RVG peptide tethered bioreducible polyethylenimine for gene delivery to brain

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.

Tumor-specific cytolysis by peptide-conjugated echogenic polymer micelles

Interest in multifunctional polymer nanoparticles for targeted delivery of anti-cancer drugs has grown significantly in recent years. In this study, tumor-targeting echogenic polymer micelles were prepared from poly(ethylene glycol) methyl ether-alkyl carbonate (mPEG-AC) derivatives, and their potential in cancer therapy was assessed. Various mPEG derivatives with carbonate linkages were synthesized via an alkyl halide reaction between mPEG and alkyl chloroformate. Micelle formation using polymer amphiphiles in aqueous media and the subsequent carbon dioxide (CO2) gas generation from the micelles was confirmed. Their ability to target neuroblastoma was substantially enhanced by incorporating the rabies virus glycoprotein (RVG) peptide. RVG-modified gas-generating micelles significantly inhibited tumor growth in a tumor-bearing mouse model owing to CO2 gas generation within tumor cells and resultant cytolytic effects, showing minimal side effects. The development of multifunctional polymer micelles may offer a promising therapeutic approach for various diseases, including cancer.

SARS-CoV-2 spike ectodomain targets α7 nicotinic acetylcholine receptors

Virus entry into animal cells is initiated by attachment to target macromolecules located on host cells. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) trimeric spike glycoprotein targets host angiotensin converting enzyme 2 to gain cellular access. The SARS-CoV-2 glycoprotein contains a neurotoxin-like region that has sequence similarities to the rabies virus and the HIV glycoproteins, as well as to snake neurotoxins, which interact with nicotinic acetylcholine receptor (nAChR) subtypes via this region. Using a peptide of the neurotoxin-like region of SARS-CoV-2 (SARS-CoV-2 glycoprotein peptide [SCoV2P]), we identified that this area moderately inhibits α3β2, α3β4, and α4β2 subtypes, while potentiating and inhibiting α7 nAChRs. These nAChR subtypes are found in target tissues including the nose, lung, central nervous system, and immune cells. Importantly, SCoV2P potentiates and inhibits ACh-induced α7 nAChR responses by an allosteric mechanism, with nicotine enhancing these effects. Live-cell confocal microscopy was used to confirm that SCoV2P interacts with α7 nAChRs in transfected neuronal-like N2a and human embryonic kidney 293 cells. The SARS-CoV-2 ectodomain functionally potentiates and inhibits the α7 subtype with nanomolar potency. Our functional findings identify that the α7 nAChR is a target for the SARS-CoV-2 glycoprotein, providing a new aspect to our understanding of SARS-CoV-2 and host cell interactions, in addition to disease pathogenesis.

Research Advances in Nucleic Acid Delivery System for Rheumatoid Arthritis Therapy

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease that affects the lives of nearly 1% of the total population worldwide. With the understanding of RA, more and more therapeutic drugs have been developed. However, lots of them possess severe side effects, and gene therapy may be a potential method for RA treatment. A nanoparticle delivery system is vital for gene therapy, as it can keep the nucleic acids stable and enhance the efficiency of transfection in vivo. With the development of materials science, pharmaceutics and pathology, more novel nanomaterials and intelligent strategies are applied to better and safer gene therapy for RA. In this review, we first summarized the existing nanomaterials and active targeting ligands used for RA gene therapy. Then, we introduced various gene delivery systems for RA treatment, which may enlighten the relevant research in the future.

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.

Targeted brain delivery of RVG29‐modified rifampicin‐loaded nanoparticles for Alzheimer's disease treatment and diagnosis

Alzheimer's disease (AD) is an aging‐related neurodegenerative disease. The main pathological features of AD are β‐amyloid protein (Aβ) deposition and tau protein hyperphosphorylation. Currently, there are no effective drugs for the etiological treatment of AD. Rifampicin (RIF) is a semi‐synthetic broad‐spectrum antibiotic with anti‐β‐amyloid deposition, anti‐inflammatory, anti‐apoptosis, and neuroprotective effects, but its application in AD treatment has been limited for its strong hydrophobicity, high toxicity, short half‐life, low bioavailability, and blood–brain barrier hindrance. We designed a novel brain‐targeted and MRI‐characteristic nanomedicine via loading rabies virus protein 29 (RVG29), rifampicin, and Gd on poly (l‐lactide) nanoparticles (RIF@PLA‐PEG‐Gd/Mal‐RVG29). The cytotoxicity assay demonstrated that RIF@PLA‐PEG‐Gd/Mal‐RVG29 had favorable biocompatibility and security. Fluorescence imaging in vivo showed that PLA‐PEG‐Gd/Mal‐RVG29 could deliver rifampicin into the brain by enhancing cellular uptake and brain targeting performance, leading to improvement of the bioavailability of rifampicin. In in vivo study, RIF@PLA‐PEG‐Gd/Mal‐RVG29 improved the spatial learning and memory capability of APP/PS1 mice in the Morris water maze, as compared to rifampicin. Immunofluorescence, TEM, immunoblotting, and H&E staining revealed that RIF@PLA‐PEG‐Gd/Mal‐RVG29 reduced Aβ deposition in hippocampal and cortex of APP/PS1 mice, improved the damage of synaptic ultrastructure, increased the expression level of PSD95 and SYP, as well as reduced the necrosis of neurons. These findings suggest that RIF@PLA‐PEG‐Gd/Mal‐RVG29 may be an effective strategy for the treatment of AD.

Tumor-targeted nano-delivery system of therapeutic RNA

The birth of RNAi technology has pioneered actionability at the molecular level. Compared to DNA, RNA is less stable and therefore requires more demanding delivery vehicles. With their flexible size, shape, structure, and accessible surface modification, non-viral vectors show great promise for application in RNA delivery. Different non-viral vectors have different ways of binding to RNA. Low immunotoxicity gives RNA significant advantages in tumor treatment. However, the delivery of RNA still has many limitations in vivo. This manuscript summarizes the size-targeting dependence of different organs, followed by a summary of nanovesicles currently in or undergoing clinical trials. It also reviews all RNA delivery systems involved in the current study, including natural, bionic, organic, and inorganic systems. It summarizes the advantages and disadvantages of different delivery methods, which will be helpful for future RNA vehicle design. It is hoped that this will be helpful for gene therapy of clinical tumors.

Polymeric Nanoparticles Properties and Brain Delivery

Safe and reliable entry to the brain is essential for successful diagnosis and treatment of diseases, but it still poses major challenges. As a result, many therapeutic approaches to treating disorders associated with the central nervous system (CNS) still only show limited success. Nano-sized systems are being explored as drug carriers and show great improvements in the delivery of many therapeutics. The systemic delivery of nanoparticles (NPs) or nanocarriers (NCs) to the brain involves reaching the neurovascular unit (NVU), being transported across the blood-brain barrier, (BBB) and accumulating in the brain. Each of these steps can benefit from specifically controlled properties of NPs. Here, we discuss how brain delivery by NPs can benefit from careful design of the NP properties. Properties such as size, charge, shape, and ligand functionalization are commonly addressed in the literature; however, properties such as ligand density, linker length, avidity, protein corona, and stiffness are insufficiently discussed. This is unfortunate since they present great value against multiple barriers encountered by the NPs before reaching the brain, particularly the BBB. We further highlight important examples utilizing targeting ligands and how functionalization parameters, e.g., ligand density and ligand properties, can affect the success of the nano-based delivery system.

Integrating disulfides into a polyethylenimine gene carrier selectively boosts significant transfection activity in lung tissue enabling robust IL-12 gene therapy against metastatic lung cancers

Bioreducible polyethylenimines (SSPEIs) are promising non-viral carriers for cancer gene therapy. However, the availability of significant gene transfection activity by SSPEIs remains a challenge. Herein, an essential step was taken to ascertain whether or not the disulfide bonds of SSPEIs play a critical role in promoting significant gene transfection activity in different tissues. Initially, a disulfide-linked linear polyethylenimine (denoted as SSLPEI) consisting of one 5.0 kDa LPEI main chain and three disulfide-linked 5.7 kDa LPEI grafts was designed and prepared to possess similar molecular weight with commercialized 25 kDa LPEI as a positive control. The SSLPEI could induce superior in vitro transfection activity in different cells to the LPEI control as well as low cytotoxicity. Notably, such enhanced in vitro transfection effect by the SSLPEI was more marked in type-II alveolar epithelial cells compared to different cancer cells. In a Balb/c nude mouse model bearing SKOV-3 tumor, the SSLPEI caused parallel level of transgene expression with the LPEI control in the tumor but significantly higher level in the mouse lung. Furthermore, the SSLPEI and LPEI groups afforded an identical antitumor efficacy against the SKOV-3 tumor via intravenous delivery of a shRNA for silencing VEGF expression in the tumor. However, via intravenous delivery of an interleukin-12 (IL-12) gene into metastatic lung cancers in a C57BL/6 mouse model, the SSLPEI group exerted markedly higher IL-12 expression level in the mouse lung and peripheral blood as compared to the LPEI group, thereby boosting IL-12 immunotherapy against the lung metastasis with longer medium survival time. The results of this work elicit that the disulfide bonds of SSPEIs play a pivotal role in enhancing gene transfection activity selectively in the lung tissue rather than solid tumor, enabling high translational potential of SSPEIs for non-viral gene therapy against metastatic lung cancers.

Efficient Anti-Glioma Therapy Through the Brain-Targeted RVG15-Modified Liposomes Loading Paclitaxel-Cholesterol Complex

Background

Glioma is the most common primary malignant brain tumor with a dreadful overall survival and high mortality. One of the most difficult challenges in clinical treatment is that most drugs hardly pass through the blood–brain barrier (BBB) and achieve efficient accumulation at tumor sites. Thus, to circumvent this hurdle, developing an effectively traversing BBB drug delivery nanovehicle is of significant clinical importance. Rabies virus glycoprotein (RVG) is a derivative peptide that can specifically bind to nicotinic acetylcholine receptor (nAChR) widely overexpressed on BBB and glioma cells for the invasion of rabies virus into the brain. Inspired by this, RVG has been demonstrated to potentiate drugs across the BBB, promote the permeability, and further enhance drug tumor-specific selectivity and penetration.

Methods

Here, we used the RVG15, rescreened from the well-known RVG29, to develop a brain-targeted liposome (RVG15-Lipo) for enhanced BBB permeability and tumor-specific delivery of paclitaxel (PTX). The paclitaxel-cholesterol complex (PTX-CHO) was prepared and then actively loaded into liposomes to acquire high entrapment efficiency (EE) and fine stability. Meanwhile, physicochemical properties, in vitro and in vivo delivery efficiency and therapeutic effect were investigated thoroughly.

Results

The particle size and zeta potential of PTX-CHO-RVG15-Lipo were 128.15 ± 1.63 nm and −15.55 ± 0.78 mV, respectively. Compared with free PTX, PTX-CHO-RVG15-Lipo exhibited excellent targeting efficiency and safety in HBMEC and C6 cells, and better transport efficiency across the BBB in vitro model. Furthermore, PTX-CHO-RVG15-Lipo could noticeably improve the accumulation of PTX in the brain, and then promote the chemotherapeutic drugs penetration in C6^luc orthotopic glioma based on in vivo imaging assays. The in vivo antitumor results indicated that PTX-CHO-RVG15-Lipo significantly inhibited glioma growth and metabasis, therefore improved survival rate of tumor-bearing mice with little adverse effect.

Conclusion

Our study demonstrated that the RVG15 was a promising brain-targeted specific ligands owing to the superior BBB penetration and tumor targeting ability. Based on the outstanding therapeutic effect both in vitro and in vivo, PTX-CHO-RVG15-Lipo was proved to be a potential delivery system for PTX to treat glioma in clinic.

Polymeric Delivery of Therapeutic Nucleic Acids

The advent of genome editing has transformed the therapeutic landscape for several debilitating diseases, and the clinical outlook for gene therapeutics has never been more promising. The therapeutic potential of nucleic acids has been limited by a reliance on engineered viral vectors for delivery. Chemically defined polymers can remediate technological, regulatory, and clinical challenges associated with viral modes of gene delivery. Because of their scalability, versatility, and exquisite tunability, polymers are ideal biomaterial platforms for delivering nucleic acid payloads efficiently while minimizing immune response and cellular toxicity. While polymeric gene delivery has progressed significantly in the past four decades, clinical translation of polymeric vehicles faces several formidable challenges. The aim of our Account is to illustrate diverse concepts in designing polymeric vectors towards meeting therapeutic goals of in vivo and ex vivo gene therapy. Here, we highlight several classes of polymers employed in gene delivery and summarize the recent work on understanding the contributions of chemical and architectural design parameters. We touch upon characterization methods used to visualize and understand events transpiring at the interfaces between polymer, nucleic acids, and the physiological environment. We conclude that interdisciplinary approaches and methodologies motivated by fundamental questions are key to designing high-performing polymeric vehicles for gene therapy.

Development of Polymeric Nanoparticles for Blood-Brain Barrier Transfer-Strategies and Challenges

Neurological disorders such as Alzheimer's disease, stroke, and brain cancers are difficult to treat with current drugs as their delivery efficacy to the brain is severely hampered by the presence of the blood-brain barrier (BBB). Drug delivery systems have been extensively explored in recent decades aiming to circumvent this barrier. In particular, polymeric nanoparticles have shown enormous potentials owing to their unique properties, such as high tunability, ease of synthesis, and control over drug release profile. However, careful analysis of their performance in effective drug transport across the BBB should be performed using clinically relevant testing models. In this review, polymeric nanoparticle systems for drug delivery to the central nervous system are discussed with an emphasis on the effects of particle size, shape, and surface modifications on BBB penetration. Moreover, the authors critically analyze the current in vitro and in vivo models used to evaluate BBB penetration efficacy, including the latest developments in the BBB-on-a-chip models. Finally, the challenges and future perspectives for the development of polymeric nanoparticles to combat neurological disorders are discussed.

Disulfide Bridging Strategies in Viral and Nonviral Platforms for Nucleic Acid Delivery

Self-assembled nanostructures that are sensitive to environmental stimuli are promising nanomaterials for drug delivery. In this class, disulfide-containing redox-sensitive strategies have gained enormous attention because of their wide applicability and simplicity of nanoparticle design. In the context of nucleic acid delivery, numerous disulfide-based materials have been designed by relying on covalent or noncovalent interactions. In this review, we highlight major advances in the design of disulfide-containing materials for nucleic acid encapsulation, including covalent nucleic acid conjugates, viral vectors or virus-like particles, dendrimers, peptides, polymers, lipids, hydrogels, inorganic nanoparticles, and nucleic acid nanostructures. Our discussion will focus on the context of the design of materials and their impact on addressing the current shortcomings in the intracellular delivery of nucleic acids.

Current Developments in Targeted Drug Delivery Systems for Glioma

BACKGROUND

Glioma is one of the most commonly observed tumours, representing about 75% of brain tumours in the adult population. Generally, glioma treatment includes surgical resection followed by radiotherapy and chemotherapy. The current chemotherapy for glioma involves the use of temozolomide, doxorubicin, monoclonal antibodies, etc. however, the clinical outcomes in patients are not satisfactory. Primarily, the blood-brain barrier hinders these drugs from reaching the target leading to the recurrence of glioma post-surgery. In addition, these drugs are not target-specific and affect the healthy cells of the body. Therefore, glioma-targeted drug delivery is essential to reduce the rate of recurrence and treat the condition with more reliable alternatives.

METHODS

A literature search was conducted to understand glioma pathophysiology, its current therapeutic approaches for targeted delivery using databases like Pub Med, Web of Science, Scopus, and Google Scholar, etc. Results: This review gives an insight to challenges associated with current treatments, factors influencing drug delivery in glioma, and recent advancements in targeted drug delivery.

CONCLUSION

The promising results could be seen with nanotechnology-based approaches, like polymeric, lipidbased, and hybrid nanoparticles in the treatment of glioma. Biotechnological developments, such as carrier peptides and gene therapy, are future prospects in glioma therapy. Therefore, these targeted delivery systems will be beneficial in clinical practices for glioma treatment.

Recent advances in the redox-responsive drug delivery nanoplatforms: A chemical structure and physical property perspective

Poor water solubility, off-target toxicity, and small therapeutic window are among major obstacles for the development of drug products. Redox-responsive drug delivery nanoplatforms not only overcome the delivery and pharmacokinetic pitfalls observed in conventional drug delivery, but also leverage the site-specific delivery properties. Cleavable diselenide and disulfide bonds in the presence of elevated reactive oxygen species (ROS) and glutathione concentration are among widely used stimuli-responsive bonds to design nanocarriers. This review covers a wide range of redox-responsive chemical structures and their properties for designing nanoparticles aiming controlled loading, delivery, and release of hydrophobic anticancer drugs at tumor site.

Small interfering RNA for cancer treatment: overcoming hurdles in delivery

In many ways, cancer cells are different from healthy cells. A lot of tactical nano-based drug delivery systems are based on the difference between cancer and healthy cells. Currently, nanotechnology-based delivery systems are the most promising tool to deliver DNA-based products to cancer cells. This review aims to highlight the latest development in the lipids and polymeric nanocarrier for siRNA delivery to the cancer cells. It also provides the necessary information about siRNA development and its mechanism of action. Overall, this review gives us a clear picture of lipid and polymer-based drug delivery systems, which in the future could form the base to translate the basic siRNA biology into siRNA-based cancer therapies.

The influx/efflux mechanisms of d-peptide ligand of nAChRs across the blood-brain barrier and its therapeutic value in treating glioma

A d-peptide ligand of the nicotine acetylcholine receptors (nAChRs), termed ^DCDX, enables drug delivery to the brain when incorporated into liposomes and has shown promise as a nanocarrier for treating brain diseases. However, few reports have described the mechanisms whereby ^DCDX-modified liposomes traverse the blood-brain barrier (BBB). Here, we studied the molecular mechanisms enabling ^DCDX (and its associated liposomes) to cross an in vitro BBB using a simulated cerebral endothelium monolayer formed by brain capillary endothelial cells (bEnd.3 cells). We also examined the mechanisms whereby ^DCDX-modified liposomes cross the BBB in vivo using the brain efflux-index method. Transport of ^DCDX and its modified liposomes was dominantly mediated via the lipid raft/caveolae endocytic pathway. Both the endoplasmic reticulum (ER) and Golgi complex participated in delivering ^DCDX-modified liposomes to the plasma membrane (PM). ^DCDX-modified liposomes also participated in the endosome/lysosome pathway (with high-efficiency BBB crossing observed in vitro), while competing for the ER/Golgi/PM pathway. In addition, nAChR α7 did not promote the transportation of ^DCDX-modified liposomes in vivo or in vitro, as assessed with α7-knockout mice and by performing α-bungarotoxin (α-Bgt) binding-competition experiments. P-glycoprotein (P-gp) was identified as the main efflux transporter across the BBB, in vivo and in vitro. Using a xenograft nude mouse model of human glioblastoma multiforme, blocking the efflux function of P-gp with verapamil enhanced the therapeutic efficiency of ^DCDX-modified liposomes that were formulated with doxorubicin against glioblastoma. The findings of this study reveal novel mechanisms underlying crossing of the BBB by ^DCDX-modified liposomes, suggesting that ^DCDX-modified liposomes can potentially serve as a powerful therapeutic tool for treating glioma.

Mendonça L, Matos L, Prata MJ, S. Jurado A, Pedroso de Lima MC, Alves S. Lysosomal Storage Disease-Associated Neuropathy: Targeting Stable Nucleic Acid Lipid Particle (SNALP)-Formulated siRNAs to the Brain as a Therapeutic Approach

More than two thirds of Lysosomal Storage Diseases (LSDs) present central nervous system involvement. Nevertheless, only one of the currently approved therapies has an impact on neuropathology. Therefore, alternative approaches are under development, either addressing the underlying enzymatic defect or its downstream consequences. Also under study is the possibility to block substrate accumulation upstream, by promoting a decrease of its synthesis. This concept is known as substrate reduction therapy and may be triggered by several molecules, such as small interfering RNAs (siRNAs). siRNAs promote RNA interference, a naturally occurring sequence-specific post-transcriptional gene-silencing mechanism, and may target virtually any gene of interest, inhibiting its expression. Still, naked siRNAs have limited cellular uptake, low biological stability, and unfavorable pharmacokinetics. Thus, their translation into clinics requires proper delivery methods. One promising platform is a special class of liposomes called stable nucleic acid lipid particles (SNALPs), which are characterized by high cargo encapsulation efficiency and may be engineered to promote targeted delivery to specific receptors. Here, we review the concept of SNALPs, presenting a series of examples on their efficacy as siRNA nanodelivery systems. By doing so, we hope to unveil the therapeutic potential of these nanosystems for targeted brain delivery of siRNAs in LSDs.

Brain Targeted Gold Liposomes Improve RNAi Delivery for Glioblastoma

INTRODUCTION

Glioblastoma (GBM) is the most common and lethal of the central nervous system (CNS) malignancies. The initiation, progression, and infiltration ability of GBMs are attributed in part to the dysregulation of microRNAs (miRNAs). Thus, targeting dysregulated miRNAs with RNA oligonucleotides (RNA interference, RNAi) has been proposed for GBM treatment. Despite promising results in the laboratory, RNA oligonucleotides have clinical limitations that include poor RNA stability and off-target effects. RNAi therapies against GBM confront an additional obstacle, as they need to cross the blood-brain barrier (BBB).

METHODS

Here, we developed gold-liposome nanoparticles conjugated with the brain targeting peptides apolipoprotein E (ApoE) and rabies virus glycoprotein (RVG). First, we functionalized gold nanoparticles with oligonucleotide miRNA inhibitors (OMIs), creating spherical nucleic acids (SNAs). Next, we encapsulated SNAs into ApoE, or RVG-conjugated liposomes, to obtain SNA-Liposome-ApoE and SNA-Liposome-RVG, respectively. We characterized each nanoparticle in terms of their size, charge, encapsulation efficiency, and delivery efficiency into U87 GBM cells in vitro. Then, they were administered intravenously (iv) in GBM syngeneic mice to evaluate their delivery efficiency to brain tumor tissue.

RESULTS

SNA-Liposomes of about 30-50 nm in diameter internalized U87 GBM cells and inhibited the expression of miRNA-92b, an aberrantly overexpressed miRNA in GBM cell lines and GBM tumors. Conjugating SNA-Liposomes with ApoE or RVG peptides increased their systemic delivery to the brain tumors of GBM syngeneic mice. SNA-Liposome-ApoE demonstrated to accumulate at higher extension in brain tumor tissues, when compared with non-treated controls, SNA-Liposomes, or SNA-Liposome-RVG.

DISCUSSION

SNA-Liposome-ApoE has the potential to advance the translation of miRNA-based therapies for GBM as well as other CNS disorders.

Breaking Barriers: Bioinspired Strategies for Targeted Neuronal Delivery to the Central Nervous System

Central nervous system (CNS) disorders encompass a vast spectrum of pathological conditions and represent a growing concern worldwide. Despite the high social and clinical interest in trying to solve these pathologies, there are many challenges to bridge in order to achieve an effective therapy. One of the main obstacles to advancements in this field that has hampered many of the therapeutic strategies proposed to date is the presence of the CNS barriers that restrict the access to the brain. However, adequate brain biodistribution and neuronal cells specific accumulation in the targeted site also represent major hurdles to the attainment of a successful CNS treatment. Over the last few years, nanotechnology has taken a step forward towards the development of therapeutics in neurologic diseases and different approaches have been developed to surpass these obstacles. The versatility of the designed nanocarriers in terms of physical and chemical properties, and the possibility to functionalize them with specific moieties, have resulted in improved neurotargeted delivery profiles. With the concomitant progress in biology research, many of these strategies have been inspired by nature and have taken advantage of physiological processes to achieve brain delivery. Here, the different nanosystems and targeting moieties used to achieve a neuronal delivery reported in the open literature are comprehensively reviewed and critically discussed, with emphasis on the most recent bioinspired advances in the field. Finally, we express our view on the paramount challenges in targeted neuronal delivery that need to be overcome for these promising therapeutics to move from the bench to the bedside.

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.

Systemic delivery of microRNA-21 antisense oligonucleotides to the brain using T7-peptide decorated exosomes

Antisense miRNA oligonucleotides against miR-21 (AMO-21) have a therapeutic potential for treatment of glioblastoma. However, glioblastoma-targeted delivery through systemic injection requires development of an efficient targeting carrier. For this purpose, a glioblastoma-targeting carrier was developed using the T7 peptide and exosomes. The transferrin receptor is overexpressed on the surface of glioblastoma cells, and T7 is a transferrin receptor-binding peptide. A T7 peptide-decorated exosome (T7-exo) was produced by incorporation of T7 into the exosome membrane as a fusion protein of T7 and Lamp2b. As a control, rabies virus glycoprotein (RVG) peptide targeting brain neuron cells was incorporated into the exosome membrane. AMO-21 was loaded into the exosomes by electroporation. In vitro studies of AMO-21 delivery showed that T7-exo had a higher delivery efficiency to C6 glioblastoma cells than unmodified exosome (Unmod-exo) and RVG-decorated exosome (RVG-exo). For in vivo delivery studies, T7-exo with AMO-21 was delivered into intracranial glioblastoma rat models by intravenous injection through the tail vein. The results showed that T7-exo delivered AMO-21 into the brain more efficiently than Unmod-exo and RVG-exo. In addition, delivery of AMO-21 using T7-exo reduced the miR-21 level in the glioblastoma efficiently. Reduction of miR-21 by AMO-21 induced the expression of PDCD4 and PTEN in tumors, resulting in reduction of tumor sizes. Taken together, these findings indicate that T7-exo is an efficient carrier of AMO-21 into the glioblastoma and may be useful in development of glioblastoma therapy.

Dual targeting of folate receptor-expressing glioma tumor-associated macrophages and epithelial cells in the brain using a carbon nanosphere-cationic folate nanoconjugate

Glioblastoma multiforme (GBM), the highly invasive form of glioma, exhibits the highest mortality in patients with brain malignancies. Increasing glioma patients' survivability is challenging, as targeting only tumor-associated malignant cells would not reduce the overall aggressiveness of the tumor mass. This is due to the inadequacy in countering pro-proliferative, invasive and metastatic factors released by tumor-mass associated macrophages (TAMs). Hence, strategically, dual targeting both tumor cells and TAMs is necessary for effective glioma treatment and increased survivability. Conventional FR-targeting systems can easily target cancer cells that overtly express folate receptors (FRs). However, FRs are expressed only moderately in both glioma cells and in TAMs. Hence, it is more challenging to coordinate dual targeting of glioma cells and TAMs with lower levels of FR expression. A recently developed carbon nanosphere (CSP) with effective blood-brain barrier (BBB) penetrability was modified with a new folic acid-cationic lipid conjugate (F8) as a targeting ligand. The uniqueness of the cationic lipid-folate conjugate is that it stably associates with the negatively charged CSP surface at about >22 mol% surface concentration, a concentration at least 5-fold higher than what is achieved for conventional FR-targeting delivery systems. This enabled dual uptake of the CSP on TAMs and tumor cells via FRs. A doxorubicin-associated FR-targeting formulation (CFD), in an orthotopic glioma model and in a glioma subcutaneous model, induced the maximum anticancer effect with enhanced average mice survivability twice that of untreated mice and without any systemic liver toxicity. Additionally, we observed a significant decrease of TAM-released pro-aggressive factors, TGF-β, STAT3, invasion and migration related sICAM-1, and other cytokines indicating anti-TAM activity of the CFD. Taken together, we principally devised, to the best of our knowledge, the first FR-targeting nano-delivery system for targeting brain-associated TAMs and tumor cells as an efficient glioma therapeutic.

Reduction sensitive CC9-PEG-SSBPEI/miR-148b nanoparticles: Synthesis, characterization, targeting delivery and application for anti-metastasis

miRNAs such as miR-148b play crucial regulatory role in tumor metastasis, but their applications are limited because they are easy to degrade in serum conditions and lack targeting ability. Herein, CC9-PEG-SSBPEI was synthesized and used as nano-carrier for miR-148b. DLS and gel retardation analyses indicated that CC9-PEG-SSBPEI could combine with miR-148b by charge interaction and formed into nanoparticles with the size changed from 811.6 nm to 146.4 nm. CC9-PEG-SSBPEI could protect miR-148b from RNase A degradation and showed a reduction sensitive release of miR-148b. FACS analysis and CLSM images displayed that the conjugated CC9 peptide improved the accumulation and penetration of the nanoparticles in HuH-7 liver cancer cells through binding with the target of miR-148b neuropilin-1(NRP-1) on the cell surface. The raised level of miR-148b in turn inhibited the expression of NRP-1 and suppressed the migration of HuH-7 liver cancer cells. Moreover, hemolysis and cytotoxicity assay demonstrated that the nanoparticles had good hemo- and cyto- compatibility. Hence, CC9-PEG-SSBPEI/miR-148b nanoparticles had the potential for targeting delivery of miR-148b and anti-metastasis of hepatocellular carcinoma (HCC) cells.

Chitosan-Based Nanocarriers for Nose to Brain Delivery

In the treatment of brain diseases, most potent drugs that have been developed exhibit poor therapeutic outcomes resulting from the inability of a therapeutic amount of the drug to reach the brain. These drugs do not exhibit targeted drug delivery mechanisms, resulting in a high concentration of the drugs in vital organs leading to drug toxicity. Chitosan (CS) is a natural-based polymer. It has unique properties such as good biodegradability, biocompatibility, mucoadhesive properties, and it has been approved for biomedical applications. It has been used to develop nanocarriers for brain targeting via intranasal administration. Nanocarriers such as nanoparticles, in situ gels, nanoemulsions, and liposomes have been developed. In vitro and in vivo studies revealed that these nanocarriers exhibited enhanced drug uptake to the brain with reduced side effects resulting from the prolonged contact time of the nanocarriers with the nasal mucosa, the surface charge of the nanocarriers, the nano size of the nanocarriers, and their capability to stretch the tight junctions within the nasal mucosa. The aforementioned unique properties make chitosan a potential material for the development of nanocarriers for targeted drug delivery to the brain. This review will focus on chitosan-based carriers for brain targeting.

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.

Non-viral nanocarriers for intracellular delivery of microRNA therapeutics

MicroRNAs are small regulatory noncoding RNAs that regulate various biological processes. Herein, we will present the development of the strategies for intracellular miRNAs delivery, and specially focus on the rational designed routes, their mechanisms of action, as well as potential therapeutics used in the host cells orin vivostudies.

Nanoparticle formulations that allow for sustained delivery and brain targeting of the neuropeptide oxytocin

Oxytocin is a promising candidate for the treatment of social-deficit disorders such as Autism Spectrum Disorder, but oxytocin cannot readily pass the blood-brain barrier. Moreover, oxytocin requires frequent dosing as it is rapidly metabolized in blood. We fabricated four polymeric nanoparticle formulations using poly(lactic-co-glycolic acid) (PLGA) or bovine serum albumin (BSA) as the base material. In order to target them to the brain, we then conjugated the materials to either transferrin or rabies virus glycoprotein (RVG) as targeting ligands. The formulations were characterized in vitro for size, zeta potential, encapsulation efficiency, and release profiles. All formulations showed slightly negative charges and sizes ranging from 100 to 278 nm in diameter, with RVG-conjugated BSA nanoparticles exhibiting the smallest sizes. No formulation was found to be immunogenic or cytotoxic. The encapsulation efficiency was ≥75% for all nanoparticle formulations. Release studies demonstrated that BSA nanoparticle formulation exhibited a faster initial burst of release compared to PLGA particles, in addition to later sustained release. This initial burst release would be favorable for clinical dosing as therapeutic effects could be quickly established, especially in combination with additional sustained release to maintain the therapeutic effects. Our size and release profile data indicate that RVG-conjugated BSA nanoparticles are the most favorable formulation for brain delivery of oxytocin.

Gene Therapies for Polyglutamine Diseases

Polyglutamine diseases are hereditary degenerative disorders of the nervous system that have remained, to this date, untreatable. Promisingly, investigation into their molecular etiology and the development of increasingly perfected tools have contributed to the design of novel strategies with therapeutic potential. Encouraging studies have explored gene therapy as a means to counteract cell demise and loss in this context. The current chapter addresses the two main focuses of research in the area: the characteristics of the systems used to deliver nucleic acids to cells and the molecular and cellular actions of the therapeutic agents. Vectors used in gene therapy have to satisfyingly reach the tissues and cell types of interest, while eliciting the lowest toxicity possible. Both viral and non-viral systems have been developed for the delivery of nucleic acids to the central nervous system, each with its respective advantages and shortcomings. Since each polyglutamine disease is caused by mutation of a single gene, many gene therapy strategies have tried to halt degeneration by silencing the corresponding protein products, usually recurring to RNA interference. The potential of small interfering RNAs, short hairpin RNAs and microRNAs has been investigated. Overexpression of protective genes has also been evaluated as a means of decreasing mutant protein toxicity and operate beneficial alterations. Recent gene editing tools promise yet other ways of interfering with the disease-causing genes, at the most upstream points possible. Results obtained in both cell and animal models encourage further delving into this type of therapeutic strategies and support the future use of gene therapy in the treatment of polyglutamine diseases.

Liposomes and lipid disks traverse the BBB and BBTB as intact forms as revealed by two-step Förster resonance energy transfer imaging

The blood-brain barrier (BBB) and the blood-brain tumor barrier (BBTB) prevent drug and nano-drug delivery systems from entering the brain. However, ligand-mediated nano-drug delivery systems have significantly enhanced the therapeutic treatment of glioma. In this study we investigated the mechanism especially the integrity of liposomes and lipid disks while traversing the BBB and BBTB both in vitro and in vivo. Fluorophores (DiO, DiI and DiD) were loaded into liposomes and lipid disks to form Förster resonance energy transfer (FRET) nano-drug delivery systems. Using brain capillary endothelial cells as a BBB model, we show that liposomes and disks are present in the cytoplasm as their intact forms and traverse the BBB with a ratio of 0.68‰ and 1.67‰, respectively. Using human umbilical vein endothelial cells as BBTB model, liposomes and disks remained intact and traversed the BBTB with a ratio of 2.31‰ and 8.32‰ at 3 h. Ex vivo imaging and immunohistochemical results revealed that liposomes and disks could traverse the BBB and BBTB in vivo as intact forms. In conclusion, these observations explain in part the mechanism by which nano-drug delivery systems increase the therapeutic treatment of glioma.

Applications of Nanoparticles Probes for Prostate Cancer Imaging and Therapy

Prostate cancer (PCa) is the most common type of cancer in men with high morbidity and mortality. However, the current treatment with drugs often leads to chemotherapy resistance. It is known that the multi-disciplines research on molecular imaging is very helpful for early diagnosing, staging, restaging and precise treatment of PCa. In the past decades, the tumor-specific targeted drugs were developed for the clinic to treat prostate cancer. Among them, the emerging nanotechnology has brought about many exciting novel diagnosis and treatments systems for PCa. Nanotechnology can greatly enhance the treatment activity of PCa and provide novel theranostics platform by utilizing the unique physical/chemical properties, targeting strategy, or by loading with imaging/therapeutic agents. Herein, this chapter focuses on state-of-art advances in imaging and diagnosing PCa with nanomaterials and highlights the approaches used for functionalization of the targeted biomolecules, and in the treatment for various aspects of PCa with multifunctional nanoparticles, nanoplatforms and nanodelivery system.

Targeted transport of nanocarriers into brain for theranosis with rabies virus glycoprotein-derived peptide

For successful theranosis of brain diseases, limited access of therapeutic molecules across blood-brain barrier (BBB) needs be overcome in brain delivery. Currently, peptide derivatives of rabies virus glycoprotein (RVG) have been exploited as delivery ligands to transport nanocarriers across BBB and specifically into the brain. The targeting peptides usually conjugate to the nanocarrier surface, and the cargoes, including siRNA, miRNA, DNA, proteins and small molecular chemicals, are complexed or encapsulated in the nanocarriers. The peptide ligand of the RVG-modified nanocarriers introduces the conjugated targeted-delivery into the brain, and the cargoes are involved in disease theranosis. The peptide-modified nanocarriers have been applied to diagnose and treat various brain diseases, such as glioma, Alzheimer's disease, ischemic injury, protein misfolding diseases etc. Since the targeting delivery system has displayed good biocompatibility and desirable therapeutic effect, it will raise a potential application in treating brain diseases.

RNA interference for glioblastoma therapy: Innovation ladder from the bench to clinical trials

Glioblastoma multiforme (GBM) is the most common and deadliest type of primary brain tumor with a prognosis of 14months after diagnosis. Current treatment for GBM patients includes "total" tumor resection, temozolomide-based chemotherapy, radiotherapy or a combination of these options. Although, several targeted therapies, gene therapy, and immunotherapy are currently in the clinic and/or in clinical trials, the overall survival of GBM patients has hardly improved over the last two decades. Therefore, novel multitarget modalities are urgently needed. Recently, RNA interference (RNAi) has emerged as a novel strategy for the treatment of most cancers, including GBM. RNAi-based therapies consist of using small RNA oligonucleotides to regulate protein expression at the post-transcriptional level. Despite the therapeutic potential of RNAi molecules, systemic limitations including short circulatory stability and low release into the tumor tissue have halted their progress to the clinic. The effective delivery of RNAi molecules through the blood-brain barrier (BBB) represents an additional challenge. This review focuses on connecting the translational process of RNAi-based therapies from in vitro evidence to pre-clinical studies. We delineate the effect of RNAi in GBM cell lines, describe their effectiveness in glioma mouse models, and compare the proposed drug carriers for the effective transport of RNAi molecules through the BBB to reach the tumor in the brain. Furthermore, we summarize the most important obstacles to overcome before RNAi-based therapy becomes a reality for GBM treatment.

Exploring the role of peptides in polymer-based gene delivery

Polymers are widely studied as non-viral gene vectors because of their strong DNA binding ability, capacity to carry large payload, flexibility of chemical modifications, low immunogenicity, and facile processes for manufacturing. However, high cytotoxicity and low transfection efficiency substantially restrict their application in clinical trials. Incorporating functional peptides is a promising approach to address these issues. Peptides demonstrate various functions in polymer-based gene delivery systems, such as targeting to specific cells, breaching membrane barriers, facilitating DNA condensation and release, and lowering cytotoxicity. In this review, we systematically summarize the role of peptides in polymer-based gene delivery, and elaborate how to rationally design polymer-peptide based gene delivery vectors.

STATEMENT OF SIGNIFICANCE

Polymers are widely studied as non-viral gene vectors, but suffer from high cytotoxicity and low transfection efficiency. Incorporating short, bioactive peptides into polymer-based gene delivery systems can address this issue. Peptides demonstrate various functions in polymer-based gene delivery systems, such as targeting to specific cells, breaching membrane barriers, facilitating DNA condensation and release, and lowering cytotoxicity. In this review, we highlight the peptides' roles in polymer-based gene delivery, and elaborate how to utilize various functional peptides to enhance the transfection efficiency of polymers. The optimized peptide-polymer vectors should be able to alter their structures and functions according to biological microenvironments and utilize inherent intracellular pathways of cells, and consequently overcome the barriers during gene delivery to enhance transfection efficiency.

Effects of tumor microenvironments on targeted delivery of glycol chitosan nanoparticles

In cancer theranostics, the main strategy of nanoparticle-based targeted delivery system has been understood by enhanced permeability and retention (EPR) effect of macromolecules. Studies on diverse nanoparticles provide a better understanding of different EPR effects depending on their structure, physicochemical properties, and chemical modifications. Recently the tumor microenvironment has been considered as another important factor for determining tumor-targeted delivery of nanoparticles, but the correlation between EPR effects and tumor microenvironment has not yet been fully elucidated. Herein, ectopic subcutaneous tumor models presenting different tumor microenvironments were established by inoculation of SCC7, U87, HT29, PC3, and A549 cancer cell lines into athymic nude mice, respectively. In the five different types of tumor-bearing mice, tumor-targeted delivery of self-assembled glycol chitosan nanoparticles (CNPs) were comparatively evaluated to identify the correlation between the tumor microenvironments and targeted delivery of CNPs. As a result, neovascularization and extents of intratumoral extracellular matrix (ECM) were both important in determining the tumor targeted delivery of CNPs. The EPR effect was maximized in the tumors which include large extent of angiogenic blood vessels and low intratumoral ECM content. This comprehensive study provides substantial evidence that the EPR effects based tumor-targeted delivery of nanoparticles can be different depending on the tumor microenvironment in individual tumors. To overcome current limitations in clinical nanomedicine, the tumor microenvironment of the patients and EPR effects in clinical tumors should also be carefully studied.

Brain-Targeted Polymers for Gene Delivery in the Treatment of Brain Diseases

Gene therapies have become a promising strategy for treating neurological disorders, such as brain cancer and neurodegenerative diseases, with the help of molecular biology interpreting the underlying pathological mechanisms. Successful cellular manipulation against these diseases requires efficient delivery of nucleic acids into brain and further into specific neurons or cancer cells. Compared with viral vectors, non-viral polymeric carriers provide a safer and more flexible way of gene delivery, although suffering from significantly lower transfection efficiency. Researchers have been devoted to solving this defect, which is attributed to the multiple barriers existing for gene therapeutics in vivo, such as systemic degradation, blood-brain barrier, and endosome trapping. This review will be mainly focused on systemically administrated brain-targeted polymers developed so far, including PEI, dendrimers, and synthetic polymers with various functions. We will discuss in detail how they are designed to overcome these barriers and how they efficiently deliver therapeutic nucleic acids into targeted cells.

Neurotensin-Conjugated Reduced Graphene Oxide with Multi-Stage Near-Infrared-Triggered Synergic Targeted Neuron Gene Transfection In Vitro and In Vivo for Neurodegenerative Disease Therapy

Delivery efficiency with gene transfection is a pivotal point in achieving maximized therapeutic efficacy and has been an important challenge with central nervous system (CNS) diseases. In this study, neurotensin (NT, a neuro-specific peptide)-conjugated polyethylenimine (PEI)-modified reduced graphene oxide (rGO) nanoparticles with precisely controlled two-stage near-infrared (NIR)-laser photothermal treatment to enhance the ability to target neurons and achieve high gene transfection in neurons. First-stage NIR laser irradiation on the cells with nanoparticles attached on the surface can increase the permeability of the cell membrane, resulting in an apparent increase in cellular uptake compared to untreated cells. In addition, second-stage NIR laser irradiation on the cells with nanoparticles inside can further induce endo/lysosomal cavitation, which not only helps nanoparticles escape from endo/lysosomes but also prevents plasmid DNA (pDNA) from being digested by DNase I. At least double pDNA amount can be released from rGO-PEI-NT/pDNA under NIR laser trigger release compared to natural release. Moreover, in vitro differentiated PC-12 cell and in vivo mice (C57BL/6) brain transfection experiments have demonstrated the highest transfection efficiency occurring when NT modification is combined with external multi-stage stimuli-responsive NIR laser treatment. The combination of neuro-specific targeting peptide and external NIR-laser-triggered aid provides a nanoplatform for gene therapy in CNS diseases.

Virus-inspired nucleic acid delivery system: Linking virus and viral mimicry

Targeted delivery of nucleic acids into disease sites of human body has been attempted for decades, but both viral and non-viral vectors are yet to meet our expectations. Safety concerns and low delivery efficiency are the main limitations of viral and non-viral vectors, respectively. The structure of viruses is both ordered and dynamic, and is believed to be the key for effective transfection. Detailed understanding of the physical properties of viruses, their interaction with cellular components, and responses towards cellular environments leading to transfection would inspire the development of safe and effective non-viral vectors. To this goal, this review systematically summarizes distinctive features of viruses that are implied for efficient nucleic acid delivery but not yet fully explored in current non-viral vectors. The assembly and disassembly of viral structures, presentation of viral ligands, and the subcellular targeting of viruses are emphasized. Moreover, we describe the current development of cationic material-based viral mimicry (CVM) and structural viral mimicry (SVM) in these aspects. In light of the discrepancy, we identify future opportunities for rational design of viral mimics for the efficient delivery of DNA and RNA.

Non-Viral Nucleic Acid Delivery Strategies to the Central Nervous System

With an increased prevalence and understanding of central nervous system (CNS) injuries and neurological disorders, nucleic acid therapies are gaining promise as a way to regenerate lost neurons or halt disease progression. While more viral vectors have been used clinically as tools for gene delivery, non-viral vectors are gaining interest due to lower safety concerns and the ability to deliver all types of nucleic acids. Nevertheless, there are still a number of barriers to nucleic acid delivery. In this focused review, we explore the in vivo challenges hindering non-viral nucleic acid delivery to the CNS and the strategies and vehicles used to overcome them. Advantages and disadvantages of different routes of administration including: systemic injection, cerebrospinal fluid injection, intraparenchymal injection and peripheral administration are discussed. Non-viral vehicles and treatment strategies that have overcome delivery barriers and demonstrated in vivo gene transfer to the CNS are presented. These approaches can be used as guidelines in developing synthetic gene delivery vectors for CNS applications and will ultimately bring non-viral vectors closer to clinical application.

Nanoparticle Technologies in the Spinal Cord

Nanoparticles are increasingly being studied within experimental models of spinal cord injury (SCI). They are used to image cells and tissue, move cells to specific regions of the spinal cord, and deliver therapeutic agents locally. The focus of this article is to provide a brief overview of the different types of nanoparticles being studied for spinal cord applications and present data showing the capability of nanoparticles to deliver the chondroitinase ABC (chABC) enzyme locally following acute SCI in rats. Nanoparticles releasing chABC helped promote axonal regeneration following injury, and the nanoparticles also protected the enzyme from rapid degradation. In summary, nanoparticles are viable materials for diagnostic or therapeutic applications within experimental models of SCI and have potential for future clinical use.

Synthesis and characterization of Fe3O4-PEG-LAC-chitosan-PEI nanoparticle as a survivin siRNA delivery system

The limited effectiveness of the conventional methods for cancer treatment makes the researchers to find novel safe and effective therapeutic strategies. One of these strategies is to use small interfering RNAs (siRNAs). A major challenge here is the siRNA delivery into the cells. The purpose of this study was to design and prepare a biocompatible, biodegradable, and safe nanosized particle for siRNA delivery into human breast cancer MCF-7 and leukemia K562 cells. Chemically synthesized magnetic nanoparticles containing polyethyleneglycol-lactate polymer (PEG-LAC), chitosan, and polyethyleneimine (PEI) were successfully prepared and used as a gene delivery vehicle. The nanoparticles were characterized by Fourier transform infrared spectroscopy and zeta potential. The Fe3O4-PEG-LAC-chitosan-PEI nanoparticle showed efficient and stable survivin siRNA loading in gel retardation assay. The cytotoxicity of the prepared nanoparticle was studied using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay and was compared with that of mitoxantrone (MTX) in combination with the prepared siRNA delivery system to evaluate the possible synergic effect of MTX and survivin siRNA. The nanoparticles with and without noncomplementary siRNA showed low toxicity against both cell lines; however, a twofold decrease was observed in cell survival percent after MTX addition to MCF-7 cells treated with either nanoparticle itself or complexed with noncomplementary siRNA. While survivin siRNA nanoplex caused threefold decrease in the cell survival percent, its combination with MTX did not result in a significant increase in the cytotoxic effect. Therefore, Fe3O4-PEG-LAC-chitosan-PEI nanoparticle should be considered as a potential carrier for enhanced survivin siRNA delivery into MCF-7 and K562 cells.