Direct cytosolic siRNA delivery by reconstituted high density lipoprotein for target-specific therapy of tumor angiogenesis

Biomimetic exosomal vesicles loaded with siRNA improves antitumor immune responses by inhibiting the secretion of tumor-derived exosome PD-L1

Tumor-derived exosome PD-L1 exhaustsTcells and permits tumor cells to evade immune surveillance; thus, the inhibition of ExoPD-L1 secretion can significantly enhance the clinical efficacy of PD-L1 antibody. In this study, we combined exosome membrane, apoA1 and phospholipid into biomimetic exosome vesicles (apoA1-bExo) which were then incubated with cholesterol modified siRNA to generate apoA1-bExo containing siRNA (apoA1-bExo/siRNA). Thepreparedvesicleswere uniformandsphericalin size and could be loaded effectively with siRNA to protect from nuclease degradation. Compared with bExo/siRNA, apoA1-bExo/siRNA showed stronger tumor targeting, tissue permeability, intracellular accumulation efficiency and antitumor efficiency. A portion of apoA1-bExo/siRNA transport siRNA occurred through the endosome-Golgi-ER pathway similar to bExo/siRNA, but mostly occurred directly through selective uptake pathways mediated by the SR-B1 receptor. apoA1-bExo/siRNA successfully achieved silencing efficiency at the transcription and protein levels (96.78 % and 94.07 %, respectively) and reduced the secretion of ExoPD-L1 from HepG2 cells to 15.92 % of that in the PBS group, thus enhancing the killing activity of co-cultured T cells on HepG2 cells. In addition, relevant pharmacodynamic indices were positively correlated with delivery efficiency and the modification of apoA1 could significantly enhance the intracellular accumulation of siRNA, thus exhibiting stronger activity than bExo/siRNA. Moreover, in addition to curing mice of their implanted tumors, blocking ExoPD-L1 secretion in combination with αPD-1 promoted the infiltration of durable antitumor hCD8+ T cells and hCD45+ T cells into tumor in a immune system-tumor dual humanized mice.

Nanodiscoidal Nucleic Acids for Gene Regulation

Therapeutic nucleic acids represent a powerful class of drug molecules to control gene expression and protein synthesis. A major challenge in this field is that soluble oligonucleotides have limited serum stability, and the majority of nucleic acids that enter the cells are trapped within endosomes. Delivery efficiency can be improved using lipid scaffolds. One such example is the nanodisc (ND), a self-assembled nanostructure composed of phospholipids and peptides and modeled after high density lipoproteins (HDLs). Herein, we describe the development of the nanodiscoidal nucleic acid (NNA) which is a ND covalently modified with nucleic acids on the top and bottom lipid faces as well as the lateral peptide belt. The 13 nm ND was doped with thiolated phospholipids and thiol-containing peptides and coupled in a one-pot reaction with oligonucleotides to achieve ∼30 DNA/NNA nucleic acid density. NNAs showed superior nuclease resistance and enhanced cellular uptake that was mediated through the scavenger receptor B1. Time-dependent Förster resonance energy transfer (FRET) analysis of internalized NNA confirmed that NNAs display increased stability. NNAs modified with clinically validated antisense oligonucleotides (ASOs) that target hypoxia inducible factor 1-α (HIF-1-α) mRNA showed enhanced activity compared with that of the soluble DNA across multiple cell lines as well as a 3D cancer spheroid model. Lastly, in vivo experiments show that ASO-modified NNAs are primarily localized into livers and kidneys, and NNAs were potent in downregulating HIF-1-α using 5-fold lower doses than previously reported. Collectively, our results highlight the therapeutic potential for NNAs.

Advanced Strategies for Overcoming Endosomal/Lysosomal Barrier in Nanodrug Delivery

Nanocarriers have therapeutic potential to facilitate drug delivery, including biological agents, small-molecule drugs, and nucleic acids. However, their efficiency is limited by several factors; among which, endosomal/lysosomal degradation after endocytosis is the most important. This review summarizes advanced strategies for overcoming endosomal/lysosomal barriers to efficient nanodrug delivery based on the perspective of cellular uptake and intracellular transport mechanisms. These strategies include promoting endosomal/lysosomal escape, using non-endocytic methods of delivery to directly cross the cell membrane to evade endosomes/lysosomes and making a detour pathway to evade endosomes/lysosomes. On the basis of the findings of this review, we proposed several promising strategies for overcoming endosomal/lysosomal barriers through the smarter and more efficient design of nanodrug delivery systems for future clinical applications.

Nucleic acid drug vectors for diagnosis and treatment of brain diseases

Nucleic acid drugs have the advantages of rich target selection, simple in design, good and enduring effect. They have been demonstrated to have irreplaceable superiority in brain disease treatment, while vectors are a decisive factor in therapeutic efficacy. Strict physiological barriers, such as degradation and clearance in circulation, blood-brain barrier, cellular uptake, endosome/lysosome barriers, release, obstruct the delivery of nucleic acid drugs to the brain by the vectors. Nucleic acid drugs against a single target are inefficient in treating brain diseases of complex pathogenesis. Differences between individual patients lead to severe uncertainties in brain disease treatment with nucleic acid drugs. In this Review, we briefly summarize the classification of nucleic acid drugs. Next, we discuss physiological barriers during drug delivery and universal coping strategies and introduce the application methods of these universal strategies to nucleic acid drug vectors. Subsequently, we explore nucleic acid drug-based multidrug regimens for the combination treatment of brain diseases and the construction of the corresponding vectors. In the following, we address the feasibility of patient stratification and personalized therapy through diagnostic information from medical imaging and the manner of introducing contrast agents into vectors. Finally, we take a perspective on the future feasibility and remaining challenges of vector-based integrated diagnosis and gene therapy for brain diseases.

Recent advances in nanotechnology approaches for non-viral gene therapy

Gene therapy has shown great potential in the treatment of many diseases by downregulating the expression of certain genes. The development of gene vectors as a vehicle for gene therapy has greatly facilitated the widespread clinical application of nucleic acid materials (DNA, mRNA, siRNA, and miRNA). Currently, both viral and non-viral vectors are used as delivery systems of nucleic acid materials for gene therapy. However, viral vector-based gene therapy has several limitations, including immunogenicity and carcinogenesis caused by the exogenous viral vectors. To address these issues, non-viral nanocarrier-based gene therapy has been explored for superior performance with enhanced gene stability, high treatment efficiency, improved tumor-targeting, and better biocompatibility. In this review, we discuss various non-viral vector-mediated gene therapy approaches using multifunctional biodegradable or non-biodegradable nanocarriers, including polymer-based nanoparticles, lipid-based nanoparticles, carbon nanotubes, gold nanoparticles (AuNPs), quantum dots (QDs), silica nanoparticles, metal-based nanoparticles and two-dimensional nanocarriers. Various strategies to construct non-viral nanocarriers based on their delivery efficiency of targeted genes will be introduced. Subsequently, we discuss the cellular uptake pathways of non-viral nanocarriers. In addition, multifunctional gene therapy based on non-viral nanocarriers is summarized, in which the gene therapy can be combined with other treatments, such as photothermal therapy (PTT), photodynamic therapy (PDT), immunotherapy and chemotherapy. We also provide a comprehensive discussion of the biological toxicity and safety of non-viral vector-based gene therapy. Finally, the present limitations and challenges of non-viral nanocarriers for gene therapy in future clinical research are discussed, to promote wider clinical applications of non-viral vector-based gene therapy.

Biomimetic nanomaterial-facilitated oxygen generation strategies for enhancing tumour treatment outcomes

Hypoxia, as a typical hallmark of the tumour microenvironment (TME), has been verified to exist in most malignancies and greatly hinders the outcome of tumour treatments, including chemotherapy, photodynamic therapy, radiotherapy, and immunotherapy. Various approaches to alleviate tumour hypoxia have been reported. Among them, biomimetic nanomaterial-facilitated tumour oxygenation strategies, based on the engagement of human endogenous proteins, red blood cells, the cell membrane, and catalase, are the most impressive due to their excellent tumour active-targeting ability and superior tumour-selective capability, which, however, have not yet been systematically reviewed. Herein, we are ready to describe the current progress in biomimetic nanomaterial-facilitated tumour oxygenation strategies and corresponding improvements in tumour treatment outputs. In this review, the underlying mechanism behind the superior effect of these biomimetic nanomaterials, compared with other materials, on alleviating the hypoxic TME is highlighted. Additionally, the ongoing problems and potential solutions are also discussed.

Lipoprotein-Inspired Nanoscavenger for the Three-Pronged Modulation of Microglia-Derived Neuroinflammation in Alzheimer's Disease Therapy

The inflammatory dysfunction of microglia from excess amyloid-β peptide (Aβ) disposal is an overlooked but pathogenic event in Alzheimer's disease (AD). Here, we exploit a native high-density lipoprotein (HDL)-inspired nanoscavenger (pHDL/Cur-siBACE1) that combines the trinity of phosphatidic acid-functionalized HDL (pHDL), curcumin (Cur), and β-site APP cleavage enzyme 1 targeted siRNA (siBACE1) to modulate microglial dysfunction. By mimicking the natural lipoprotein transport route, pHDL can penetrate the blood-brain barrier and sequentially target Aβ plaque, where Aβ catabolism is accelerated without microglial dysfunction. The benefit results are from a three-pronged modulation strategy, including promoted Aβ clearance with an antibody-like Aβ binding affinity, normalized microglial dysfunction by blocking the NF-κB pathway, and reduced Aβ production by gene silence (44%). After treatment, the memory deficit and neuroinflammation of APPswe/PSEN 1dE9 mice are reversed. Collectively, this study highlights the double-edged sword role of microglia and provides a promising tactic for modulating microglial dysfunction in AD treatment.

Modulating intracellular pathways to improve non-viral delivery of RNA therapeutics

RNA therapeutics (e.g. siRNA, oligonucleotides, mRNA, etc.) show great potential for the treatment of a myriad of diseases. However, to reach their site of action in the cytosol or nucleus of target cells, multiple intra- and extracellular barriers have to be surmounted. Several non-viral delivery systems, such as nanoparticles and conjugates, have been successfully developed to meet this requirement. Unfortunately, despite these clear advances, state-of-the-art delivery agents still suffer from relatively low intracellular delivery efficiencies. Notably, our current understanding of the intracellular delivery process is largely oversimplified. Gaining mechanistic insight into how RNA formulations are processed by cells will fuel rational design of the next generation of delivery carriers. In addition, identifying which intracellular pathways contribute to productive RNA delivery could provide opportunities to boost the delivery performance of existing nanoformulations. In this review, we discuss both established as well as emerging techniques that can be used to assess the impact of different intracellular barriers on RNA transfection performance. Next, we highlight how several modulators, including small molecules but also genetic perturbation technologies, can boost RNA delivery by intervening at differing stages of the intracellular delivery process, such as cellular uptake, intracellular trafficking, endosomal escape, autophagy and exocytosis.

NIR Light-Triggered Chemo-Phototherapy by ICG Functionalized MWNTs for Synergistic Tumor-Targeted Delivery

The combinational application of photothermal therapy (PTT), chemotherapy, and nanotechnology is a booming therapeutic strategy for cancer treatment. Multi-walled carbon nanotube (MWNT) is often utilized as drug carrier in biomedical fields with excellent photothermal properties, and indocyanine green (ICG) is a near-infrared (NIR) dye approved by FDA. In addition, ICG is also a photothermal agent that can strongly absorb light energy for tumor ablation. Herein, we explored a synergistic strategy by connecting MWNT and a kind of ICG derivate ICG-NH₂ through hyaluronic acid (HA) that possesses CD44 receptor targeting ability, which largely enhanced the PTT effect of both MWNT and ICG-NH₂. To realize the synergistic therapeutic effect of chemotherapy and phototherapy, doxorubicin (DOX) was attached on the wall of MWNT via π-π interaction to obtain the final MWNT-HA-ICG/DOX nanocomplexes. Both in vitro and in vivo experiments verified the great therapeutic efficacy of MWNT-HA-ICG/DOX nanocomplexes, which was characterized by improved photothermal performance, strengthened cytotoxicity, and elevated tumor growth inhibition based on MCF-7 tumor models. Therefore, this synergistic strategy we report here might offer a new idea with promising application prospect for cancer treatment.

Combination of Nanomaterials in Cell-Based Drug Delivery Systems for Cancer Treatment

Cell-based drug delivery systems have shown tremendous advantages in cancer treatment due to their distinctive properties. For instance, delivery of therapeutics using tumor-tropic cells like neutrophils, lymphocytes and mesenchymal stem cells can achieve specific tumor targeting due to the "Trojan Horse" effect. Other circulatory cells like erythrocytes and platelets can greatly improve the circulation time of nanoparticles due to their innate long circulation property. Adipocytes, especially cancer-associated adipocytes, play key roles in tumor development and metabolism, therefore, adipocytes are regarded as promising bio-derived nanoplatforms for anticancer targeted drug delivery. Nanomaterials are important participants in cell-based drug delivery because of their unique physicochemical characteristics. Therefore, the integration of various nanomaterials with different cell types will endow the constructed delivery systems with many attractive properties due to the merits of both. In this review, a number of strategies based on nanomaterial-involved cell-mediated drug delivery systems for cancer treatment will be summarized. This review discusses how nanomaterials can be a benefit to cell-based therapies and how cell-derived carriers overcome the limitations of nanomaterials, which highlights recent advancements and specific biomedical applications based on nanomaterial-mediated, cell-based drug delivery systems.

Lipids and Lipid Derivatives for RNA Delivery

RNA-based therapeutics have shown great promise in treating a broad spectrum of diseases through various mechanisms including knockdown of pathological genes, expression of therapeutic proteins, and programmed gene editing. Due to the inherent instability and negative-charges of RNA molecules, RNA-based therapeutics can make the most use of delivery systems to overcome biological barriers and to release the RNA payload into the cytosol. Among different types of delivery systems, lipid-based RNA delivery systems, particularly lipid nanoparticles (LNPs), have been extensively studied due to their unique properties, such as simple chemical synthesis of lipid components, scalable manufacturing processes of LNPs, and wide packaging capability. LNPs represent the most widely used delivery systems for RNA-based therapeutics, as evidenced by the clinical approvals of three LNP-RNA formulations, patisiran, BNT162b2, and mRNA-1273. This review covers recent advances of lipids, lipid derivatives, and lipid-derived macromolecules used in RNA delivery over the past several decades. We focus mainly on their chemical structures, synthetic routes, characterization, formulation methods, and structure-activity relationships. We also briefly describe the current status of representative preclinical studies and clinical trials and highlight future opportunities and challenges.

High-density lipoproteins: A promising tool against cancer

High-density lipoproteins (HDL) are well known for their protective role against the development and progression of atherosclerosis. Atheroprotection is mainly due to the key role of HDL within the reverse cholesterol transport, and to their ability to exert a series of antioxidant and anti-inflammatory activities. Through the same mechanisms HDL could also affect cancer cell proliferation and tumor progression. Many types of cancers share common alterations of cellular metabolism, including lipid metabolism. In this context, not only fatty acids but also cholesterol and its metabolites play a key role. HDL were shown to reduce cancer cell content of cholesterol, overall rewiring cholesterol homeostasis. In addition, HDL reduce oxidative stress and the levels of pro-inflammatory molecules in cancer cells and in the tumor microenvironment (TME). Here, HDL can also help in reverting tumor immune escape and in inhibiting angiogenesis. Interestingly, HDL are good candidates for drug delivery, targeting antineoplastic agents to the tumor mass mainly through their binding to the scavenger receptor BI. Since they could affect cancer development and progression per se, HDL-based drug delivery systems may render cancer cells more sensitive to antitumor agents and reduce the development of drug resistance.

Design and evaluation of glutathione responsive glycosylated camptothecin nanosupramolecular prodrug

A novel tumor-targeted glutathione responsive Glycosylated-Camptothecin nanosupramolecular prodrug (CPT-GL NSp) was designed and fabricated via a disulfide bond. The effects of glycoligand with different polarities on solubility, self-assembly, stability, cellular uptake, and glutathione responsive cleaving were explored, and an optimal glycosylated ligand was selected for nanosupramolecular prodrug. It has been found that CPT-GL NSp exhibited higher drug loading than traditional nanoparticles. Among of which maltose modified NSp had the strongest anti-tumor effects than that of glucose and maltotriose. CPT-SS-Maltose had a similar anti-tumor ability to Irinotecan (IR), but the superior performance in solubility, hemolysis, and uptake of HepG2 cells.

Advanced and Innovative Nano-Systems for Anticancer Targeted Drug Delivery

The encapsulation of therapeutic agents into nano-based drug delivery system for cancer treatment has received considerable attention in recent years. Advancements in nanotechnology provide an opportunity for efficient delivery of anticancer drugs. The unique properties of nanoparticles not only allow cancer-specific drug delivery by inherent passive targeting phenomena and adopting active targeting strategies, but also improve the pharmacokinetics and bioavailability of the loaded drugs, leading to enhanced therapeutic efficacy and safety compared to conventional treatment modalities. Small molecule drugs are the most widely used anticancer agents at present, while biological macromolecules, such as therapeutic antibodies, peptides and genes, have gained increasing attention. Therefore, this review focuses on the recent achievements of novel nano-encapsulation in targeted drug delivery. A comprehensive introduction of intelligent delivery strategies based on various nanocarriers to encapsulate small molecule chemotherapeutic drugs and biological macromolecule drugs in cancer treatment will also be highlighted.

Biomimetic camouflage delivery strategies for cancer therapy

Cancer remains a significant challenge despite the progress in developing different therapeutic approaches. Nanomedicine has been explored as a promising novel cancer therapy. Recently, biomimetic camouflage strategies have been investigated to change the bio-fate of therapeutics and target cancer cells while reducing the unwanted exposure on normal tissues. Endogenous components (e.g., proteins, polysaccharides, and cell membranes) have been used to develop anticancer drug delivery systems. These biomimetic systems can overcome biological barriers and enhance tumor cell-specific uptake. The tumor-targeting mechanisms include ligand-receptor interactions and stimuli-responsive (e.g., pH-sensitive and light-sensitive) delivery. Drug delivery carriers composed of endogenous components represent a promising approach for improving cancer treatment efficacy. In this paper, different biomimetic drug delivery strategies for cancer treatment are reviewed with a focus on the discussion of their advantages and potential applications.

EGFR Targeted Cetuximab-Valine-Citrulline (vc)-Doxorubicin Immunoconjugates- Loaded Bovine Serum Albumin (BSA) Nanoparticles for Colorectal Tumor Therapy

Background

Specific modifications to carriers to achieve targeted delivery of chemotherapeutics into malignant tissues are a critical point for efficient diagnosis and therapy. In this case, bovine serum albumin (BSA) was conjugated with cetuximab–valine–citrulline (vc)–doxorubicin (DOX) to target epidermal growth factor receptor (EGFR) and enable the release of drug in EGFR-overexpressed tumor cells.

Methods

Maleimidocaproyl–valine–citrulline–p-aminobenzylcarbonyl-p-nitrophenol (MC-Val-Cit-PAB-PNP) and DOX were used to synthesize MC-Val-Cit-PAB-DOX, which was further linked with cetuximab to prepare antibody–drug conjugates (ADCs). Then, the ADCs were adsorbed to the surface of the BSA nanoparticles (NPs), which were prepared by a desolvation method to obtain cetuximab-vc-DOX-BSA-NPs. The cetuximab-vc-DOX conjugates adsorbed on the surface of the BSA nanoparticles were determined and optimized by size exclusion chromatography. An in vitro cytotoxicity study was conducted using a colon carcinoma cell line with different EGFR-expression levels to test the selectivity of cetuximab-vc-DOX-NPs.

Results

The vc-DOX and cetuximab-vc-DOX conjugates were both synthesized successfully and their structural characteristics confirmed by ¹H-NMR and SDS-PAGE. The MTT assay showed stronger cytotoxicity of cetuximab-vc-DOX-NPs versus control IgG-vc-DOX-NPs in EGFR–overexpressing RKO cells. Cellular binding and intracellular accumulation determined by flow cytometry and confocal laser scanning microscopy revealed the strong binding ability of cetuximab-vc-DOX-NPs to RKO cells. The in vivo imaging study demonstrated that cetuximab-vc-DOX-NPs exhibited higher fluorescent intensity in tumor tissues than non-decorated nanoparticles (IgG-vc-DOX-NPs). In vivo tumor inhibition and survival tests showed that cetuximab-vc-DOX-NPs revealed higher tumor inhibition efficacy and lower systemic toxicity than control IgG-vc-DOX- NPs

Conclusion

The obtained results emphasize that cetuximab-vc-DOX-NPs, with good tumor-targeting ability and low systemic toxicity, are a promising targeting system for drug delivery.

Reconstituted high density lipoprotein (rHDL), a versatile drug delivery nanoplatform for tumor targeted therapy

rHDL is a synthesized drug delivery nanoplatform exhibiting excellent biocompatibility, which possesses most of the advantages of HDL. rHDL shows almost no toxicity and can be degraded to non-toxic substances in vivo. The severe limitation of the application of various antitumor agents is mainly due to their low bioavailability, high toxicity, poor stability, etc. Favorably, antitumor drug-loaded rHDL nanoparticles (NPs), which are known as an important drug delivery system (DDS), help to change the situation a lot. This DDS shows an outstanding active-targeting ability towards tumor cells and improves the therapeutic effect during antitumor treatment while overcoming the shortcomings mentioned above. In the following text, we will mainly focus on the various applications of rHDL in tumor targeted therapy by describing the properties, preparation, receptor active-targeting ability and antitumor effects of antineoplastic drug-loaded rHDL NPs.

Viral Mimicry as a Design Template for Nucleic Acid Nanocarriers

Therapeutic nucleic acids hold immense potential in combating undruggable, gene-based diseases owing to their high programmability and relative ease of synthesis. While the delivery of this class of therapeutics has successfully entered the clinical setting, extrahepatic targeting, endosomal escape efficiency, and subcellular localization. On the other hand, viruses serve as natural carriers of nucleic acids and have acquired a plethora of structures and mechanisms that confer remarkable transfection efficiency. Thus, understanding the structure and mechanism of viruses can guide the design of synthetic nucleic acid vectors. This review revisits relevant structural and mechanistic features of viruses as design considerations for efficient nucleic acid delivery systems. This article explores how viral ligand display and a metastable structure are central to the molecular mechanisms of attachment, entry, and viral genome release. For comparison, accounted for are details on the design and intracellular fate of existing nucleic acid carriers and nanostructures that share similar and essential features to viruses. The review, thus, highlights unifying themes of viruses and nucleic acid delivery systems such as genome protection, target specificity, and controlled release. Sophisticated viral mechanisms that are yet to be exploited in oligonucleotide delivery are also identified as they could further the development of next-generation nonviral nucleic acid vectors.

Small interfering RNAs (siRNAs) based gene silencing strategies for the treatment of glaucoma: Recent advancements and future perspectives

RNA-interference-based mechanisms, especially the use of small interfering RNAs (siRNAs), have been under investigation for the treatment of several ailments and have shown promising results for ocular diseases including glaucoma. The eye, being a confined compartment, serves as a good target for the delivery of siRNAs. This review focuses on siRNA-based strategies for gene silencing to treat glaucoma. We have discussed the ocular structures and barriers to gene therapy (tear film, corneal, conjunctival, vitreous, and blood ocular barriers), methods of administration for ocular gene delivery (topical instillation, periocular, intracameral, intravitreal, subretinal, and suprachoroidal routes) and various viral and non-viral vectors in siRNA-based therapy for glaucoma. The components and mechanism of siRNA-based gene silencing have been mentioned briefly followed by the basic strategies and challenges faced during siRNA therapeutics development. We have emphasized different therapeutic targets for glaucoma which have been under research by scientists and the current siRNA-based drugs used in glaucoma treatment. We also mention briefly strategies for siRNA-based treatment after glaucoma surgery.

In vivo gene delivery mediated by non-viral vectors for cancer therapy

Gene therapy by expression constructs or down-regulation of certain genes has shown great potential for the treatment of various diseases. The wide clinical application of nucleic acid materials dependents on the development of biocompatible gene carriers. There are enormous various compounds widely investigated to be used as non-viral gene carriers including lipids, polymers, carbon materials, and inorganic structures. In this review, we will discuss the recent discoveries on non-viral gene delivery systems. We will also highlight the in vivo gene delivery mediated by non-viral vectors to treat cancer in different tissue and organs including brain, breast, lung, liver, stomach, and prostate. Finally, we will delineate the state-of-the-art and promising perspective of in vivo gene editing using non-viral nano-vectors.

Overcoming Hypoxia-Restrained Radiotherapy Using an Erythrocyte-Inspired and Glucose-Activatable Platform

Radiotherapy (RT) as one of the most powerful cancer treatment strategies has been greatly restricted by tumor hypoxia. A mounting effort has been devoted to develop oxygen delivery systems for boosting the RT effect. Unluckily, those systems only supplied modest oxygen, which could not afford more than once and long-time RT. Herein, we describe the development of a glucose-regulated drug release platform, allowing for a long-term tumor normoxic microenvironment and repeated RT for a long time. The repeated cycles resulted in sustained high Endostar plasma levels, which dramatically normalized the tumor vasculature and chronically reversed tumor hypoxia. Taking advantage of the inexhaustible supply of oxygen, Endo@GOx-ER enabled RT achieved an impressive cancer treatment output. To the best of our knowledge, our strategy is the initial attempt to overcome tumor-hypoxia-limited RT through the normalization of tumor vasculature by using an erythrocyte-inspired and glucose-activatable platform and it visually casts a light on the clinical development.

Photoactivation of sulfonated polyplexes enables localized gene silencing by DsiRNA in breast cancer cells

Translation potential of RNA interference nanotherapeutics remains challenging due to in vivo off-target effects and poor endosomal escape. Here, we developed novel polyplexes for controlled intracellular delivery of dicer substrate siRNA, using a light activation approach. Sulfonated polyethylenimines covalently linked to pyropheophorbide-α for photoactivation and bearing modified amines (sulfo-pyro-PEI) for regulated endosomal escape were investigated. Gene knock-down by the polymer-complexed DsiRNA duplexes (siRNA-NPs) was monitored in breast cancer cells. Surprisingly, sulfo-pyro-PEI/siRNA-NPs failed to downregulate the PLK1 or eGFP proteins. However, photoactivation of these cell associated-polyplexes with a 661-nm laser clearly restored knock-down of both proteins. In contrast, protein down-regulation by non-sulfonated pyro-PEI/siRNA-NPs occurred without any laser treatments, indicating cytoplasmic disposition of DsiRNA followed a common intracellular release mechanism. Therefore, sulfonated pyro-PEI holds potential as a unique trap and release light-controlled delivery platform for on-demand gene silencing bearing minimal off target effects.

Mimetic sHDL nanoparticles: A novel drug-delivery strategy to target triple-negative breast cancer

BACKGROUND

Withanolides are naturally derived heat shock protein 90 inhibitors that are potent in preclinical models of triple negative breast cancers. Conjugation to synthetic high-density lipoprotein nanoparticles improves solubility and targets delivery to the scavenger receptor B1. Triple negative breast cancers highly overexpress the scavenger receptor B1, and we hypothesize that encapsulation of the novel withalongolide A 4,19,27-triacetate by synthetic high-density lipoprotein will have enhanced efficacy against triple negative breast cancers in vivo.

METHODS

Validated human triple negative breast cancer cell lines were evaluated for the scavenger receptor B1 expression by quantitative polymerase chain reaction and Western blot. Withalongolide A 4,19,27-triacetate inhibitory concentration₅₀ values were obtained using CellTiter-Glo assays (Promega, Madison, WI, USA). The scavenger receptor B1-mediated drug uptake was evaluated in vitro under fluorescence microscopy and in vivo with IVIS imaging of mouse xenografts (MD-MBA-468LN). To evaluate drug efficacy, mice were treated with synthetic high-density lipoprotein alone, withalongolide A 4,19,27-triacetate alone, withalongolide A 4,19,27-triacetate synthetic high-density lipoprotein, and chemotherapy or Prussian blue stain (control).

RESULTS

Triple negative breast cancer cell lines had greater scavenger receptor B1 expression by quantitative polymerase chain reaction and Western blot versus controls. Fluorescent-labeled synthetic high-density lipoprotein uptake was scavenger receptor B1-mediated in vitro, and in vivo tumor uptake using IVIS imaging demonstrated significantly increased tumor radiant efficiency versus control. Inhibitory concentration₅₀ for withalongolide A 4,19,27-triacetate-treated cells with or without synthetic high-density lipoprotein encapsulation were 70-fold to 200-fold more potent than synthetic high-density lipoprotein alone. In triple negative breast cancer mouse xenografts, treatment with synthetic high-density lipoprotein withalongolide A 4,19,27-triacetate resulted in a 54% decrease in tumor volume compared with the control or with synthetic high-density lipoprotein alone.

CONCLUSION

The synthetic high-density lipoprotein withalongolide A 4,19,27-triacetate nanoconjugates are potent against triple negative breast cancers and show improved scavenger receptor B1-mediated targeting. Treatment with synthetic high-density lipoprotein-encapsulated withalongolide A 4,19,27-triacetate is able to significantly decrease the growth of tumor in mice compared with the control and has better efficacy than the current standard of care, warranting further evaluation as a novel therapeutic agent.

Comparison of Mechanisms of Endothelial Cell Protections Between High-Density Lipoprotein and Apolipoprotein A-I Mimetic Peptide

Apolipoprotein A-I (apoA-I) mimetic peptide, D-4F, exhibits anti-atherogenic effects similar to high-density lipoprotein (HDL). However, it remains elusive whether D-4F and HDL share similar molecular mechanisms underlying anti-atherogenic effects and endothelial cell protections. We here compared the metabolic changes in endothelial cells induced by D-4F and HDL against oxidized low-density lipoprotein (ox-LDL), which may be of benefit to understanding the protective mechanisms of HDL and D-4F. Functional assays, including wound healing, transwell migration, and tube formation, were used to evaluate the pro-angiogenic effects of HDL and D-4F. NMR-based metabolomic analysis was employed to explore the protective mechanisms underlying HDL and D-4F. Partial least-squares discriminant analysis (PLS-DA) was performed to assess metabolic profiles, and orthogonal PLS-DA (OPLS-DA) was carried out to identify characteristic metabolites. Moreover, significantly altered metabolic pathways were also analyzed. We found that ox-LDL impaired the migration and tube formation of endothelial cells. Metabolomic analysis showed that ox-LDL triggered oxidative stress, impaired glycolysis, and enhanced glycerophospholipid metabolism. Both HDL and D-4F improved the migration and angiogenesis of endothelial cells, alleviated oxidative stress, and ameliorated disordered glycolysis impaired by ox-LDL. Strikingly, HDL partially attenuated the disturbed glycerophospholipid metabolism, whereas D-4F did not show this effect. In summary, although D-4F shared the similar protective effects with HDL on the migration and angiogenesis of endothelial cells, it could not deduce the molecular mechanisms of HDL completely. Nevertheless, D-4F possesses the potentiality to be exploited as clinically applicable agent for endothelial cell protection and cardiovascular disease treatment.

The role of high-density lipoproteins in antitumor drug delivery

High-density lipoproteins (HDLs) are the smallest lipoprotein with the highest level of protein in their surface. The main role of HDLs are reverse transport of cholesterol from peripheral tissues to the liver. More recently, HDLs have been considered as a new drug delivery system because of their small size, proper surface properties, long circulation time, biocompatibility, biodegradability, and low immune stimulation. Delivery of anticancer drug to the tumor tissue is a major obstacle against successful chemotherapy, which is because of the toxicity and poor aqueous solubility of these drugs. Loading chemotherapeutic drugs in the lipid core of HDLs can overcome the aforementioned problems and increase the efficiency of drug delivery. In this review, we discuss the use of HDLs particles in drug delivery to the tumor tissue and explain some barriers and limitations that exist in the use of HDLs as an ideal delivery vehicle.

A TRAIL-Delivered Lipoprotein-Bioinspired Nanovector Engineering Stem Cell-Based Platform for Inhibition of Lung Metastasis of Melanoma

Genetically engineered mesenchymal stem cells (MSCs), as non-viral gene delivery platforms, are rapidly evolving in tumor therapy due to their low immunogenicity and natural tumor-homing capacity. Methods: In this paper, we selected reconstituted high-density lipoprotein (rHDL), a lipoprotein-bioinspired nanovector with specific binding ability to scavenger receptor B type I (SR-BI) expressed on MSCs, as a transfection agent to genetically modify MSCs. pDNA encoding tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) was used as a functional gene to be transfected into the nucleus of MSCs for TRAIL expression. Lauric acid-coupled polyethyleneimine (PEI-LA) as an amphiphilic cationic polymer was synthesized to electrostatically bind to pDNA, and then incorporated into rHDL to form rHDL/PEI-LA/pDNA nanoparticles. Results: The nanoparticles exhibited homogenous particle size and excellent serum stability in vitro. Meanwhile, this SR-BI-targeted rHDL performed efficient intracellular gene delivery, specific lysosome-independent mechanism of cellular uptake and high transfection of pDNA towards MSCs. Moreover, high TRAIL expression in MSCs was detected after rHDL-mediated transfection. In vitro and in vivo results indicated that genetically engineered MSCs could accurately target to B16F10 cells, thereby producing significant apoptosis-inducing effect on aggressive melanoma. Conclusion: TRAIL-expressing MSCs engineered by rHDL nanovector was an efficient and hypotoxic method for stem cells-based pulmonary melanoma metastasis-targeting therapy.

Protein-based vehicles for biomimetic RNAi delivery

Broad translational success of RNA interference (RNAi) technology depends on the development of effective delivery approaches. To that end, researchers have developed a variety of strategies, including chemical modification of RNA, viral and non-viral transfection approaches, and incorporation with delivery vehicles such as polymer- and lipid-based nanoparticles, engineered and native proteins, extracellular vesicles (EVs), and others. Among these, EVs and protein-based vehicles stand out as biomimetically-inspired approaches, as both proteins (e.g. Apolipoprotein A-1, Argonaute 2, and Arc) and EVs mediate intercellular RNA transfer physiologically. Proteins specifically offer significant therapeutic potential due to their biophysical and biochemical properties as well as their ability to facilitate and tolerate manipulation; these characteristics have made proteins highly successful translational therapeutic molecules in the last two decades. This review covers engineered protein vehicles for RNAi delivery along with what is currently known about naturally-occurring extracellular RNA carriers towards uncovering design rules that will inform future engineering of protein-based vehicles.

KIAA1199 promotes invasion and migration in non-small-cell lung cancer (NSCLC) via PI3K-Akt mediated EMT

KIAA1199 is often upregulated in cancer cells, including non-small-cell lung cancer (NSCLC). Although KIAA1199 is associated with aggressive tumor phenotype and poor survival in NSCLC, little is known about its functional role in NSCLC progression. Using archived clinical samples, we evaluated KIAA1199 messenger RNA (mRNA) and protein expression in NSCLC tissues and correlated with NSCLC clinicopathological characteristics as well as overall survival. Using NSCLC cell lines, KIAA1199 was either silenced using gene-specific shRNA or overexpressed to assess the impact on EMT signaling pathways. Finally, in a mouse xenograft NSCLC model, we determine the therapeutic potential of KIAA1199 repression. Our data showed that KIAA1199 was significantly upregulated in NSCLC tissues compared to adjacent normal tissues both at the mRNA (P < 0.001) and protein levels (P < 0.05). KIAA1199 overexpression is an independent prognostic marker for overall survival (HR = 1.833). In NSCLC cell lines, KIAA1199 expression directly influences the expression of EMT markers, EMT-inducing transcription factors (EMT-TFs), and EMT signaling molecules. Knocking down of KIAA1199 expression in the mouse NSCLC xenograft model significantly suppressed tumor growth and augmented the efficacy of chemotherapy (n = 5; P < 0.05). We conclude that KIAA1199 is not only a prognostic marker but a novel therapeutic target in NSCLC through regulating EMT signaling pathway. KEY MESSAGES: KIAA1199 overexpression is an independent prognostic marker in NSCLC. KIAA1199 expression directly influences the expression of EMT markers. KIAA1199 promotes invasion and migration in NSCLC via PI3K-Akt mediated EMT.

Reconstituted HDL: Drug Delivery Platform for Overcoming Biological Barriers to Cancer Therapy

Drug delivery to malignant tumors is limited by several factors, including off-target toxicities and suboptimal benefits to cancer patient. Major research efforts have been directed toward developing novel technologies involving nanoparticles (NPs) to overcome these challenges. Major obstacles, however, including, opsonization, transport across cancer cell membranes, multidrug-resistant proteins, and endosomal sequestration of the therapeutic agent continue to limit the efficiency of cancer chemotherapy. Lipoprotein-based drug delivery technology, "nature's drug delivery system," while exhibits highly desirable characteristics, it still needs substantial investment from private/government stakeholders to promote its eventual advance to the bedside. Consequently, this review focuses specifically on the synthetic (reconstituted) high-density lipoprotein rHDL NPs, evaluating their potential to overcome specific biological barriers and the challenges of translation toward clinical utilization and commercialization. This highly robust drug transport system provides site-specific, tumor-selective delivery of anti-cancer agents while reducing harmful off-target effects. Utilizing rHDL NPs for anti-cancer therapeutics and tumor imaging revolutionizes the future strategy for the management of a broad range of cancers and other diseases.

Immune lipoprotein nanostructures inspired relay drug delivery for amplifying antitumor efficiency

Chemo-immunotherapy represents an appealing approach to improving cancer treatment. Simultaneously administrating chemotherapeutics with immunoadjuvants can elicit potent tumor death and immune responses. Herein, high density lipoprotein (HDL) inspired immune lipoprotein was proposed for relay drug delivery and amplifying antitumor therapy. Lipophilic AS1411 aptamer-immunoadjuvant CpG fused sequences (Apt-CpG-DSPE) were conjugated to facilitate decoration onto HDLs; and doxorubicin (Dox) was successively intercalated into the consecutive base pairs of Apt-CpG to complete immune HDL nanodrug imHDL/Apt-CpG-Dox. For relay drug delivery, imHDL/Apt-CpG-Dox underwent site-specific structure collapse in tumor intercellular substances inspired from HDL biofunctions (sequential module I); subsequently, dissociated Apt-CpG-Dox was endocytosed into tumor cells mediated by the recognition of AS1411 and nucleolin (sequential module II), translocating Dox to nucleus and enabling tumor ablation and antigens release. The liberated CpG motif further evoked antigen recognition, induced vast secretion of pro-inflammatory cytokines and potentiated host antitumor immunity. Our studies demonstrated that HDL biomimetic platform based relay drug delivery strategy outperformed the monotherapy counterparts in malignant tumor models, eventually generating an augmented antitumor efficacy.

Formulation and in vitro evaluation of a siRNA delivery nanosystem decorated with gH625 peptide for triple negative breast cancer theranosis

The development of an efficient small interfering RNA (siRNA) delivery system has held scientists interest since the discovery of the RNA interference mechanism (RNAi). This strategy gives hope for the treatment of many severe diseases. Herein, we developed hybrid nanovectors able to deliver siRNA to triple negative breast cancer cells. The nanovectors are based on PEGylated superparamagnetic iron oxide nanoparticles (SPION) functionalized with gH625 peptide, chitosan and poly-l-arginine. Every component has a key role and specific function: SPION is the core scaffolding the nanovector; PEG participates in the colloidal stability and the immune stealthiness; gH625 peptide promotes the nanovector internalization into cancer cells; cationic polymers provide the siRNA protection and favor siRNA endosomal escape and delivery to cytosol. The formulation was optimized by varying the amount of each compound. The efficacy of the siRNA retention and protection were investigated in the presence of high concentration of serum. Optimized nanovectors show a high uptake by MDA-MB-231 cells. The resulting down regulation of GFP expression was 73 ± 3% with our nanovector compared to 59 ± 8% obtained with the siRNA-Oligofectamine™ complex in the same conditions.

Endocytosis of lipoproteins

During their metabolism, all lipoproteins undergo endocytosis, either to be degraded intracellularly, for example in hepatocytes or macrophages, or to be re-secreted, for example in the course of transcytosis by endothelial cells. Moreover, there are several examples of internalized lipoproteins sequestered intracellularly, possibly to exert intracellular functions, for example the cytolysis of trypanosoma. Endocytosis and the subsequent intracellular itinerary of lipoproteins hence are key areas for understanding the regulation of plasma lipid levels as well as the biological functions of lipoproteins. Indeed, the identification of the low-density lipoprotein (LDL)-receptor and the unraveling of its transcriptional regulation led to the elucidation of familial hypercholesterolemia as well as to the development of statins, the most successful therapeutics for lowering of cholesterol levels and risk of atherosclerotic cardiovascular diseases. Novel limiting factors of intracellular trafficking of LDL and the LDL receptor continue to be discovered and to provide drug targets such as PCSK9. Surprisingly, the receptors mediating endocytosis of high-density lipoproteins or lipoprotein(a) are still a matter of controversy or even new discovery. Finally, the receptors and mechanisms, which mediate the uptake of lipoproteins into non-degrading intracellular itineraries for re-secretion (transcytosis, retroendocytosis), storage, or execution of intracellular functions, are largely unknown.

Non-viral delivery systems for CRISPR/Cas9-based genome editing: Challenges and opportunities

In recent years, CRISPR (clustered regularly interspaced short palindromic repeat)/Cas (CRISPR-associated) genome editing systems have become one of the most robust platforms in basic biomedical research and therapeutic applications. To date, efficient in vivo delivery of the CRISPR/Cas9 system to the targeted cells remains a challenge. Although viral vectors have been widely used in the delivery of the CRISPR/Cas9 system in vitro and in vivo, their fundamental shortcomings, such as the risk of carcinogenesis, limited insertion size, immune responses and difficulty in large-scale production, severely limit their further applications. Alternative non-viral delivery systems for CRISPR/Cas9 are urgently needed. With the rapid development of non-viral vectors, lipid- or polymer-based nanocarriers have shown great potential for CRISPR/Cas9 delivery. In this review, we analyze the pros and cons of delivering CRISPR/Cas9 systems in the form of plasmid, mRNA, or protein and then discuss the limitations and challenges of CRISPR/Cas9-based genome editing. Furthermore, current non-viral vectors that have been applied for CRISPR/Cas9 delivery in vitro and in vivo are outlined in details. Finally, critical obstacles for non-viral delivery of CRISPR/Cas9 system are highlighted and promising strategies to overcome these barriers are proposed.

Fundamentals of siRNA and miRNA therapeutics and a review of targeted nanoparticle delivery systems in breast cancer

Gene silencing via RNA interference (RNAi) is rapidly evolving as a personalized approach to cancer treatment. The effector molecules-small interfering RNAs (siRNAs) and microRNAs (miRNAs)-can be used to silence or "switch off" specific cancer genes. Currently, the main barrier to implementing siRNA- and miRNA-based therapies in clinical practice is the lack of an effective delivery system that can protect the RNA molecules from nuclease degradation, deliver to them to tumor tissue, and release them into the cytoplasm of the target cancer cells, all without inducing adverse effects. Here, we review the fundamentals of RNAi, cell membrane transport pathways, and factors that affect intracellular delivery. We discuss the advantages and disadvantages of the various types of nanoparticle delivery systems, with a focus on those that have been investigated in breast cancer in vivo.

Reconstituted high-density lipoproteins: novel biomimetic nanocarriers for drug delivery

High-density lipoproteins (HDL) are naturally-occurring nanoparticles that are biocompatible, non-immunogenic and completely biodegradable. These endogenous particles can circulate for an extended period of time and transport lipids, proteins and microRNA from donor cells to recipient cells. Based on their intrinsic targeting properties, HDL are regarded as promising drug delivery systems. In order to produce on a large scale and to avoid blood borne pollution, reconstituted high-density lipoproteins (rHDL) possessing the biological properties of HDL have been developed. This review summarizes the biological properties and biomedical applications of rHDL as drug delivery platforms. It focuses on the emerging approaches that have been developed for the generation of biomimetic nanoparticles rHDL to overcome the biological barriers to drug delivery, aiming to provide an alternative, promising avenue for efficient targeting transport of nanomedicine.

Targeted Delivery of siRNA Therapeutics to Malignant Tumors

Over the past 20 years, a diverse group of ligands targeting surface biomarkers or receptors has been identified with several investigated to target siRNA to tumors. Many approaches to developing tumor-homing peptides, RNA and DNA aptamers, and single-chain variable fragment antibodies by using phage display, in vitro evolution, and recombinant antibody methods could not have been imagined by researchers in the 1980s. Despite these many scientific advances, there is no reason to expect that the ligand field will not continue to evolve. From development of ligands based on novel or existing biomarkers to linking ligands to drugs and gene and antisense delivery systems, several fields have coalesced to facilitate ligand-directed siRNA therapeutics. In this review, we discuss the major categories of ligand-targeted siRNA therapeutics for tumors, as well as the different strategies to identify new ligands.

Transporting carriers for intracellular targeting delivery via non-endocytic uptake pathways

To develop novel therapies for clinical treatments, it increasingly depends on sophisticated delivery systems that facilitate the drugs entry into targeting cells. Profound understanding of cellular uptake routes for transporting carriers promotes the optimization of performance in drug delivery systems. Although endocytic pathway is the most important part of cellular uptake routes for many delivery systems, it suffers the trouble of enzymatic degradation of transporting carriers trapped in endosomes/lysosomes. Therefore, it is desirable to develop alternative transporting methods for delivery systems via non-endocytic pathways to achieve more effective intracellular delivery. In this review, we summarize the literature exploring transporting carriers that mediate intracellular delivery via non-endocytic pathways to present the current research status in this field. Cell-penetrating peptides, pH (low) insertion peptides, and nanoparticles are categorized to exhibit their ability to directly transport various cargos into cytoplasm via non-endocytic uptake in different cell lines. It is hoped that this review can spur the interesting on development of drug delivery systems via non-endocytic uptake pathway.

Rerouting Native HDL to Predetermined Receptors for Improved Tumor-Targeted Gene Silencing Therapy

High-density lipoprotein (HDL) is an outstanding biocompatible nanovector for tumor-targeted delivery of multimodel drugs in cancer therapy. However, this seemingly promising delivery platform demonstrates an adverse accumulation in liver and adrenal due to the primary expression of natural target scavenger receptor class B type I (SR-BI), which overexpressed in malignant cells as well. Therefore, we endowed native HDLs with rerouting capacity, that is, enabling HDLs to get away from natural receptors (SR-BI) to selectively alternate tumor-rich receptors. The α_vβ₃-integrin specific cyclic-RGDyk peptide was conjugated with HDL-protein component apolipoprotein A-I (apoA-I), demonstrating high substitution degree of 26.2%. Afterward, RGD-modified apoA-I was introduced to fabricate cholesterol siRNA-loaded HDL nanoparticles (RGD-HDL/Ch-siRNA) for specific affinity with tumor angiogenesis and α_vβ₃ integrin on tumor surface. After preparation, RGD-HDL/Ch-siRNA shared desirable particle size, efficient siRNA protection during blood circulation, and favorable proton sponge effect. α_vβ₃ integrin-associated superior rerouting capacity, endocytosis pathway, and rapid endolysosome escape were confirmed both in vitro and in vivo. For targeted gene silencing therapy, Pokemon-specific siRNA (siPokemon) was introduced as RNA interference candidate; the enhanced antitumor efficacy and decreased Pokemon expression level were commendably confirmed by tumor growth inhibition, survival period extension, and western blot analysis. Collectively, cyclic-RGDyk modification endows native HDLs with rerouting capacity to specific α_vβ₃ integrin receptor, which provides a promising strategy to extend malignancy targeting potential of native HDL to a broader purview.

The apolipoprotein A-I mimetic peptide, D-4F, restrains neointimal formation through heme oxygenase-1 up-regulation

D‐4F, an apolipoprotein A‐I (apoA‐I) mimetic peptide, possesses distinctly anti‐atherogenic effects. However, the biological functions and mechanisms of D‐4F on the hyperplasia of vascular smooth muscle cells (VSMCs) remain unclear. This study aimed to determine its roles in the proliferation and migration of VSMCs. In vitro, D‐4F inhibited VSMC proliferation and migration induced by ox‐LDL in a dose‐dependent manner. D‐4F up‐regulated heme oxygenase‐1 (HO‐1) expression in VSMCs, and the PI3K/Akt/AMP‐activated protein kinase (AMPK) pathway was involved in these processes. HO‐1 down‐regulation with siRNA or inhibition with zinc protoporphyrin (Znpp) impaired the protective effects of D‐4F on the oxidative stress and the proliferation and migration of VSMCs. Moreover, down‐regulation of ATP‐binding cassette transporter A1 (ABCA1) abolished the activation of Akt and AMPK, the up‐regulation of HO‐1 and the anti‐oxidative effects of D‐4F. In vivo, D‐4F restrained neointimal formation and oxidative stress of carotid arteries in balloon‐injured Sprague Dawley rats. And inhibition of HO‐1 with Znpp decreased the inhibitory effects of D‐4F on neointimal formation and ROS production in arteries. In conclusion, D‐4F inhibited VSMC proliferation and migration in vitro and neointimal formation in vivo through HO‐1 up‐regulation, which provided a novel prophylactic and therapeutic strategy for anti‐restenosis of arteries.