Selective gene delivery for cancer therapy using cationic liposomes: in vivo proof of applicability

TPGS-b-PBAE Copolymer-Based Polyplex Nanoparticles for Gene Delivery and Transfection In Vivo and In Vitro

Poly (β-amino ester) (PBAE) is an exceptional non-viral vector that is widely used in gene delivery, owing to its exceptional biocompatibility, easy synthesis, and cost-effectiveness. However, it carries a high surface positive charge that may cause cytotoxicity. Therefore, hydrophilic d-α-tocopherol polyethylene glycol succinate (TPGS) was copolymerised with PBAE to increase the biocompatibility and to decrease the potential cytotoxicity of the cationic polymer-DNA plasmid polyplex nanoparticles (NPs) formed through electrostatic forces between the polymer and DNA. TPGS-b-PBAE (TBP) copolymers with varying feeding molar ratios were synthesised to obtain products of different molecular weights. Their gene transfection efficiency was subsequently evaluated in HEK 293T cells using green fluorescent protein plasmid (GFP) as the model because free GFP is unable to easily pass through the cell membrane and then express as a protein. The particle size, ζ-potential, and morphology of the TBP2-GFP polyplex NPs were characterised, and plasmid incorporation was confirmed through gel retardation assays. The TBP2-GFP polyplex NPs effectively transfected multiple cells with low cytotoxicity, including HEK 293T, HeLa, Me180, SiHa, SCC-7 and C666-1 cells. We constructed a MUC2 (Mucin2)-targeting CRISPR/cas9 gene editing system in HEK 293T cells, with gene disruption supported by oligodeoxynucleotide (ODN) insertion in vitro. Additionally, we developed an LMP1 (latent membrane protein 1)-targeting CRISPR/cas9 gene editing system in LMP1-overexpressing SCC7 cells, which was designed to cleave fragments expressing the LMP1 protein (related to Epstein-Barr virus infection) and thus to inhibit the growth of the cells in vivo. As evidenced by in vitro and in vivo experiments, this system has great potential for gene therapy applications.

A novel method for the development of plasmid DNA-loaded nanoliposomes for cancer gene therapy

We aimed to develop a simple yet novel method to prepare plasmid DNA-loaded nanoliposomes for cancer gene therapy. Murine interleukin-12 (mIL-12) pDNA-loaded nanoliposomes were prepared via novel freeze-drying of a monophase solution method. The physicochemical characteristics, cytotoxicity, and transfection efficiency of the prepared nanoliposomes in murine CT-26 colon carcinoma cells were evaluated. Furthermore, tumor progression and survival rate in CT-26 colon carcinoma-bearing BALB/c mice subsequent to direct intratumoral injections were investigated over a period of 40 days. Using this preparation method, nanoliposomes with particle size of around 300 nm and zeta potential of 96.5 mV were obtained. The transmission electron microscope results showed that the liposomes were nano-sized and almost spherical. The agarose gel retardation assay revealed the pDNA encapsulation in the nanoliposomes. The nanoliposomes with 72.4% encapsulation efficiency and low cell toxicity could significantly improve mIL-12 expression by approximately 25-fold relative to the naked mIL-12 pDNA. There was a significant tumor growth inhibition after repeated injections of mIL-12 pDNA-loaded nanoliposomes. This is the first study on the freeze-drying of a monophase solution method as a simple yet novel technique for the preparation of pDNA-loaded nanoliposomes. Given the ease of preparation method and promising in vitro and in vivo characteristics, this investigation demonstrates advances in pDNA lipid formulation for cancer gene therapy.

Development of a New Hyaluronic Acid Based Redox-Responsive Nanohydrogel for the Encapsulation of Oncolytic Viruses for Cancer Immunotherapy

Oncolytic viruses (OVs) are emerging as promising and potential anti-cancer therapeutic agents, not only able to kill cancer cells directly by selective intracellular viral replication, but also to promote an immune response against tumor. Unfortunately, the bioavailability under systemic administration of OVs is limited because of undesired inactivation caused by host immune system and neutralizing antibodies in the bloodstream. To address this issue, a novel hyaluronic acid based redox responsive nanohydrogel was developed in this study as delivery system for OVs, with the aim to protect the OVs following systemic administration. The nanohydrogel was formulated by water in oil (W/O) nanoemulsion method and cross-linked by disulfide bonds derived from the thiol groups of synthesized thiolated hyaluronic acid. One DNA OV Ad[I/PPT-E1A] and one RNA OV Rigvir^® ECHO-7 were encapsulated into the developed nanohydrogel, respectively, in view of their potential of immunovirotherapy to treat cancers. The nanohydrogels showed particle size of approximately 300–400 nm and negative zeta potential of around −13 mV by dynamic light scattering (DLS). A uniform spherical shape of the nanohydrogel was observed under the scanning electron microscope (SEM) and transmission electron microscope (TEM), especially, the successfully loading of OV into nanohydrogel was revealed by TEM. The crosslinking between the hyaluronic acid chains was confirmed by the appearance of new peak assigned to disulfide bond in Raman spectrum. Furthermore, the redox responsive ability of the nanohydrogel was determined by incubating the nanohydrogel into phosphate buffered saline (PBS) pH 7.4 with 10 μM or 10 mM glutathione at 37 °C which stimulate the normal physiological environment (extracellular) or reductive environment (intracellular or tumoral). The relative turbidity of the sample was real time monitored by DLS which indicated that the nanohydrogel could rapidly degrade within 10 h in the reductive environment due to the cleavage of disulfide bonds, while maintaining the stability in the normal physiological environment after 5 days. Additionally, in vitro cytotoxicity assays demonstrated a good oncolytic activity of OVs-loaded nanohydrogel against the specific cancer cell lines. Overall, the results indicated that the developed nanohydrogel is a delivery system appropriate for viral drugs, due to its hydrophilic and porous nature, and also thanks to its capacity to maintain the stability and activity of encapsulated viruses. Thus, nanohydrogel can be considered as a promising candidate carrier for systemic administration of oncolytic immunovirotherapy.

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.

Hyperbranched poly(β-amino ester) based polyplex nanopaticles for delivery of CRISPR/Cas9 system and treatment of HPV infection associated cervical cancer

Persistent high-risk HPV infection is the main factor for cervical cancer. HPV E7 oncogene plays an important role in HPV carcinogenesis. Down-regulation of E7 oncogene expression could induce growth inhibition in HPV-positive cells and thus treats HPV related cervical cancer. Here we developed a non-virus gene vector based on poly(amide-amine)-poly(β-amino ester) hyperbranched copolymer (hPPC) for the delivery of CRISPR/Cas9 system to specifically cleave HPV E7 oncogene in HPV-positive cervical cancer cells. The diameter of polyplex nanoparticles (NPs) formed by hPPCs/linear poly(β-amino ester) (PBAE) and plasmids were approximately 300 nm. These hPPCs/PBAE-green fluorescence protein plasmids polyplex NPs showed high transfection efficiency and low toxicity in cells and mouse organs. By cleaving HPV16 E7 oncogene, reducing the expression of HPV16 E7 protein and increasing intracellular retinoblastoma 1 (RB1) amount, hPPCs/PBAE-CRISPR/Cas9 therapeutic plasmids polyplex NPs, especially highly branched hPPC1-plasmids polyplex NPs, exhibited strong growth inhibition of cervical cancer cells in vitro and xenograft tumors in nude mice. Together, the hPPCs/PBAE polyplex NPs to deliver HPV16 E7 targeted CRISPR/Cas9 system in this study could potentially be applied to treat HPV-related cervical cancer.

Anti-EGF Receptor Aptamer-Guided Co-Delivery of Anti-Cancer siRNAs and Quantum Dots for Theranostics of Triple-Negative Breast Cancer

Many aptamers have been evaluated for their ability as drug delivery vehicles to target ligands, and a variety of small interfering RNAs (siRNAs) have been tested for their anti-cancer properties. However, since these two types of molecules have similar physicochemical properties, it has so far been difficult to formulate siRNA-encapsulating carriers guided by aptamers. Here, we propose aptamer-coupled lipid nanocarriers encapsulating quantum dots (QDs) and siRNAs for theragnosis of triple-negative breast cancer (TNBC).

Methods: Hydrophobic QDs were effectively incorporated into lipid bilayers, and then therapeutic siRNAs were complexed with QD-lipid nanocarriers (QLs). Finally, anti-EGFR aptamer-lipid conjugates were inserted into the QLs for TNBC targeting (aptamo-QLs). TNBC-targeting aptamo-QLs were directly compared to anti-EGFR antibody-coupled immuno-QLs. The in vitro delivery of therapeutic siRNAs and QDs to target cells was assessed by flow cytometry and confocal microscopy. The in vivo targeting of siRNAs to tumors and their therapeutic efficacy were evaluated in mice carrying MDA-MB-231 tumors.

Results: Both types of EGFR-targeting QLs showed enhanced delivery to target cancer cells, resulting in more effective gene silencing and enhanced tumor imaging compared to non-targeting control QLs. Moreover, combinatorial therapy with Bcl-2 and PKC-ι siRNAs loaded into the anti-EGFR QLs was remarkably effective in inhibiting tumor growth and metastasis.

Conclusion: In general, the aptamo-QLs showed competitive in vivo delivery and therapeutic efficacy compared to immuno-QLs under the same experimental conditions. Our results show that the anti-EGFR aptamer-guided lipid carriers may be a potential theranostic delivery vehicle for RNA interference and fluorescence imaging of TNBCs.

A 89Zr-labeled lipoplex nanosystem for image-guided gene delivery: design, evaluation of stability and in vivo behavior

Background

With the advances in radiopharmaceutical research, the development of image-guided therapy has become a major interest. While the development of theranostic nanotherapeutics is frequently associated with cancer chemotherapy, phototherapy and radiotherapy, there is little information available on the in vivo monitoring of gene delivery systems and the application of image-guided approach in gene therapy. The goal of this work was to determine the in vivo behavior of DNA delivery nanosystems - based on cationic gemini surfactants – designed for image-guided gene therapy. We tested the feasibility of monitoring tumor accumulation of gene delivery nanoparticles by positron emission tomography.

Methods

To be able to conjugate radiotracers to the nanoparticles, a deferoxamine-modified gemini surfactant was synthesized, DNA-containing lipoplex nanoparticles were formulated, and radiolabeled with Zirconium-89 (⁸⁹Zr). The pharmacokinetics and biodistribution of ⁸⁹Zr labeled surfactant and ⁸⁹Zr labeled nanoparticles were monitored in mice by microPET/CT imaging and ex vivo gamma counting.

Results

Modification of the nanoparticles with deferoxamine did not alter their physicochemical properties. The radiolabeled nanoparticles (labeling efficiency of 95±3%) were stable in PBS and serum. The biological half-life of the ⁸⁹Zr labeled nanoparticles was significantly higher compared to ⁸⁹Zr labeled surfactant. As expected, the nanoparticles had significantly higher liver accumulation than the radiolabeled surfactant alone and lower kidney accumulation. Tumor uptake was detected at 2 hours post injection and decreased throughout the 3-day monitoring.

Conclusion

We propose that radiolabeling DNA delivery lipoplex nanosystems is a promising approach for the design and optimization of image-guided nanomedicines, especially in the context of cancer gene therapy.

SATB1 siRNA-encapsulated immunoliposomes conjugated with CD44 antibodies target and eliminate gastric cancer-initiating cells

Purpose

Gastric cancer, the cancer initiated from the stomach, is ranked as the third most frequent reason of cancer death worldwide. Gastric cancer-initiating cells (CICs) are one of the crucial causes for the metastasis and recurrence of gastric cancer, and CD44 is considered to be one marker for gastric CICs. Special AT-rich sequence binding protein 1 (SATB1) is a protein that promotes cancer progression, metastasis, and invasion and also participates in the maintenance of CICs. In this study, we investigated the therapeutic effect of SATB1 siRNA against gastric CICs and we constructed SATB1 siRNA-encapsulated immunoliposomes conjugated with CD44 antibodies (CD44-SATB1-ILs) to enhance the therapeutic effect of SATB1 siRNA against gastric CICs.

Methods

We investigated the therapeutic effect of the SATB1 suppression by SATB1 siRNA on CD44⁺ gastric CICs. CD44-SATB1-ILs were developed by the lyophilization/hydration approach. The targeting and cytotoxic effect of CD44-SATB1-ILs toward gastric CICs were evaluated in vitro.

Results

In this study, for the first time, we confirmed that SATB1 suppression by SATB1 siRNA preferentially eliminated CD44⁺ gastric CICs. The results showed that CD44-SATB1-ILs could efficiently and specifically promote the SATB1 siRNA delivery to CD44⁺ gastric CICs, achieving superior therapeutic effects against CD44⁺ gastric CICs than non-targeted liposomes.

Conclusion

As far as we know, our report is the first research that indicated the promotion of siRNA delivery via nanoparticles to gastric CICs and achievement of superior therapeutic effect against gastric CICs by utilization of CD44 antibody. Therefore, CD44-SATB1-ILs represent an up-and-coming approach for eliminating gastric CICs and also a promising treatment for therapy of gastric cancer.

Tumor specific delivery and therapy mediate by integrin β6-target immunoliposomes for β6-siRNA in colon carcinoma

Adjuvant chemotherapy does not achieve the desired therapeutic efficacy in colon cancer as a result of the deficient reaction. Gene therapy using small interfering RNAs (siRNAs) delivered by target delivering system represents a potent and specific strategy in tumor therapy. Integrinβ6 is exclusively expressed in malignant colonic epithelia, associated with the progression, metastasis, and chemotherapeutic resistance of colon cancer. Accordingly, designing an efficient and targeted delivery system for β6-siRNA could be a potential approach to improve therapeutic efficacy of colon cancer. Here, we designed the Integrinβ6 target immunoliposomes for highly efficient and selective delivery of β6-siRNA in colon cancer, which consequently resulted in greatly growth suppression, invasion and metastasis of colon cancer cells. Moreover, it was able to greatly inhibit the tumor growing in vivo.

Diacetylenic lipids in the design of stable lipopolymers able to complex and protect plasmid DNA

Different viral and non-viral vectors have been designed to allow the delivery of nucleic acids in gene therapy. In general, non-viral vectors have been associated with increased safety for in vivo use; however, issues regarding their efficacy, toxicity and stability continue to drive further research. Thus, the aim of this study was to evaluate the potential use of the polymerizable diacetylenic lipid 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine (DC8,9PC) as a strategy to formulate stable cationic lipopolymers in the delivery and protection of plasmid DNA. Cationic lipopolymers were prepared following two different methodologies by using DC8,9PC, 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), and the cationic lipids (CL) 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP), stearylamine (SA), and myristoylcholine chloride (MCL), in a molar ratio of 1:1:0.2 (DMPC:DC8,9PC:CL). The copolymerization methodology allowed obtaining cationic lipopolymers which were smaller in size than those obtained by the cationic addition methodology although both techniques presented high size stability over a 166-day incubation period at 4°C. Cationic lipopolymers containing DOTAP or MCL were more efficient in complexing DNA than those containing SA. Moreover, lipopolymers containing DOTAP were found to form highly stable complexes with DNA, able to resist serum DNAses degradation. Furthermore, neither of the cationic lipopolymers (with or without DNA) induced red blood cell hemolysis, although metabolic activity determined on the L-929 and Vero cell lines was found to be dependent on the cell line, the formulation and the presence of DNA. The high stability and DNA protection capacity as well as the reduced toxicity determined for the cationic lipopolymer containing DOTAP highlight the potential advantage of using lipopolymers when designing novel non-viral carrier systems for use in in vivo gene therapy. Thus, this work represents the first steps toward developing a cationic lipopolymer-based gene delivery system using polymerizable and cationic lipids.

Host-Guest Interaction-Based Self-Engineering of Nano-Sized Vesicles for Co-Delivery of Genes and Anticancer Drugs

On the basis of host-guest interactions, this study reported a kind of linear-hyperbranched supramolecular amphiphile and its assembled vesicles for the combined achievement of drug encapsulation and DNA delivery. Amine-attached β-cyclodextrin-centered hyperbranched polyglycerol and linear adamantane-terminated octadecane were arranged to spontaneously interlink together and then self-assemble into nanoscale vesicles. As the model of a hydrophilic agent, DOX·HCl was demonstrated to be readily loaded into the hollow cavity of the vesicles. The drug release pattern could be controlled by adjusting the environmental acidity, favoring the intracellularly fast drug liberation in response to the cellular lysosomal microenvironment. The nanovesicles displayed superior serum-tolerant transgene ability and significantly lower cytotoxicity compared to those of PEI25K, the gold standard of gene delivery vectors. The drug-loaded nanovesicle can co-deliver DNA payloads into cells and allow the preferable accumulation of two payloads in nuclei. The drug encapsulation was found to have little influence on the transfection. This co-delivery vehicle presents a good example of rational design of cationic supramolecular vesicles for stimulus-responsive drug/DNA transport.

Functional liposomes in the cancer-targeted drug delivery

Cancer is considered as one of the most severe health problems and is currently the third most common cause of death in the world after heart and infectious diseases. Novel therapies are constantly being discovered, developed and trialed. Many of the current anticancer agents exhibit non-ideal pharmaceutical and pharmacological properties and are distributed non-specifically throughout the body. This results in death of the both normal healthy and malignant cells and substantially leads to accruing a variety of serious toxic side effects. Therefore, the efficient systemic therapy of cancer is almost impossible due to harmful side effects of anticancer agents to the healthy organs and tissues. Furthermore, several problems such as low bioavailability of the drugs, low drug concentrations at the site of action, lack of drug specificity and drug-resistance also cause many restrictions on clinical applications of these drugs in the tumor therapy. Different types of the liposomal formulations have been used in medicine due to their distinctive advantages associated with their structural flexibility in the encapsulation of various agents with different physicochemical properties. They can also mediate delivery of the cargo to the appropriate cell type and subcellular compartment, reducing the effective dosage and possible side effects which are related to high systemic concentrations. Therefore, these novel systems were found very promising and encouraging dosage forms for the treatment of different types of cancer by increasing efficiency and reducing the systemic toxicity due to the specific drug delivery and targeting.

Engineered nanoparticles for drug delivery in cancer therapy

In medicine, nanotechnology has sparked a rapidly growing interest as it promises to solve a number of issues associated with conventional therapeutic agents, including their poor water solubility (at least, for most anticancer drugs), lack of targeting capability, nonspecific distribution, systemic toxicity, and low therapeutic index. Over the past several decades, remarkable progress has been made in the development and application of engineered nanoparticles to treat cancer more effectively. For example, therapeutic agents have been integrated with nanoparticles engineered with optimal sizes, shapes, and surface properties to increase their solubility, prolong their circulation half-life, improve their biodistribution, and reduce their immunogenicity. Nanoparticles and their payloads have also been favorably delivered into tumors by taking advantage of the pathophysiological conditions, such as the enhanced permeability and retention effect, and the spatial variations in the pH value. Additionally, targeting ligands (e.g., small organic molecules, peptides, antibodies, and nucleic acids) have been added to the surface of nanoparticles to specifically target cancerous cells through selective binding to the receptors overexpressed on their surface. Furthermore, it has been demonstrated that multiple types of therapeutic drugs and/or diagnostic agents (e.g., contrast agents) could be delivered through the same carrier to enable combination therapy with a potential to overcome multidrug resistance, and real-time readout on the treatment efficacy. It is anticipated that precisely engineered nanoparticles will emerge as the next-generation platform for cancer therapy and many other biomedical applications.

Nanodrug delivery systems: a promising technology for detection, diagnosis, and treatment of cancer

Nanotechnology has enabled the development of novel therapeutic and diagnostic strategies, such as advances in targeted drug delivery systems, versatile molecular imaging modalities, stimulus responsive components for fabrication, and potential theranostic agents in cancer therapy. Nanoparticle modifications such as conjugation with polyethylene glycol have been used to increase the duration of nanoparticles in blood circulation and reduce renal clearance rates. Such modifications to nanoparticle fabrication are the initial steps toward clinical translation of nanoparticles. Additionally, the development of targeted drug delivery systems has substantially contributed to the therapeutic efficacy of anti-cancer drugs and cancer gene therapies compared with nontargeted conventional delivery systems. Although multifunctional nanoparticles offer numerous advantages, their complex nature imparts challenges in reproducibility and concerns of toxicity. A thorough understanding of the biological behavior of nanoparticle systems is strongly warranted prior to testing such systems in a clinical setting. Translation of novel nanodrug delivery systems from the bench to the bedside will require a collective approach. The present review focuses on recent research efforts citing relevant examples of advanced nanodrug delivery and imaging systems developed for cancer therapy. Additionally, this review highlights the newest technologies such as microfluidics and biomimetics that can aid in the development and speedy translation of nanodrug delivery systems to the clinic.

Non-metallic nanomaterials in cancer theranostics: a review of silica- and carbon-based drug delivery systems

The rapid development in nanomaterials has brought great opportunities to cancer theranostics, which aims to combine diagnostics and therapy for cancer treatment and thereby improve the healthcare of patients. In this review we focus on the recent progress of several cancer theranostic strategies using mesoporous silica nanoparticles and carbon-based nanomaterials. Silicon and carbon are both group IV elements; they have been the most abundant and significant non-metallic substances in human life. Their intrinsic physical/chemical properties are of critical importance in the fabrication of multifunctional drug delivery systems. Responsive nanocarriers constructed using these nanomaterials have been promising in cancer-specific theranostics during the past decade. In all cases, either a controlled texture or the chemical functionalization is coupled with adaptive properties, such as pH-, light-, redox- and magnetic field- triggered responses. Several studies in cells and mice models have implied their underlying therapeutic efficacy; however, detailed and long-term in vivo clinical evaluations are certainly required to make these bench-made materials compatible in real bedside circumstances.

Efficient downregulation of VEGF in retinal pigment epithelial cells by integrin ligand-labeled liposome-mediated siRNA delivery

BACKGROUND

The purpose of this study was to demonstrate the effectiveness of an integrin peptide ligand-labeled liposomal delivery system loaded with vascular endothelial growth factor (VEGF)-siRNA in a model study of gene therapy for retinopathy using human retinal pigment epithelial cells.

METHODS

Arg(R)-Gly(G)-Asp(D) motif peptide conjugating polyethylene glycol modified (RGD-PEGylated) liposomes were prepared using a thin-film hydration method and optimized for surface charge, particle size, small interfering RNA (siRNA) load, and entrapment efficiency. Reverse transcriptase-polymerase chain reaction and enzyme-linked immunosorbent assays were used to determine VEGF levels in retinal pigment epithelial cells. Cytotoxicity was determined using the 3-[4, 5-dimethylthiazol-2-yl]-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay and flow cytometry.

RESULTS

Physicochemical properties, including particle size, zeta potential, and siRNA load, of the prepared RGD-PEGylated liposomes and their entrapment efficiency were determined to be within the following ranges: 123.8-234.1 nm, 17.31-40.09 m V, 5.27%-6.33%, and >97%, respectively. RGD-PEGylated liposome-mediated fluorescent-labeled siRNA delivery demonstrated significantly enhanced cellular uptake, and 3 mol% RGD-PEGylated liposomes (having 3β-[N-(N', N'-dimethylaminoethane) carbamoyl] cholesterol (DC-cholesterol) DSPE and DSPE-PEG(2000)-RGD with molar ratio of 50/47/3) were shown to have better efficacy with regard to specificity for retinal pigment epithelial cells, reduced cytotoxicity, and knockdown of the target molecule.

CONCLUSION

By integrin receptor-mediated endocytosis, 3 mol% RGD-PEGylated liposomes were shown to be a suitable vector when loaded with VEGF-siRNA for efficient downregulation of VEGF in retinal pigment epithelial cells at both the protein and gene levels. This integrin ligand-modified liposomal delivery system has therapeutic potential for ocular gene therapy.

Future of the particle replication in nonwetting templates (PRINT) technology

Particle replication in nonwetting templates (PRINT) is a continuous, roll-to-roll, high-resolution molding technology which allows the design and synthesis of precisely defined micro- and nanoparticles. This technology adapts the lithographic techniques from the microelectronics industry and marries these with the roll-to-roll processes from the photographic film industry to enable researchers to have unprecedented control over particle size, shape, chemical composition, cargo, modulus, and surface properties. In addition, PRINT is a GMP-compliant (GMP=good manufacturing practice) platform amenable for particle fabrication on a large scale. Herein, we describe some of our most recent work involving the PRINT technology for application in the biomedical and material sciences.

Virus-modified exosomes for targeted RNA delivery; a new approach in nanomedicine

A major goal in biomedical research is to clinically reverse the cause of disease rather than treating the symptoms. Gene therapy has the potential to meet this goal and the discovery of RNA interference (RNAi) has lead to a new class of highly selective therapeutics. However, initial enthusiasm is reduced due to safety concerns associated with virus-based delivery vectors that are used for in vivo delivery. Viral vectors for siRNA delivery into target cells are used because of their high target specificity and delivery efficacy (endosomal escape). Recent discoveries suggest that a specialized form of nano-sized lipid vesicles called exosomes can incorporate and transport functional RNAs into target cells and may serve as an attractive alternative. Evidence is accumulating that most pluricellular organisms sustain exosome-based communications via inter-cellular exchange of mRNA and miRNAs between cells. We discovered that viruses have found ways to exploit this communication pathway and we argue here that adaptations of exosomes imposed by viruses maybe exploited for superior delivery of RNA in vivo. We discuss recent discoveries in exosome biogenesis their physical properties, targeting and delivery strategies and how the knowledge of exosome production in virus infected cells could propel their entry into clinical settings.

Application of poly(ethylene glycol)-distearoylphosphatidylethanolamine (PEG-DSPE) block copolymers and their derivatives as nanomaterials in drug delivery

Poly(ethylene glycol)–distearoylphosphatidylethanolamine (PEG-DSPE) block copolymers are biocompatible and amphiphilic polymers that can be widely utilized in the preparation of liposomes, polymeric nanoparticles, polymer hybrid nanoparticles, solid lipid nanoparticles, lipid–polymer hybrid nanoparticles, and microemulsions. Particularly, the terminal groups of PEG can be activated and linked to various targeting ligands, which can prolong the circulation time, improve the drug bioavailability, reduce undesirable side effects, and especially target specific cells, tissues, and even the intracellular localization in organelles. This review herein aims to describe recent developments in drug carriers exploiting PEG-DSPE block copolymers and their derivatives, and the incorporation of different ligands to the end groups of PEG-DSPE to target delivery, focusing on their modification approaches, advantages, applications, and the probable associated drawbacks.

Cytofectin amine head group modification and degree of liposome pegylation: factors influencing gene transfer

The effectiveness of liposome-mediated gene transfer methods hinges, in part, on the nature of the interaction between the DNA cargo and the liposomes. Here we have examined the effect of quaternization of the cytofectin cationic head group on this interaction and the effect of concentration of the biocompatible, protective polymer polyethylene glycol₂₀₀₀ (PEG₂₀₀₀) on transfection activity. Thus 3β[N-(N’,N’-dimethylaminopropane)-carbamoyl] cholesterol (Chol-T) and 3β[N-(N’,N’,N’-trimethylammonium propane)-carbamoyl] cholesterol iodide (Chol-Q), differing only in the degree of head group methylation, have been formulated into liposomes with polyethylene glycol₂₀₀₀-distearoylphosphatidyl ethanolamine (DSPE PEG₂₀₀₀) and the neutral co-lipid dioleoylphosphatidylethanolamine (DOPE). Their DNA-binding characteristics have been determined and the gene transfer capabilities of resulting lipoplexes have been examined in HEK 293 human embryonic kidney cells. Quaternary ammonium Chol-Q liposomes were found to bind DNA more avidly than their tertiary amine Chol-T counterparts. The inclusion of PEG₂₀₀₀ in liposome formulations resulted in an increase in the optimal liposome-DNA binding ratio. Chol-T liposomes promoted transgene activity levels 5 times greater than those obtained with Chol-Q lipoplexes. Furthermore, a drop in transfection activity of only 17% was noted on increase of liposome pegylation from 2 to 5 mole percent. The study's findings suggest that strong association between cationic liposomes and DNA may lead to reduced levels of transfection activity as a result of poor release of nucleic acid after cellular uptake.

Eukaryotic expression vectors bearing genes encoding cytotoxic proteins for cancer gene therapy

Cancer gene therapy is a promising direction for the treatment of cancer patients. A primary goal of all cancer therapies is to selectively target and kill tumour cells. Such therapies are administered via different approaches, including both viral and non-viral delivery; however, both methods have advantages and disadvantages. Transcriptional targeting enables genes encoding toxic proteins to be expressed directly in cancer cells. Numerous vectors have been created with the purpose of killing cancer cells, and some have successfully suppressed malignant tumours. Data concerning the function of vectors bearing genes that encode cytotoxic proteins under the control of different promoters, including tissue/tumour specific and constitutive promoters, is summarised here. This review focuses on vectors that bear genes encoding diphtheria toxin, Pseudomonas exotoxin A, caspases, gef, streptolysin, and melittin. Data describing the efficacy of such vectors have been summarised. Notably, there are vectors that killed cancer cell lines originating from the same type of cancer with differential efficiency. Thus, there is differential inhibition of cancer cell growth dependent on the cell line. In this review, the constructs employing genes whose expression induces cell death and the efficiency with which they suppress cancer cell growth will be summarised.

Novel RGD-lipid conjugate-modified liposomes for enhancing siRNA delivery in human retinal pigment epithelial cells

BACKGROUND

Human retinal pigment epithelial cells are promising target sites for small interfering RNA (siRNA) that might be used for the prevention and/or treatment of choroidal neovascularization by inhibiting the expression of angiogenic factor; for example, by downregulating expression of the vascular endothelial growth factor gene.

METHODS

A novel functional lipid, DSPE-PEG-RGD, a Arg(R)-Gly(G)-Asp(D) motif peptide conjugated to 1, 2-distearoyl-sn-glycero-3-phosphoethanolamine- N-[maleimide (polyethylene glycol)-2000], was synthesized for the preparation of siRNA-loaded RGD-PEGylated liposomes to enhance uptake of encapsulated siRNA in retinal pigment epithelial cells. Various liposomes, with 1 mol% and 5 mol% PEGylated lipid or 1 mol% and 5 mol% RGD-PEGylated lipid, were fabricated.

RESULTS

Characterization of the liposomes, including siRNA entrapment efficiency, average particle size and ζ-potential, were determined to be as follows: >96%, 129.7 ± 51 to 230.7 ± 60.7 nm, and 17.3 ± 0.6 to 32 ± 1.3 mV, respectively. For the in vitro retinal pigment epithelial cell studies, the RGD-PEGylated liposomes had high delivery efficiency with siRNA delivery, about a four-fold increase compared with the PEGylated liposomes. Comparison of the various liposomes showed that the 1 mol% RGD-modified liposome had less cytotoxicity and higher siRNA delivery efficiency than the other liposomes. The antibody blocking assay confirmed that uptake of the 1 mol% RGD-PEGylated liposome was via integrin receptor- mediated endocytosis in retinal pigment epithelial cells.

CONCLUSION

The results of this study suggest that RGD-PEGylated liposomes might be useful for siRNA delivery into retinal pigment epithelial cells by integrin receptor-medicated endocytosis.

Liposome based delivery systems in pancreatic cancer treatment: from bench to bedside

Despite rapid advances in cancer diagnosis and treatment, pancreatic cancer remains one of the most difficult human malignancies to be treated, with a mortality rate nearly equal to its incidence. Although gemcitabine has been established as the standard first-line treatment for advanced pancreatic cancer, gemcitabine-based combination chemotherapy showed either marginal or no improvement in survival. Developments in liposomal delivery systems have facilitated the targeting of specific agents for cancer treatment. Such systems could be developed as platforms for future multi-functional theranostic nanodevices tailor-made for the combined detection of early cancer and functional drug delivery. We systemically review liposome based drug-delivery systems, which can provide improved pharmacokinetics, reduced side effects and potentially increased tumor uptake, for pancreatic cancer therapy. Novel liposomal formulations allowing for higher tumor targeting efficiencies and used in current clinical trials to treat this challenging disease are emphasized.

A review on composite liposomal technologies for specialized drug delivery

The combination of liposomes with polymeric scaffolds could revolutionize the current state of drug delivery technology. Although liposomes have been extensively studied as a promising drug delivery model for bioactive compounds, there still remain major drawbacks for widespread pharmaceutical application. Two approaches for overcoming the factors related to the suboptimal efficacy of liposomes in drug delivery have been suggested. The first entails modifying the liposome surface with functional moieties, while the second involves integration of pre-encapsulated drug-loaded liposomes within depot polymeric scaffolds. This attempts to provide ingenious solutions to the limitations of conventional liposomes such as short plasma half-lives, toxicity, stability, and poor control of drug release over prolonged periods. This review delineates the key advances in composite technologies that merge the concepts of depot polymeric scaffolds with liposome technology to overcome the limitations of conventional liposomes for pharmaceutical applications.

A reexamination of active and passive tumor targeting by using rod-shaped gold nanocrystals and covalently conjugated peptide ligands

The targeted delivery of nanoparticles to solid tumors is one of the most important and challenging problems in cancer nanomedicine, but the detailed delivery mechanisms and design principles are still not well understood. Here we report quantitative tumor uptake studies for a class of elongated gold nanocrystals (called nanorods) that are covalently conjugated to tumor-targeting peptides. A major advantage in using gold as a "tracer" is that the accumulated gold in tumors and other organs can be quantitatively determined by elemental mass spectrometry (gold is not a natural element found in animals). Thus, colloidal gold nanorods are stabilized with a layer of polyethylene glycols (PEGs) and are conjugated to three different ligands: (i) a single-chain variable fragment (ScFv) peptide that recognizes the epidermal growth factor receptor (EGFR); (ii) an amino terminal fragment (ATF) peptide that recognizes the urokinase plasminogen activator receptor (uPAR); and (iii) a cyclic RGD peptide that recognizes the a(v)β(3) integrin receptor. Quantitative pharmacokinetic and biodistribution data show that these targeting ligands only marginally improve the total gold accumulation in xenograft tumor models in comparison with nontargeted controls, but their use could greatly alter the intracellular and extracellular nanoparticle distributions. When the gold nanorods are administered via intravenous injection, we also find that active molecular targeting of the tumor microenvironments (e.g., fibroblasts, macrophages, and vasculatures) does not significantly influence the tumor nanoparticle uptake. These results suggest that for photothermal cancer therapy, the preferred route of gold nanorod administration is intratumoral injection instead of intravenous injection.

Transferrin receptor-targeted liposomes encapsulating anti-BCR-ABL siRNA or asODN for chronic myeloid leukemia treatment

The present work aimed at the development and application of transferrin receptor (TrfR)-targeted sterically stabilized liposomes encapsulating anti-BCR-ABL siRNA or asODN. Transferrin was coupled to the surface of liposomes encapsulating siRNA or asODN through the postinsertion method. Cell association and internalization were assessed by flow cytometry and confocal microscopy, respectively. BCR-ABL mRNA and Bcr-Abl protein levels were evaluated by qRT-PCR and Western blot, respectively. Cell viability was assessed using the resazurin reduction method. The amount of coupled transferrin and the size and stability over time of the liposomes were very satisfactory and reproducible. The siRNA encapsulation yield was dependent on the concentration of the encapsulation buffer used (20 or 300 mM), as opposed to asODN encapsulation yield which was high for both concentrations tested. Cell association and internalization studies were performed in leukemia cell lines treated with liposomes coupled to Trf (Trf-liposomes) or albumin (BSA-liposomes) or with nontargeted liposomes (NT-liposomes) encapsulating fluorescently labeled siRNA (Cy3-siRNA). These experiments clearly indicated that BSA- and NT-liposomes have no ability to promote the delivery of the encapsulated nucleic acids and that the Trf-liposomes deliver the nucleic acids by a Trf receptor-dependent mechanism. The Trf-liposomes encapsulating siRNA or asODN promote sequence-specific down-regulation of the BCR-ABL mRNA, although a certain extent of nonspecific sequence effects at the protein and cell viability level were observed. Overall, our results indicate that Trf-liposomes encapsulating gene silencing tools allow combining molecular and cellular targeting, which is a valuable approach for cancer treatment.

Mesenchymal stem cells: a promising targeted-delivery vehicle in cancer gene therapy

The targeting drug delivery systems (TDDS) have attracted extensive attention of researchers in recent years. More and more drug/gene targeted delivery carriers, such as liposome, magnetic nanoparticles, ligand-conjugated nanoparticles, microbubbles, etc., have been developed and under investigation for their application. However, the currently investigated drug/gene carriers have several disadvantages, which limit their future use in clinical practice. Therefore, design and development of novel drug/gene delivery vehicles has been a hot area of research. Recent studies have shown the ability of mesenchymal stem cells (MSCs) to migrate towards and engraft into the tumor sites, which make them a great hope for efficient targeted-delivery vehicles in cancer gene therapy. In this review article, we examine the promising of using mesenchymal stem cells as a targeted-delivery vehicle for cancer gene therapy, and summarize various challenges and concerns regarding these therapies.

Building Cell Selectivity into CPP-Mediated Strategies

There is a pressing need for more effective and selective therapies for cancer and other diseases. Consequently, much effort is being devoted to the development of alternative experimental approaches based on selective systems, which are designed to be specifically directed against target cells. In addition, a large number of highly potent therapeutic molecules are being discovered. However, they do not reach clinical trials because of their low delivery, poor specificity or their incapacity to bypass the plasma membrane. Cell-penetrating peptides (CPPs) are an open door for cell-impermeable compounds to reach intracellular targets. Putting all these together, research is sailing in the direction of the design of systems with the capacity to transport new drugs into a target cell. Some CPPs show cell type specificity while others require modifications or form part of more sophisticated drug delivery systems. In this review article we summarize several strategies for directed drug delivery involving CPPs that have been reported in the literature.

DC-Chol/DOPE cationic liposomes: a comparative study of the influence factors on plasmid pDNA and siRNA gene delivery

Cationic liposomes (CLs) composed of 3beta-[N-(N',N'-dimethylaminoethane) carbamoyl] cholesterol (DC-Chol) and dioleoylphosphatidylethanolamine (DOPE) (DC-Chol/DOPE liposomes) have been classified as one of the most efficient gene delivery systems. Our study aims to examine the effect of the molar ratio of DC-Chol/DOPE, PEGylation and serum on the pDNA (plasmid pDNA) and siRNA (small interfering RNA) transfection of DC-Chol/DOPE liposomes. The results showed that the most efficient DC-Chol/DOPE liposomes for pDNA or siRNA delivery were at a 1:2 or 1:1 molar ratio of DC-Chol/DOPE, respectively. The transfection efficiency of DC-Chol/DOPE liposomes increased along with increased weight ratio of DC-Chol/siRNA. However, the pDNA transfection efficiency decreased along with increased weight ratio of DC-Chol/pDNA from 3/1. As expected, PEGylation decreased siRNA and pDNA transfection efficiency of DC-Chol/DOPE liposomes. In PEGylated DC-Chol/DOPE liposomes, increased weight ratio of DC-Chol/pDNA from 3/1 did not lead to higher pDNA transfection efficiency, whereas increased weight ratio of DC-Chol/siRNA resulted in increased siRNA transfection efficiency. Furthermore, the serum did not significantly inhibit the pDNA and siRNA transfection efficiency of DC-Chol/DOPE liposomes. In conclusion, our results elucidated the influence factors of DC-Chol/DOPE liposome transfection and would reveal that siRNA and pDNA transfection mechanisms were different in DC-Chol/DOPE liposomes.

Role of nanocarrier systems in cancer nanotherapy

Cancer continues to be a major cause of morbidity and mortality worldwide. While discovery of new drugs and cancer chemotherapy opened a new era for the treatment of tumors, optimized concentration of drug at the target site is only possible at the expense of severe side effects. Nanoscale carrier systems have the potential to limit drug toxicity and achieve tumor localization. When linked with tumor-targeting moieties, such as tumor-specific ligands or monoclonal antibodies, the nanocarriers can be used to target cancer-specific receptors, tumor antigens, and tumor vasculatures with high affinity and precision. This article is an overview of advances and prospects in the applications of nanocarrier technology in cancer therapy. Applications of nanoliposomes, dendrimers, and nanoparticles in cancer therapy are explained, along with their preparation methods and targeting strategies.

Complexation of siRNA and pDNA with cationic liposomes: the important aspects in lipoplex preparation

In the last two decades, cationic liposomes have been investigated as vehicles for nucleic acids [plasmid DNA (pDNA) and small interfering RNA (siRNA)] delivery in vitro and in vivo. The formation of cationic liposomes-nucleic acids complexes, termed lipoplexes, depends on a number of experimental variables. The quality of the nucleic acid and the cationic liposome as well as the selection of diluents for diluting the concentrated stocks strongly affect the resulting lipoplexes and their efficiency of gene-expression or gene-silencing effect following transfection. In addition, the molar ratio of cationic lipid nitrogen (N) to siRNA or pDNA phosphate (P) (N/P ratio) influences the final characteristics of the lipoplexes, such as size, surface zeta potential, and reproducibility, thereby reflecting their efficiency following transfection. The methods presented in this chapter could be helpful to obtain reliable and reproducible lipoplexes and experimental results.

Lyophilized HER2-specific PEGylated immunoliposomes for active siRNA gene silencing

The development of a tumor-specific immunoliposome delivering small interfering RNA (siRNA) represents a practical way in cancer gene therapy. In this study, we developed PEGylated 3beta-[N-(N', N'-dimethylaminoethane) carbamoyl] cholesterol (DC-Chol)/dioleoylphosphatidyl ethanolamine (DOPE) immunoliposomes conjugated with the Fab' of recombinant humanized anti-HER2 monoclonal antibody (PIL) for siRNA delivery. The results demonstrated that the lyophilized PIL (LPIL) prepared by the lyophilization/rehydration method possessed a significantly enhanced HER1 gene, a model target, silencing ability compared with PIL in HER2-overexpressing SK-BR3 cells. Among a series of LPIL with different PEGylation degree, LPIL containing 2.5%PEG (2.5%PEG LPIL) showed the best HER1 gene silencing activity. Confocal microscope studies demonstrated that 2.5%PEG LPIL could specifically bind to SK-BR3 cells and were sequentially internalized into them. Using RhoA as a cancer therapeutic target, 2.5%PEG LPIL entrapping anti-RhoA siRNA could specifically silence RhoA expression and inhibit cell invasion in SK-BR3 cells. In conclusion, these finding demonstrated the potential use of 2.5%PEG LPIL in specifically delivering siRNA to HER2-overexpressing cancers.

Flow cytometry and live confocal analysis for the evaluation of the uptake and intracellular distribution of FITC-ODN into HaCaT cells

In this study, the mechanism of the internalization and the cellular distribution of 59 fluorescein conjugated PS-ODN (FITC-ODN) after transfection with different mixed lipidic vesicles/oligo complexes (lipoplexes) have been investigated. Mixed lipidic vesicles were prepared with one of the most used cationic lipid (DOTAP) and different amounts of a cholic acid (UDCA) to release the oligo into HaCaT cells. Using flow cytometry, the cellular uptake of the oligo was studied with and without different inhibitors able to block selectively the different pathways involved in the internalization mechanism. The intracellular distribution of the oligo was analyzed by confocal laser scanning microscopy (CLSM), treating the cells with the lipoplexes and directly observing without any fixing procedure. To better carry out the colocalization studies, fluorescent-labeled markers, specific for the different cellular compartments, were coincubated with 59 fluorescein-conjugated 29-mer phosphorotioate oligonucleotide (FITC-ODN). The different lipidic vesicles affect the internalization mechanism of FITC-ODN. After using the inhibitors, the uptake of complexes involved a different internalization mechanism. The live CLSM analysis demonstrated that, after 1 hour from the complex incubation, the oligo was transferred into cells and localized into the endosomes; after 24 hours, the oligo was intracellularly localized close to the nuclear structure in a punctuate pattern. However, the results from fusion experiments showed also a binding of a quite low amount of oligo with the cell membranes.

Novel cholesterol-based cationic lipids for gene delivery

Gene therapy based on gene delivery is a promising strategy for the treatment of human disease. Here we present data on structure/biological activity of new biodegradable cholesterol-based cationic lipids with various heterocyclic cationic head groups and linker types. Enhanced accumulation of nucleic acids in the cells mediated by the lipids was demonstrated by fluorescent microscopy and flow cytometry. Light scattering and atomic force microscopy were used to find structure/transfection activity correlations for the lipids. We found that the ability of the lipids to stimulate intracellular accumulation of the oligodeoxyribonucleotides and plasmid DNA correlates well with their ability to form in solution lipid/NA complexes of sizes that do not exceed 100 nm. Screening of the lipids revealed the most promising transfection agents both in terms of low toxicity and efficient delivery: cholesterol-based lipids with positively charged pyridine and methyl imidazole head groups and either the ester or carbamate linker.

Nonviral gene vector formation in monodispersed picolitre incubator for consistent gene delivery

A novel picolitre incubator based microfluidic system for consistent nonviral gene carrier formulation is presented. A cationic lipid-based carrier is the most attractive nonviral solution for delivering plasmid DNA, shRNA, or drugs for pharmaceutical research and RNAi applications. The size of the cationic lipid and DNA complex (CL-DNA), or the lipoplex, is one of the important variations for consistency of gene transfection. CL-DNA size, in turn, may be controlled by factors such as the cationic lipid and DNA mixing order, mixing rate, and mixture incubation time. The Picolitre Microfluidic Reactor and Incubator (PMRI) system described here is able to control these parameters in order to create homogeneous CL-DNA. Compared with conventional CL-DNA preparation techniques involving hand-shaking or vortexing, the PMRI system demonstrates a greater ability to constantly and uniformly mix cationic lipids and DNA simultaneously. After mixing in the picolitre droplet reactors, the cationic lipid and DNA is incubated within the picolitre incubator to form CL-DNA. The PMRI generates a narrower size distribution band, while also turning the sample loading, mixing and incubation steps into an integrated process enabling the consistent formation of CL-DNA. The coefficient of variation (CV) of transfection efficiency is 0.05 and 0.30 for PMRI-based and conventional methods, respectively. In addition, this paper demonstrates that the gene transfection efficiency of lipoplex created in the PMRI is more reproducible.