Cytoplasmic delivery of liposomes into MCF-7 breast cancer cells mediated by cell-specific phage fusion coat protein

Achieving Endo/Lysosomal Escape Using Smart Nanosystems for Efficient Cellular Delivery

The delivery of therapeutic agents faces significant hurdles posed by the endo-lysosomal pathway, a bottleneck that hampers clinical effectiveness. This comprehensive review addresses the urgent need to enhance cellular delivery mechanisms to overcome these obstacles. It focuses on the potential of smart nanomaterials, delving into their unique characteristics and mechanisms in detail. Special attention is given to their ability to strategically evade endosomal entrapment, thereby enhancing therapeutic efficacy. The manuscript thoroughly examines assays crucial for understanding endosomal escape and cellular uptake dynamics. By analyzing various assessment methods, we offer nuanced insights into these investigative approaches' multifaceted aspects. We meticulously analyze the use of smart nanocarriers, exploring diverse mechanisms such as pore formation, proton sponge effects, membrane destabilization, photochemical disruption, and the strategic use of endosomal escape agents. Each mechanism's effectiveness and potential application in mitigating endosomal entrapment are scrutinized. This paper provides a critical overview of the current landscape, emphasizing the need for advanced delivery systems to navigate the complexities of cellular uptake. Importantly, it underscores the transformative role of smart nanomaterials in revolutionizing cellular delivery strategies, leading to a paradigm shift towards improved therapeutic outcomes.

Advances in functional lipid nanoparticles: from drug delivery platforms to clinical applications

Since Doxil's first clinical approval in 1995, lipid nanoparticles have garnered great interest and shown exceptional therapeutic efficacy. It is clear from the licensure of two RNA treatments and the mRNA-COVID-19 vaccination that lipid nanoparticles have immense potential for delivering nucleic acids. The review begins with a list of lipid nanoparticle types, such as liposomes and solid lipid nanoparticles. Then it moves on to the earliest lipid nanoparticle forms, outlining how lipid is used in a variety of industries and how it is used as a versatile nanocarrier platform. Lipid nanoparticles must then be functionally modified. Various approaches have been proposed for the synthesis of lipid nanoparticles, such as High-Pressure Homogenization (HPH), microemulsion methods, solvent-based emulsification techniques, solvent injection, phase reversal, and membrane contractors. High-pressure homogenization is the most commonly used method. All of the methods listed above follow four basic steps, as depicted in the flowchart below. Out of these four steps, the process of dispersing lipids in an aqueous medium to produce liposomes is the most unpredictable step. A short outline of the characterization of lipid nanoparticles follows discussions of applications for the trapping and transporting of various small molecules. It highlights the use of rapamycin-coated lipid nanoparticles in glioblastoma and how lipid nanoparticles function as a conjugator in the delivery of anticancer-targeting nucleic acids. High biocompatibility, ease of production, scalability, non-toxicity, and tailored distribution are just a meager of the enticing allowances of using lipid nanoparticles as drug delivery vehicles. Due to the present constraints in drug delivery, more research is required to utterly realize the potential of lipid nanoparticles for possible clinical and therapeutic purposes.

(Nano)platforms in breast cancer therapy: Drug/gene delivery, advanced nanocarriers and immunotherapy

Breast cancer is the most malignant tumor in women, and there is no absolute cure for it. Although treatment modalities including surgery, chemotherapy, and radiotherapy are utilized for breast cancer, it is still a life-threatening disease for humans. Nanomedicine has provided a new opportunity in breast cancer treatment, which is the focus of the current study. The nanocarriers deliver chemotherapeutic agents and natural products, both of which increase cytotoxicity against breast tumor cells and prevent the development of drug resistance. The efficacy of gene therapy is boosted by nanoparticles and the delivery of CRISPR/Cas9, Noncoding RNAs, and RNAi, promoting their potential for gene expression regulation. The drug and gene codelivery by nanoparticles can exert a synergistic impact on breast tumors and enhance cellular uptake via endocytosis. Nanostructures are able to induce photothermal and photodynamic therapy for breast tumor ablation via cell death induction. The nanoparticles can provide tumor microenvironment remodeling and repolarization of macrophages for antitumor immunity. The stimuli-responsive nanocarriers, including pH-, redox-, and light-sensitive, can mediate targeted suppression of breast tumors. Besides, nanoparticles can provide a diagnosis of breast cancer and detect biomarkers. Various kinds of nanoparticles have been employed for breast cancer therapy, including carbon-, lipid-, polymeric- and metal-based nanostructures, which are different in terms of biocompatibility and delivery efficiency.

Efficient pre-treatment for pancreatic cancer using chloroquine-loaded nanoparticles targeting pancreatic stellate cells

Pancreatic stellate cells (PSCs) play a key role in desmoplastic stroma, which is a characteristic of pancreatic ductal adenocarcinoma (PDAC), and they also enhance the malignancy of pancreatic cancer cells. Our previous study reported chloroquine's mitigating effects on PSC activation; however, the drug is known to induce adverse effects in clinical practice. The present study aimed to reduce chloroquine doses and develop a useful pre-treatment that targets PSCs using nanoparticles. Poly lactic-co-glycolic acid (PLGA) nanoparticles were used as carriers and loaded with indocyanine green (Nano-ICG) or chloroquine (Nano-CQ). Tumor accumulation of Nano-ICG was evaluated using an in vivo imaging system. The effects of chloroquine, Nano-CQ and/or chemotherapy drug gemcitabine were investigated in an orthotopic xenograft mouse model. Nano-ICG selectively accumulated in pancreatic tumors and persisted therein for over 7 days after administration. Additionally, Nano-ICG accumulated in the peritoneal metastasized regions, but not in the liver, kidney and normal pancreatic tissues. Nano-CQ reduced the density of activated PSCs at lower chloroquine doses and significantly restrained tumor progression in combination with gemcitabine. In conclusion, the PLGA nanosystem successfully delivered the drug to pancreatic tumors. Nano-CQ efficiently reduced PSC activation and may be a promising novel pre-treatment strategy for PDAC.

Escaping the endosome: assessing cellular trafficking mechanisms of non-viral vehicles

Non-viral vehicles hold therapeutic promise in advancing the delivery of a variety of cargos in vitro and in vivo, including small molecule drugs, biologics, and especially nucleic acids. However, their efficacy at the cellular level is limited by several delivery barriers, with endolysosomal degradation being most significant. The entrapment of vehicles and their cargo in the acidified endosome prevents access to the cytosol, nucleus, and other subcellular compartments. Understanding the factors that contribute to uptake and intracellular trafficking, especially endosomal entrapment and release, is key to overcoming delivery obstacles within cells. In this review, we summarize and compare experimental techniques for assessing the extent of endosomal escape of a variety of non-viral vehicles and describe proposed escape mechanisms for different classes of lipid-, polymer-, and peptide-based delivery agents. Based on this evaluation, we present forward-looking strategies utilizing information gained from mechanistic studies to inform the rational design of efficient delivery vehicles.

Nanoplatforms for Targeted Stimuli-Responsive Drug Delivery: A Review of Platform Materials and Stimuli-Responsive Release and Targeting Mechanisms

To achieve the promise of stimuli-responsive drug delivery systems for the treatment of cancer, they should (1) avoid premature clearance; (2) accumulate in tumors and undergo endocytosis by cancer cells; and (3) exhibit appropriate stimuli-responsive release of the payload. It is challenging to address all of these requirements simultaneously. However, the numerous proof-of-concept studies addressing one or more of these requirements reported every year have dramatically expanded the toolbox available for the design of drug delivery systems. This review highlights recent advances in the targeting and stimuli-responsiveness of drug delivery systems. It begins with a discussion of nanocarrier types and an overview of the factors influencing nanocarrier biodistribution. On-demand release strategies and their application to each type of nanocarrier are reviewed, including both endogenous and exogenous stimuli. Recent developments in stimuli-responsive targeting strategies are also discussed. The remaining challenges and prospective solutions in the field are discussed throughout the review, which is intended to assist researchers in overcoming interdisciplinary knowledge barriers and increase the speed of development. This review presents a nanocarrier-based drug delivery systems toolbox that enables the application of techniques across platforms and inspires researchers with interdisciplinary information to boost the development of multifunctional therapeutic nanoplatforms for cancer therapy.

Antimicrobial peptide AR-23 derivatives with high endosomal disrupting ability enhance poly(l-lysine)-mediated gene transfer

Background

pH‐sensitive peptides are a relatively new strategy for conquering the poor endosomal release of cationic polymer‐mediated transfection. Modification of antimicrobial peptides by exchanging positively‐charged residues with negatively‐charged glutamic acid residues (Glu) greatly improves its lytic activity at the endosomal pH, which could improve cationic polymer‐mediated transfection.

Methods

In the present study, we investigated the effect of the number of Glu substituted for positively‐charged residues on the endosomal escape activity of AR‐23 and the ability of mutated AR‐23 with respect to enhancing cationic polymer‐mediated transfection. Three analogs were synthesized by replacing the positively‐charged residues in the AR‐23 sequence with Glu one‐by‐one.

Results

The pH‐sensitive lysis ability of the peptides, the effect of peptides on the physicochemical characteristics, the intracellular trafficking, the transfection efficiency and the cytotoxicity of the polyplexes were determined. Increased lytic activity of peptides was observed with the increased number of Glu replacement in the AR‐23 sequence at acidic pH. The number of Glu substituted for positively‐charged residues of AR‐23 dramatically affects its lysis ability at neutral pH. Triple‐Glu substitution in the AR‐23 sequence greatly improved poly(l‐lysine)‐mediated gene transfection efficiency at the same time as maintaining low cytotoxicity.

Conclusions

The results indicate that replacement of positively‐charged residues with sufficient Glu residues may be considered as a method for designing pH‐sensitive peptides, which could be applied as potential enhancers for improving cationic polymer‐mediated transfection.

Stimuli-responsive Drug Delivery Nanocarriers in the Treatment of Breast Cancer

Stimuli-responsive drug-delivery nanocarriers (DDNs) have been increasingly reported in the literature as an alternative for breast cancer therapy. Stimuli-responsive DDNs are developed with materials that present a drastic change in response to intrinsic/chemical stimuli (pH, redox and enzyme) and extrinsic/physical stimuli (ultrasound, Near-infrared (NIR) light, magnetic field and electric current). In addition, they can be developed using different strategies, such as functionalization with signaling molecules, leading to several advantages, such as (a) improved pharmaceutical properties of liposoluble drugs, (b) selectivity with the tumor tissue decreasing systemic toxic effects, (c) controlled release upon different stimuli, which are all fundamental to improving the therapeutic effectiveness of breast cancer treatment. Therefore, this review summarizes the use of stimuli-responsive DDNs in the treatment of breast cancer. We have divided the discussions into intrinsic and extrinsic stimuli and have separately detailed them regarding their definitions and applications. Finally, we aim to address the ability of these stimuli-responsive DDNs to control the drug release in vitro and the influence on breast cancer therapy, evaluated in vivo in breast cancer models.

Endosomal escape enhancing compounds facilitate functional delivery of extracellular vesicle cargo

Aim: Extracellular vesicles (EVs) are desirable delivery vehicles for therapeutic cargoes. We aimed to load EVs with Cre recombinase protein and determine whether functional delivery to cells could be improved by using endosomal escape enhancing compounds. Materials & methods: Overexpressed CreFRB protein was actively loaded into EVs by rapalog-induced dimerization to CD81FKBP, or passively loaded by overexpression in the absence of rapalog. Functional delivery of CreFRB was analysed using a HEK293 Cre reporter cell line in the absence and presence of endosomal escape enhancing compounds. Results: The EVs loaded with CreFRB by both active and passive mechanisms were able to deliver functional CreFRB to recipient cells only in the presence of endosomal escape enhancing compounds chloroquine and UNC10217938A. Conclusion: The use of endosomal escape enhancing compounds in conjunction with EVs loaded with therapeutic cargoes may improve efficacy of future EV based therapeutics.

Peptide-based gene delivery vectors

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

Landscape Phage: Evolution from Phage Display to Nanobiotechnology

The development of phage engineering technology has led to the construction of a novel type of phage display library-a collection of nanofiber materials with diverse molecular landscapes accommodated on the surface of phage particles. These new nanomaterials, called the "landscape phage", serve as a huge resource of diagnostic/detection probes and versatile construction materials for the preparation of phage-functionalized biosensors and phage-targeted nanomedicines. Landscape-phage-derived probes interact with biological threat agents and generate detectable signals as a part of robust and inexpensive molecular recognition interfaces introduced in mobile detection devices. The use of landscape-phage-based interfaces may greatly improve the sensitivity, selectivity, robustness, and longevity of these devices. In another area of bioengineering, landscape-phage technology has facilitated the development and testing of targeted nanomedicines. The development of high-throughput phage selection methods resulted in the discovery of a variety of cancer cell-associated phages and phage proteins demonstrating natural proficiency to self-assemble into various drug- and gene-targeting nanovehicles. The application of this new "phage-programmed-nanomedicines" concept led to the development of a number of cancer cell-targeting nanomedicine platforms, which demonstrated anticancer efficacy in both in vitro and in vivo experiments. This review was prepared to attract the attention of chemical scientists and bioengineers seeking to develop functionalized nanomaterials and use them in different areas of bioscience, medicine, and engineering.

Sensitive colorimetric immunoassay of Vibrio parahaemolyticus based on specific nonapeptide probe screening from a phage display library conjugated with MnO2 nanosheets with peroxidase-like activity

Pathogen detection continues to receive significant attention due to the harmful effects of pathogens on public health. Herein, specific nonapeptide-fusion proteins pVIII (pVIII fusion) were isolated from phage VQTVQIGSD (designated by the sequence of a fused foreign peptide), which was specifically screened from the f8/9 landscape phage library against Vibrio parahaemolyticus (V. parahaemolyticus) in a high-throughput way. The as-prepared V. parahaemolyticus-specific recognition element is cheaper and more available than antibodies. Further, a highly sensitive colorimetric immunoassay for V. parahaemolyticus was established using pVIII fusion as capture probes coupled with protein-templated MnO₂ nanosheets (NSs) as signal probes. In the presence of a target bacterium, V. parahaemolyticus, a sandwich-type complex of pVIII fusion-V. parahaemolyticus-MnO₂ NS@pVIII fusion was formed through specific recognition of pVIII fusion and V. parahaemolyticus. The signal probes (MnO₂ NSs) could catalyze the reaction of 3,3',5,5'-tetramethylbenzidine and H₂O₂ to generate a colorimetric change. The proposed V. parahaemolyticus detection method demonstrated a wide detection range (20-10⁴ colony-forming units (CFU) mL^-1), low limit of detection (15 CFU mL^-1), excellent selectivity, and high reliability for real marine samples, showing potential application in marine microbiological detection and control.

Prussian blue decorated mesoporous silica hybrid nanocarriers for photoacoustic imaging-guided synergistic chemo-photothermal combination therapy

Herein, Prussian blue decorated mesoporous silica PB@MSH-EDA NPs are fabricated for efficient photoacoustic imaging guided chemo-photothermal combination therapy.

Guiding nanomaterials to tumors for breast cancer precision medicine: from tumor-targeting small-molecule discovery to targeted nanodrug delivery

Precision medicine emphasizes patient-specific formulation for treatment of diseases, especially cancer. However, in targeted cancer treatment, because the expression level of tumor receptors in each patient varies even for the same type of cancer, the ligand/receptor-mediated approach does not seem promising for precision medicine. In this work, we demonstrated our strategy of using a phage display technique for breast cancer precision medicine. Using in vivo biopanning, we first selected an MCF-7 breast tumor-targeting peptide, then tested the effectiveness of the as-selected peptide in tumor homing and finally conjugated the peptide to a model photothermal drug, namely, gold nanorods, to achieve enhanced cancer killing efficacy. The peptides identified by the phage display technique can guide the drug to the tumors without the need to know the exact receptors on the tumor. This approach requires significantly less effort to explore patient-specific targeting molecules for precision medicine.

Autonomous self-navigating drug-delivery vehicles: from science fiction to reality

Low efficacy of targeted nanomedicines in biological experiments enforced us to challenge the traditional concept of drug targeting and suggest a paradigm of ‘addressed self-navigating drug-delivery vehicles,’ in which affinity selection of targeting peptides and vasculature-directed in vivo phage screening is replaced by the migration selection, which explores ability of ‘promiscuous’ phages and their proteins to migrate through the tumor-surrounding cellular barriers, using a ‘hub and spoke’ delivery strategy, and penetrate into the tumor affecting the diverse tumor cell population. The ‘self-navigating’ drug-delivery paradigm can be used as a theoretical and technical platform in design of a novel generation of molecular medications and imaging probes for precise and personal medicine.

[Formula: see text]

A Triphenylphosphonium-Functionalized Mitochondriotropic Nanocarrier for Efficient Co-Delivery of Doxorubicin and Chloroquine and Enhanced Antineoplastic Activity

Drug delivery systems that target subcellular organelles and, in particular, mitochondria are considered to have great potential in treating disorders that are associated with mitochondrial dysfunction, including cancer or neurodegenerative diseases. To this end, a novel hyperbranched mitochondriotropic nanocarrier was developed for the efficient co-delivery of two different (both in chemical and pharmacological terms) bioactive compounds. The carrier is based on hyperbranched poly(ethyleneimine) functionalized with triphenylphosphonium groups that forms ~100 nm diameter nanoparticles in aqueous media and can encapsulate doxorubicin (DOX), a well-known anti-cancer drug, and chloroquine (CQ), a known chemosensitizer with arising potential in anticancer medication. The anticancer activity of this system against two aggressive DOX-resistant human prostate adenocarcinoma cell lines and in in vivo animal studies was assessed. The co-administration of encapsulated DOX and CQ leads to improved cell proliferation inhibition at extremely low DOX concentrations (0.25 μΜ). In vivo experiments against DU145 human prostate cancer cells grafted on immunodeficient mice resulted in tumor growth arrest during the three-week administration period and no pervasive side effects. The findings put forward the potential of such targeted low dose combination treatments as a therapeutic scheme with minimal adverse effects.

Design of pH-sensitive peptides from natural antimicrobial peptides for enhancing polyethylenimine-mediated gene transfection

BACKGROUND

Poor endosomal release is a major barrier of polyplex-mediated gene transfection. Antimicrobial peptides (AMPs) are commonly used to improve polyethylenimine (PEI)-mediated gene transfection by increasing endosomal release. In the present study, we designed novel pH-sensitive peptides that highly enhance transfection efficiency compared to their parent peptides.

METHODS

Two analogues of melittin (Mel) and RV-23 (RV) were synthesized by replacing the positively-charged residues in their sequences with glutamic acid residues. The pH-sensitive lysis ability of the peptides, the effect of the peptides on physicochemical characteristics, the intracellular trafficking, the transfection efficiency, and the cytotoxicity of the polyplexes were determined.

RESULTS

The acidic peptides showed pH-sensitive lytic activity. The hemolytic activity of acidic peptides at pH 5.0 was higher than that at pH 7.4. The incorporation of acidic peptides did not affect the DNA binding ability of PEI but affected the physicochemical characteristics of the PEI/DNA polyplexes, which may be beneficial for endosomal release and gene transfection. The incorporation of acidic peptides into PEI/DNA polyplexes enhanced the PEI-mediated transfection efficiency corresponding to up to 42-fold higher luciferase activity compared to that of PEI alone.

CONCLUSIONS

The results of the present study indicate that replacement of positively-charged residues with glutamic acid residues in the AMP sequence yields pH-sensitive peptides, which enhance the transfection efficiency of PEI/DNA polyplexes in various cell lines.

Engineering chemically modified viruses for prostate cancer cell recognition

Specific detection of circulating tumor cells and characterization of their aggressiveness could improve cancer diagnostics and treatment. Metastasis results from such tumor cells, and causes the majority of cancer deaths. Chemically modified viruses could provide an inexpensive and efficient approach to detect tumor cells and quantitate their cell surface biomarkers. However, non-specific adhesion between the cell surface receptors and the virus surface presents a challenge. This report describes wrapping the virus surface with different PEG architectures, including as fusions to oligolysine, linkers, spacers and scaffolded ligands. The reported PEG wrappers can reduce by >75% the non-specific adhesion of phage to cell surfaces. Dynamic light scattering verified the non-covalent attachment by the reported wrappers as increased sizes of the virus particles. Further modifications resulted in specific detection of prostate cancer cells expressing PSMA, a key prostate cancer biomarker. The approach allowed quantification of PSMA levels on the cell surface, and could distinguish more aggressive forms of the disease.

Selection of Lung Cancer-Specific Landscape Phage for Targeted Drug Delivery

Cancer cell-specific diagnostic or therapeutic tools are commonly believed to significantly increase the success rate of cancer diagnosis and targeted therapies. To extend the repertoire of available cancer cell-specific phage fusion proteins and study their efficacy as navigating moieties, we used two landscape phage display libraries f8/8 and f8/9 displaying an 8- or 9-mer random peptide fusion to identify a panel of novel peptide families that are specific to Calu-3 cells. Using a phage capture assay, we showed that two of the selected phage clones, ANGRPSMT and VNGRAEAP (phage and their recombinant proteins are named by the sequence of the fusion peptide), are selective for the Calu-3 cell line in comparison to phenotypically normal lung epithelial cells and distribute into unique subcellular fractions.

Synthesis of amine-polyglycidol functionalised Fe3O4@SiO2nanocomposites for magnetic hyperthermia, pH-responsive drug delivery, and bioimaging applications

We report the biocompatible Fe₃O₄@SiO₂@APG-F nanocomposite for drug delivery and hyperthermia applications. The Fe₃O₄@SiO₂@APG-F nanocomposite could serve as a good hyperthermia agent, drug delivery carrier, and fluorescent contrast agent.

Beyond phage display: non-traditional applications of the filamentous bacteriophage as a vaccine carrier, therapeutic biologic, and bioconjugation scaffold

For the past 25 years, phage display technology has been an invaluable tool for studies of protein-protein interactions. However, the inherent biological, biochemical, and biophysical properties of filamentous bacteriophage, as well as the ease of its genetic manipulation, also make it an attractive platform outside the traditional phage display canon. This review will focus on the unique properties of the filamentous bacteriophage and highlight its diverse applications in current research. Particular emphases are placed on: (i) the advantages of the phage as a vaccine carrier, including its high immunogenicity, relative antigenic simplicity and ability to activate a range of immune responses, (ii) the phage's potential as a prophylactic and therapeutic agent for infectious and chronic diseases, (iii) the regularity of the virion major coat protein lattice, which enables a variety of bioconjugation and surface chemistry applications, particularly in nanomaterials, and (iv) the phage's large population sizes and fast generation times, which make it an excellent model system for directed protein evolution. Despite their ubiquity in the biosphere, metagenomics work is just beginning to explore the ecology of filamentous and non-filamentous phage, and their role in the evolution of bacterial populations. Thus, the filamentous phage represents a robust, inexpensive, and versatile microorganism whose bioengineering applications continue to expand in new directions, although its limitations in some spheres impose obstacles to its widespread adoption and use.

Combinatorial synthesis and screening of cancer cell-specific nanomedicines targeted via phage fusion proteins

Active tumor targeting of nanomedicines has recently shown significant improvements in the therapeutic activity of currently existing drug delivery systems, such as liposomal doxorubicin (Doxil/Caelyx/Lipodox). Previously, we have shown that isolated pVIII major coat proteins of the fd-tet filamentous phage vector, containing cancer cell-specific peptide fusions at their N-terminus, can be used as active targeting ligands in a liposomal doxorubicin delivery system in vitro and in vivo. Here, we show a novel major coat protein isolation procedure in 2-propanol that allows spontaneous incorporation of the hydrophobic protein core into preformed liposomal doxorubicin with minimal damage or drug loss while still retaining the targeting ligand exposed for cell-specific targeting. Using a panel of 12 structurally unique ligands with specificity toward breast, lung, and/or pancreatic cancer, we showed the feasibility of pVIII major coat proteins to significantly increase the throughput of targeting ligand screening in a common nanomedicine core. Phage protein-modified Lipodox samples showed an average doxorubicin recovery of 82.8% across all samples with 100% of protein incorporation in the correct orientation (N-terminus exposed). Following cytotoxicity screening in a doxorubicin-sensitive breast cancer line (MCF-7), three major groups of ligands were identified. Ligands showing the most improved cytotoxicity included: DMPGTVLP, ANGRPSMT, VNGRAEAP, and ANDVYLD showing a 25-fold improvement (p < 0.05) in toxicity. Similarly DGQYLGSQ, ETYNQPYL, and GSSEQLYL ligands with specificity toward a doxorubicin-insensitive pancreatic cancer line (PANC-1) showed significant increases in toxicity (2-fold; p < 0.05). Thus, we demonstrated proof-of-concept that pVIII major coat proteins can be screened in significantly higher throughput to identify novel ligands displaying improved therapeutic activity in a desired cancer phenotype.

Diseases originate and terminate by genes: unraveling nonviral gene delivery

The world is driving in to the era of transformation of chemical therapeutic molecules to biological genetic material therapeutics, and that is where the biological drugs especially "genes" come into existence. These genes worked as "magical bullets" to specifically silence faulty genes responsible for progression of diseases. Viral gene delivery research is far ahead of nonviral gene delivery technique. However, with more advancement in polymer science, new ways are opening for better and efficient nonviral gene delivery. But efficient delivery method is always considered as a bottleneck for gene delivery as success of which will decide the fate of gene in cells. During the past decade, it became evident that extracellular as well as intracellular barriers compromise the transfection efficiency of nonviral vectors. The challenge for gene therapy research is to pinpoint the rate-limiting steps in this complex process and implement strategies to overcome the biological physiochemical and metabolic barriers encountered during targeting. The synergy between studies that investigate the mechanism of breaking in and breaking out of nonviral gene delivery carrier through various extracellular and intracellular barriers with desired characteristics will enable the rational design of vehicles and revolutionize the treatment of various diseases.

Paclitaxel-loaded PEG-PE-based micellar nanopreparations targeted with tumor-specific landscape phage fusion protein enhance apoptosis and efficiently reduce tumors

In an effort to improve the therapeutic index of cancer chemotherapy, we developed an advanced nanopreparation based on the combination of landscape phage display to obtain new targeting ligands with micellar nanoparticles for tumor targeting of water-insoluble neoplastic agents. With paclitaxel as a drug, this self-assembled nanopreparation composed of MCF-7-specific phage protein and polyethylene glycol-phosphatidylethanolamine (PEG-PE) micelles showed selective toxicity to target cancer cells rather than nontarget, non cancer cells in vitro. In vivo, the targeted phage micelles triggered a dramatic tumor reduction and extensive necrosis as a result of improved tumor delivery of paclitaxel. The enhanced anticancer effect was also verified by an enhanced apoptosis and reduced tumor cell proliferation following the treatment with the targeted micellar paclitaxel both in vitro and in vivo. The absence of hepatotoxicity and pathologic changes in tissue sections of vital organs, together with maintenance of overall health of mice following the treatment, further support its translational potential as an effective and safe chemotherapy for improved breast cancer treatment.

pH-responsive magnetic core-shell nanocomposites for drug delivery

Polymer-modified nanoparticles, which can load anticancer drugs such as doxorubicin (DOX), showing the release in response to a specific trigger, have been paid much attention in cancer therapy. In our study, a pH-sensitive drug-delivery system consisting of Fe3O4@mSiO2 core-shell nanocomposite (about 65 nm) and a β-thiopropionate-poly(ethylene glycol) "gatekeeper" (P2) has been successfully synthesized as a drug carrier (Fe3O4@mSiO2@P2). Because of the hydrolysis of the β-thiopropionate linker under mildly acidic conditions, Fe3O4@mSiO2@P2 shows a pH-sensitive release performance based on the slight difference between a tumor (weakly acid) and normal tissue (weakly alkaline). And before reaching the tumor site, the drug-delivery system shows good drug retention. Notably, the nanocomposites are quickly taken up by HeLa cells due to their small particle size and the poly(ethylene glycol) modification, which is significant for increasing the drug efficiency as well as the cancer therapy of the drug vehicles. The excellent biocompatibility and selective release performance of the nanocomposites combined with the magnetic targeted ability are expected to be promising in the potential application of cancer treatment.

A display of pH-sensitive fusogenic GALA peptide facilitates endosomal escape from a Bio-nanocapsule via an endocytic uptake pathway

Background

An affibody-displaying bio-nanocapsule (Z_HER2-BNC) with a hepatocyte specificity derived from hepatitis B virus (HBV) was converted into an affibody, Z_HER2, that recognizes HER2 receptors. This affibody was previously reported to be the result of the endocytosis-dependent specific uptake of proteins and siRNA into target cancer cells. To assist the endosomal escape of inclusions, a helper lipid with pH-sensitive fusogenic ability (1,2-dioleoyl-sn-glycero-3-phos phoethanolamine; DOPE) was conjugated with a Z_HER2-BNC.

Findings

In this study, we displayed a pH-sensitive fusogenic GALA peptide on the surface of a particle in order to confer the ability of endosomal escape to a Z_HER2-BNC. A GALA-displaying Z_HER2-BNC purified from yeast uneventfully formed a particle structure. Furthermore, endosomal escape of the particle was facilitated after endocytic uptake and release of the inclusions to the cytoplasm without the cell toxicity.

Conclusion

The genetic fusion of a GALA peptide to the virus-like particle confers the ability of endosomal escape.

Phage protein-targeted cancer nanomedicines

Nanoencapsulation of anticancer drugs improves their therapeutic indices by virtue of the enhanced permeation and retention effect which achieves passive targeting of nanoparticles in tumors. This effect can be significantly enhanced by active targeting of nanovehicles to tumors. Numerous ligands have been proposed and used in various studies with peptides being considered attractive alternatives to antibodies. This is further reinforced by the availability of peptide phage display libraries which offer an unlimited reservoir of target-specific probes. In particular landscape phages with multivalent display of target-specific peptides which enable the phage particle itself to become a nanoplatform creates a paradigm for high throughput selection of nanoprobes setting the stage for personalized cancer management. Despite its promise, this conjugate of combinatorial chemistry and nanotechnology has not made a significant clinical impact in cancer management due to a lack of using robust processes that facilitate scale-up and manufacturing. To this end we proposed the use of phage fusion protein as the navigating modules of novel targeted nanomedicine platforms which are described in this review.

Enhanced tumor delivery and antitumor activity in vivo of liposomal doxorubicin modified with MCF-7-specific phage fusion protein

A novel strategy to improve the therapeutic index of chemotherapy has been developed by the integration of nanotechnology with phage technique. The objective of this study was to combine phage display, identifying tumor-targeting ligands, with a liposomal nanocarrier for targeted delivery of doxorubicin. Following the proof of concept in cell-based experiments, this study focused on in vivo assessment of antitumor activity and potential side-effects of phage fusion protein-modified liposomal doxorubicin. MCF-7-targeted phage-Doxil treatments led to greater tumor remission and faster onset of antitumor activity than the treatments with non-targeted formulations. The enhanced anticancer effect induced by the targeted phage-Doxil correlated with an improved tumor accumulation of doxorubicin. Tumor sections consistently revealed enhanced apoptosis, reduced proliferation activity and extensive necrosis. Phage-Doxil-treated mice did not show any sign of hepatotoxicity and maintained overall health. Therefore, MCF-7-targeted phage-Doxil seems to be an active and tolerable chemotherapy for breast cancer treatment.

FROM THE CLINICAL EDITOR

The authors of this study successfully combined phage display with a liposomal nanocarrier for targeted delivery of doxorubicin using MCF-7-targeted phage-Doxil nanocarriers in a rodent model. The method demonstrated improved efficiency and reduced hepatotoxicity, paving the way to future clinical trials addressing breast cancer.

Spatial-temporal event adaptive characteristics of nanocarrier drug delivery in cancer therapy

In cancer therapy, drug delivery is a complex process that aims to transit the cargo to the destination with as little damage to the normal tissue as possible. In the last decade, tremendous development and research on nanomedicine have been exploring an ideal system with efficient drug transportation and release property. For this end, series of barriers need to be circumvented by nanomedicine, including systemic barriers, such as biosurface adsorption, phagocytic clearance, bloodstream washing, interstitial pressure, degradation, as well as intracellular barriers, such as cell membrane reorganization and internalization, endo/lysosomal escape, cytosolic or subcellular localization. Rather than being random, these barriers follow a specific spatial-temporal sequence. Therefore, the nanocarriers have to be endowed with characteristics that are adaptive to particular biological milieu on systemic and intracellular levels. To this end, we reviewed the correlations between the spatial-temporal sequences of drug delivery and nanocarrier characteristics in cancer therapy, as well as strategies to achieve efficient drug delivery upon both systemic and intracellular levels.

Peptide targeted lipid nanoparticles for anticancer drug delivery

Encapsulating anticancer drugs in nanoparticles has proven to be an effective mechanism to alter the pharmacokinetic and pharmacodynamic profiles of the drugs, leading to clinically useful cancer therapeutics like Doxil and DaunoXome. Underdeveloped tumor vasculature and lymphatics allow these first-generation nanoparticles to passively accumulate within the tumor, but work to create the next-generation nanoparticles that actively participate in the tumor targeting process is underway. Lipid nanoparticles functionalized with targeting peptides are among the most often studied. The goal of this article is to review the recently published literature of targeted nanoparticles to highlight successful designs that improved in vivo tumor therapy, and to discuss the current challenges of designing these nanoparticles for effective in vivo performance.

Landscape phages and their fusion proteins targeted to breast cancer cells

Breast cancer is a leading cause of death among women in the USA. The efficacy of existing anticancer therapeutics can be improved by targeting them through conjugation with ligands binding to cellular receptors. Recently, we developed a novel drug targeting strategy based on the use of pre-selected cancer-specific 'fusion pVIII proteins' (fpVIII), as targeting ligands. To study the efficiency of this approach in animal models, we developed a panel of breast cancer cell-binding phages as a source of targeted fpVIIIs. Two landscape phage peptide libraries (8-mer f8/8 and 9-mer f8/9) were screened to isolate 132 phage variants that recognize breast carcinoma cells MCF-7 and ZR-75-1 and internalize into the cells. When tested for their interaction with the breast cancer cells in comparison with liver cancer cells HepG2, human mammary cells MCF-10A cells and serum, 16 of the phage probes selectively interacted with the breast cancer cells whereas 32 bound both breast and liver cancer cells. The most prominent cancer-specific phage DMPGTVLP, demonstrating sub-nanomolar Kd in interaction with target cells, was used for affinity chromatography of cellular membrane molecules to reveal its potential binding receptor. The isolated protein was identified by direct sequencing as cellular surface nucleolin. This conclusion was confirmed by inhibition of the phage-cell interaction with nucleolin antibodies. Other prominent phage binders VPTDTDYS, VEEGGYIAA, and DWRGDSMDS demonstrate consensus motifs common to previously identified cancer-specific peptides. Isolated phage proteins exhibit inherent binding specificity towards cancer cells, demonstrating the functional activity of the selected fused peptides. The selected phages, their peptide inserts and intact fusion proteins can serve as promising ligands for the development of targeted nanomedicines and their study in model mice with xenograft of human cells MCF-7 and ZR-75-1.

Optimization of Landscape Phage Fusion Protein-Modified Polymeric PEG-PE Micelles for Improved Breast Cancer Cell Targeting

Amphiphilic landscape phage fusion proteins with high affinity and selectivity towards breast cancer MCF-7 (Michigan Cancer Foundation-7) cells self-assemble with polymeric PEG-PE conjugates to form mixed micelles (phage-micelles) capable of cancer cell-targeted delivery of poorly-soluble drugs. While the PEG corona provides the stability and longevity to the micelles, its presence is a potential steric difficulties for the interaction of phage fusion protein with cell surface targets. We attempted to address this problem by controlling the length of the PEG block and the phage fusion protein quantity, selecting the optimal ones to produce a reasonable retention of the targeting affinity and selectivity of the MCF-7-specific phage fusion protein. Three PEG-PE conjugates with different PEG lengths were used to construct phage- and plain-micelles, followed by FACS analysis of the effect of the PEG length on their binding affinity and selectivity towards target MCF-7 cells using either a MCF-7 cell monoculture or a cell co-culture model composed of target cancer MCF-7 cells and non-target, non-cancer C166 cells expressing GFP (Green Fluorescent Protein). Both, the length of PEG and quantity of phage fusion protein had a profound impact on the targetability of the phage-micelles. Phage-micelles prepared with PEG_2k-PE achieved a desirable binding affinity and selectivity. Incorporation of a minimal concentration of phage protein, up to 0.5%, produced maximal targeting efficiency towards MCF-7 cells. Overall, phage-micelles with PEG_2k-PE and 0.5% of phage protein represent the optimal formulation for targeting towards breast cancer cells.

On the mechanism of targeting of phage fusion protein-modified nanocarriers: only the binding peptide sequence matters

The integration of pharmaceutical nanocarriers with phage display techniques is emerging as a new paradigm for targeted cancer nanomedicines. We explored the direct use of landscape phage fusion proteins for the self-assembly of phage-derived binding peptides to liposomes for cancer cell targeting. The primary purpose of this study was to elucidate the targeting mechanism with a particular emphasis on the relative contributions of the two motifs that make up the landscape phage fusion protein (a binding peptide and the phage pVIII coat protein) to the targeting efficiency. Using transmission electron microscopy and dynamic light scattering, we confirmed the formation of phage-liposomes. Using FACS analysis, fluorescence microscopy, and fluorescence photospectrometry, we found that liposomes modified with MCF-7-specific phage fusion proteins (MCF-7 binding peptide, DMPGTVLP, fused to the phage PVIII coat protein) provided a strong and specific association with target MCF-7 cancer cells but not with cocultured, nontarget cells including C166-GFP and NIH3T3. The substitution for the binding peptide fused to phage pVIII coat protein abolished the targeting specificity. The addition of free binding peptide, DMPGTVLP, competitively inhibited the interaction of MCF-7-specific phage-liposomes with target MCF-7 cells but showed no reduction of MCF-7-associated plain liposomes. The proteolysis of the binding peptide reduced MCF-7 cell-associated phage-liposomes in a proteinase K (PK) concentration-dependent manner with no effect on the binding of plain liposomes to MCF-7 cells. Overall, only the binding peptide motif was involved in the targeting specificity of phage-liposomes. The presence of phage pVIII coat protein did not interfere with the targeting efficiency.

Design of multifunctional non-viral gene vectors to overcome physiological barriers: dilemmas and strategies

Gene-based therapeutics hold great promise for medical advancement and have been used to treat various human diseases with mixed success. However, their therapeutic application in vivo is limited due largely to several physiological barriers. The design of non-viral gene vectors with the ability to overcome delivery obstacles is currently under extensive investigation. These efforts have placed an emphasis on the development of multifunctional vectors able to execute multiple tasks to simultaneously overcome both extracellular and intracellular obstacles. However, the assembly of these different functionalities into a single system to create multifunctional gene vectors faces many conflicts that largely limit the safe and efficient application of lipoplexes and polyplexes in a systemic delivery. In the review, we have described the dilemmas inherent in the design of a viable, non-viral gene vector equipped with multiple functionalities. The strategies directed towards individual delivery barriers are first summarized, followed by a focus on the design of so-called smart multifunctional vectors with the capability to overcome the delivery difficulties of gene medicines, including the so-called the "polycation dilemma", the "PEG dilemma" and the "package and release dilemma".

Delivery of siRNA into breast cancer cells via phage fusion protein-targeted liposomes

Efficacy of siRNAs as potential anticancer therapeutics can be increased by their targeted delivery into cancer cells via tumor-specific ligands. Phage display offers a unique approach to identify highly specific and selective ligands that can deliver nanocarriers to the site of disease. In this study, we proved a novel approach for intracellular delivery of siRNAs into breast cancer cells through their encapsulation into liposomes targeted to the tumor cells with preselected intact phage proteins. The targeted siRNA liposomes were obtained by a fusion of two parental liposomes containing spontaneously inserted siRNA and fusion phage proteins. The presence of pVIII coat protein fused to a MCF-7 cell-targeting peptide DMPGTVLP in the liposomes was confirmed by Western blotting. The novel phage-targeted siRNA-nanopharmaceuticals demonstrate significant down-regulation of PRDM14 gene expression and PRDM14 protein synthesis in the target MCF-7 cells. This approach offers the potential for development of new anticancer siRNA-based targeted nanomedicines.

FROM THE CLINICAL EDITOR

In this study, the authors report a novel approach for targeted intracellular delivery of siRNAs into breast cancer cells through encapsulation into liposomes targeted to the tumor cells with preselected intact phage proteins.

Paclitaxel-loaded polymeric micelles modified with MCF-7 cell-specific phage protein: enhanced binding to target cancer cells and increased cytotoxicity

Polymeric micelles are used as pharmaceutical carriers to increase solubility and bioavailability of poorly water-soluble drugs. Different ligands are used to prepare targeted polymeric micelles. Earlier, we developed the method for use of specific landscape phage fusion coat proteins as targeted delivery ligands and demonstrated the efficiency of this approach with doxorubicin-loaded PEGylated liposomes. Here, we describe a MCF-7 cell-specific micellar formulation self-assembled from the mixture of the micelle-forming amphiphilic polyethylene glycol-phosphatidylethanolamine (PEG-PE) conjugate, MCF-7-specific landscape phage fusion coat protein, and the hydrophobic drug paclitaxel. These micelles demonstrated a very low cmc value and specific binding to target cells. Using an in vitro coculture model, FACS analysis, and fluorescence microscopy we showed that MCF-7 targeted phage-micelles preferentially bound to target cells compared to nontarget cells. As a result, targeted paclitaxel-loaded phage-micelles demonstrated a significantly higher cytotoxicity toward target MCF-7 cells than free drug or nontargeted micelle formulations, but failed to show such a differential toxicity toward nontarget C166 cells. Overall, cancer cell-specific phage proteins identified from phage display peptide libraries can serve as targeting ligands ("substitute antibody") for polymeric micelle-based pharmaceutical preparations.