of σ2 receptors.

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.

Drug Delivery Across the Blood-Brain Barrier: A New Strategy for the Treatment of Neurological Diseases

The blood-brain barrier (BBB) serves as a highly selective barrier between the blood and the central nervous system (CNS), and its main function is to protect the brain from foreign substances. This physiological property plays a crucial role in maintaining CNS homeostasis, but at the same time greatly limits the delivery of drug molecules to the CNS, thus posing a major challenge for the treatment of neurological diseases. Given that the high incidence and low cure rate of neurological diseases have become a global public health problem, the development of effective BBB penetration technologies is important for enhancing the efficiency of CNS drug delivery, reducing systemic toxicity, and improving the therapeutic outcomes of neurological diseases. This review describes the physiological and pathological properties of the BBB, as well as the current challenges of trans-BBB drug delivery, detailing the structural basis of the BBB and its role in CNS protection. Secondly, this paper reviews the drug delivery strategies for the BBB in recent years, including physical, biological and chemical approaches, as well as nanoparticle-based delivery technologies, and provides a comprehensive assessment of the effectiveness, advantages and limitations of these delivery strategies. It is hoped that the review in this paper will provide valuable references and inspiration for future researchers in therapeutic studies of neurological diseases.

Irisin: A Multifaceted Hormone Bridging Exercise and Disease Pathophysiology

The fibronectin domain-containing protein 5 (FNDC5), or irisin, is an adipo-myokine hormone produced during exercise, which shows therapeutic potential for conditions like metabolic disorders, osteoporosis, sarcopenia, obesity, type 2 diabetes, and neurodegenerative diseases, including Alzheimer's disease (AD). This review explores its potential across various pathophysiological processes that are often considered independent. Elevated in healthy states but reduced in diseases, irisin improves muscle-adipose communication, insulin sensitivity, and metabolic balance by enhancing mitochondrial function and reducing oxidative stress. It promotes osteogenesis and mitigates bone loss in osteoporosis and sarcopenia. Irisin exhibits anti-inflammatory effects by inhibiting NF-κB signaling and countering insulin resistance. In the brain, it reduces amyloid-β toxicity, inflammation, and oxidative stress, enhancing brain-derived neurotrophic factor (BDNF) signaling, which improves cognition and synaptic health in AD models. It also regulates dopamine pathways, potentially alleviating neuropsychiatric symptoms like depression and apathy. By linking physical activity to systemic health, irisin emphasizes its role in the muscle-bone-brain axis. Its multifaceted benefits highlight its potential as a therapeutic target for AD and related disorders, with applications in prevention, in treatment, and as a complement to exercise strategies.

The piper at the gates of brain: A systematic review of surface modification strategies on lipid nanoparticles to overcome the Blood-Brain-Barrier

The Blood-Brain Barrier (BBB) significantly impedes drug delivery to the central nervous system. Nanotechnology, especially surface-functionalized lipid nanoparticles, offers innovative approaches to overcome this barrier. However, choosing an effective functionalization strategy is challenging due to the lack of detailed comparative analysis in current literature. Our systematic review examined various functionalization strategies and their impact on BBB permeability from 2041 identified articles, of which 80 were included for data extraction. Peptides were the most common modification (18) followed by mixed strategies (12) proteins (9), antibodies (7), and other strategies (8). Interestingly, 26 studies showed BBB penetration with unmodified or modified nanoparticles using commonly applied strategies such as PEGylation or surfactant addition. Statistical analysis across 42 studies showed correlation between higher in vivo permeation improvements and nanoparticle type, size, and functionalization category. The highest ratios were found for nanostructured lipid carriers or biomimetic systems, in studies with particle sizes under 150 nm, and in those applying mixed functionalization strategies. The interstudy heterogeneity we observed highlights the importance of adopting standardized evaluation protocols to enhance comparability. Our systematic review aims to provide a comparative insight and identify future research directions in the development of more effective lipid nanoparticle systems for drug delivery to the brain to help improve the treatment of neurological and psychiatric disorders and brain tumours.

Oxime Linked Doxorubicin Glycoconjugates Improve the Specific Targeting of Glioblastoma in High-Grade Glioma Therapy

The treatment of glioblastoma (GBM) represents an urgent challenge for public health due to the inability to effectively deliver anticancer agents, such as doxorubicin (DOX), through the blood-brain barrier (BBB). Herein we report the synthesis of two novel DOX glycoconjugates using an oxime linkage that maintained the intercalation capability of the planar anthracycline ring of DOX, as demonstrated by UV-vis and fluorescence experiments in the presence of DNA. The biological effect of DOX glycoconjugates was evaluated in GBM cell lines, showing an enhanced cytotoxic and pro-apoptotic effect of 7 as compared to 4 and to conventional DOX. These data were confirmed in an in vitro coculture BBB model in which DOX glycoconjugate 7 showed high capability to cross a cellular monolayer and exert its cytotoxic effect on GBM cells. The results show that conjugation with glucose may represent a helpful tool to increase chemotherapy effectiveness in poor-responding GBM patients.

Mannose-Functionalized Chitosan-Coated PLGA Nanoparticles for Brain-Targeted Codelivery of CBD and BDNF for the Treatment of Alzheimer's Disease

Alzheimer's disease (AD) is a common neurodegenerative disease causing cognitive and memory decline. AD is characterized by the deposition of amyloid-β and hypophosphorylated forms of tau protein. AD brains are found to be associated with neurodegeneration, oxidative stress, and inflammation. Cannabidiol (CBD) shows neuroprotective, antioxidant, and anti-inflammatory properties and simultaneously reduces amyloid-β production and tau hyperphosphorylation. The brain-derived neurotrophic factor (BDNF) plays a vital role in the development and maintenance of the plasticity of the central nervous system. A decline of BDNF levels in AD patients results in reduced plasticity and neuronal cell death. Current therapeutics against AD are limited to only symptomatic relief, necessitating a therapeutic strategy that reverses cognitive decline. In this scenario, combination therapy of CBD and BDNF could be a fruitful strategy for the treatment of AD. We designed mannose-conjugated chitosan-coated poly(d,l-lactide-co-glycolide (PLGA) (CHTMAN-PLGA) nanoparticles for the codelivery of CBD and BDNF to the brain. Chitosan is modified with mannose to specifically target the glucose transporter-1 (GLUT-1) receptor abundantly present in the blood-brain barrier for selectively delivering therapeutics to the brain. The CBD-encapsulated nanoparticles showed an average hydrodynamic diameter of 306 ± 8.12 nm and a zeta potential of 31.7 ± 1.53 mV. The coated nanoparticles prolonged encapsulated CBD release from the PLGA matrix. The coated nanoparticles exhibited sustained release of CBD for up to 22 days with 91.68 ± 2.91% release of the encapsulated drug. The coated nanoparticles, which had a high positive zeta potential (31.7 ± 1.53 mV), encapsulated the plasmid DNA. The qualitative transfection efficiency was investigated using CHTMAN-PLGA-CBD/pGFP in bEND.3, primary astrocytes, and primary neurons, while the quantitative transfection efficiency of the delivery system was determined using CHTMAN-PLGA-CBD/pBDNF. In vitro, the pBDNF transfection study revealed that the BDNF expression was 4-fold higher for CHTMAN-PLGA-CBD/pBDNF than for naked pBDNF in all of the cell lines. The cytotoxicity and hemocompatibility of the designed nanoparticles were tested in bEND.3 cells and red blood cells, respectively, and the nanoparticles were found to be nontoxic and hemocompatible. Hence, mannose-conjugated chitosan-coated PLGA nanoparticles could be useful as brain-targeting delivery vehicles for the codelivery of CBD and BDNF for possible AD treatment.

Targeting strategies with lipid vectors for nucleic acid supplementation therapy in Fabry disease: a systematic review

Fabry disease (FD) results from a lack of activity of the lysosomal enzyme α-Galactosidase A (α-Gal A), leading to the accumulation of glycosphingolipids in several different cell types. Protein supplementation by pDNA or mRNA delivery presents a promising strategy to tackle the underlying genetic defect in FD. Protein-coding nucleic acids in FD can be either delivered to the most affected sites by the disease, including heart, kidney and brain, or to specialized organs that can act as a production factory of the enzyme, such as the liver. Lipid-based systems are currently at the top of the ranking of non-viral nucleic acid delivery systems, and their versatility allows the linking to the surface of a wide range of molecules to control their biodistribution after intravenous administration. This systematic review follows the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement guidelines and provides an overview and discussion of the targeting ligands that have been employed so far to actively vectorize intravenously administered non-viral vectors based on lipid carriers to clinically relevant organs in the treatment of FD, for protein-coding nucleic acid (pDNA and mRNA) supplementation. Among the thirty-two studies included, the majority focus on targeting the liver and brain. The targeting of the heart has been reported to a lesser degree, whereas no articles addressing kidney-targeting have been recorded. Although a great effort has been made to develop organ-specific nucleic acid delivery systems, the design of active-targeted carriers with high quality, good clinical translation, and large-scale manufacturing capacity is still challenging.

Dual-targeting liposomes modified with BTP-7 and pHA for combined delivery of TCPP and TMZ to enhance the anti-tumour effect in glioblastoma cells

AIM

To construct a novel nano-carrier with dual ligands to achieve superior anti-tumour efficacy and lower toxic side effects.

METHODS

Liposomes were prepared by thin film hydration method. Ultraviolet, high performance liquid chromatography, nano-size analyser, ultrafiltration centrifugation, dialysis, transmission electron microscope, flow cytometry, Cell Counting Kit-8, confocal laser scanning microscopy, transwell, and tumorsphere assay were used to study the characterisations, cytotoxicity, and in vitro targeting of dg-Bcan targeting peptide (BTP-7)/pHA-temozolomide (TMZ)/tetra(4-carboxyphenyl)porphyrin (TCPP)-Lip.

RESULTS

BTP-7/pHA-TMZ/TCPP-Lip was a spheroid with a mean diameters of 143 ± 3.214 nm, a polydispersity index of 0.203 ± 0.025 and a surface charge of -22.8 ± 0.425 mV. The drug loadings (TMZ and TCPP) are 7.40 ± 0.23% and 2.05 ± 0.03% (mg/mg); and the encapsulation efficiencies are 81.43 ± 0.51% and 84.28 ± 1.64% (mg/mg). The results showed that BTP-7/pHA-TMZ/TCPP-Lip presented enhanced targeting and cytotoxicity.

CONCLUSION

BTP-7/pHA-TMZ/TCPP-Lip can specifically target the tumour cells to achieve efficient drug delivery, and improve the anti-tumour efficacy and reduces the systemic toxicity.

Systematic Review of Genetic Substrate Reduction Therapy in Lysosomal Storage Diseases: Opportunities, Challenges and Delivery Systems

BACKGROUND

Genetic substrate reduction therapy (gSRT), which involves the use of nucleic acids to downregulate the genes involved in the biosynthesis of storage substances, has been investigated in the treatment of lysosomal storage diseases (LSDs).

OBJECTIVE

To analyze the application of gSRT to the treatment of LSDs, identifying the silencing tools and delivery systems used, and the main challenges for its development and clinical translation, highlighting the contribution of nanotechnology to overcome them.

METHODS

A systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) reporting guidelines was performed. PubMed, Scopus, and Web of Science databases were used for searching terms related to LSDs and gene-silencing strategies and tools.

RESULTS

Fabry, Gaucher, and Pompe diseases and mucopolysaccharidoses I and III are the only LSDs for which gSRT has been studied, siRNA and lipid nanoparticles being the silencing strategy and the delivery system most frequently employed, respectively. Only in one recently published study was CRISPR/Cas9 applied to treat Fabry disease. Specific tissue targeting, availability of relevant cell and animal LSD models, and the rare disease condition are the main challenges with gSRT for the treatment of these diseases. Out of the 11 studies identified, only two gSRT studies were evaluated in animal models.

CONCLUSIONS

Nucleic acid therapies are expanding the clinical tools and therapies currently available for LSDs. Recent advances in CRISPR/Cas9 technology and the growing impact of nanotechnology are expected to boost the clinical translation of gSRT in the near future, and not only for LSDs.

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.

Myricetin Oligomer Triggers Multi-Receptor Mediated Penetration and Autophagic Restoration of Blood-Brain Barrier for Ischemic Stroke Treatment

Restoration of blood-brain barrier (BBB) dysfunction, which drives worse outcomes of ischemic stroke, is a potential target for therapeutic opportunities, whereas a sealed BBB blocks the therapeutics entrance into the brain, making the BBB protection strategy paradoxical. Post ischemic stroke, hypoxia/hypoglycemia provokes the up-regulation of transmembrane glucose transporters and iron transporters due to multiple metabolic disorders, especially in brain endothelial cells. Herein, we develop a myricetin oligomer-derived nanostructure doped with Ce to bypass the BBB which is cointermediated by glucose transporters and iron transporters such as glucose transporters 1 (GLUT1), sodium/glucose cotransporters 1 (SGLT1), and transferrin(Tf) reporter (TfR). Moreover, it exhibits BBB restoration capacity by regulating the expression of tight junctions (TJs) through the activation of protective autophagy. The myricetin oligomers scaffold not only acts as targeting moiety but is the prominent active entity that inherits all diverse pharmacological activities of myricetin. The suppression of oxidative damage, M1 microglia activation, and inflammatory factors makes it a multitasking nanoagent with a single component as the scaffold, targeting domain and curative components.

Effects of paracetamol/acetaminophen on the expression of solute carriers (SLCs) in late-gestation fetal rat brain, choroid plexus and the placenta

Solute carriers (SLCs) regulate transfer of a wide range of molecules across cell membranes using facilitative or secondary active transport. In pregnancy, these transporters, expressed at the placental barrier, are important for delivery of nutrients to the fetus, whilst also limiting entry of potentially harmful substances, such as drugs. In the present study, RNA-sequencing analysis was used to investigate expression of SLCs in the fetal (embryonic day 19) rat brain, choroid plexus and placenta in untreated control animals and following maternal paracetamol treatment. In the treated group, paracetamol (15 mg/kg) was administered to dams twice daily for 5 days (from embryonic day 15 to 19). In untreated animals, overall expression of SLCs was highest in the placenta. In the paracetamol treatment group, expression of several SLCs was significantly different compared with control animals, with ion, amino acid, neurotransmitter and sugar transporters most affected. The number of SLC transcripts that changed significantly following treatment was the highest in the choroid plexus and lowest in the brain. All SLC transcripts that changed in the placenta following paracetamol treatment were downregulated. These results suggest that administration of paracetamol during pregnancy could potentially disrupt fetal nutrient homeostasis and affect brain development, resulting in major consequences for the neonate and extending into childhood.

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.

Targeted strategies to deliver boron agents across the blood-brain barrier for neutron capture therapy of brain tumors

Boron neutron capture therapy (BNCT), as an innovative radiotherapy technology, has demonstrated remarkable outcomes when compared to conventional treatments in the management of recurrent and refractory brain tumors. However, in BNCT of brain tumors, the blood-brain barrier is a main stumbling block for restricting the transport of boron drugs to brain tumors, while the tumor targeting and retention of boron drugs also affect the BNCT effect. This review focuses on the recent development of strategies for delivering boron drugs crossing the blood-brain barrier and targeting brain tumors, providing new insights for the development of efficient boron drugs for the treatment of brain tumors.

Functionalized Nanomaterials Capable of Crossing the Blood-Brain Barrier

The blood-brain barrier (BBB) is a specialized semipermeable structure that highly regulates exchanges between the central nervous system parenchyma and blood vessels. Thus, the BBB also prevents the passage of various forms of therapeutic agents, nanocarriers, and their cargos. Recently, many multidisciplinary studies focus on developing cargo-loaded nanoparticles (NPs) to overcome these challenges, which are emerging as safe and effective vehicles in neurotheranostics. In this Review, first we introduce the anatomical structure and physiological functions of the BBB. Second, we present the endogenous and exogenous transport mechanisms by which NPs cross the BBB. We report various forms of nanomaterials, carriers, and their cargos, with their detailed BBB uptake and permeability characteristics. Third, we describe the effect of regulating the size, shape, charge, and surface ligands of NPs that affect their BBB permeability, which can be exploited to enhance and promote neurotheranostics. We classify typical functionalized nanomaterials developed for BBB crossing. Fourth, we provide a comprehensive review of the recent progress in developing functional polymeric nanomaterials for applications in multimodal bioimaging, therapeutics, and drug delivery. Finally, we conclude by discussing existing challenges, directions, and future perspectives in employing functionalized nanomaterials for BBB crossing.

Neuronanomedicine for Alzheimer's and Parkinson's disease: Current progress and a guide to improve clinical translation

Neuronanomedicine is an emerging multidisciplinary field that aims to create innovative nanotechnologies to treat major neurodegenerative disorders, such as Alzheimer's (AD) and Parkinson's disease (PD). A key component of neuronanomedicine are nanoparticles, which can improve drug properties and demonstrate enhanced safety and delivery across the blood-brain barrier, a major improvement on existing therapeutic approaches. In this review, we critically analyze the latest nanoparticle-based strategies to modify underlying disease pathology to slow or halt AD/PD progression. We find that a major roadblock for neuronanomedicine translation to date is a poor understanding of how nanoparticles interact with biological systems (i.e., bio-nano interactions), which is partly due to inconsistent reporting in published works. Accordingly, this review makes a set of specific recommendations to help guide researchers to harness the unique properties of nanoparticles and thus realise breakthrough treatments for AD/PD.

Overcoming challenges in glioblastoma treatment: targeting infiltrating cancer cells and harnessing the tumor microenvironment

Glioblastoma (GB) is a highly malignant primary brain tumor with limited treatment options and poor prognosis. Despite current treatment approaches, including surgical resection, radiation therapy, and chemotherapy with temozolomide (TMZ), GB remains mostly incurable due to its invasive growth pattern, limited drug penetration beyond the blood-brain barrier (BBB), and resistance to conventional therapies. One of the main challenges in GB treatment is effectively eliminating infiltrating cancer cells that remain in the brain parenchyma after primary tumor resection. We've reviewed the most recent challenges and surveyed the potential strategies aimed at enhancing local treatment outcomes.

Blood-cerebrospinal fluid barrier permeability of metals/metalloids and its determinants in pediatric patients

Concerns regarding adverse effects of metal/metalloids exposure on brain development and neurological disorders among children are increasing. However, the transport patterns of metals/metalloids across the blood-cerebrospinal fluid barrier (BCSFB) need to be clarified in children. A total of 99 Chinese pediatric patients were enrolled from February 2020 to August 2021, with a median age of 6.76 months. We detected 16 metal/metalloid levels in matched serum and cerebrospinal fluid (CSF) samples using inductively coupled plasma mass spectrometry. The BCSFB permeability of metals/metalloids were estimated and the potential effects of biomedical parameters were explored. Most metals/metalloids were detectable among > 80.0% of CSF samples. Significant correlations were observed between strontium (Sr, r = 0.46), molybdenum (Mo, r = 0.50), and cadmium (Cd, r = 0.24) concentrations in serum and CSF (P < 0.05). Ratios of metal/metalloid levels in CSF to serum (Rmetal) ranged from 0.02 to 0.74, and hazardous metals/metalloids including arsenic (As), Cd, lead (Pb), thallium (Tl), and manganese (Mn) showed high transfer efficiencies across the BCSFB (Rmetals > 0.5). With the adjustment of age and sex, albumin, β2-microglobulin, and total protein levels in CSF were positively associated with copper (Cu) permeability (FDR-adjusted P < 0.05), while glucose in CSF was negatively correlated with calcium (Ca), Cu, Sr, and Mo BCSFB permeability (FDR-adjusted P < 0.05). Q-Alb promoted Cu permeability across the BCSFB (FDR-adjusted P < 0.001), while C-reactive protein levels in serum were positively associated with selenium (Se) permeability (FDR-adjusted P = 0.046). For the first time, our findings provided data for the BCSFB permeability of 16 metals/metalloids in children, and indicated that some biomedical parameters could influence the transformation of metals/metalloids from serum to CSF. Metals/metalloids with strong BCSFB permeability warrant attention for their potential neurotoxicity.

RNAi therapies: Expanding applications for extrahepatic diseases and overcoming delivery challenges

The era of RNA medicine has become a reality with the success of messenger RNA (mRNA) vaccines against COVID-19 and the approval of several RNA interference (RNAi) agents in recent years. Particularly, therapeutics based on RNAi offer the promise of targeting intractable and previously undruggable disease genes. Recent advances have focused in developing delivery systems to enhance the poor cellular uptake and insufficient pharmacokinetic properties of RNAi therapeutics and thereby improve its efficacy and safety. However, such approach has been mainly achieved via lipid nanoparticles (LNPs) or chemical conjugation with N-Acetylgalactosamine (GalNAc), thus current RNAi therapy has been limited to liver diseases, most likely to encounter liver-targeting limitations. Hence, there is a huge unmet medical need for intense evolution of RNAi therapeutics delivery systems to target extrahepatic tissues and ultimately extend their indications for treating various intractable diseases. In this review, challenges of delivering RNAi therapeutics to tumors and major organs are discussed, as well as their transition to clinical trials. This review also highlights innovative and promising preclinical RNAi-based delivery platforms for the treatment of extrahepatic diseases.

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.

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.

Recent Advancements in Nanomaterials: A Promising Way to Manage Neurodegenerative Disorders

Neurodegenerative diseases (NDs) such as dementia, Alzheimer's disease, Parkinson's disease, frontotemporal dementia, and amyotrophic lateral sclerosis are some of the most prevalent disorders currently afflicting healthcare systems. Many of these diseases share similar pathological hallmarks, including elevated oxidative stress, mitochondrial dysfunction, protein misfolding, excitotoxicity, and neuroinflammation, all of which contribute to the deterioration of the nervous system's structure and function. The development of diagnostic and therapeutic materials in the monitoring and treatment of these diseases remains challenging. One of the biggest challenges facing therapeutic and diagnostic materials is the blood-brain barrier (BBB). The BBB is a multifunctional membrane possessing a plethora of biochemical, cellular, and immunological features that ensure brain homeostasis by preventing the entry and accumulation of unwanted compounds. With regards to neurodegenerative diseases, the recent application of tailored nanomaterials (nanocarriers and nanoparticles) has led to advances in diagnostics and therapeutics. In this review, we provide an overview of commonly used nanoparticles and their applications in NDs, which may offer new therapeutic strategies for the prevention and treatment of neurodegenerative diseases.

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.

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.

Molecular Heterogeneity of the Brain Endothelium

The blood-brain barrier (BBB) is part of a neurovascular structure located in the brain's micro vessels, that is essential to maintain brain homeostasis, but prevents the brain uptake of most drugs. Because of its importance in neuro-pharmacotherapy, the BBB has been the subject of extensive research since its discovery over 100 years ago. Major advances in understanding the structure and function of the barrier have been made. Drugs are re-designed to cross the BBB. However, despite these efforts, overcoming the BBB efficiently to treat brain diseases safely remains challenging. The majority of BBB research studies focus on the BBB as a homogenous structure throughout the different brain regions. However, this simplification may lead to an inadequate understanding of the BBB function with significant therapeutic consequences. From this perspective, we analyzed the gene and protein expression profiles of the BBB in the micro vessels from the brains of mice that were isolated from two different brain regions, namely the cortex and the hippocampus. The expression profile of the inter-endothelial junctional protein (claudin-5), three ABC transporters (P-glycoprotein, Bcrp and Mrp-1), and three BBB receptors (lrp-1, TRF and GLUT-1) were analyzed. Our gene and protein analysis showed that the brain endothelium in the hippocampus exhibits different expression profiles compared to the brain cortex. Specifically, brain endothelial cells (BECs) of the hippocampus express higher gene levels of abcb1, abcg2, lrp1, and slc2a1 compared to the BECs of the cortex regions with a trend of increase for claudin-5, while BECs of the cortex express higher gene levels of abcc1 and trf compared to the hippocampus. At the protein levels, the P-gp expression was found to be significantly higher in the hippocampus compared to the cortex, while TRF was found to be up-regulated in the cortex. These data suggest that the structure and function of the BBB are not homogeneous, and imply that drugs are not delivered similarly among the different brain regions. Appreciation of the BBB heterogeneity by future research programs is thus critical for efficient drug delivery and the treatment of brain diseases.

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.

Transferrin receptor 1 targeted nanomedicine for brain tumor therapy

Achieving effective drug delivery to traverse the blood-brain barrier (BBB) and target tumor cells remains the greatest challenge for brain tumor therapy. Importantly, the overexpressed membrane receptors on the brain endothelial cells, especially transferrin receptor 1 (TfR1), which mediate their ligands/antibodies to overcome the BBB by transcytosis, have been emerging as promising targets for brain tumor therapy. By employing ligands (e.g., transferrin, H-ferritin), antibodies or targeting peptides of TfR1 or aptamers, various functional nano-formulations have been developed in the last decade. These agents showed great potential for the treatment of brain diseases due to their ideal size, high loading capacity, controlled drug release and suitable pharmacokinetics. Herein, we summarize the latest advances on TfR1-targeted nanomedicine for brain tumor therapy. Moreover, we also discuss the strategies of improving stability, targeting ability and accumulation of nano-formulations in brain tumors for better outcomes. In this review, we hope to provide inspiration for the rational design of TfR1-targeted nanomedicine against brain tumors.

A Review on Recent Advances in Mannose-Functionalized Targeted Nanocarrier Delivery Systems in Cancer and Infective Therapeutics

Unmodified nanocarriers used in the chemotherapy of cancers and various infectious diseases exhibit prolonged blood circulation time, prevent enzymatic degradation and increase chemical stability of encapsulated therapeutics. However, off-target effect and lack of specificity associated with unmodified nanoparticles (NPs) limit their applications in the health care system. Mannose (Man) receptors with significant overexpression on antigen-presenting cells and macrophages are among the most admired targets for cancer and anti-infective therapeutics. Therefore, development of Man functionalized nanocarriers targeting Man receptors, for target specific drug delivery in the chemotherapy have been extensively studied. Present review expounds diverse Man-conjugated NPs with their potential for targeted drug delivery, improved biodistribution profiles and localization. Additionally, the review gives detailed account of the interactions of mannosylated NPs with various biological systems and their characterization not discussed in earlier published reports is discussed.

Applications of Nanoparticles in Alzheimer's Disease

With the rapid aging of the global population, the prevalence of neurodegenerative diseases has become a significant concern, with Alzheimer's disease (AD) being the most common. However, the clinical trials of many drugs targeting AD have failed due to the challenges posed by the blood-brain barrier (BBB), which makes intracerebral administration of drugs difficult. However, nanoparticles (NPs) may aid in the delivery of such drugs. NPs are materials with sizes between 1-100 nm that offer several advantages, such as improving biocompatibility, prolonging half-life, transporting large molecules, crossing the BBB to deliver to the central nervous system, and exhibiting good targeting ability. In addition to drug delivery, NPs also have excellent diagnostic potential, and multifunctional NPs can integrate the advantages of diagnosis, targeting, and treatment. This mini-review article provides an overview of NPs, including the composition of the carrier, strategies for crossing the BBB, and different targets of AD pathology, with the aim of providing guidance for the development prospects of NPs.

Peptides as Pharmacological Carriers to the Brain: Promises, Shortcomings and Challenges

Central nervous system (CNS) diseases are among the most difficult to treat, mainly because the vast majority of the drugs fail to cross the blood-brain barrier (BBB) or to reach the brain at concentrations adequate to exert a pharmacological activity. The obstacle posed by the BBB has led to the in-depth study of strategies allowing the brain delivery of CNS-active drugs. Among the most promising strategies is the use of peptides addressed to the BBB. Peptides are versatile molecules that can be used to decorate nanoparticles or can be conjugated to drugs, with either a stable link or as pro-drugs. They have been used to deliver to the brain both small molecules and proteins, with applications in diverse therapeutic areas such as brain cancers, neurodegenerative diseases and imaging. Peptides can be generally classified as receptor-targeted, recognizing membrane proteins expressed by the BBB microvessels (e.g., Angiopep2, CDX, and iRGD), "cell-penetrating peptides" (CPPs; e.g. TAT_47-57, SynB1/3, and Penetratin), undergoing transcytosis through unspecific mechanisms, or those exploiting a mixed approach. The advantages of peptides have been extensively pointed out, but so far few studies have focused on the potential negative aspects. Indeed, despite having a generally good safety profile, some peptide conjugates may display toxicological characteristics distinct from those of the peptide itself, causing for instance antigenicity, cardiovascular alterations or hemolysis. Other shortcomings are the often brief lifetime in vivo, caused by the presence of peptidases, the vulnerability to endosomal/lysosomal degradation, and the frequently still insufficient attainable increase of brain drug levels, which remain below the therapeutically useful concentrations. The aim of this review is to analyze not only the successful and promising aspects of the use of peptides in brain targeting but also the problems posed by this strategy for drug delivery.

Designed Multifunctional Peptides for Intracellular Targets

Nature’s way for bioactive peptides is to provide them with several related functions and the ability to cooperate in performing their job. Natural cell-penetrating peptides (CPP), such as penetratins, inspired the design of multifunctional constructs with CPP ability. This review focuses on known and novel peptides that can easily reach intracellular targets with little or no toxicity to mammalian cells. All peptide candidates were evaluated and ranked according to the predictions of low toxicity to mammalian cells and broad-spectrum activity. The final set of the 20 best peptide candidates contains the peptides optimized for cell-penetrating, antimicrobial, anticancer, antiviral, antifungal, and anti-inflammatory activity. Their predicted features are intrinsic disorder and the ability to acquire an amphipathic structure upon contact with membranes or nucleic acids. In conclusion, the review argues for exploring wide-spectrum multifunctionality for novel nontoxic hybrids with cell-penetrating peptides.

Machine learning for the micropeptide encoded by LINC02381 regulates ferroptosis through the glucose transporter SLC2A10 in glioblastoma

Glioblastoma (GBM) is the most common primary intracranial tumor in the central nervous system, and resistance to temozolomide is an important reason for the failure of GBM treatment. We screened out that Solute Carrier Family 2 Member 10 (SLC2A10) is significantly highly expressed in GBM with a poor prognosis, which is also enriched in the NF-E2 p45-related factor 2 (NRF2) signalling pathway. The NRF2 signalling pathway is an important defence mechanism against ferroptosis. SLC2A10 related LINC02381 is highly expressed in GBM, which is localized in the cytoplasm/exosomes, and LINC02381 encoded micropeptides are localized in the exosomes. The micropeptide encoded by LINC02381 may be a potential treatment strategy for GBM, but the underlying mechanism of its function is not precise yet. We put forward the hypothesis: “The micropeptide encoded by LINC02381 regulates ferroptosis through the glucose transporter SLC2A10 in GBM.” This study innovatively used machine learning for micropeptide to provide personalized diagnosis and treatment plans for precise treatment of GBM, thereby promoting the development of translational medicine. The study aimed to help find new disease diagnoses and prognostic biomarkers and provide a new strategy for experimental scientists to design the downstream validation experiments.

Lipid-based nanoparticles and RNA as innovative neuro-therapeutics

RNA-delivery is a promising tool to develop therapies for difficult to treat diseases such as neurological disorders, by silencing pathological genes or expressing therapeutic proteins. However, in many cases RNA delivery requires a vesicle that could effectively protect the molecule from bio-degradation, bypass barriers i.e., the blood brain barrier, transfer it to a targeted tissue and efficiently release the RNA inside the cells. Many vesicles such as viral vectors, and polymeric nanoparticles have been mentioned in literature. In this review, we focus in the discussion of lipid-based advanced RNA-delivery platforms. Liposomes and lipoplexes, solid lipid nanoparticles and lipid nanoparticles are the main categories of lipidic platforms for RNA-delivery to the central nervous systems (CNS). A variety of surface particles' modifications and routes of administration have been studied to target CNS providing encouraging results in vivo. It is concluded that lipid-based nanoplatforms will play a key role in the development of RNA neuro-therapies.

Self-Assembled Nanoscale Materials for Neuronal Regeneration: A Focus on BDNF Protein and Nucleic Acid Biotherapeutic Delivery

Enabling challenging applications of nanomedicine and precision medicine in the treatment of neurodegenerative disorders requires deeper investigations of nanocarrier-mediated biomolecular delivery for neuronal targeting and recovery. The successful use of macromolecular biotherapeutics (recombinant growth factors, antibodies, enzymes, synthetic peptides, cell-penetrating peptide–drug conjugates, and RNAi sequences) in clinical developments for neuronal regeneration should benefit from the recent strategies for enhancement of their bioavailability. We highlight the advances in the development of nanoscale materials for drug delivery in neurodegenerative disorders. The emphasis is placed on nanoformulations for the delivery of brain-derived neurotrophic factor (BDNF) using different types of lipidic nanocarriers (liposomes, liquid crystalline or solid lipid nanoparticles) and polymer-based scaffolds, nanofibers and hydrogels. Self-assembled soft-matter nanoscale materials show favorable neuroprotective characteristics, safety, and efficacy profiles in drug delivery to the central and peripheral nervous systems. The advances summarized here indicate that neuroprotective biomolecule-loaded nanoparticles and injectable hydrogels can improve neuronal survival and reduce tissue injury. Certain recently reported neuronal dysfunctions in long-COVID-19 survivors represent early manifestations of neurodegenerative pathologies. Therefore, BDNF delivery systems may also help in prospective studies on recovery from long-term COVID-19 neurological complications and be considered as promising systems for personalized treatment of neuronal dysfunctions and prevention or retarding of neurodegenerative disorders.

Improvement of synaptic plasticity by nanoparticles and the related mechanisms: Applications and prospects

Synaptic plasticity is an important basis of learning and memory and participates in brain network remodelling after different types of brain injury (such as that caused by neurodegenerative diseases, cerebral ischaemic injury, posttraumatic stress disorder (PTSD), and psychiatric disorders). Therefore, improving synaptic plasticity is particularly important for the treatment of nervous system-related diseases. With the rapid development of nanotechnology, increasing evidence has shown that nanoparticles (NPs) can cross the blood-brain barrier (BBB) in different ways, directly or indirectly act on nerve cells, regulate synaptic plasticity, and ultimately improve nerve function. Therefore, to better elucidate the effect of NPs on synaptic plasticity, we review evidence showing that NPs can improve synaptic plasticity by regulating different influencing factors, such as neurotransmitters, receptors, presynaptic membrane proteins and postsynaptic membrane proteins, and further discuss the possible mechanism by which NPs improve synaptic plasticity. We conclude that NPs can improve synaptic plasticity and restore the function of damaged nerves by inhibiting neuroinflammation and oxidative stress, inducing autophagy, and regulating ion channels on the cell membrane. By reviewing the mechanism by which NPs regulate synaptic plasticity and the applications of NPs for the treatment of neurological diseases, we also propose directions for future research in this field and provide an important reference for follow-up research.

Functionalized nanoparticles for brain targeted BDNF gene therapy to rescue Alzheimer's disease pathology in transgenic mouse model

Brain-derived neurotrophic factor (BDNF) is actively produced and utilized in cortical circuits throughout life to sustain neuronal function and synaptic plasticity. In animal models of Alzheimer's Disease (AD), highly invasive BDNF gene therapy using viral vectors has successfully shown enhanced synaptic protein expression, proliferation of neurons and attenuation of amyloidogenic processes. However, to eliminate virus-related safety issues and invasive procedures, our present study has explored brain-targeted lipid-based nanoparticles that can deliver plasmid encoding BDNF to brain in a safe and efficient manner. Efficacy of these nanoparticles was tested in early (6-months) and advanced stage (9-months) transgenic APP/PS1 AD mice. Liposomes were surface-functionalized with brain targeting ligand, mannose, and cell-penetrating peptides (rabies virus-derived peptide or penetratin). These bifunctionalized nanoparticles enhanced BDNF expression by ~2 times and resulted in >40% (p < 0.05) reduction in toxic amyloid-beta peptides in 6- and 9-months old APP/PS1 mice brains compared to their age-matched untreated controls. Plaque load was reduced ~7 and ~3 times (p < 0.05), respectively, whereas synaptic proteins, synaptophysin and PSD-95, were found to be increased >90% (p < 0.05) in both age groups of transgenic mice treated with bifunctionalized nanoparticles. No untoward adverse effects were observed throughout treatment, suggesting a safe and effective strategy to rescue AD pathology.

Enhancing autophagy in Alzheimer's disease through drug repositioning

Alzheimer's disease (AD) is one of the biggest human health threats due to increases in aging of the global population. Unfortunately, drugs for treating AD have been largely ineffective. Interestingly, downregulation of macroautophagy (autophagy) plays an essential role in AD pathogenesis. Therefore, targeting autophagy has drawn considerable attention as a therapeutic approach for the treatment of AD. However, developing new therapeutics is time-consuming and requires huge investments. One of the strategies currently under consideration for many diseases is "drug repositioning" or "drug repurposing". In this comprehensive review, we have provided an overview of the impact of autophagy on AD pathophysiology, reviewed the therapeutics that upregulate autophagy and are currently used in the treatment of other diseases, including cancers, and evaluated their repurposing as a possible treatment option for AD. In addition, we discussed the potential of applying nano-drug delivery to neurodegenerative diseases, such as AD, to overcome the challenge of crossing the blood brain barrier and specifically target molecules/pathways of interest with minimal side effects.

Synthesis and Characterization of Fatty Acid Grafted Chitosan Polymeric Micelles for Improved Gene Delivery of VGF to the Brain through Intranasal Route

Multifunctional fatty acid grafted polymeric micelles are an effective and promising approach for drug and gene delivery to the brain. An alternative approach to bypass the blood-brain barrier is administration through intranasal route. Multifunctional fatty acid grafted polymeric micelles were prepared and characterized for pVGF delivery to the brain. In vitro pVGF expression was analyzed in bEnd.3 cells, primary astrocytes, and neurons. Comparative in-vivo pVGF expression was analyzed to evaluate the effective route of administration between intranasal and intravenous. Biocompatible, multifunctional polymeric micelles were prepared, having an average size of 200 nm, and cationic zeta potential. Modified polymers were found to be hemo- and cyto-compatible. When transfected with the different modified chitosan formulations, significantly (p < 0.05) higher VGF expression was observed in primary astrocytes and neurons using the mannose, Tat peptide, and oleic acid grafted chitosan polymer. Compared to intravenous administration, intranasal administration of pVGF in polyplex formulation led to significantly (p < 0.05) higher pVGF expression. Developed multifunctional polymeric micelles were an effective pVGF delivery platform to the brain. Mannose and Tat ligand tagging improved the pVGF delivery to the brain.

A Review of the Common Neurodegenerative Disorders: Current Therapeutic Approaches and the Potential Role of Nanotherapeutics

Neurodegenerative disorders are primarily characterized by neuron loss. The most common neurodegenerative disorders include Alzheimer’s and Parkinson’s disease. Although there are several medicines currently approved for managing neurodegenerative disorders, a large majority of them only help with associated symptoms. This lack of pathogenesis-targeting therapies is primarily due to the restrictive effects of the blood–brain barrier (BBB), which keeps close to 99% of all “foreign substances” out of the brain. Since their discovery, nanoparticles have been successfully used for targeted delivery into many organs, including the brain. This review briefly describes the pathophysiology of Alzheimer’s, Parkinson’s disease, and amyotrophic lateral sclerosis, and their current management approaches. We then highlight the major challenges of brain-drug delivery, followed by the role of nanotherapeutics for the diagnosis and treatment of various neurological disorders.

Nanoparticle-Guided Brain Drug Delivery: Expanding the Therapeutic Approach to Neurodegenerative Diseases

Neurodegenerative diseases (NDs) represent a heterogeneous group of aging-related disorders featured by progressive impairment of motor and/or cognitive functions, often accompanied by psychiatric disorders. NDs are denoted as 'protein misfolding' diseases or proteinopathies, and are classified according to their known genetic mechanisms and/or the main protein involved in disease onset and progression. Alzheimer's disease (AD), Parkinson's disease (PD) and Huntington's disease (HD) are included under this nosographic umbrella, sharing histopathologically salient features, including deposition of insoluble proteins, activation of glial cells, loss of neuronal cells and synaptic connectivity. To date, there are no effective cures or disease-modifying therapies for these NDs. Several compounds have not shown efficacy in clinical trials, since they generally fail to cross the blood-brain barrier (BBB), a tightly packed layer of endothelial cells that greatly limits the brain internalization of endogenous substances. By engineering materials of a size usually within 1-100 nm, nanotechnology offers an alternative approach for promising and innovative therapeutic solutions in NDs. Nanoparticles can cross the BBB and release active molecules at target sites in the brain, minimizing side effects. This review focuses on the state-of-the-art of nanoengineered delivery systems for brain targeting in the treatment of AD, PD and HD.

Understanding Drug Delivery to the Brain Using Liposome-Based Strategies: Studies that Provide Mechanistic Insights Are Essential

Brain drug delivery may be restricted by the blood-brain barrier (BBB), and enhancement by liposome-based drug delivery strategies has been investigated. As access to the human brain is limited, many studies have been performed in experimental animals. Whereas providing interesting data, such studies have room for improvement to provide mechanistic insight into the rate and extent of specifically BBB transport and intrabrain distribution processes that all together govern CNS target delivery of the free drug. This review shortly summarizes BBB transport and current liposome-based strategies to overcome BBB transport restrictions, with the emphasis on how to determine the individual mechanisms that all together determine the time course of free drug brain concentrations, following their administration as such, and in liposomes. Animal studies using microdialysis providing time course information on unbound drug in plasma and brain are highlighted, as these provide the mechanistic information needed to understand BBB drug transport of the drug, and the impact of a liposomal formulations of that drug on BBB transport. Overall, these studies show that brain distribution of a drug administered as liposomal formulation depends on both drug properties and liposomal formulation characteristics. In general, evidence suggests that active transporters at the BBB, either being influx or efflux transporters, are circumvented by liposomes. It is concluded that liposomal formulations may provide interesting changes in BBB transport. More mechanistic studies are needed to understand relevant mechanisms in liposomal drug delivery to the brain, providing an improved basis for its prediction in human using animal data.

A Review of Brain-Targeted Nonviral Gene-Based Therapies for the Treatment of Alzheimer's Disease

Diseases of the central nervous system (CNS) are difficult to treat owing to the complexity of the brain and the presence of a natural blood-brain-barrier (BBB). Alzheimer's disease (AD) is one of the major progressive and currently incurable neurodegenerative disorders of the CNS, which accounts for 60-80% of cases of dementia. The pathophysiology of AD involves the accumulation of amyloid beta (Aβ) plaques and neurofibrillary tangles (NFTs) in the brain. Additionally, synaptic loss and imbalance of neuronal signaling molecules are characterized as important markers of AD. Existing treatments of AD help in the management of its symptoms and aim toward the maintenance of cognitive functions, behavior, and attenuation of gradual memory loss. Over the past decade, nonviral gene therapy has attracted increasing interest due to its various advantages over its viral counterparts. Moreover, advancements in nonviral gene technology have led to their increasing contributions in clinical trials. However, brain-targeted nonviral gene delivery vectors come across various extracellular and intracellular barriers, limiting their ability to transfer the therapeutic gene into the target cells. Chief barriers to nonviral gene therapy have been discussed briefly in this review. We have also highlighted the rapid advancement of several nonviral gene therapies for AD, which are broadly categorized into physical and chemical methods. These methods aim to modulate Aβ, beta-site amyloid precursor protein (APP) cleaving enzyme 1 (BACE1), apolipoprotein E, or neurotrophic factors' expression in the CNS. Overall, this review discusses challenges and recent advancements of nonviral gene therapy for AD.

In vitro and in vivo optimization of liposomal nanoparticles based brain targeted vgf gene therapy

Vgf (non-acronymic), a neurotrophin stimulated protein which plays a crucial role in learning, synaptic activity, and neurogenesis, is markedly downregulated in the brain of Alzheimer's disease (AD) patients. However, since vgf is a large polar protein, a safe and efficient gene delivery vector is critical for its delivery across the blood brain barrier (BBB). This research work demonstrates brain-targeted liposomal nanoparticles optimized for delivering plasmid encoding vgf across BBB and transfecting brain cells. Brain targeting was achieved by surface functionalization using glucose transporter-1 targeting ligand (mannose) and brain targeted cell-penetrating peptides (chimeric rabies virus glycoprotein fragment, rabies virus derived peptide, penetratin peptide, or CGNHPHLAKYNGT peptide). The ligands were conjugated to lipid via nucleophilic substitution reaction resulting in >75% binding efficiency. The liposomes were formed by film hydration technique demonstrating size <200 nm, positive zeta potential (15-20 mV), and polydispersity index <0.3. The bifunctionalized liposomes demonstrated ∼3 pg/µg protein vgf transfection across in vitro BBB, and ∼80 pg/mg protein in mice brain which was 1.5-2 fold (p < 0.05) higher compared to untreated control. The nanoparticles were also biocompatible in vitro and in vivo, suggesting a safe and efficient gene delivery system to treat AD.

D-Serine produces antidepressant-like effects in mice through suppression of BDNF signaling pathway and regulation of synaptic adaptations in the nucleus accumbens

OBJECTIVE

D-Serine is a crucial endogenous co-agonist of N-methyl-D-aspartate receptors (NMDARs) in the central nervous system and can affect the function of the brain derived neurotrophic factor (BDNF) system, which plays an essential role in modulating synaptic plasticity. The current study aimed to systematically evaluate the role and mechanisms of D-serine in depressive behavior in nucleus accumbens (NAc).

METHODS

D-Serine concentration in the chronic social defeat stress (CSDS) model in NAc was measured using high-performance liquid chromatography (HPLC). The antidepressant-like effects of D-serine were identified using forced swim test (FST) and tail suspension test (TST) in control mice and then assessed in CSDS model. We applied social interaction and sucrose preference tests to identify the susceptibility of CSDS model. Western blotting was further performed to assess the changes of BDNF signaling cascade in NAc after CSDS and D-serine treatment. The BDNF signaling inhibitor (K252a) was also used to clarify the antidepressant-like mechanism of D-serine. Moreover, D-serine effects on synaptic plasticity in NAc were investigated using electrophysiological methods.

RESULTS

D-Serine concentration was decreased in depression susceptible mice in NAc. D-Serine injections into NAc exhibited antidepressant-like effects in FST and TST without affecting the locomotor activity of mice. D-Serine was also effective in CSDS model of depression. Moreover, D-serine down-regulated the BDNF signaling pathway in NAc during CSDS procedure. Furthermore, BDNF signaling inhibitor (K252a) enhanced the antidepressant effects of D-serine. We also found that D-serine was essential for NMDARs-dependent long-term depression (LTD).

CONCLUSION

D-Serine exerts antidepressant-like effects in mice mediated through restraining the BDNF signaling pathway and regulating synaptic plasticity in NAc.