Grafting of cell-penetrating peptide to receptor-targeted liposomes improves their transfection efficiency and transport across blood-brain barrier model

Erjingpill bionic cerebrospinal fluid alleviates LPS-induced inflammatory response in BV2 cells by inhibiting glycolysis via mTOR

ETHNOPHARMACOLOGICAL RELEVANCE

Erjingpill, a well-known prescription documented in the classic Chinese medical text "Shengji Zonglu," has been proven to have effective alleviating effects on neuroinflammation in Alzheimer's disease (AD). Although the alterations in microglial cell glycolysis are known to play a crucial role in the development of neuroinflammation, it remains unclear whether the anti-neuroinflammatory effects of Erjingpill are associated with its impact on microglial cell glycolysis.

AIM OF THE STUDY

This study aims to determine whether Erjingpill exerts anti-neuroinflammatory effects by influencing microglial cell glycolysis.

MATERIALS AND METHODS

Firstly, Erjingpill decoction was prepared into an Erjingpill bionic cerebrospinal fluid (EBCF) through a process of in vitro intestinal absorption, hepatocyte incubation, and blood-brain barrier (BBB) transcytosis. Subsequently, UPLC/Q-TOF-MS/MS technology was used to analyze the compounds in Erjingpill and EBCF. Next, an in vitro neuroinflammation model was established by LPS-induced BV2 cells. The impact of EBCF on BV2 cell proliferation activity was evaluated using the CCK-8 assay, while the NO release was assessed using the Griess assay. Additionally, mRNA levels of pro-inflammatory factors (IL-1β, IL-6, TNF-α, and COX-2), anti-inflammatory factors (IL-10, IL-4, Arg-1, and TGF-β), M1 microglial markers (iNOS, CD86), M2 microglial markers (CD36, CD206), and glycolytic enzymes (HK2, GLUT1, PKM, and LDHA) were measured using qPCR. Furthermore, protein expression of microglial activation marker Iba-1, M1 marker iNOS, and M2 marker CD206 were identified through immunofluorescence, while concentrations of pro-inflammatory cytokines IL-1β and TNF-α were measured using ELISA. Enzymatic activity of glycolytic enzymes (HK, PK, and LDH) was assessed using assay kits, and the protein levels of pro-inflammatory factors (IL-1β, iNOS, and COX-2), anti-inflammatory factors (IL-10 and Arg-1), and key glycolytic proteins GLUT1 and PI3K/AKT/mTOR were detected by Western blot.

RESULTS

Through the analysis of Erjingpill and EBCF, 144 compounds were identified in Erjingpill and 40 compounds were identified in EBCF. The results demonstrated that EBCF effectively inhibited the elevation of inflammatory factors and glycolysis levels in LPS-induced BV2 cells, promoted polarization of M1 microglial cells towards the M2 phenotype, and suppressed the PI3K/AKT/mTOR inflammatory pathway. Moreover, EBCF alleviated LPS-induced BV2 cell inflammatory response by modulating mTOR to inhibit glycolysis.

CONCLUSIONS

EBCF exhibits significant anti-neuroinflammatory effects, likely attributed to its modulation of mTOR to inhibit microglial cell glycolysis. This study furnishes experimental evidence supporting the clinical utilization of Erjingpill for preventing and treating AD.

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.

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.

CRISPR/Cas9 targeting liposomes knocked down multidrug resistance proteins in brain endothelial cells as a model to predict potential pharmacoresistance

This investigation aimed to use CRISPR-Cas9 gene-editing to knock down P-glycoprotein (P-gp) expression and then establish a feasible cell line to evaluate the potential pharmacoresistance of therapeutic agents mediated by efflux. A cationic liposome was prepared as a "smart bomb" by conjugating with a peptide-based targeting ligand (THRPPMWSPVWP), specifically binding to transferrin receptors at the blood-brain barrier (BBB), and then formed a nanocomplex with P-gp knockdown CRISPR/Cas9 plasmid. Higher uptakes of targeted and stable liposomes in bEND.3 cells were observed compared to non-peptide conjugated ones (p < 0.05). The P-gp transporters were successfully knocked down by the cell-nontoxic CRISPR/Cas9 targeted liposomes and P-gp associated ATP activities were higher in the transfected cells (p < 0.05). Functional studies of knocked down cells were evaluated by using prototypical P-gp substrates rhodamine 123 and doxorubicin. More accumulation of rhodamine 123 and higher cytotoxic sensitivity of doxorubicin was observed in the transfected cells as compared with those in the wild-type cells.

The protective effects of hyperoside on Ang II-mediated apoptosis of bEnd.3 cells and injury of blood-brain barrier model in vitro

Background

Hypertension and its associated dysfunction of the blood-brain barrier (BBB) are considered to contribute to cerebral small vessel disease (cSVD). Angiotensin II (Ang II), as an important vasoactive peptide of the renin-angiotensin system (RAS), is not only a pivotal molecular signal in hypertension, but also causes BBB leakage, cSVD and its related cognitive impair. Hyperoside (Hyp), a flavone glycoside, has antioxidant, antiphlogistic and anti-apoptosis effects. In this study, we investigate the protection of Hyp on apoptosis of bEnd.3 cells and BBB disruption in vitro induced by Ang II.

Methods

We used bEnd.3 cells to imitate a BBB monolayer model and explored the protection of Hyp on Ang II-induced BBB leakage. The apoptotic activity was assessed by TUNEL staining and flow cytometry. The expression of apoptosis pathway related proteins, tight junction proteins and transcytosis related proteins were detected by western blot assay. The BBB model permeability was detected through measuring the flux of sodium fluorescein (Na-F).

Results

We found that Hyp can not only effectively inhibit the apoptosis of bEnd.3 induced by Ang II, but also protect the structural soundness and functional integrity of BBB model by affecting the expression levels of junctional adhesion molecule A (JAM-A), Claudin-5, zonula occludens-1 (ZO-1), Caveolin-1 (Cav-1) and major facilitator superfamily domain-containing protein 2a (Mfsd2a).

Conclusion

Hyp might be a potent compound for preventing Ang II-induced BBB disruption.

Investigation of Trends in the Research on Transferrin Receptor-Mediated Drug Delivery via a Bibliometric and Thematic Analysis

This study systematically reviews and characterizes the existing literature on transferrin/transferrin receptor-mediated drug delivery. Transferrin is an iron-binding protein. It can be used as a ligand to deliver various proteins, genes, ions, and drugs to the target site via transferrin receptors for therapeutic or diagnostic purposes via transferrin receptors. This study is based on a cross-sectional bibliometric analysis of 583 papers limited to the subject areas of pharmacology, toxicology, and pharmaceutics as extracted from the Scopus database in mid-September 2022. The data were analyzed, and we carried out a performance analysis and science mapping. There was a significant increase in research from 2018 onward. The countries that contributed the most were the USA and China, and most of the existing research was found to be from single-country publications. Research studies on transferrin/transferrin receptor-mediated drug delivery focus on drug delivery across the blood-brain barrier in the form of nanoparticles. The thematic analysis revealed four themes: transferrin/transferrin receptor-mediated drug delivery to the brain, cancer cells, gene therapy, nanoparticles, and liposomes as drug delivery systems. This study is relevant to academics, practitioners, and decision makers interested in targeted and site-specific drug delivery.

Membrane Internalization Mechanisms and Design Strategies of Arginine-Rich Cell-Penetrating Peptides

Cell-penetrating peptides (CPPs) have been discovered to deliver chemical drugs, nucleic acids, and macromolecules to permeate cell membranes, creating a novel route for exogenous substances to enter cells. Up until now, various sequence structures and fundamental action mechanisms of CPPs have been established. Among them, arginine-rich peptides with unique cell penetration properties have attracted substantial scientific attention. Due to the positively charged essential amino acids of the arginine-rich peptides, they can interact with negatively charged drug molecules and cell membranes through non-covalent interaction, including electrostatic interactions. Significantly, the sequence design and the penetrating mechanisms are critical. In this brief synopsis, we summarize the transmembrane processes and mechanisms of arginine-rich peptides; and outline the relationship between the function of arginine-rich peptides and the number of arginine residues, arginine optical isomers, primary sequence, secondary and ternary structures, etc. Taking advantage of the penetration ability, biomedical applications of arginine-rich peptides have been refreshed, including drug/RNA delivery systems, biosensors, and blood-brain barrier (BBB) penetration. Understanding the membrane internalization mechanisms and design strategies of CPPs will expand their potential applications in clinical trials.

The role of cell-penetrating peptides in potential anti-cancer therapy

Due to the complex physiological structure, microenvironment and multiple physiological barriers, traditional anti-cancer drugs are severely restricted from reaching the tumour site. Cell-penetrating peptides (CPPs) are typically made up of 5-30 amino acids, and can be utilised as molecular transporters to facilitate the passage of therapeutic drugs across physiological barriers. Up to now, CPPs have widely been used in many anti-cancer treatment strategies, serving as an excellent potential choice for oncology treatment. However, their drawbacks, such as the lack of cell specificity, short duration of action, poor stability in vivo, compatibility problems (i.e. immunogenicity), poor therapeutic efficacy and formation of unwanted metabolites, have limited their further application in cancer treatment. The cellular uptake mechanisms of CPPs involve mainly endocytosis and direct penetration, but still remain highly controversial in academia. The CPPs-based drug delivery strategy could be improved by clever design or chemical modifications to develop the next-generation CPPs with enhanced cell penetration capability, stability and selectivity. In addition, some recent advances in targeted cell penetration that involve CPPs provide some new ideas to optimise CPPs.

Synthesis and Evaluation of High Functionality and Quality Cell-penetrating Peptide Conjugated Lipid for Octaarginine Modified PEGylated Liposomes In U251 and U87 Glioma Cells

The use of peptide ligand modified PEGylated liposomes has been widely investigated for tumor targeting. Peptides are mainly inserted in the liposomal lipid bilayer using PEG_2K-lipid spacer (Peptide-PEG_2K-DSPE). However, a lower cellular uptake from longer nonlinear PEG_2K spacer was reported, we here synthesized a high functionality and quality (HFQ) lipid with a short, linear serine-glycine repeated peptide [(SG)₅] spacer. The objective of the current study is to develop novel octaarginine (R₈) peptide-HFQ lipid grafted PEGylated liposomes for glioma cells targeting. In vitro liposomes characterization showed that the mean particle size of all liposomal formulations was in the nano-scale range < 120 nm, with a small PDI value (i.e. ∼0.2) and had a spherical shape under Transmission Electron Microscope, indicating a homogenous particle size distribution. The flow cytometry in vitro cellular association data with U251 MG and U87 cells revealed that 1.5% R₈-(SG)₅-lipid-PEGylated liposomes exhibited significantly higher cellular association of ∼15.87 and 7.59-fold than the conventional R₈-PEG_2K-lipid-PEGylated liposomes (10.4 and 6.19-fold), respectively, relative to the unmodified PEGylated liposomes. Moreover, intracellular distribution studies using confocal laser scanning microscopy (CLSM) corroborated the results of the in vitro cell association. The use of ligand-HFQ-lipid liposomes could be a potential alternative to ligand-PEG_2K-lipid-modified liposomes as a drug delivery system for tumor targeting.

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.

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

Targeting gene-based therapeutics to the brain is a strategy actively sought to treat Alzheimer's disease (AD). Recent findings discovered the role of apolipoprotein E (ApoE) isoforms in the clearance of toxic amyloid beta proteins from the brain. ApoE2 isoform is beneficial for preventing AD development, whereas ApoE4 is a major contributing factor to the disease. In this paper, we demonstrated efficient brain-targeted delivery of ApoE2 encoding plasmid DNA (pApoE2) using glucose transporter-1 (glut-1) targeted liposomes. Liposomes were surface-functionalized with a glut-1 targeting ligand mannose (MAN) and a cell-penetrating peptide (CPP) to enhance brain-targeting and cellular internalization, respectively. Among various CPPs, rabies virus glycoprotein peptide (RVG) or penetratin (Pen) was selected as a cell-penetration enhancer. Dual (RVGMAN and PenMAN)-functionalized liposomes were cytocompatible at 100 nM phospholipid concentration and demonstrated significantly higher expression of ApoE2 in bEnd.3 cells, primary neurons, and astrocytes compared to monofunctionalized and unmodified (plain) liposomes. Dual-modified liposomes also showed ∼2 times higher protein expression than other formulation controls in neurons cultured below the in vitro BBB model. These results translated well to in vivo efficacy study with significantly higher transfection of pApoE2 in the C57BL/6 mice brain following single tail vein administration of RVGMAN and PenMAN functionalized liposomes without any noticeable signs of toxicity. These results illustrate the potential of surface-modified liposomes for safe and brain-targeted delivery of the pApoE2 gene for effective AD therapy.

Tumor Targeted Delivery of an Anti-Cancer Therapeutic: An In Vitro and In Vivo Evaluation

The limited effectiveness of current therapeutics against malignant brain gliomas has led to an urgent need for development of new formulations against these tumors. Chelator Dp44mT (di-2-pyridylketone-4,4-dimethyl-3-thiosemicarbazone) presents a promising candidate to defeat gliomas due to its exceptional anti-tumor activity and its unique ability to overcome multidrug resistance. The goal of this study is to develop a targeted nano-carrier for Dp44mT delivery to glioma tumors and to assess its therapeutic efficacy in vitro and in vivo. Dp44mT is loaded into poly(ethylene glycol) (PEG)ylated poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) decorated with glioma-targeting ligand Interlukin 13 (IL13). IL13-conjugation enhanced the NP uptake by glioma cells and also improved their transport across an in vitro blood-brain-barrier (BBB) model. This targeted formulation showed an outstanding toxicity towards glioma cell lines and patient-derived stem cells in vitro, with IC₅₀ values less than 125 nM, and caused no significant death in healthy brain microvascular endothelial cells. In vivo, when tested on a xenograft mouse model, IL13-conjugated Dp44mT-NPs reduced the glioma tumor growth by ≈62% while their untargeted counterparts reduced the tumor growth by only ≈16%. Notably, this formulation does not cause any significant weight loss or kidney/liver toxicity in mice, demonstrating its great therapeutic potential.

Photodynamic therapy, priming and optical imaging: Potential co-conspirators in treatment design and optimization - a Thomas Dougherty Award for Excellence in PDT paper

Photodynamic therapy is a photochemistry-based approach, approved for the treatment of several malignant and non-malignant pathologies. It relies on the use of a non-toxic, light activatable chemical, photosensitizer, which preferentially accumulates in tissues/cells and, upon irradiation with the appropriate wavelength of light, confers cytotoxicity by generation of reactive molecular species. The preferential accumulation however is not universal and, depending on the anatomical site, the ratio of tumor to normal tissue may be reversed in favor of normal tissue. Under such circumstances, control of the volume of light illumination provides a second handle of selectivity. Singlet oxygen is the putative favorite reactive molecular species although other entities such as nitric oxide have been credibly implicated. Typically, most photosensitizers in current clinical use have a finite quantum yield of fluorescence which is exploited for surgery guidance and can also be incorporated for monitoring and treatment design. In addition, the photodynamic process alters the cellular, stromal, and/or vascular microenvironment transiently in a process termed photodynamic priming, making it more receptive to subsequent additional therapies including chemo- and immunotherapy. Thus, photodynamic priming may be considered as an enabling technology for the more commonly used frontline treatments. Recently, there has been an increase in the exploitation of the theranostic potential of photodynamic therapy in different preclinical and clinical settings with the use of new photosensitizer formulations and combinatorial therapeutic options. The emergence of nanomedicine has further added to the repertoire of photodynamic therapy's potential and the convergence and co-evolution of these two exciting tools is expected to push the barriers of smart therapies, where such optical approaches might have a special niche. This review provides a perspective on current status of photodynamic therapy in anti-cancer and anti-microbial therapies and it suggests how evolving technologies combined with photochemically-initiated molecular processes may be exploited to become co-conspirators in optimization of treatment outcomes. We also project, at least for the short term, the direction that this modality may be taking in the near future.

MicroRNAs and target genes in epileptogenesis

Epilepsy is a chronic brain dysfunction. Current antiepileptic medicines cannot prevent epileptogenesis. Increasing data have shown that microRNAs (miRNAs) are selectively altered within the epileptic hippocampi of experimental models and human tissues, and these alterations affect the genes that control epileptogenesis. Furthermore, manipulation of miRNAs in animal models can modify epileptogenesis. As a result, miRNAs have been proposed as promising targets for treating epilepsy. We searched PubMed using the terms "microRNAs/miRNAs AND epilepsy", "microRNAs/miRNAs AND epileptogenesis", and "microRNAs/miRNAs AND seizure". We selected the articles in which the relationship between miRNAs and target gene(s) was validated and manipulation of miRNAs in in vivo epilepsy models modified epileptogenesis during the chronic phase via gene regulation. A total of 13 miRNAs were found in the present review. Based on the current analysis of miRNAs and their target gene(s), each miRNA has limitations as a potential epilepsy target. Importantly, miR-211 or miR-128 transgenic mice displayed seizures. These findings highlight new developments for epileptogenesis prevention. Developing novel strategies to modify epileptogenesis will be effective in curing epilepsy patients. This article provides an overview of the clinical application of miRNAs as novel targets for epilepsy.

Dual-Modified Liposome for Targeted and Enhanced Gene Delivery into Mice Brain

The development of neuropharmaceutical gene delivery systems requires strategies to obtain efficient and effective brain targeting as well as blood-brain barrier (BBB) permeability. A brain-targeted gene delivery system based on a transferrin (Tf) and cell-penetrating peptide (CPP) dual-functionalized liposome, CPP-Tf-liposome, was designed and investigated for crossing BBB and permeating into the brain. We selected three sequences of CPPs [melittin, Kaposi fibroblast growth factor (kFGF), and penetration accelerating sequence-R8] and compared their ability to internalize into the cells and, subsequently, improve the transfection efficiency. Study of intracellular uptake indicated that liposomal penetration into bEnd.3 cells, primary astrocytes, and primary neurons occurred through multiple endocytosis pathways and surface modification with Tf and CPP enhanced the transfection efficiency of the nanoparticles. A coculture in vitro BBB model reproducing the in vivo anatomophysiological complexity of the biologic barrier was developed to characterize the penetrating properties of these designed liposomes. The dual-functionalized liposomes effectively crossed the in vitro barrier model followed by transfecting primary neurons. Liposome tissue distribution in vivo indicated superior ability of kFGF-Tf-liposomes to overcome BBB and reach brain of the mice after single intravenous administration. These findings demonstrate the feasibility of using strategically designed liposomes by combining Tf receptor targeting with enhanced cell penetration as a potential brain gene delivery vector. SIGNIFICANCE STATEMENT: Rational synthesis of efficient brain-targeted gene carrier included modification of liposomes with a target-specific ligand, transferrin, and with cell-penetrating peptide to enhance cellular internalization. Our study used an in vitro triple coculture blood-brain barrier (BBB) model as a tool to characterize the permeability across BBB and functionality of designed liposomes prior to in vivo biodistribution studies. Our study demonstrated that rational design and characterization of BBB permeability are efficient strategies for development of brain-targeted gene carriers.

In vitro and in vivo characterization of CPP and transferrin modified liposomes encapsulating pDNA

The limitations imposed on brain therapy by the blood-brain barrier (BBB) have warranted the development of carriers that can overcome and deliver therapeutic agents into the brain. We strategically designed liposomal nanoparticles encasing plasmid DNA for efficient transfection and translocation across the in vitro BBB model as well as in vivo brain-targeted delivery. Liposomes were surface modified with two ligands, cell-penetrating peptide (PFVYLI or R9F2) for enhanced internalization into cells and transferrin (Tf) ligand for targeting transferrin-receptor expressed on brain capillary endothelial cells. Dual-modified liposomes encapsulating pDNA demonstrated significantly (P < 0.05) higher in vitro transfection efficiency compared to single-modified nanoparticles. R9F2Tf-liposomes showed superior ability to cross in vitro BBB and, subsequently, transfect primary neurons. Additionally, these nanoparticles crossed in vivo BBB and reached brain parenchyma of mice (6.6%) without causing tissue damage. Transferrin receptor-targeting with enhanced cell penetration is a relevant strategy for efficient brain-targeted delivery of genes.

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

Alzheimer's disease (AD), the most common cause of dementia, inflicts enormous suffering to patients and their family members. It is the third deadliest disease, affecting 46.8 million people worldwide. Brain-derived neurotrophic factor (BDNF) is involved in the development, maintenance, and plasticity of the central nervous system. This crucial protein is significantly reduced in AD patients leading to reduced plasticity and neuronal death. In this study, we demonstrate the targeted delivery of the BDNF gene to the brain using liposome nanoparticles. These liposomes were surface modified with glucose transporter-1 targeting ligand (mannose) and cell penetrating peptides (penetratin or rabies virus glycoprotein) to promote selective and enhanced delivery to the brain. Surface modified liposomes showed significantly higher transfection of BDNF in primary astrocytes and neurons, compared to unmodified (plain) liposomes. BDNF transfection via dual modified liposomes resulted in an increase in presynaptic marker synaptophysin protein in primary neuronal cells, which is usually found to be reduced in AD patients. Liposomes surface modified with mannose and cell penetrating peptides demonstrated ∼50% higher transport across the in vitro blood brain barrier (BBB) model and showed significantly higher transfection efficiency in primary neuronal cells compared to plain liposomes. These results were correlated with significantly higher transport of surface modified liposomes (∼7% of injected dose/gram of tissue) and BDNF transfection (∼1.7 times higher than baseline level) across BBB following single intravenous administration in C57BL/6 mice without any signs of inflammation or toxicity. Overall, this study suggests a safe and targeted strategy to increase BDNF protein in the brain, which has the potential to reverse AD pathophysiology.

Efficient neuronal targeting and transfection using RVG and transferrin-conjugated liposomes

Effective transport of therapeutic nucleic acid to brain has been a challenge for the success of gene therapy for treating brain diseases. In this study, we proposed liposomal nanoparticles modified with brain targeting ligandsfor active brain targeting with enhanced BBB permeation and delivery of genes to brain. We targeted transferrin and nicotinic acetylcholine receptors by conjugating transferrin (Tf) and rabies virus glycoprotein (RVG) peptide to surface of liposomes. Liposomal formulations showed homogeneous particle size and ability to protect plasmid DNA against enzymatic degradation. These nanoparticles were internalized by brain endothelial cells, astrocytes and primary neuronal cells through energy-dependent endocytosis pathways. RVG-Tf coupled liposomes showed superior ability to transfect cells compared to liposomes without surface modification or single modification. Characterization of permeability through blood brain barrier (BBB) and functionality of designed liposomes were performed using an in vitro triple co-culture BBB model. Liposome-RVG-Tf efficiently translocated across in vitro BBB model and, consecutively, transfected primary neuronal cells. Notably, brain-targeted liposomes promoted in vivo BBB permeation. These studies suggest that modifications of liposomes with brain-targeting ligands are a promising strategy for delivery of genes to brain.

Biodistribution of TAT or QLPVM coupled to receptor targeted liposomes for delivery of anticancer therapeutics to brain in vitro and in vivo

Combination therapy has emerged as an efficient way to deliver chemotherapeutics for treatment of glioblastoma. It provides collaborative approach of targeting cancer cells by acting via multiple mechanisms, thereby reducing drug resistance. However, the presence of impermeable blood brain barrier (BBB) restricts the delivery of chemotherapeutic drugs into the brain. To overcome this limitation, we designed a dual functionalized liposomes by modifying their surface with transferrin (Tf) and a cell penetrating peptide (CPP) for receptor and adsorptive mediated transcytosis, respectively. In this study, we used two different CPPs (based on physicochemical properties) and investigated the influence of insertion of CPP to Tf-liposomes on biocompatibility, cellular uptake, and transport across the BBB both in vitro and in vivo. The biodistribution profile of Tf-CPP liposomes showed more than 10 and 2.7 fold increase in doxorubicin and erlotinib accumulation in mice brain, respectively as compared to free drugs with no signs of toxicity.

Development and screening of brain-targeted lipid-based nanoparticles with enhanced cell penetration and gene delivery properties

Background

The potential of gene therapy for treatment of neurological disorders can be explored using designed lipid-based nanoparticles such as liposomes, which have demonstrated ability to deliver nucleic acid to brain cells. We synthesized liposomes conjugated to cell-penetrating peptides (CPPs) (vascular endothelial-cadherin-derived peptide [pVec], pentapeptide QLPVM and HIV-1 trans-activating protein [TAT]) and transferrin (Tf) ligand, and examined the influence of surface modifications on the liposome delivery capacity and transfection efficiency of encapsulated plasmid DNA. The design of liposomes was based on targeting molecular recognition of transferrin receptor overexpressed on the blood–brain barrier (BBB) with enhanced internalization ability of CPPs.

Methods

CPP-Tf-liposomes were characterized by particle size distribution, zeta potential, protection of encapsulated plasmid DNA, uptake mechanisms and transfection efficiencies. An in vitro triple co-culture BBB model selected the liposomal formulations that were able to cross the in vitro BBB and subsequently, transfect primary neuronal cells. The in vivo biodistribution and biocompatibility of selected formulations were also investigated in mice.

Results

Liposomal formulations were able to protect the encapsulated plasmid DNA against enzymatic degradation and presented low hemolytic potential and low cytotoxicity at 100 nM phospholipid concentration. Cellular internalization of nanoparticles occurred via multiple endocytosis pathways. CPP-Tf-conjugated liposomes mediated robust transfection of brain endothelial (bEnd.3), primary glial and primary neuronal cells. Liposomes modified with Tf and TAT demonstrated superior ability to cross the barrier layer and subsequently, transfect neuronal cells compared to other formulations. Quantification of fluorescently labeled liposomes and in vivo imaging demonstrated that this system could efficiently overcome the BBB and penetrate the brain of mice (7.7% penetration of injected dose).

Conclusion

In vitro screening platforms are important tools to enhance the success of brain-targeted gene delivery systems. The potential of TAT-Tf-liposomes as efficient brain-targeted gene carriers in vitro and in vivo was suggested to be related to the presence of selected moieties on the nanoparticle surface.

Dual functionalized liposomes for efficient co-delivery of anti-cancer chemotherapeutics for the treatment of glioblastoma

Glioblastoma is a hostile brain tumor associated with high infiltration leading to poor prognosis. Anti-cancer chemotherapeutic agents have limited access into the brain due to the presence of the blood brain barrier (BBB). In this study, we designed a dual functionalized liposomal delivery system, surface modified with transferrin (Tf) for receptor mediated transcytosis and a cell penetrating peptide-penetratin (Pen) for enhanced cell penetration. We loaded doxorubicin and erlotinib into liposomes to enhance their translocation across the BBB to glioblastoma tumor. In vitro cytotoxicity and hemocompatibility studies demonstrated excellent biocompatibility for in vivo administration. Co-delivery of doxorubicin and erlotinib loaded Tf-Pen liposomes revealed significantly (p < 0.05) higher translocation (~15%) across the co-culture endothelial barrier resulting in regression of tumor in the in vitro brain tumor model. The biodistribution of Tf-Pen liposomes demonstrated ~12 and 3.3 fold increase in doxorubicin and erlotinib accumulation in mice brain, respectively compared to free drugs. In addition, Tf-Pen liposomes showed excellent antitumor efficacy by regressing ~90% of tumor in mice brain with significant increase in the median survival time (36 days) along with no toxicity. Thus, we believe that this study would have high impact for treating patients with glioblastoma.

Functionalized liposomal nanoparticles for efficient gene delivery system to neuronal cell transfection

Liposome based delivery systems provide a promising strategy for treatment of neurodegenerative diseases. A rational design of brain-targeted liposomes can support the development of more efficient treatments with drugs and gene materials. Here, we characterized surface modified liposomes with transferrin (Tf) protein and penetratin (Pen), a cell-penetrating peptide, for efficient and targeted gene delivery to brain cells. PenTf-liposomes efficiently encapsulated plasmid DNA, protected them against enzymatic degradation and exhibited a sustained in vitro release kinetics. The formulation demonstrated low cytotoxicity and was non-hemolytic. Liposomes were internalized into cells mainly through energy-dependent pathways especially clathrin-mediated endocytosis. Reporter gene transfection and consequent protein expression in different cell lines were significantly higher using PenTf-liposomes compared to unmodified liposomes. The ability of these liposomes to escape from endosomes can be an important factor which may have likely contributed to the high transfection efficiency observed. Rationally designed bifunctional targeted-liposomes provide an efficient tool for improving the targetability and efficacy of synthesized delivery systems. This investigation of liposomal properties attempted to address cell differences, as well as, vector differences, in gene transfectability. The findings indicate that PenTf-liposomes can be a safe and non-invasive approach to transfect neuronal cells through multiple endocytosis pathways.

Modulating the antibody density changes the uptake and transport at the blood-brain barrier of both transferrin receptor-targeted gold nanoparticles and liposomal cargo

Transport of the majority of therapeutic molecules to the brain is precluded by the presence of the blood-brain barrier (BBB) rendering efficient treatment of many neurological disorders impossible. This BBB, nonetheless, may be circumvented by targeting receptors and transport proteins expressed on the luminal surface of the brain capillary endothelial cells (BCECs). The transferrin receptor (TfR) has remained a popular target since its original description for this purpose, although clinical progression of TfR-targeted drug constructs or nanomedicines remains unsuccessful. One proposed issue pertaining to the use of TfR-targeting in nanomedicines is the efficient tuning of the ligand density on the nanoparticle surface. We studied the impact of TfR antibody density on the uptake and transport of nanoparticles into the brain, taking a parallel approach to investigate the impact on both antibody-functionalized gold nanoparticles (AuNPs) and cargo-loaded liposomes. We report that among three different low-range mean ligand densities (0.15, 0.3, and 0.6 ∗ 10³ antibodies/μm²), the highest density yielded the highest ability towards both targeting of the BCECs and subsequent transport across the BBB in vivo, and in vitro using primary cultures of the murine BBB. We also find that TfR-targeting on liposomes in the mouse may induce severe adverse effects after intravenous administration.

Peptide-based gene delivery vectors

Gene therapy as a strategy for disease treatment requires safe and efficient gene delivery systems that encapsulate nucleic acids and deliver them to effective sites in the cell.

Dual functionalized liposome-mediated gene delivery across triple co-culture blood brain barrier model and specific in vivo neuronal transfection

Gene therapy has become a promising approach for neurodegenerative disease treatment, however there is an urgent need to develop an efficient gene carrier to transport gene across the blood brain barrier (BBB). In this study, we strategically designed dual functionalized liposomes for efficient neuronal transfection by combining transferrin (Tf) receptor targeting and enhanced cell penetration utilizing penetratin (Pen). A triple cell co-culture model of BBB confirmed the ability of the liposomes to cross the barrier layer and transfect primary neuronal cells. In vivo quantification of PenTf-liposomes demonstrated expressive accumulation in the brain (12%), without any detectable cellular damage or morphological change. The efficacy of these nanoparticles containing plasmid β-galactosidase in modulating transfection was assessed by β-galactosidase expression in vivo. As a consequence of accumulation in the brain, PenTf-liposomes significantly induced gene expression in mice. Immunofluorescence studies of brain sections of mice after tail vein injection of liposomes encapsulating pDNA encoding GFP (pGFP) illustrate the superior ability of dual-functionalized liposomes to accumulate in the brain and transfect neurons. Taken together, the multifunctional liposomes provide an excellent gene delivery platform for neurodegenerative diseases.

Co-delivery of doxorubicin and erlotinib through liposomal nanoparticles for glioblastoma tumor regression using an in vitro brain tumor model

Glioma is a highly malignant tumor that starts in the glial cells of brain. Tumor cells reproduce quickly and infiltrate rapidly in high grade glioma. Permeability of chemotherapeutic agents into brain is restricted owing to the presence of blood brain barrier (BBB). In this study, we developed a dual functionalized liposomal delivery system for efficient transport of chemotherapeutics across BBB for the treatment of glioma. Liposomes were surface modified with transferrin (Tf) for receptor targeting, and cell penetrating peptide PFVYLI (PFV) to increase translocation of doxorubicin (Dox) and Erlotinib (Erlo) across the BBB into glioblastoma (U87) tumor cells. In vitro cytotoxicity and hemolysis studies were performed to assess biocompatibility of liposomal nanoparticles. Cellular uptake studies demonstrated efficient internalization of Dox and Erlo in U87, brain endothelial (bEnd.3), and glial cells. In addition, dual functionalized liposomes showed significantly (p < 0.05) higher apoptosis in U87 cells. Significantly (p < 0.05) higher translocation of dual functionalized liposomes across the BBB and delivering chemotherapeutic drugs to the glioblastoma tumor cells inside PLGA-Chitosan scaffold resulted in approximately 52% tumor cell death, using in vitro brain tumor model.

Dual Functionalized 5-Fluorouracil Liposomes as Highly Efficient Nanomedicine for Glioblastoma Treatment as Assessed in an In Vitro Brain Tumor Model

Drug delivery to the brain has been a major challenge due to the presence of the blood-brain barrier, which limits the uptake of most chemotherapeutics into brain. We developed a dual-functionalized liposomal delivery system, conjugating cell penetrating peptide penetratin to transferrin-liposomes (Tf-Pen-conjugated liposomes) to enhance the transport of an anticancer chemotherapeutic drug, 5-fluorouracil (5-FU), across the blood-brain barrier into the tumor cells. The in vitro cellular uptake study showed that the dual-functionalized liposomes are capable of higher cellular uptake in glioblastoma (U87) and brain endothelial (bEnd.3) cells monolayer. In addition, dual-functionalized liposomes demonstrated significantly higher apoptosis in U87 cells. The liposomal nanoparticles showed excellent blood compatibility and in vitro cell viability, as studied by hemolysis and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, respectively. The 5-FU-loaded dual-functionalized liposomes demonstrated higher transport across the brain endothelial barrier and delivered 5-FU to tumor cells inside poly(lactic-co-glycolic acid)-chitosan scaffold (an in vitro brain tumor model), resulting in significant tumor regression.

Liposomal CpG-ODN: An in vitro and in vivo study on macrophage subtypes responses, biodistribution and subsequent therapeutic efficacy in mice models of cancers

CpG oligodeoxynucleotides (CpG-ODN), a common immune stimulator and vaccine adjuvant, was reported to switch Tumor Associated Macrophages (TAMs) from M2 to M1 phenotype inducing anti-tumor responses. Liposomes are of the successfully applied carriers for CpG-ODN. The aim of present study was design and preparation of a liposomal formulation containing phosphodiester CpG-ODN, evaluation of its effect on macrophages responses, and subsequent antitumor responses in mice. Liposomal formulations containing phosphodiester CpG-ODN or non-CpG-ODN were prepared and characterized. MTT reduction assay in four different cell lines, uptake, arginase and iNOS activity evaluation in macrophage cell lines, biodistribution study and therapeutic anti-tumor effects of formulations in mice bearing C26 colon carcinoma or B16F0 melanoma were carried out. The size of liposomes containing CpG-ODN was ~200 nm with the encapsulation efficiency of 33%. The iNOS activity assay showed high nitric oxide (NO) level in M2 phenotype of macrophage cell lines treated by liposomes containing CpG-ODN. In mice which received liposomes containing CpG-ODN as a monotherapy, maximum tumor growth delay with remarkable survival improvement was observed compared to control groups. Biodistribution study showed the accumulation of liposomal formulation in tumor micro-environment. In conclusion, considerable anti-tumor responses observed by liposomes containing CpG-ODN was due to enhanced delivery of CpG-ODN to immune cells and subsequent initiation of anti-tumoral immune responses.

Cleavable Multifunctional Targeting Mixed Micelles with Sequential pH-Triggered TAT Peptide Activation for Improved Antihepatocellular Carcinoma Efficacy

Although tumor-targeting nanovehicles for hepatocellular carcinoma (HCC) chemotherapy have attracted great research and clinic interest, the poor cancer penetration, inefficient cellular uptake, and slow intracellular drug release greatly compromise their therapeutic outcomes. In this work, a multifunctional mixed micellar system, consisting of glycyrrhetinic acid (GA) for specific liver-targeting, trans-activator of transcription (TAT) peptide for potent cell penetration, and pH-sensitive poly(β-amino ester) polymers for acidic-triggered drug release, was developed to provide HCC-targeting delivery and pH-triggered release of doxorubicin (DOX). These micelles were hypothesized to efficaciously accumulate in HCC site by the guide of GA ligands, enter into cancer cells facilitated by the activated TAT peptide on the micellar surface, and finally rapidly release DOX in cytoplasm. To demonstrate this design, DOX was initially loaded in micelles modified with both GA and TAT (DOX/GA@TAT-M) with high drug loading efficiency and pH-sensitive drug release profiles. The HCC-targeting cellular uptake and synergetic anticancer efficacy were tested, indicating DOX/GA@TAT-M could be specifically and effectively internalized into HCC cells by the effect of GA targeting and TAT penetrating with enhanced cytotoxicity. In addition, the prolonged circulation time and enhanced accumulation in tumor facilitated its potent tumor growth inhibition activity in vivo. These results demonstrated that the cleavable multifunctional mixed micelles with tumor targeting, controlled TAT peptide activation, and sequential pH-sensitive drug release could be an efficient strategy for HCC treatment.

GE11 peptide modified and reduction-responsive hyaluronic acid-based nanoparticles induced higher efficacy of doxorubicin for breast carcinoma therapy

Novel breast carcinoma dual-targeted redox-responsive nanoparticles (NPs) based on cholesteryl-hyaluronic acid conjugates were designed for intracellular delivery of the antitumor drug doxorubicin (DOX). A series of reduction-responsive hyaluronic acid derivatives grafted with hydrophobic cholesteryl moiety (HA-ss-Chol) and GE11 peptide conjugated HA-ss-Chol (GE11-HA-ss-Chol) were synthesized. The obtained conjugates showed attractive self-assembly characteristics and high drug loading capacity. GE11-HA-ss-Chol NPs were highly stable under conditions mimicking normal physiological conditions, while showing a fast degradation of the vehicle's structure and accelerating the drug release dramatically in the presence of intracellular reductive environment. Furthermore, the cellular uptake assay confirmed GE11-HA-ss-Chol NPs were taken up by MDA-MB-231 cells through CD44- and epidermal growth factor receptor-mediated endocytosis. The internalization pathways of GE11-HA-ss-Chol NPs might involve clathrin-mediated endocytosis and macropinocytosis. The intracellular distribution of DOX in GE11-HA-ss-Chol NPs showed a faster release and more efficient nuclear delivery than the insensitive control. Enhanced in vitro cytotoxicity of GE11-HA-ss-Chol DOX-NPs further confirmed the superiority of their dual-targeting and redox-responsive capacity. Moreover, in vivo imaging investigation in MDA-MB-231 tumor-bearing mice confirmed that GE11-HA-ss-Chol NPs labeled with 1,1'-dioctadecyl-3,3,3',3'-tetramethylindotricarbocyanine iodide, a near-infrared fluorescence dye, possessed a preferable tumor accumulation ability as compared to the single-targeting counterpart (HA-ss-Chol NPs). The antitumor efficacy showed an improved therapy efficacy and lower systemic side effect. These results suggest GE11-HA-ss-Chol NPs provide a good potential platform for antitumor drugs.

Progress and perspectives on targeting nanoparticles for brain drug delivery

Due to the ability of the blood-brain barrier (BBB) to prevent the entry of drugs into the brain, it is a challenge to treat central nervous system disorders pharmacologically. The development of nanotechnology provides potential to overcome this problem. In this review, the barriers to brain-targeted drug delivery are reviewed, including the BBB, blood-brain tumor barrier (BBTB), and nose-to-brain barrier. Delivery strategies are focused on overcoming the BBB, directly targeting diseased cells in the brain, and dual-targeted delivery. The major concerns and perspectives on constructing brain-targeted delivery systems are discussed.

In vitro screening of nanomedicines through the blood brain barrier: A critical review

The blood-brain barrier accounts for the high attrition rate of the treatments of most brain disorders, which therefore remain one of the greatest health-care challenges of the twenty first century. Against this background of hindrance to brain delivery, nanomedicine takes advantage of the assembly at the nanoscale of available biomaterials to provide a delivery platform with potential to raising brain levels of either imaging or therapeutic agents. Nevertheless, to prevent later failure due to ineffective drug levels at the target site, researchers have been endeavoring to develop a battery of in vitro screening procedures that can predict earlier in the drug discovery process the ability of these cutting-edge drug delivery platforms to cross the blood-brain barrier for biomedical purposes. This review provides an in-depth analysis of the currently available in vitro blood-brain barrier models (both cell-based and non-cell-based) with the focus on their suitability for understanding the biological brain distribution of forthcoming nanomedicines. The relationship between experimental factors and underlying physiological assumptions that would ultimately lead to a more predictive capacity of their in vivo performance, and those methods already assayed for the evaluation of the brain distribution of nanomedicines are comprehensively discussed.

The Role of Cell-Penetrating Peptide and Transferrin on Enhanced Delivery of Drug to Brain

The challenge of effectively delivering therapeutic agents to brain has led to an entire field of active research devoted to overcome the blood brain barrier (BBB) and efficiently deliver drugs to brain. This review focusses on exploring the facets of a novel platform designed for the delivery of drugs to brain. The platform was constructed based on the hypothesis that a combination of receptor-targeting agent, like transferrin protein, and a cell-penetrating peptide (CPP) will enhance the delivery of associated therapeutic cargo across the BBB. The combination of these two agents in a delivery vehicle has shown significantly improved (p < 0.05) translocation of small molecules and genes into brain as compared to the vehicle with only receptor-targeting agents. The comprehensive details of the uptake mechanisms and properties of various CPPs are illustrated here. The application of this technology, in conjunction with nanotechnology, can potentially open new horizons for the treatment of central nervous system disorders.

Effect of integrin receptor-targeted liposomal paclitaxel for hepatocellular carcinoma targeting and therapy

The major aim of the present study was to develop an integrin receptor-targeted liposomal paclitaxel (PTX) to enhance the targeting specificity and therapeutic effect of PTX on hepatocellular carcinoma (HCC) cells. The specific Arg-Gly-Asp (RGD) ligand was conjugated to 1,2-distearoylphosphatidylethanolamine-polyethylene glycol 2000 to prepare the RGD-modified liposomes (RGD-LP). Furthermore, physicochemical characteristics of RGD-LP, including particle size, ζ potential, encapsulation efficiency and in vitro PTX release, were evaluated. RGD-modified liposomes were selected as the carrier for the present study, as they exhibit good biocompatibility and are easy to modify using RGD. The cellular uptake efficacy of RGD-LP by HepG2 cells was 3.3-fold higher than that of liposomes without RGD, indicating that RGD-LP may specifically target HepG2 cells by overexpressing integrin αvβ3 receptors. The RGD modification appeared to enhance the anti-proliferative activity of LP-PTX against HepG2 cells, with the extent of anti-proliferative activity dependent on the concentration of PTX and the incubation time. Additionally, evaluation of the homing specificity and anticancer efficacy of RGD-LP on the tumor spheroids indicated that solid tumor penetration was enhanced by the modification of RGD. In agreement with these in vitro findings, in vivo investigations demonstrated that RGD-LP-PTX exhibited a greater inhibitory effect on tumor growth in HepG2-bearing mice than LP-PTX or free PTX. Thus, RGD-LPs may represent an efficient targeted PTX delivery system for the treatment of patients with HCC.

Transferrin-conjugated doxorubicin-loaded lipid-coated nanoparticles for the targeting and therapy of lung cancer

In the present study, a targetable vector was developed for the targeted delivery of anticancer agents, consisting of lipid-coated poly D,L-lactic-co-glycolic acid nanoparticles (PLGA-NP) that were modified with transferrin (TF). Doxorubicin (DOX) was used as a model drug for lung cancer therapy. The use of these NPs combined the advantages and avoided the disadvantages exhibited individually by liposomes and polymeric NPs during drug delivery. The lipid coating of the polymeric core was confirmed by transmission electron microscopy. The physicochemical characteristics of transferrin-conjugated lipid-coated NPs (TF-LP), including the particle size, zeta potential, morphology, encapsulation efficiency and in vitro DOX release, were also evaluated. The cellular uptake investigation in the present study found that TF-LP was more efficiently endocytosed by the A549 cells, than LP and PLGA-NPs. Furthermore, the anti-proliferative effect exhibited by DOX-loaded TF-LPs on A549 cells and the inhibition of tumor spheroid growth was stronger compared with the effect of DOX-loaded lipid-coated PLGA-NPs and PLGA-NPs. In the in vivo component of the present study, TF-LP demonstrated the best inhibitory effect on tumor growth in the A549 tumor-bearing mice. It was concluded that TF-LP may be an efficient targeted drug-delivery system for lung cancer therapy.

Neuroprotection against degeneration of sk-N-mc cells using neuron growth factor-encapsulated liposomes with surface cereport and transferrin

Liposomes with Cereport (RMP-7) and transferrin (Tf) (RMP-7/Tf/liposomes) were employed to target the blood-brain barrier (BBB) and to inhibit the degeneration of neurons insulted with fibrillar β-amyloid peptide 1-42 (Aβ1-42). Neuron growth factor (NGF)-encapsulated RMP-7/Tf/liposomes (RMP-7/Tf/NGF-liposomes) were used to permeate a monolayer of human brain-microvascular endothelial cells (HBMECs) regulated by human astrocytes (HAs) and to treat Aβ1-42 -attacked SK-N-MC cells. An increase in RMT-7 concentration increased the particle size, zeta potential, propidium iodide (PI) permeability, and NGF permeability, but decreased the cross-linking efficiency of RMT-7, viability of HBMECs and HAs, and transendothelial electrical resistance (TEER). In addition, an increase in Tf concentration enhanced the particle size, viability of HBMECs, HAs, and SK-N-MC cells, PI permeability, and NGF permeability, but reduced the zeta potential, cross-linking efficiency of RMT-7 and Tf, and TEER. RMP-7/Tf/NGF-liposomes can transport NGF across the BBB and improve the neuroprotection for Alzheimer's disease therapy in preclinical trials.

Angiopep-2 and activatable cell-penetrating peptide dual-functionalized nanoparticles for systemic glioma-targeting delivery

Gliomas are hard to treat because of the two barriers involved: the blood-brain barrier and blood-tumor barrier. In this study, a dual-targeting ligand, angiopep-2, and an activatable cell-penetrating peptide (ACP) were functionalized onto nanoparticles for glioma-targeting delivery. The ACP was constructed by conjugating RRRRRRRR (R8) with EEEEEEEE through a matrix metalloproteinase-2 (MMP-2)-sensitive linker. ACP modification effectively enhanced the C6 cellular uptake because of the high expression of MMP-2 on C6 cells. The uptake was inhibited by batimastat, an MMP-2 inhibitor, suggesting that the cell-penetrating property of the ACP was activated by MMP-2. By combining the dual-targeting delivery effect of angiopep-2 and activatable cell-penetrating property of the ACP, the dual-modified nanoparticles (AnACNPs) displayed higher glioma localization than that of single ligand-modified nanoparticles. After loading with docetaxel, a common chemotherapeutic, AnACNPs showed the most favorable antiglioma effect both in vitro and in vivo. In conclusion, a novel drug delivery system was developed for glioma dual targeting and glioma penetrating. The results demonstrated that the system effectively targeted gliomas and provided the most favorable antiglioma effect.

Nanostructures: a platform for brain repair and augmentation

Nanoscale structures have been at the core of research efforts dealing with integration of nanotechnology into novel electronic devices for the last decade. Because the size of nanomaterials is of the same order of magnitude as biomolecules, these materials are valuable tools for nanoscale manipulation in a broad range of neurobiological systems. For instance, the unique electrical and optical properties of nanowires, nanotubes, and nanocables with vertical orientation, assembled in nanoscale arrays, have been used in many device applications such as sensors that hold the potential to augment brain functions. However, the challenge in creating nanowires/nanotubes or nanocables array-based sensors lies in making individual electrical connections fitting both the features of the brain and of the nanostructures. This review discusses two of the most important applications of nanostructures in neuroscience. First, the current approaches to create nanowires and nanocable structures are reviewed to critically evaluate their potential for developing unique nanostructure based sensors to improve recording and device performance to reduce noise and the detrimental effect of the interface on the tissue. Second, the implementation of nanomaterials in neurobiological and medical applications will be considered from the brain augmentation perspective. Novel applications for diagnosis and treatment of brain diseases such as multiple sclerosis, meningitis, stroke, epilepsy, Alzheimer's disease, schizophrenia, and autism will be considered. Because the blood brain barrier (BBB) has a defensive mechanism in preventing nanomaterials arrival to the brain, various strategies to help them to pass through the BBB will be discussed. Finally, the implementation of nanomaterials in neurobiological applications is addressed from the brain repair/augmentation perspective. These nanostructures at the interface between nanotechnology and neuroscience will play a pivotal role not only in addressing the multitude of brain disorders but also to repair or augment brain functions.

Synergistic dual-ligand doxorubicin liposomes improve targeting and therapeutic efficacy of brain glioma in animals

Therapeutic outcome for the treatment of glioma was often limited due to low permeability of delivery systems across the blood-brain barrier (BBB) and poor penetration into the tumor tissue. In order to overcome these hurdles, we developed the dual-targeting doxorubicin liposomes conjugated with cell-penetrating peptide (TAT) and transferrin (T7) (DOX-T7-TAT-LIP) for transporting drugs across the BBB, then targeting brain glioma, and penetrating into the tumor. The dual-targeting effects were evaluated by both in vitro and in vivo experiments. In vitro cellular uptake and three-dimensional tumor spheroid penetration studies demonstrated that the system could not only target endothelial and tumor monolayer cells but also penetrate tumor to reach the core of the tumor spheroids and inhibit the growth of the tumor spheroids. In vivo imaging further demonstrated that T7-TAT-LIP provided the highest tumor distribution. The median survival time of tumor-bearing mice after administering DOX-T7-TAT-LIP was significantly longer than those of the single-ligand doxorubicin liposomes and free doxorubicin. In conclusion, the dual-ligand liposomes comodified with T7 and TAT possessed strong capability of synergistic targeted delivery of payload into tumor cells both in vitro and in vivo, and they were able to improve the therapeutic efficacy of brain glioma in animals.

Shuttle-cargo fusion molecules of transport peptides and the hD2/3 receptor antagonist fallypride: a feasible approach to preserve ligand-receptor binding?

To determine if the conjugation of a small receptor ligand to a peptidic carrier to potentially facilitate transport across the blood-brain barrier (BBB) by "molecular Trojan horse" transcytosis is feasible, we synthesized several transport peptide-fallypride fusion molecules as model systems and determined their binding affinities to the hD2 receptor. Although they were affected by conjugation, the binding affinities were found to be still in the nanomolar range (between 1.5 and 64.2 nM). In addition, homology modeling of the receptor and docking studies for the most potent compounds were performed, elucidating the binding modes of the fusion molecules and the structure elements contributing to the observed high receptor binding. Furthermore, no interaction between the hybrid compounds and P-gp, the main excretory transporter of the BBB, was found. From these results, it can be inferred that the approach to deliver small neuroreceptor ligands across the BBB by transport peptide carriers is feasible.