Improving the efficacy of liposome-mediated vascular gene therapy via lipid surface modifications

Cationic Liposomes Carrying HPV16 E6-siRNA Inhibit the Proliferation, Migration, and Invasion of Cervical Cancer Cells

The E6 and E7 oncoproteins of high-risk types of human papillomavirus (HR-HPV) are crucial for the development of cervical cancer (CC). Small interfering RNAs (siRNAs) are explored as novel therapies that silence these oncogenes, but their clinical use is hampered by inefficient delivery systems. Modification (pegylation) with polyethylene glycol (PEG) of liposomal siRNA complexes (siRNA lipoplexes) may improve systemic stability. We studied the effect of siRNA targeting HPV16 E6, delivered via cationic liposomes (lipoplexes), on cellular processes in a cervical carcinoma cell line (CaSki) and its potential therapeutic use. Lipoplexes-PEG-HPV16 E6, composed of DOTAP, Chol, DOPE, and DSPE-PEG2000 were prepared. The results showed that pegylation (5% DSPE-PEG2000) provided stable siRNA protection, with a particle size of 86.42 ± 3.19 nm and a complexation efficiency of over 80%; the siRNA remained stable for 30 days. These lipoplexes significantly reduced HPV16 E6 protein levels and restored p53 protein expression, inhibiting carcinogenic processes such as proliferation by 25.74%, migration (95.7%), and cell invasion (97.8%) at concentrations of 20 nM, 200 nM, and 80 nM, respectively. In conclusion, cationic lipoplexes-PEG-HPV16 E6 show promise as siRNA carriers for silencing HPV16 E6 in CC.

Ionizable Lipids from Click Reactions for Lipid Nanoparticle Assembling and mRNA Delivery

Ionizable lipid-containing lipid nanoparticles (LNPs) are regarded as promising nonviral vectors for gene therapy delivery systems. Rationale design of the ionizable lipid structure based on initial screening of ionizable lipid molecule libraries combined with systematic comparison and analysis on the physical chemical parameters related to delivery efficiency greatly accelerated the discovery of novel LNP candidates for delivering various nucleic acid therapeutics like mRNAs (mRNAs). Based on the copper-catalyzed azide-alkyne click reaction, which is highly efficient and biocompatible, we were able to obtain the lipid molecule library containing a common triazole moiety between different lipid tails and various substituents as hydrophilic head groups. Herein, we systematically investigated the change of pKa values of different ionizable lipid molecules with different substituents as head groups in the click-based lipid library, mapping the pKa value change to different steps in the process of the LNP assembly and mRNA delivery. Systematic analyses on the data including the pKa value of the ionized lipids and the encapsulation and delivery efficiency of mRNA in LNPs with these ionized lipids provided the possibility of rational design on the head and tail structure for the triazole containing ionized lipids to realize highly efficient delivery of different mRNAs.

Navigating the landscape: Prospects and hurdles in targeting vascular smooth muscle cells for atherosclerosis diagnosis and therapy

Vascular smooth muscle cells (VSMCs) have emerged as pivotal contributors throughout all phases of atherosclerotic plaque development, effectively dispelling prior underestimations of their prevalence and significance. Recent lineage tracing studies have unveiled the clonal nature and remarkable adaptability inherent to VSMCs, thereby illuminating their intricate and multifaceted roles in the context of atherosclerosis. This comprehensive review provides an in-depth exploration of the intricate mechanisms and distinctive characteristics that define VSMCs across various physiological processes, firmly underscoring their paramount importance in shaping the course of atherosclerosis. Furthermore, this review offers a thorough examination of the significant strides made over the past two decades in advancing imaging techniques and therapeutic strategies with a precise focus on targeting VSMCs within atherosclerotic plaques, notably spotlighting meticulously engineered nanoparticles as a promising avenue. We envision the potential of VSMC-targeted nanoparticles, thoughtfully loaded with medications or combination therapies, to effectively mitigate pro-atherogenic VSMC processes. These advancements are poised to contribute significantly to the pivotal objective of modulating VSMC phenotypes and enhancing plaque stability. Moreover, our paper also delves into recent breakthroughs in VSMC-targeted imaging technologies, showcasing their remarkable precision in locating microcalcifications, dynamically monitoring plaque fibrous cap integrity, and assessing the therapeutic efficacy of medical interventions. Lastly, we conscientiously explore the opportunities and challenges inherent in this innovative approach, providing a holistic perspective on the potential of VSMC-targeted strategies in the evolving landscape of atherosclerosis research and treatment.

TCF7L2 (rs7903146) But Not CDKAL1 (rs7754840) Gene Polymorphisms Increase the Risk of New-Onset Diabetes After Kidney Transplant

OBJECTIVES

Incidence of new-onset diabetes after transplant negatively affects graft and patient survival. Obesity, impaired fasting glucose before transplant, and a history of diabetes in first-degree relatives are well-defined risk factors. TCF7L2 and CDKAL1 gene polymorphisms have been implicated in the pathogenesis.We investigated the effect of single gene polymorphisms of TCF7L2 (rs7903146) and CDKAL1 (rs7754840) on new-onset diabetes in renal transplant recipients.

MATERIALS AND METHODS

We evaluated 239 renal transplant recipients. TCF7L2 and CDKAL1 gene polymorphisms were assessed by polymerase chain reaction.

RESULTS

Mean patient age was 43 ± 13 years. There were 148 male patients (61.9%), and 91 were female (38.1%). New-onset diabetes was detected in 55 patients (23%). In 20 cases (36%), the glycemic disorder was transient; 61% of patients required insulin therapy. In terms of CDKAL1, 108 patients had the wild-type allele, 112 had a single-allele mutation, and 19 had a 2-allele mutation (45.2%, 46.9%, and 7.9%, respectively). In terms of TCF7L2, 163 of the patients had the wild-type allele, 49 had a single-allele mutation, and 27 had a 2-allele mutation (68%, 20%, and 11%, respectively). New-onset diabetes-related factors were age at transplant, body mass index after transplant (calculated as weight in kilograms divided by height in meters squared), tacrolimus, mycophenolate, andTCF7L2 polymorphism but not CDKAL1 polymorphism. After multiple regression analysis, the effect of TCF7L2 polymorphism persisted. A single allelic change resulted in a risk factor 1.4 times higher for new-onset diabetes after transplant (P = .043; 95% CI, 1.142-1.874) and a double allelic change was 2.7 times higher (P < .01; 95% CI, 1.310-4.073).

CONCLUSIONS

TCF7L2 (rs7903146) gene polymorphism is an independent risk factor for new-onset diabetes in Turkish renal transplant patients. This study is the first in Turkey to show the distribution and effect of these genes in kidney transplant patients.

Targeting and delivery of microRNA-targeting antisense oligonucleotides in cardiovascular diseases

Discovered three decades ago, microRNAs (miRNAs) are now recognized as key players in the pathophysiology of multiple human diseases, including those affecting the cardiovascular system. As such, miRNAs have emerged as promising therapeutic targets for preventing the onset and/or progression of several cardiovascular diseases. Anti-miRNA antisense oligonucleotides or "antagomirs" precisely block the activity of specific miRNAs and are therefore a promising therapeutic strategy to repress pathological miRNAs. In this review, we describe advancements in antisense oligonucleotide chemistry that have significantly improved efficacy and safety. Moreover, we summarize recent approaches for the targeted delivery of antagomirs to cardiovascular tissues, highlighting major advantages as well as limitations of viral (i.e., adenovirus, adeno-associated virus, and lentivirus) and non-viral (i.e., liposomes, extracellular vesicles, and polymer nanoparticles) delivery systems. We discuss recent preclinical studies that use targeted antagomir delivery systems to treat three major cardiovascular diseases (atherosclerosis, myocardial infarction, and cardiac hypertrophy, including hypertrophy caused by hypertension), highlighting therapeutic results and discussing challenges that limit clinical applicability.

Ionizable Lipids with Triazole Moiety from Click Reaction for LNP-Based mRNA Delivery

Ionizable lipid-containing lipid nanoparticles (LNPs) as a non-viral vector with good safety and potency have been considered as an ideal delivery system for gene therapy. The screening of ionizable lipid libraries with common features but diverse structures holds the promise of finding new candidates for LNPs to deliver different nucleic acid drugs such as messenger RNAs (mRNAs). Chemical strategies for the facile construction of ionizable lipid libraries with diverse structure are in high demand. Here, we report on the ionizable lipids containing the triazole moiety prepared by the copper-catalyzed alkyne-azide click reaction (CuAAC). We demonstrated that these lipids served well as the major component of LNPs, in order to encapsulate mRNA using luciferase mRNA as the model system. Thus, this study shows the potential of click chemistry in the preparation of lipid libraries for LNP assembly and mRNA delivery.

MiR-146a encapsulated liposomes reduce vascular inflammatory responses through decrease of ICAM-1 expression, macrophage activation, and foam cell formation

Vascular insults can create an inflammatory cascade involving endothelial cell, smooth muscle cell, and macrophage activation which can eventually lead to vascular disease such as atherosclerosis. Several studies have identified microRNA 146a's (miR-146a) anti-inflammatory potential based on its role in regulating the nuclear factor kappa beta (NF-κβ) pathway. Therefore, in this study, we introduced exogenous miR-146a encapsulated by liposomes to lipopolysaccharide (LPS) stimulated vascular cells and macrophages to reduce inflammatory responses. First, the miR-146a encapsulated liposomes showed uniform size (radius 96.4 ± 4.22 nm) and round shape, long term stability (at least two months), high encapsulation efficiency (69.73 ± 0.07%), and were well transfected to human aortic endothelial cells (HAECs), human aortic smooth muscle cells (SMCs), and human differentiated monocytes (U937 cells). In addition, we demonstrated that miR-146a encapsulated liposomes reduced vascular inflammation responses in HAECs and SMCs through inhibition of ICAM-1 expression and decreased monocyte adhesion. In macrophages, miR-146a liposome treatment demonstrated decreased production of proinflammatory cytokines, tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β), as well as reduced oxidized low-density lipoprotein (ox-LDL) uptake and foam cell formation. Thus, based on these results, miR-146a encapsulated liposomes may be promising for reducing vascular inflammation by targeting its multiple associated mediators.

Bis-Boronic Acid Liposomes for Carbohydrate Recognition and Cellular Delivery

Liposomes are effective therapeutic delivery nanocarriers due to their ability to encapsulate and enhance the pharmacokinetic properties of a wide range of drugs and diagnostic agents. A primary area in which improvement is needed for liposomal drug delivery is to enhance the delivery of these nanocarriers to cells. Cell membrane glycans provide exciting targets for liposomal delivery since they are often densely clustered on cell membranes and glycan overabundance and aberrant glycosylation patterns are a common feature of diseased cells. Herein, we report a liposome platform incorporating bis-boronic acid lipids (BBALs) to increase valency in order to achieve selective saccharide sensing and enhance cell surface binding interactions based on carbohydrate binding interactions. In order to vary properties, multiple BBALs ( 1a-d ) with variable linkers in between the binding units were designed and synthesized. Fluorescence-based microplate screening of carbohydrate binding showed that these compounds exhibit varying binding properties depending on their structures. Additionally, fluorescence microscopy experiments indicated enhancements in cellular association when BBALs were incorporated in liposomes. These results demonstrate that multivalent BBALs serve as an exciting glycan binding liposome system for targeted liposome delivery.

Emerging landscape of cell-penetrating peptide-mediated nucleic acid delivery and their utility in imaging, gene-editing, and RNA-sequencing

The safety issues like immunogenicity and unacceptable cancer risk of viral vectors for DNA/mRNA vaccine delivery necessitate the development of non-viral vectors with no toxicity. Among the non-viral strategies, cell-penetrating peptides (CPPs) have been a topic of interest recently because of their ability to cross plasma membranes and facilitate nucleic acids delivery both in vivo and in vitro. In addition to the application in the field of gene vaccine and gene therapy, CPPs based nucleic acids delivery have been proved by its potential application like gene editing, RNA-sequencing, and imaging. Here, we focus on summarizing the recent applications and progress of CPPs-mediated nucleic acids delivery and discuss the current problems and solutions in this field.

Liposomes, new carriers for delivery of genes and anticancer drugs: a systematic review

Today, nanoscience has grown and developed in various fields of medicine and treatment, including cancer treatment. Currently, the existing treatments, including chemotherapy and radiotherapy, cause side effects that are unpleasant to the patient. Due to the fact that anticancer drugs cause severe and widespread side effects, liposomes are considered as new drug carriers to minimize the untimely destruction of the drug when it is delivered to the target tissue and to prevent the side effects of toxic drugs. This systematic review study examined the importance of using liposomes as new drug carriers for the delivery of genes and anticancer drugs. The articles published in English in the databases of Google scholar, WoS, PubMed, Embase, Scopus and science direct were reviewed. According to the results of this study, a new targeted nanosystem has been used for loading and delivering anticancer drugs, genes and controlled drug release which has a significant therapeutic effect compared to the same amount of free drug. In general, liposomal systems have been considered because of their capability in preserving the effect of the drug along with reducing the side effects and toxicity of the drug, especially in the case of anticancer drugs. Accumulation of the drug in a target tissue which results in a reduction of the drug entry into other tissues is the main reason for reducing the side effects of these drugs.

Exosome-mediated mRNA delivery in vivo is safe and can be used to induce SARS-CoV-2 immunity

Functional delivery of mRNA has high clinical potential. Previous studies established that mRNAs can be delivered to cells in vitro and in vivo via RNA-loaded lipid nanoparticles (LNPs). Here we describe an alternative approach using exosomes, the only biologically normal nanovesicle. In contrast to LNPs, which elicited pronounced cellular toxicity, exosomes had no adverse effects in vitro or in vivo at any dose tested. Moreover, mRNA-loaded exosomes were characterized by efficient mRNA encapsulation (∼90%), high mRNA content, consistent size, and a polydispersity index under 0.2. Using an mRNA encoding the red light-emitting luciferase Antares2, we observed that mRNA-loaded exosomes were superior to mRNA-loaded LNPs at delivering functional mRNA into human cells in vitro. Injection of Antares2 mRNA-loaded exosomes also led to strong light emission following injection into the vitreous fluid of the eye or into the tissue of skeletal muscle in mice. Furthermore, we show that repeated injection of Antares2 mRNA-loaded exosomes drove sustained luciferase expression across six injections spanning at least 10 weeks, without evidence of signal attenuation or adverse injection site responses. Consistent with these findings, we observed that exosomes loaded with mRNAs encoding immunogenic forms of the SARS-CoV-2 Spike and Nucleocapsid proteins induced long-lasting cellular and humoral responses to both. Taken together, these results demonstrate that exosomes can be used to deliver functional mRNA to and into cells in vivo.

Liposomal Nanocarriers Designed for Sub-Endothelial Matrix Targeting under Vascular Flow Conditions

Vascular interventions result in the disruption of the tunica intima and the exposure of sub-endothelial matrix proteins. Nanoparticles designed to bind to these exposed matrices could provide targeted drug delivery systems aimed at inhibiting dysfunctional vascular remodeling and improving intervention outcomes. Here, we present the progress in the development of targeted liposomal nanocarriers designed for preferential collagen IV binding under simulated static vascular flow conditions. PEGylated liposomes (PLPs), previously established as effective delivery systems in vascular cells types, served as non-targeting controls. Collagen-targeting liposomes (CT-PLPs) were formed by conjugating established collagen-binding peptides to modified lipid heads via click chemistry (CTL), and inserting them at varying mol% either at the time of PLP assembly or via micellar transfer. All groups included fluorescently labeled lipid species for imaging and quantification. Liposomes were exposed to collagen IV matrices statically or via hemodynamic flow, and binding was measured via fluorometric analyses. CT-PLPs formed with 5 mol% CTL at the time of assembly demonstrated the highest binding affinity to collagen IV under static conditions, while maintaining a nanoparticle characterization profile of ~50 nm size and a homogeneity polydispersity index (PDI) of ~0.2 favorable for clinical translation. When liposomes were exposed to collagen matrices within a pressurized flow system, empirically defined CT-PLPs demonstrated significant binding at shear stresses mimetic of physiological through pathological conditions in both the venous and arterial architectures. Furthermore, when human saphenous vein explants were perfused with liposomes within a closed bioreactor system, CT-PLPs demonstrated significant ex vivo binding to diseased vascular tissue. Ongoing studies aim to further develop CT-PLPs for controlled targeting in a rodent model of vascular injury. The CT-PLP nanocarriers established here show promise as the framework for a spatially controlled delivery platform for future application in targeted vascular therapeutics.

Advances in the Formulation and Assembly of Non-Cationic Lipid Nanoparticles for the Medical Application of Gene Therapeutics

Lipid nanoparticles have become increasingly popular delivery platforms in the field of gene therapy, but bench-to-bedside success has been limited. Many liposomal gene vectors are comprised of synthetic cationic lipids, which are associated with lipid-induced cytotoxicity and immunogenicity. Natural, non-cationic PEGylated liposomes (PLPs) demonstrate favorable biocompatibility profiles but are not considered viable gene delivery vehicles due to inefficient nucleic acid loading and reduced cellular uptake. PLPs can be modified with cell-penetrating peptides (CPPs) to enhance the intracellular delivery of liposomal cargo but encapsulate leakage upon CPP-PLP assembly is problematic. Here, we aimed to identify parameters that overcome these performance barriers by incorporating nucleic acid condensers during CPP-PLP assembly and screening variable ethanol injection parameters for optimization. CPP-PLPs were formed with R8-amphiphiles via pre-insertion, post-insertion and post-conjugation techniques and liposomes were characterized for size, surface charge, homogeneity, siRNA encapsulation efficiency and retention and cell associative properties. Herein we demonstrate that pre-insertion of stearylated R8 into PLPs is an efficient method to produce non-cationic CPP-PLPs and we provide additional assembly parameter specifications for a modified ethanol injection technique that is optimized for siRNA encapsulation/retention and enhanced cell association. This assembly technique could provide improved clinical translation of liposomal based gene therapy applications.

Assembly strategy of liposome and polymer systems for siRNA delivery

In recent years, gene therapy has made tremendous progress in the development of disease treatment. Among them, siRNA offers specificity of gene silencing, ease of synthesis, and short development period, and has been intensively studied worldwide. However, siRNA as the hydrophilic polyanion is easily degraded in vivo and poorly taken up into cells and so, the benefits of its powerful gene silencing ability will not be realized until better carriers are developed that are capable of protecting siRNA and delivering it intact to the cytoplasm of the target cells. Cationic liposomes (CL) and cationic polymers (CP) are the main non-viral siRNA vectors, there have been a lot of reports on the use of these two carriers to deliver siRNA. Whereas, as far as we know, there have been few review articles that provide an in-depth summary of the siRNA loading principle and internal structures of the siRNA delivery system. We summarize the formation principle and assembly structure of the cationic liposome-siRNA and polymer-siRNA complexes, and point out their advantages and characteristics and also show how to perfect their assembly and improve their clinical application in the future. It supports some useful suggestions for siRNA therapy, specifically, safe and efficient delivery.

Multifunctional Delivery Systems for Peptide Nucleic Acids

The number of applications of peptide nucleic acids (PNAs)-oligonucleotide analogs with a polyamide backbone-is continuously increasing in both in vitro and cellular systems and, parallel to this, delivery systems able to bring PNAs to their targets have been developed. This review is intended to give to the readers an overview on the available carriers for these oligonucleotide mimics, with a particular emphasis on newly developed multi-component- and multifunctional vehicles which boosted PNA research in recent years. The following approaches will be discussed: (a) conjugation with carrier molecules and peptides; (b) liposome formulations; (c) polymer nanoparticles; (d) inorganic porous nanoparticles; (e) carbon based nanocarriers; and (f) self-assembled and supramolecular systems. New therapeutic strategies enabled by the combination of PNA and proper delivery systems are discussed.

PEGylation and Cell-Penetrating Peptides: Glimpse into the Past and Prospects in the Future

Several drug molecules have shown low bioavailability and pharmacokinetic profile due to metabolism by enzymes, excretion by the renal system, or due to other physiochemical properties of drug molecules. These problems have resulted in the loss of efficacy and the gain of side effects associated with drug molecules. PEGylation is one of the strategies to overcome these pharmacokinetic issues and has been successful in the clinic. Cell-penetrating Peptides (CPPs) help to deliver molecules across biological membranes and could be used to deliver cargo selectively to the intracellular site or to the drug target. Hence CPPs could be used to improve the efficacy and selectivity of the drug. However, due to the peptidic nature of CPPs, they have a low pharmacokinetic profile. Using PEGylation and CPPs together as a component of a drug delivery system, the and efficacy of drug molecules could be improved. The other important pharmacokinetic properties such as short half-life, solubility, stability, absorption, metabolism, and elimination could be also improved. Here in this review, we summarized PEGylated CPPs or PEGylation based formulations for CPPs used in a drug delivery system for several biomedical applications until August 2019.

Barriers and Strategies of Cationic Liposomes for Cancer Gene Therapy

Cationic liposomes (CLs) have been regarded as the most promising gene delivery vectors for decades with the advantages of excellent biodegradability, biocompatibility, and high nucleic acid encapsulation efficiency. However, the clinical use of CLs in cancer gene therapy is limited because of many uncertain factors in vivo. Extracellular barriers such as opsonization, rapid clearance by the reticuloendothelial system and poor tumor penetration, and intracellular barriers, including endosomal/lysosomal entrapped network and restricted diffusion to the nucleus, make CLs not the ideal vector for transferring extrinsic genes in the body. However, the obstacles in achieving productive therapeutic effects of nucleic acids can be addressed by tailoring the properties of CLs, which are influenced by lipid compositions and surface modification. This review focuses on the physiological barriers of CLs against cancer gene therapy and the effects of lipid compositions on governing transfection efficiency, and it briefly discusses the impacts of particle size, membrane charge density, and surface modification on the fate of CLs in vivo, which may provide guidance for their preclinical studies.

IL-1β suppression of VE-cadherin transcription underlies sepsis-induced inflammatory lung injury

Unchecked inflammation is a hallmark of inflammatory tissue injury in diseases such as acute respiratory distress syndrome (ARDS). Yet the mechanisms of inflammatory lung injury remain largely unknown. Here we showed that bacterial endotoxin lipopolysaccharide (LPS) and cecal ligation and puncture-induced (CLP-induced) polymicrobial sepsis decreased the expression of transcription factor cAMP response element binding (CREB) in lung endothelial cells. We demonstrated that endothelial CREB was crucial for VE-cadherin transcription and the formation of the normal restrictive endothelial adherens junctions. The inflammatory cytokine IL-1β reduced cAMP generation and CREB-mediated transcription of VE-cadherin. Furthermore, endothelial cell-specific deletion of CREB induced lung vascular injury whereas ectopic expression of CREB in the endothelium prevented the injury. We also observed that rolipram, which inhibits type 4 cyclic nucleotide phosphodiesterase-mediated (PDE4-mediated) hydrolysis of cAMP, prevented endotoxemia-induced lung vascular injury since it preserved CREB-mediated VE-cadherin expression. These data demonstrate the fundamental role of the endothelial cAMP-CREB axis in promoting lung vascular integrity and suppressing inflammatory injury. Therefore, strategies aimed at enhancing endothelial CREB-mediated VE-cadherin transcription are potentially useful in preventing sepsis-induced lung vascular injury in ARDS.

Investigating the Impact of Delivery System Design on the Efficacy of Self-Amplifying RNA Vaccines

messenger RNA (mRNA)-based vaccines combine the positive attributes of both live-attenuated and subunit vaccines. In order for these to be applied for clinical use, they require to be formulated with delivery systems. However, there are limited in vivo studies which compare different delivery platforms. Therefore, we have compared four different cationic platforms: (1) liposomes, (2) solid lipid nanoparticles (SLNs), (3) polymeric nanoparticles (NPs) and (4) emulsions, to deliver a self-amplifying mRNA (SAM) vaccine. All formulations contained either the non-ionizable cationic lipid 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) or dimethyldioctadecylammonium bromide (DDA) and they were characterized in terms of physico-chemical attributes, in vitro transfection efficiency and in vivo vaccine potency. Our results showed that SAM encapsulating DOTAP polymeric nanoparticles, DOTAP liposomes and DDA liposomes induced the highest antigen expression in vitro and, from these, DOTAP polymeric nanoparticles were the most potent in triggering humoral and cellular immunity among candidates in vivo.

Cell Penetrating Peptides, Novel Vectors for Gene Therapy

Cell penetrating peptides (CPPs), also known as protein transduction domains (PTDs), first identified ~25 years ago, are small, 6-30 amino acid long, synthetic, or naturally occurring peptides, able to carry variety of cargoes across the cellular membranes in an intact, functional form. Since their initial description and characterization, the field of cell penetrating peptides as vectors has exploded. The cargoes they can deliver range from other small peptides, full-length proteins, nucleic acids including RNA and DNA, liposomes, nanoparticles, and viral particles as well as radioisotopes and other fluorescent probes for imaging purposes. In this review, we will focus briefly on their history, classification system, and mechanism of transduction followed by a summary of the existing literature on use of CPPs as gene delivery vectors either in the form of modified viruses, plasmid DNA, small interfering RNA, oligonucleotides, full-length genes, DNA origami or peptide nucleic acids.

Structure-function relationships of nonviral gene vectors: Lessons from antimicrobial polymers

In recent years, substantial advances have been achieved in the design and synthesis of nonviral gene vectors. However, lack of effective and biocompatible vectors still remains a major challenge that hinders their application in clinical settings. In the past decade, there has been a rapid expansion of cationic antimicrobial polymers, due to their potent, rapid, and broad-spectrum biocidal activity against resistant microbes, and biocompatible features. Given that antimicrobial polymers share common features with nonviral gene vectors in various aspects, such as membrane affinity, functional groups, physicochemical characteristics, and unique macromolecular architectures, these polymers may provide us with inspirations to overcome challenges in the design of novel vectors toward more safe and efficient gene delivery in clinic. Building off these observations, we provide here an overview of the structure-function relationships of polymers for both antimicrobial applications and gene delivery by elaborating some key structural parameters, including functional groups, charge density, hydrophobic/hydrophilic balance, MW, and macromolecular architectures. By borrowing a leaf from antimicrobial agents, great advancement in the development of newer nonviral gene vectors with high transfection efficiency and biocompatibility will be more promising. STATEMENT OF SIGNIFICANCE: The development of gene delivery is still in the preclinical stage for the lack of effective and biocompatible vectors. Given that antimicrobial polymers share common features with gene vectors in various aspects, such as membrane affinity, functional groups, physicochemical characteristics, and unique macromolecular architectures, these polymers may provide us with inspirations to overcome challenges in the design of novel vectors toward more safe and efficient gene delivery in clinic. In this review, we systematically summarized the structure-function relationships of antimicrobial polymers and gene vectors, with which the design of more advanced nonviral gene vectors is anticipated to be further boosted in the future.

The Efficacy of Systemic Doxycycline Administration as an Inhibitor of Intimal Hyperplasia after Balloon Angioplasty Arterial Injury

BACKGROUND

Intimal hyperplasia (IH) is the most common indicator for secondary intervention in peripheral vascular disease. Matrix metalloproteinases (MMPs) play a role in IH development due to their degradation of the extracellular matrix. Doxycycline (Doxy), a member of the tetracycline family of antibiotics, is a potent MMP inhibitor. We have previously shown that Doxy inhibits MMP activity and vascular smooth muscle cell migration in vitro. We hypothesized that Doxy would decrease MMP activity in vivo and inhibit the development of IH in a rodent model of vascular injury.

METHODS AND RESULTS

Doxy (400 mg/pellet) was delivered by a slow-release pellet implanted 3 days prior to or at the time of balloon angioplasty (BA) of the common carotid artery in female rats. At 14 days post-BA, intima-to-media (I:M) ratios were 0.77 ± 0.21 and 1.04 ± 0.32 in the Doxy treated groups, respectively, compared to 1.25 ± 0.26 in the control group (P = not significant; n = 3). Additionally, the tested dose of Doxy in either group had no inhibitory effect on membrane type 1-MMP or MMP-2 tissue levels, as measured by immunohistochemistry, or on systemic levels of MMP, as measured by total MMP serum levels using enzyme-linked immunosorbent assay. At 14 days post-BA, VSMC proliferation in the injured artery was increased to Doxy treatment prior to and at the time of surgery (23.5 ± 3.4 and 27.2 ± 3.9%, respectively), compared to control (11.4 ± 0.4%; n = 3), as measured by proliferating cellular nuclear antigen immunostaining.

CONCLUSIONS

In our in vivo model of vascular injury, systemic Doxy administration prior to or at the time of vascular injury does not significantly hinder the progression of IH development. Additional doses and routes of administration could be examined in order to correlate therapeutic serum levels of Doxy with effective MMP inhibition in serum and arterial tissue. However, alternative drug delivery systems are needed in order to optimize therapeutic administration of targeted MMP inhibitors for the prevention of IH development.

Cell mimetic liposomal nanocarriers for tailored delivery of vascular therapeutics

Liposomal delivery systems (LDSs) have been at the forefront of medicinal nanotechnology for over three decades. Increasing LDS association to target cells and cargo delivery is crucial to bolstering overall nanodrug efficacy. Our laboratory aims to develop LDSs for molecular therapeutics aimed at vascular pathology. We have previously established a liposome platform that is an effective delivery system for RNA interference in vascular cell types by using polyethylene glycol (PEG) decorated liposomes bearing an octa-arginine (R8) cell penetrating peptide (CPP). Further tailoring liposome membranes to mimic vascular cell membrane lipid constituents may be a promising strategy for increasing cargo delivery. Here we aimed to develop liposomal formulations that could make use of diacylglycerol (DAG) and phosphatidylserine (PS), naturally occurring lipid species that are known to influence vascular cell function, as a facile and efficient means to increase nanodrug efficacy without compromising clinical viability. We investigated the ability of DAG and PS to amplify the cellular uptake of our previously established LDS platform loaded with small interfering ribonucleic acid (siRNA) cargo. Cellular fluorescence microscopy experiments were performed in conjunction with quantitative cell association assays and cytotoxicity assays to analyze the effect of DAG/PS on the differential delivery of fluorescently-tagged liposomes to vascular smooth muscle cells (VSMCs) and vascular endothelial cells (VECs) and on liposomal-mediated toxicity. In these studies, significant, dose-dependent increases in association to target cells were observed, as well as cell-type specific effects on cell viability. The stability and encapsulation-efficiency of the DAG/PS-modified LDSs were analyzed by standard nanoparticle characterization methods, and siRNA transfection efficacy was quantified to gauge delivery potential as a function of DAG/PS modification. Our results suggest that the signaling lipids tested here imbue our LDS architectures with increased therapeutic potential, without compromising stability, encapsulation efficiency, or biocompatibility, thus presenting a natural strategy to increase nanodrug efficacy and specificity.

Liposome: composition, characterisation, preparation, and recent innovation in clinical applications

In the last decades, pharmaceutical interested researches aimed to develop novel and innovative drug delivery techniques in the medical and pharmaceutical fields. Recently, phospholipid vesicles (Liposomes) are the most known versatile assemblies in the drug delivery systems. The discovery of liposomes arises from self-forming enclosed phospholipid bilayer upon coming in contact with the aqueous solution. Liposomes are uni or multilamellar vesicles consisting of phospholipids produced naturally or synthetically, which are readily non-toxic, biodegradable, and are readily produced on a large scale. Various phospholipids, for instance, soybean, egg yolk, synthetic, and hydrogenated phosphatidylcholine consider the most popular types used in different kinds of formulations. This review summarises liposomes composition, characterisation, methods of preparation, and their applications in different medical fields including cancer therapy, vaccine, ocular delivery, wound healing, and some dermatological applications.

The promoted delivery of RRM2 siRNA to vascular smooth muscle cells through liposome-polycation-DNA complex conjugated with cell penetrating peptides

Peripheral vascular disease (PVD) is a prevalent vascular disease that affect a large number of patients. The establishment of optimal treatments to mitigate the intimal hyperplasia (IH)-induced restenosis would help relieve the health burden of the PVD. Ribonucleotide reductase M2 (RRM2) is critical to cellular migration and proliferation. We have previously demonstrated that suppression of RRM2 expression could substantially inhibit hepatocellular carcinoma cell proliferation and migration. We hereby developed RRM2 small interfering RNA (siRNA)-loaded cell penetrating peptides-conjugated liposome-polycation-DNA complex (LPD) (RRM2-CLPD), aiming to inhibit the migration and proliferation of vascular smooth muscle cells (VSMCs) crucial for IH. RRM2-CLPD is of a small size (∼150 nm) and high siRNA encapsulation efficiency (∼90%). Further, we demonstrated that RRM2-CLPD could significantly inhibited RRM2 gene and protein expression by ∼80%. Notably, RRM2-CLPD was able to effectively bind to VSMCs, resulting in significant cellular proliferation and migration inhibition. Taken together, RRM2-CLPD represent a very promising treatment for IH.