Self-crosslinked human serum albumin nanocarriers for systemic delivery of polymerized siRNA to tumors

Use of Albumin for Drug Delivery as a Diagnostic and Therapeutic Tool

Drug delivery is an important topic that has attracted the attention of researchers in recent years. Albumin nanoparticles play a significant role in drug delivery as a carrier due to their unique characteristics. Albumin is non-toxic, biocompatible, and biodegradable. Its structure is such that it can interact with different drugs, which makes the treatment of the disease faster and also reduces the side effects of the drug. Albumin nanoparticles can be used in the diagnosis and treatment of many diseases, including cancer, diabetes, Alzheimer's, etc. These nanoparticles can connect to some compounds, such as metal nanoparticles, antibodies, folate, etc. and create a powerful nanostructure for drug delivery. In this paper, we aim to investigate albumin nanoparticles in carrier format for drug delivery application. In the beginning, different types of albumin and their preparation methods were discussed, and then albumin nanoparticles were discussed in detail in diagnosing and treating various diseases.

Effects of Albumin-Chlorogenic Acid Nanoparticles on Apoptosis and PI3K/Akt/mTOR Pathway Inhibitory Activity in MDA-MB-435s Cells

In this study, we synthesized, characterized, and explored the anti-microbial and anti-cancer effects of albumin-chlorogenic acid nanoparticles (NPs). Characterization studies with a UV-vis spectrophotometer, FTIR, PL spectrum, TEM, FESEM, XRD, and DLA analysis showed patterns confirming the physio-chemical nature of biogenic nanocomposites. Further, anti-microbial studies using bacterial strains Staphylococcus aureus, Streptococcus pneumonia, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Vibrio cholera, and fungal strain Candida albicans showed significant (p < 0.05) anti-bacterial and anti-fungal activities. Next, we used MDA-MB-435s, a human cell line, to evaluate the anti-cancer effects of albumin-chlorogenic acid NPs. Cytotoxic studies revealed its IC50 concentration at 24 μg/mL after a 24 h treatment of MDA-MB-435s cells. We chose this IC50 dose to analyze albumin-chlorogenic acid NPs anti-cancer effects in vitro. MDA-MB-435s cells exposed to our NPs were studied via AO/EtBr staining, cell cycle analyses via PI staining, the status of whole genomic damage via comet assay, levels of apoptotic cells via annexin V/PI staining, ROS generation via DCFH-DA staining, an assay of antioxidant enzymes catalase, superoxide dismutase, and antioxidant GSH, via ELISA analyses of apoptotic markers caspase-3, 8, 9, Bax, Bcl-2, CytC, and p53, PI3/AKT/mTOR pathway. Our results collectively showed albumin-chlorogenic acid NPs induced apoptosis via p53-dependent and PI3/AKT/mTOR inhibition in MDA-MB-435s cells. Our results denote albumin-chlorogenic acid NPs can be used as an effective candidate for anti-microbial and anti-cancer applications; however, further in vivo confirmatory studies are warranted.

Films, Gels and Electrospun Fibers from Serum Albumin Globular Protein for Medical Device Coating, Biomolecule Delivery and Regenerative Engineering

Albumin is a natural biomaterial that is abundantly available in blood and body fluids. It is clinically used as a plasma expander, thereby increasing the plasma thiol concentration due to its cysteine residues. Albumin is a regulator of intervascular oncotic pressure, serves as an anti-inflammatory modulator, and it has a buffering role due to its histidine imidazole residues. Because of its unique biological and physical properties, albumin has also emerged as a suitable biomaterial for coating implantable devices, for cell and drug delivery, and as a scaffold for tissue engineering and regenerative medicine. As a biomaterial, albumin can be used as surface-modifying film or processed either as cross-linked protein gels or as electrospun fibers. Herein we have discussed how albumin protein can be utilized in regenerative medicine as a hydrogel and as a fibrous mat for a diverse role in successfully delivering drugs, genes, and cells to targeted tissues and organs. The review of prior studies indicated that albumin is a tunable biomaterial from which different types of scaffolds with mechanical properties adjustable for various biomedical applications can be fabricated. Based on the progress made to date, we concluded that albumin-based device coatings, delivery of drugs, genes, and cells are promising strategies in regenerative and personalized medicine.

Serum albumin and nucleic acids biodistribution: from molecular aspects to biotechnological applications

Serum albumin (SA) is the most abundant protein in plasma and represents the main carrier of endogenous and exogenous compounds. Several evidence supports the notion that SA binds single and double stranded deoxy- and ribonucleotides at two sites, with values of the dissociation equilibrium constant (i.e., K_d ) ranging from micromolar to nanomolar values. This can be relevant from a physiological and pathological point of view as in human plasma circulate cell-free nucleic acids (cfNAs), which are single and double stranded NAs released by different tissues via apoptosis, necrosis, and secretions. Albeit SA shows low hydrolytic reactivity toward DNA and RNA, the high plasma concentration of this protein and the occurrence of several SA receptors may be pivotal for sequestering and hydrolyzing cfNAs. Therefore, pathological conditions like cancer, characterized by altered levels of human SA or by altered SA post-translational modifications, may influence cfNAs distribution and metabolism. Besides, the stability, solubility, biocompatibility, and low immunogenicity make SA a golden share for biotechnological applications related to the delivery of therapeutic NAs (TNAs). Indeed, pre-clinical studies report the therapeutic potential of SA:TNAs complexes in precision cancer therapy. Here, the molecular and biotechnological implications of SA:NAs interaction are discussed, highlighting new perspectives into SA plasmatic functions. This article is protected by copyright. All rights reserved.

Multimeric RNAs for efficient RNA-based therapeutics and vaccines

There has been a growing interest in RNA therapeutics globally, and much progress has been made in this area, which has been further accelerated by the clinical applications of RNA-based vaccines against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Following these successful clinical trials, various technologies have been developed to improve the efficacy of RNA-based drugs. Multimerization of RNA therapeutics is one of the most attractive approaches to ensure high stability, high efficacy, and prolonged action of RNA-based drugs. In this review, we offer an overview of the representative approaches for generating repetitive functional RNAs by chemical conjugation, structural self-assembly, enzymatic elongation, and self-amplification. The therapeutic and vaccine applications of engineered multimeric RNAs in various diseases have also been summarized. By outlining the current status of multimeric RNAs, the potential of multimeric RNA as a promising treatment strategy is highlighted.

Emerging Albumin-Binding Anticancer Drugs for Tumor-Targeted Drug Delivery: Current Understandings and Clinical Translation

Albumin has shown remarkable promise as a natural drug carrier by improving pharmacokinetic (PK) profiles of anticancer drugs for tumor-targeted delivery. The exogenous or endogenous albumin enhances the circulatory half-lives of anticancer drugs and passively target the tumors by the enhanced permeability and retention (EPR) effect. Thus, the albumin-based drug delivery leads to a potent antitumor efficacy in various preclinical models, and several candidates have been evaluated clinically. The most successful example is Abraxane, an exogenous human serum albumin (HSA)-bound paclitaxel formulation approved by the FDA and used to treat locally advanced or metastatic tumors. However, additional clinical translation of exogenous albumin formulations has not been approved to date because of their unexpectedly low delivery efficiency, which can increase the risk of systemic toxicity. To overcome these limitations, several prodrugs binding endogenous albumin covalently have been investigated owing to distinct advantages for a safe and more effective drug delivery. In this review, we give account of the different albumin-based drug delivery systems, from laboratory investigations to clinical applications, and their potential challenges, and the outlook for clinical translation is discussed. In addition, recent advances and progress of albumin-binding drugs to move more closely to the clinical settings are outlined.

Protein Nanoparticles: Uniting the Power of Proteins with Engineering Design Approaches

Protein nanoparticles, PNPs, have played a long-standing role in food and industrial applications. More recently, their potential in nanomedicine has been more widely pursued. This review summarizes recent trends related to the preparation, application, and chemical construction of nanoparticles that use proteins as major building blocks. A particular focus has been given to emerging trends related to applications in nanomedicine, an area of research where PNPs are poised for major breakthroughs as drug delivery carriers, particle-based therapeutics or for non-viral gene therapy.

Albumin-Based Therapeutics Capable of Glutathione Consumption and Hydrogen Peroxide Generation for Synergetic Chemodynamic and Chemotherapy of Cancer

A nanoscale therapeutic system with good biocompatibility was facilely fabricated by the coassembly of human serum albumin and glucose oxidase (GOD), where the former was pretreated with metal ions through a chelating agent or the chemotherapeutic prodrug oxaliplatin (Oxa(IV)). Among different chelating metal ions used, Mn²⁺ ion was selected to produce hydroxyl radical (•OH) efficiently through Fenton-like reaction, while GOD loaded in the system was able to generate a large amount of hydrogen peroxide for promoting efficient conversion into highly toxic •OH. In the meanwhile, the conversion of the Oxa(IV) prodrug into chemotherapeutic Oxa(II) was beneficial for the consumption of glutathione, thereby enhancing the chemodynamic therapy (CDT) efficacy. Based on the combined chemotherapy and CDT, the treatment with this system leads to superior antitumor outcome.

Nano drug delivery systems improve metastatic breast cancer therapy

Despite continual progress in the technologies and regimens for cancer therapy, the treatment outcome of fatal metastatic breast cancer is far from satisfactory. Encouragingly, nanotechnology has emerged as a valuable tool to optimize drug delivery process in cancer therapy via preventing the cargos from degradation, improving the tumor-targeting efficiency, enhancing therapeutic agents' retention in specific sites, and controlling drug release. In the last decade, several mechanisms of suppressing tumor metastasis by functional nano drug delivery systems (NDDSs) have been revealed and a guidance for the rational design of anti-metastasis NDDSs is summarized, which consist of three aspects: optimization of physiochemical properties, tumor microenvironment remodeling, and biomimetic strategies. A series of medicinal functional biomaterials and anti-metastatic breast cancer NDDSs constructed by our team are introduced in this review. It is hoped that better anti-metastasis strategies can be inspired and applied in clinic.

Albumin Nanostructures for Nucleic Acid Delivery in Cancer: Current Trend, Emerging Issues, and Possible Solutions

Cancer is one of the major health problems worldwide, and hence, suitable therapies with enhanced efficacy and reduced side effects are desired. Gene therapy, involving plasmids, small interfering RNAs, and antisense oligonucleotides have been showing promising potential in cancer therapy. In recent years, the preparation of various carriers for nucleic acid delivery to the tumor sites is gaining attention since intracellular and extracellular barriers impart major challenges in the delivery of naked nucleic acids. Albumin is a versatile protein being used widely for developing carriers for nucleic acids. It provides biocompatibility, tumor specificity, the possibility for surface modification, and reduces toxicity. In this review, the advantages of using nucleic acids in cancer therapy and the challenges associated with their delivery are presented. The focus of this article is on the different types of albumin nanocarriers, such as nanoparticles, polyplexes, and nanoconjugates, employed to overcome the limitations of the direct use of nucleic acids in vivo. This review also highlights various approaches for the modification of the surface of albumin to enhance its transfection efficiency and targeted delivery in the tumor sites.

Natural Phyto-Antioxidant Albumin Nanoagents to Treat Advanced Alzheimer's Disease

Phytotherapeutic approaches are of immense value in the treatment of advanced Alzheimer's disease (AD) because of their diverse biological components and potential multitarget mechanisms. In this study, quercetin, a natural neuroprotective flavonoid, was encapsulated in human serum albumin to obtain HSA@QC nanoparticles (HQ NPs) as a natural phyto-antioxidant albumin nanoagent for the treatment of advanced AD. HQ NPs showed excellent antioxidant effects and protected PC12 cells from H2O2-induced oxidative damage. The intranasal administration of HQ NPs in 11-month-old APP/PS1 mice, which represented advanced AD, effectively prevented the loss of body weight, increased survival rates, and significantly reduced oxidative stress, Aβ aggregation, neuronal apoptosis, and synaptic damage in the brain. It also ultimately reversed severely impaired cognitive function. In addition to their favorable anti-AD effects, HQ NPs exhibited excellent biosafety and biocompatibility owing to their natural composition and are expected to become an ideal choice for future drug development and clinical applications.

Programmably tiling rigidified DNA brick on gold nanoparticle as multi-functional shell for cancer-targeted delivery of siRNAs

Small interfering RNA (siRNA) is an effective therapeutic to regulate the expression of target genes in vitro and in vivo. Constructing a siRNA delivery system with high serum stability, especially responsive to endogenous stimuli, remains technically challenging. Herein we develop anti-degradation Y-shaped backbone-rigidified triangular DNA bricks with sticky ends (sticky-YTDBs) and tile them onto a siRNA-packaged gold nanoparticle in a programmed fashion, forming a multi-functional three-dimensional (3D) DNA shell. After aptamers are arranged on the exterior surface, a biocompatible siRNA-encapsulated core/shell nanoparticle, siRNA/Ap-CS, is achieved. SiRNAs are internally encapsulated in a 3D DNA shell and are thus protected from enzymatic degradation by the outermost layer of YTDB. The siRNAs can be released by endogenous miRNA and execute gene silencing within tumor cells, causing cell apoptosis higher than Lipo3000/siRNA formulation. In vivo treatment shows that tumor growth is completely (100%) inhibited, demonstrating unique opportunities for next-generation anticancer-drug carriers for targeted cancer therapies.

A tumor-activatable peptide supramolecular nanoplatform for the delivery of dual-gene targeted siRNAs for drug-resistant cancer treatment

Combinatorial short interference RNA (siRNA) technology for the silencing of multiple genes is expected to provide an effective therapeutic approach for cancer with complex genetic mutation and dysregulation. Herein we present a tumor-activatable supramolecular nanoplatform for the delivery of siRNAs to target telomerase and telomeres for paclitaxel-resistant non-small-cell lung cancer (A549/PTX) treatment. Two different sequences of siRNA are incorporated in a single nanoparticle, which is obtained by self-assembly from a peptide dendrimer. The siRNA stability is improved by the nanoparticle in the presence of serum compared to free siRNA, and these siRNAs are protected from RNA enzyme degradation. In the tumor extracellular acid environment, the PEG corona of the nanoparticle is removed to promote the internalization of siRNAs into tumor cells. The disulfide linkages between the nanoparticle and siRNAs are cleared in the reductive environment of the tumor cells, and the siRNAs are released in the cytoplasm. In vitro experiments show that the gene expression of hTERT and TRF2 at the mRNA and protein levels of A549/PTX tumor cells is down-regulated, which results in cooperative restraining proliferation and invasion of A549/PTX tumor cells. For the tumor cell-targeting function of the MUC1 aptamer and the EPR effect, sufficient tumor accumulation of nanoparticles was observed. Meanwhile, a shift of negative surface charge of nanoparticles to positive charge in the tumor extracellular microenvironment enhances deep penetration of siRNA-incorporating nanoparticles into tumor tissues. In vivo animal studies support that successful down-regulation of hTERT and TRF2 gene expression achieves effective inhibition of the growth and neovascularization of drug-resistant tumor cells. This work has provided a new avenue for drug-resistant cancer treatment by designing and synthesizing a tumor-activatable nanoplatform to achieve the delivery of dual-gene targeted combinatorial siRNAs.

Preparation Optimization of Bovine Serum Albumin Nanoparticles and Its Application for siRNA Delivery

BACKGROUND

siRNA brings hope for cancer therapy. However, there are many obstacles for application of siRNA in clinical. Because of the excellent biocompatibility, non-toxicity and non-immunogenicity of bovine serum albumin (BSA), BSA-based nanoparticles have been widely designed as a drug carrier system.

METHODS

The optimal formula for BSA NPs preparation was investigated by central composite design response surface methodology (CCD-RSM), BSA-based survivin-siRNA delivery system (BSA NPs/siRNA) was characterized by dynamic light scattering, atomic force microscope, transmission electron microscope and Bradford method. The in vitro anti-tumor effect and mechanism of BSA NPs were investigated by confocal microscopic imaging, MTT assay, RT-qPCR and ELISA analysis. Moreover, the anti-tumor effect, distribution and biosafety of BSA NPs were studied in vivo.

RESULTS

The optimal formula for BSA NPs was settled to be 20 mg/mL for BSA concentration, 9 for pH value, 136% for crosslinking degree and 1.6 mL/min for speed of ethanol addition. BSA NPs/siRNA could remain stable at 4°C for 4 weeks and protect siRNA from degradation by RNase A. Besides, BSA NPs/siRNA could maintain a sustained release of siRNA and promote the uptake of siRNA significantly. The survivin-mRNA level and the survivin-protein level were decreased by 55% ± 1.6% and 54% ± 1.6% separately. The in vivo tumor inhibition results suggested that the tumor inhibition rate of BSA NPs/siRNA-treated group was 54% ± 12% and was similar with that of DOX-treated group (57% ± 9.2%, P > 0.05). The biosafety results confirmed that BSA NPs/siRNA could not induce significant damages to the main organs and blood in vivo.

CONCLUSION

These results demonstrated that CCD-RSM was an effective tool for preparation analysis, and the BSA NPs/siRNA was a promising system for siRNA-based gene therapy.

Albumin-based nanoparticles: a promising strategy to overcome cancer drug resistance

Circumvention of cancer drug resistance is one of the major investigations in nanomedicine. In this regard, nanotechnology-based drug delivery has offered various implications. However, protein-based nanocarriers have been a versatile choice compared to other nanomaterials, provided by their favorable characteristics and safety profiles. Specifically, albumin-based nanoparticles have been demonstrated to be an effective drug delivery system, owing to the inherent targeting modalities of albumin, through gp60- and SPARC-mediated receptor endocytosis. Furthermore, surface functionalization was exploited for active targeting, due to albumin’s abundance of carboxylic and amino groups. Stimuli-responsive drug release has also been pertained to albumin nano-systems. Therefore, albumin-based nanocarriers could potentially overcome cancer drug resistance through bypassing drug efflux, enhancing drug uptake, and improving tumor accumulation. Moreover, albumin nanocarriers improve the stability of various therapeutic cargos, for instance, nucleic acids, which allows their systemic administration. This review highlights the recent applications of albumin nanoparticles to overcome cancer drug resistance, the nano-fabrication techniques, as well as future perspectives and challenges.

A non-viral nano-delivery system targeting epigenetic methyltransferase EZH2 for precise acute myeloid leukemia therapy

Acute myeloid leukemia (AML), which is common in the elderly population, accounts for poor long-term survival with a high possibility of relapse. The associated lack of currently developed therapeutics is directing the search for new therapeutic targets relating to AML. EZH2 (Enhancer of Zeste Homolog 2) is a histone methyltransferase member of the polycomb-group (PcG) family, and its significant overexpression in AML means it has emerged as a potential epigenetic target. Here, we propose the human serum albumin (HSA) nanoparticle based delivery of small interfering RNA (siRNA), which can target EZH2-expressing genes in AML. EZH2 specific siRNA loaded in a polyethyleneimine (PEI) conjugated HSA nanocarrier can overcome the systemic instability of siRNA and precisely target the AML cell population for increased EZH2 gene silencing. A stable nanosized complex (HSANPs-PEI@EZH2siRNA), achieved via the electrostatic interaction of PEI and EZH2 siRNA, shows increased systemic stability and hemocompatibility, and enhanced EZH2 gene silencing activity in vitro, compared to conventional transfection reagents. HSANPs-PEI@EZH2siRNA-treated AML cells showed downregulated EZH2, which is associated with a reduced level of Bmi-1 protein, and H3K27me3 and H2AK119ub modification. The ubiquitin-mediated proteasomal degradation pathway plays a critical role in the downregulation of associated proteins following HSANPs-PEI@EZH2siRNA exposure to AML cells. c-Myb is the AML-responsive transcription factor that directly binds on the EZH2 promoter and was downregulated in HSANPs-PEI@EZH2siRNA-treated AML cells. The systemic exposure to HSANPs-PEI@EZH2siRNA of AML engrafted immunodeficient nude mice displayed efficient EZH2 gene silencing and a reduced AML cell population in peripheral blood and bone marrow. The present study demonstrates a non-viral siRNA delivery system for epigenetic targeting based superior anti-leukemic therapy.

Nanotechnology for angiogenesis: opportunities and challenges

Angiogenesis plays a critical role within the human body, from the early stages of life (i.e., embryonic development) to life-threatening diseases (e.g., cancer, heart attack, stroke, wound healing). Many pharmaceutical companies have expended huge efforts on both stimulation and inhibition of angiogenesis. During the last decade, the nanotechnology revolution has made a great impact in medicine, and regulatory approvals are starting to be achieved for nanomedicines to treat a wide range of diseases. Angiogenesis therapies involve the inhibition of angiogenesis in oncology and ophthalmology, and stimulation of angiogenesis in wound healing and tissue engineering. This review aims to summarize nanotechnology-based strategies that have been explored in the broad area of angiogenesis. Lipid-based, carbon-based and polymeric nanoparticles, and a wide range of inorganic and metallic nanoparticles are covered in detail. Theranostic and imaging approaches can be facilitated by nanoparticles. Many preparations have been reported to have a bimodal effect where they stimulate angiogenesis at low dose and inhibit it at higher doses.

Exosome-mediated siRNA delivery to suppress postoperative breast cancer metastasis

High recurrence and metastasis of triple-negative breast cancer (TNBC) after operation is a leading cause of breast cancer related death. The pre-metastatic niche (PMN) is an environment in a secondary organ conducive to the metastasis of a primary tumor. Herein, we identify exosomes from autologous breast cancer cells that show effective lung targeting ability. Based on this, we developed the biomimetic nanoparticles (cationic bovine serum albumin (CBSA) conjugated siS100A4 and exosome membrane coated nanoparticles, CBSA/siS100A4@Exosome) to improve drug delivery to the lung PMN. CBSA/siS100A4@Exosome self-assembled nanoparticles formed homogeneous sizes of ~200 nm, protected siRNA from degradation, and showed excellent biocompatibility. Further in vivo studies showed that CBSA/siS100A4@Exosome had a higher affinity toward lung in comparison to the CBSA/siS100A4@Liposome, and exhibited outstanding gene-silencing effects that significantly inhibited the growth of malignant breast cancer cells. Taken together, these results indicate that CBSA/siS100A4@Exosome self-assembled nanoparticles are a promising strategy to suppress postoperative breast cancer metastasis.

High siRNA loading powder for inhalation prepared by co-spray drying with human serum albumin

The development of small interfering RNA (siRNA) formulation for pulmonary delivery is a key to the clinical translation of siRNA therapeutics for the treatment of respiratory diseases. Most inhalable siRNA powder formulations published to date were limited by the siRNA content which was often too low to be clinically relevant. This study aimed to prepare inhalable siRNA powder formulations that contained high siRNA loading of over 6% w/w by spray drying, with human serum albumin (HSA) investigated as a dispersion enhancer to improve the aerosol performance. The effect of siRNA, HSA and solute concentrations in the formulations were evaluated systemically using factorial analyses. All the spray dried siRNA powders exhibited excellent aerosol performance with fine particle fraction (FPF) consistently over 50% in all the formulations. An enrichment of HSA on the particle surface was observed. Surface corrugation was more prominent as HSA composition increased. Importantly, the bioactivity of siRNA was successfully preserved upon spray drying as demonstrated in the in vitro transfection study, and up to 78% of intact siRNA retained in the spray dried powder. Overall, HSA is an effective dispersion enhancer and spray drying is an appropriate technique to produce inhalable dry powder with high siRNA loading for further investigation.

Tumor-Specific Expansion of Oxidative Stress by Glutathione Depletion and Use of a Fenton Nanoagent for Enhanced Chemodynamic Therapy

Amplifying intracellular oxidative stress effectively destroys cancer cells. In addition, iron-mediated Fenton reaction converts endogenous H₂O₂ to produce hypertoxic hydroxyl radical (^•OH), resulting in irreversible oxidative damage to combat tumor cells. This method is known as chemodynamic therapy (CDT). Overexpressed glutathione (GSH) in tumor cells efficiently scavenges ^•OH, significantly reducing the curative effects of CDT. To overcome this challenge and enhance intracellular oxidative stress, iron oxide nanocarriers loaded with β-lapachone (Lapa) drugs (Fe₃O₄-HSA@Lapa) were constructed and had both Fenton-like agents and GSH depletion properties to amplify intracellular oxidative stress. Release of Lapa selectively increases tumor site-specific generation of H₂O₂ via NAD(P)H: quinone oxidoreductase 1 (NQO1) catalysis. Subsequently, the iron ions released from the ionization of Fe₃O₄ in the acidic environment selectively convert H₂O₂ into highly toxic ^•OH by Fenton reaction, dramatically improving CDT with minimal systemic toxicity due to low NQO1 expression in normal tissues. Meanwhile, released Lapa consumes GSH in the tumor, amplifying oxidative stress and enhancing the efficacy of CDT. Designed Fe₃O₄-HSA@Lapa nanoparticles (NPs) exhibit perfect targeting capability, prolonged blood circulation, and increased tumor accumulation. Furthermore, Fe₃O₄-HSA@Lapa NPs effectively enhance the inhibition of tumor growth and reduce the side effects of anticancer drugs. This work establishes a remarkably enhanced tumor-selective CDT against NQO1-overexpressing tumors by significantly inducing intratumoral oxidative stress with minimal side effects.

Current Transport Systems and Clinical Applications for Small Interfering RNA (siRNA) Drugs

Small interfering RNAs (siRNAs) are an attractive new agent with potential as a therapeutic tool because of its ability to inhibit specific genes for many conditions, including viral infections and cancers. However, despite this potential, many challenges remain, including off-target effects, difficulties with delivery, immune responses, and toxicity. Traditional genetic vectors do not guarantee that siRNAs will silence genes in vivo. Rational design strategies, such as chemical modification, viral vectors, and non-viral vectors, including cationic liposomes, polymers, nanocarriers, and bioconjugated siRNAs, provide important opportunities to overcome these challenges. We summarize the results of research into vector delivery of siRNAs as a therapeutic agent from their design to clinical trials in ophthalmic diseases, cancers, respiratory diseases, and liver virus infections. Finally, we discuss the current state of siRNA delivery methods and the need for greater understanding of the requirements.

Development and evaluation of a CEACAM6-targeting theranostic nanomedicine for photoacoustic-based diagnosis and chemotherapy of metastatic cancer

Metastasis is the leading cause of cancer-related deaths. A number of chemotherapeutic and early diagnosis strategies, including nanomedicine, have been developed to target metastatic tumor cells. However, simultaneous inhibition and imaging of metastasis is yet to be fully achieved. Methods: To overcome this limitation, we have developed human serum albumin-based nanoparticles (tHSA-NPs) with photoacoustic imaging capability, which target carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6). CEACAM6 is highly expressed in metastatic anoikis-resistant tumor cells. Results:In vitro, the CEACAM6-targeting tHSA-NPs efficiently targeted CEACAM6-overexpressing metastatic anoikis-resistant tumor cells. In vivo, CEACAM6-targeting tHSA-NPs administered intravenously to BALB/c nude mice efficiently inhibited lung metastasis in circulating anoikis-resistant tumor cells compared to the controls. In addition, anoikis-resistant tumor cells can be successfully detected by photoacoustic imaging, both in vitro and in vivo, using the intrinsic indocyanine green-binding affinity of albumin. Conclusion: In summary, the CEACAM6-targeting albumin-based nanoparticles allowed the delivery of drugs and photoacoustic imaging to metastatic anoikis-resistant tumor cells in vitro and in vivo. Based on the expression of CEACAM6 in a variety of tumors, CEACAM6-targeting nanomedicine might be used to target various types of metastatic tumor cells.

Roles of Albumin-Binding Proteins in Cancer Progression and Biomimetic Targeted Drug Delivery

Nutrient transporters have attracted significant attention for their promising application in biomimetic delivery. Due to the active consumption of nutrients, cancer cells generally overexpress nutrient transporters to meet their increased need for energy and materials. For example, albumin-binding proteins (ABPs) are highly overexpressed in malignant cells, stromal cells, and tumor vessel endothelial cells responsible for albumin uptake. ABP (e.g., SPARC) is a promising target for tumor-specific drug delivery, and albumin has been widely used as a biomimetic delivery carrier. Apart from the transportation function, ABPs are closely associated with neoplasia, invasion, and metastasis. Herein, a summary of the roles of ABP in cancer progression and the application of albumin-based biomimetic tumor-targeted delivery through the ABP pathway is presented.

Harnessing albumin as a carrier for cancer therapies

Serum albumin, a natural ligand carrier that is highly concentrated and long-circulating in the blood, has shown remarkable promise as a carrier for anti-cancer agents. Albumin is able to prolong the circulation half-life of otherwise rapidly cleared drugs and, importantly, promote their accumulation within tumors. The applications for using albumin as a cancer drug carrier are broad and include both traditional cancer chemotherapeutics and new classes of biologics. Strategies for leveraging albumin for drug delivery can be classified broadly into exogenous and in situ binding formulations that utilize covalent attachment, non-covalent association, or encapsulation in albumin-based nanoparticles. These methods have shown remarkable preclinical and clinical successes that are examined in this review.

Human serum albumin nanoparticles for ocular delivery of bevacizumab

Bevacizumab-loaded nanoparticles (B-NP) were prepared by a desolvation process followed by freeze-drying, without any chemical, physical or enzymatic cross-linkage. Compared with typical HSA nanoparticles cross-linked with glutaraldehyde (B-NP-GLU), B-NP displayed a significantly higher mean size (310 nm vs. 180 nm) and a lower negative zeta potential (-15 mV vs. -36 mV). On the contrary, B-NP displayed a high payload of approximately 13% when measured by a specific ELISA, whereas B-NP-GLU presented a very low bevacizumab loading (0.1 μg/mg). These results could be related to the inactivation of bevacizumab after reacting with glutaraldehyde. From B-NP, bevacizumab was released following an initial burst effect, proceeded by a continuous release of bevacizumab at a rate of 6 μg/h. Cytotoxicity studies in ARPE cells were carried out at a single dose up to 72 h and with repeated doses over a 5-day period. Neither bevacizumab nor B-NP altered cell viability even when repeated doses were used. Finally, B-NP were labeled with ^99mTc and administered as eye drops in rats. ^99mTc-B-NP remained in the eye for at least 4 h while ^99mTc-HSA was rapidly drained from the administration point. In summary, HSA nanoparticles may be an appropriate candidate for ocular delivery of bevacizumab.

Enhancing the Therapeutic Delivery of Oligonucleotides by Chemical Modification and Nanoparticle Encapsulation

Oligonucleotide (ON) drugs, including small interfering RNA (siRNA), microRNA (miRNA) and antisense oligonucleotides, are promising therapeutic agents. However, their low membrane permeability and sensitivity to nucleases present challenges to in vivo delivery. Chemical modifications of the ON offer a potential solution to improve the stability and efficacy of ON drugs. Combined with nanoparticle encapsulation, delivery at the site of action and gene silencing activity of chemically modified ON drugs can be further enhanced. In the present review, several types of ON drugs, selection of chemical modification, and nanoparticle-based delivery systems to deliver these ON drugs are discussed.

Role of the Protein Corona Derived from Human Plasma in Cellular Interactions between Nanoporous Human Serum Albumin Particles and Endothelial Cells

The presence of a protein corona on various synthetic nanomaterials has been shown to strongly influence how they interact with cells. However, it is unclear if the protein corona also exists on protein particles, and if so, its role in particle-cell interactions. In this study, pure human serum albumin (HSA) particles were fabricated via mesoporous silica particle templating. Our data reveal that various serum proteins adsorbed on the particles, when exposed to human blood plasma, forming a corona. In human umbilical vein endothelial cells (HUVECs), the corona was shown to decrease particle binding to the cell membrane, increase the residence time of particles in early endosomes, and reduce the amount of internalized particles within the first hours of exposure to particles. These findings reveal important information regarding the mechanisms used by vascular endothelial cells to internalize protein-based particulate materials exposed to blood plasma. The ability to control the cellular recognition of these organic particles is expected to aid the advancement of HSA-based materials for intravenous drug delivery.

Serum albumin as a local therapeutic agent in cell therapy and tissue engineering

Albumin is a major plasma protein that has become ubiquitous in regenerative medicine research. As such, many studies have examined its structure and advantageous properties. However, a systematic and comprehensive understanding of albumin's role, capabilities and therapeutic potential still eludes the field. In the present work, we review how albumin is applied in tissue engineering, including cell culture and storage, in vitro fertilization and transplantation. Furthermore, we discuss how albumin's physiological role extends beyond a carrier for metal ions, fatty acids, pharmacons and growth factors. Albumin acts as a bacteriostatic coating that simultaneously promotes attachment and proliferation of eukaryotic cells. These properties with the combination of free radical scavenging, neutrophil activation and as a buffer molecule already make the albumin protein beneficial in healing processes supporting functional tissue remodeling. Nevertheless, recent data revealed that albumin can be synthesized by osteoblasts and its local concentration is raised after bone trauma. Interestingly, by increasing the local albumin concentration in vivo, faster bone healing is achieved, possibly because albumin recruits endogenous stem cells and promotes the growth of new bone. These data also suggest an active role of albumin, even though a specific receptor has not yet been identified. Together, this discussion sheds light on why the extravascular use of the albumin molecule is in the scope of scientific investigations and why it should be considered as a local therapeutic agent in regenerative medicine. © 2016 BioFactors, 43(3):315-330, 2017.

Delivery strategies and potential targets for siRNA in major cancer types

Small interfering RNA (siRNA) has gained attention as a potential therapeutic reagent due to its ability to inhibit specific genes in many genetic diseases. For many years, studies of siRNA have progressively advanced toward novel treatment strategies against cancer. Cancer is caused by various mutations in hundreds of genes including both proto-oncogenes and tumor suppressor genes. In order to develop siRNAs as therapeutic agents for cancer treatment, delivery strategies for siRNA must be carefully designed and potential gene targets carefully selected for optimal anti-cancer effects. In this review, various modifications and delivery strategies for siRNA delivery are discussed. In addition, we present current thinking on target gene selection in major tumor types.

Technological development of structural DNA/RNA-based RNAi systems and their applications

RNA interference (RNAi)-based gene therapy has drawn tremendous attention due to its highly specific gene regulation by selective degradation of any target mRNA. There have been multiple reports regarding the development of various cationic materials for efficient siRNA delivery, however, many studies still suffer from the conventional delivery problems such as suboptimal transfection performance, a lack of tissue specificity, and potential cytotoxicity. Despite the huge therapeutic potential of siRNAs, conventional gene carriers have failed to guarantee successful gene silencing in vivo, thus not warranting clinical trials. The relatively short double-stranded structure of siRNAs has resulted in uncompromising delivery formulations, as well as low transfection efficiency, compared with the conventional nucleic acid drugs such as plasmid DNAs. Recent developments in structural siRNA and RNAi nanotechnology have enabled more refined and reliable in vivo gene silencing with multiple advantages over naked siRNAs. This review focuses on recent progress in the development of structural DNA/RNA-based RNAi systems and their potential therapeutic applications. In addition, an extensive list of prior reports on various RNAi systems is provided and categorized by their distinctive molecular characters.

Pharmacokinetics and biodistribution of recently-developed siRNA nanomedicines

Small interfering RNA (siRNA) is a promising drug candidate, expected to have broad therapeutic potentials toward various diseases including viral infections and cancer. With recent advances in bioconjugate chemistry and carrier technology, several siRNA-based drugs have advanced to clinical trials. However, most cases address local applications or diseases in the filtering organs, reflecting remaining challenges in systemic delivery of siRNA. The difficulty in siRNA delivery is in large part due to poor circulation stability and unfavorable pharmacokinetics and biodistribution profiles of siRNA. This review describes the pharmacokinetics and biodistribution of siRNA nanomedicines, focusing on those reported in the past 5years, and their pharmacological effects in selected disease models such as hepatocellular carcinoma, liver infections, and respiratory diseases. The examples discussed here will provide an insight into the current status of the art and unmet needs in siRNA delivery.

Reducible Dimeric Conjugates of Small Internally Segment Interfering RNA for Efficient Gene Silencing

The condensation of nucleic acids into compact nanoparticles with cationic carriers is a powerful tool for translocating exogenous nucleic acids into cells. To date, most efforts have been focused on the development of novel gene carriers for safe and efficient gene delivery. However, small interfering RNA (siRNA) is generally not strongly associated with cationic carriers due to its stiff structure and low spatial charge density. To overcome this limitation, this work introduces a well-defined dimeric conjugate of small internally segment interfering RNA (sisiRNA) linked via a disulfide bond for enhanced cellular uptake and gene silencing. Dimeric sisiRNA is synthesized through oxidizing two monomeric sisiRNA molecules, each of which consists of a sense strand carrying a nick and an antisense strand modified with a thiol group at the 3'-end. The nick in the sense strand enables the dimeric sisiRNA to be more effectively condensed into nanosized complexes due to the increased structural flexibility, which results in a higher gene silencing efficiency compared with the dimeric siRNA containing the intact sense strands. The results indicate that the discontinuity of the sense strands is a simple method of adding more flexibility to various siRNA-based nanostructures for enhanced gene silencing.

A toxic organic solvent-free technology for the preparation of PEGylated paclitaxel nanosuspension based on human serum albumin for effective cancer therapy

Clinically, paclitaxel (PTX) is one of most commonly prescribed therapies against a wide range of solid neoplasms. Despite its success, the clinical applicability of PTX (Taxol^®) is severely hampered by systemic toxicities induced by Cremophor EL. While attempts to bypass the need for Cremophor EL have been developed through platforms such as Abraxane™, nab™ relies heavily on the use of organic solvents, namely, chloroform. The toxicity introduced by residual chloroform poses a potential risk to patient health. To mitigate the toxicities of toxic organic solvent-based manufacture methods, we have designed a method for the formulation of PTX nanosuspensions (PTX-PEG [polyethylene glycol]-HSA [human serum albumin]) that eliminates the dependence on toxic organic solvents. Coined the solid-dispersion technology, this technique permits the dispersion of PTX into PEG skeleton without the use of organic solvents or Cremophor EL as a solubilizer. Once the PTX-PEG dispersion is complete, the dispersion can be formulated with HSA into nanosuspensions suitable for intravenous administration. Additionally, the incorporation of PEG permits the prolonged circulation through the steric stabilization effect. Finally, HSA-mediated targeting permits active receptor-mediated endocytosis for enhanced tumor uptake and reduced side effects. By eliminating the need for both Cremophor EL and organic solvents while simultaneously increasing antitumor efficacy, this method provides a superior alternative to currently accepted methods for PTX delivery.

SiRNA gene therapy using albumin as a carrier

RNA interference or post-transcriptional gene silencing is one of the latest, innovative, highly specific, and efficient technologies for gene therapy application in molecular oncology. It is already a well-established research tool for analyses of molecular mechanisms for various diseases including cancer as it efficiently silences the expression of genes of interest. However, for its proper therapeutic use, an efficient tumor-specific in-vivo delivery mechanism is essential. Many scientific groups and companies are involved in the development of efficient in-vivo delivery mechanisms for small interfering RNA, but are still struggling. The present article suggests utilization of albumin as a delivery module for small interfering RNA as it is an endogenous natural nanoparticle known for its binding properties to various endogenous metabolites, drugs, and metal ions.

Co-delivery of VEGF and Bcl-2 dual-targeted siRNA polymer using a single nanoparticle for synergistic anti-cancer effects in vivo

Cancer is a multifactorial disease which involves complex genetic mutation and dysregulation. Combinatorial RNAi technology and concurrent multiple gene silencing are expected to provide advanced strategies for effective cancer therapy, but a safe and effective carrier system is a prerequisite to successful siRNA delivery in vivo. We previously developed an effective tumor-targeting siRNA delivery system for in vivo application. In response to the success of this development, herein we present a dual-gene targeted siRNA and its delivery system, to achieve synergistic effects in cancer therapy. Two different sequences of siRNA were chemically modified to be randomly copolymerized in a single backbone of siRNA polymer (Dual-poly-siRNA), and the resulting Dual-poly-siRNA was incorporated into tumor-homing glycol chitosan nanoparticles. Based on the stability in serum and delivery in a tumor-targeted manner, intravenously administered Dual-poly-siRNA carrying glycol chitosan nanoparticles (Dual-NP) demonstrated successful dual-gene silencing in tumors. Notably, co-delivery of VEGF and Bcl-2 targeting siRNA led to more effective cancer therapy for convenient application.

Notch1 targeting siRNA delivery nanoparticles for rheumatoid arthritis therapy

Notch pathway plays a pivotal role in synoviocytes involved in progression of rheumatoid arthritis (RA). Herein, we designed the Notch1 targeting siRNA delivery nanoparticles (siRNA-NPs) in order to confirm the anti-inflammatory effect in collagen-induced arthritis (CIA) model. The siRNA-NPs were successfully produced by encapsulating polymerized siRNA (poly-siRNA) into thiolated glycol chitosan (tGC) nanoparticles in aqueous condition. The in vitro Notch1 inhibition of siRNA-NPs in murine macrophage cell (RAW 264.7) was confirmed using confocal microscopy and real time PCR. Fluorescently labeled siRNA-NPs were successfully transfected in RAW 264.7 and modulated the expression of Notch1 in mRNA level. For in vivo study, siRNA-NPs exhibited the higher targeting efficiency in the arthritic joins of CIA mice, confirmed by the near-infrared fluorescence (NIRF) imaging. Furthermore, inhibition of Notch1 with siRNA-NPs resulted in retarded progression of inflammation, bone erosion, and cartilage damage in CIA mice. Novel Notch1 targeting siRNA delivery system of siRNA-NPs showed effective RA treatment by suppressing Notch1 signaling pathway without undesirable severe toxicity. Thus, Notch1 inhibiting siRNA-NPs demonstrated the great potential in RA therapeutics that was hard to be achieved using conventional drugs.

Enhanced gene silencing through human serum albumin-mediated delivery of polyethylenimine-siRNA polyplexes

Small interfering RNA (siRNA) targeted therapeutics (STT) offers a compelling alternative to tradition medications for treatment of genetic diseases by providing a means to silence the expression of specific aberrant proteins, through interference at the expression level. The perceived advantage of siRNA therapy is its ability to target, through synthetic antisense oligonucleotides, any part of the genome. Although STT provides a high level of specificity, it is also hindered by poor intracellular uptake, limited blood stability, high degradability and non-specific immune stimulation. Since serum proteins has been considered as useful vehicles for targeting tumors, in this study we investigated the effect of incorporation of human serum albumin (HSA) in branched polyethylenimine (bPEI)-siRNA polyplexes in their internalization in epithelial and endothelial cells. We observed that introduction of HSA preserves the capacity of bPEI to complex with siRNA and protect it against extracellular endonucleases, while affording significantly improved internalization and silencing efficiency, compared to bPEI-siRNA polyplexes in endothelial and metastatic breast cancer epithelial cells. Furthermore, the uptake of the HSA-bPEI-siRNA ternary polyplexes occurred primarily through a caveolae-mediated endocytosis, thus providing evidence for a clear role for HSA in polyplex internalization. These results provide further impetus to explore the role of serum proteins in delivery of siRNA.

Enhanced antitumor efficacies of multifunctional nanocomplexes through knocking down the barriers for siRNA delivery

Multifunctional nanocomplexes (NCs) consisting of urocanic acid-modified galactosylated trimethyl chitosan (UA-GT) conjugates as polymeric vectors, poly(allylamine hydrochloride)-citraconic anhydride (PAH-Cit) as charge-reversible crosslinkers, and vascular endothelial growth factor (VEGF) siRNA as therapeutic genes, were rationally designed to simultaneously overcome the extracellular, cellular, and intracellular barriers for siRNA delivery. The strong physical stability of UA-GT/PAH-Cit/siRNA NCs (UA-GT NCs) at pH 7.4 and 6.5 endowed protection from massive dilution, competitive ions, and ubiquitous nucleases in the blood and tumorous microenvironment. Their internalization into hepato-carcinoma cells was facilitated through the recognition of galactose receptors, followed by effective escape from endosomes/lysosomes owing to the strong buffering capacity of imidazole residues. At the meantime, the endosomal/lysosomal acidity triggered the charge reversal of PAH-Cit in UA-GT NCs, thus evoking their structural disassembly and subsequently accelerated release of siRNA in the cytosol. As a result, robust in vivo performance in terms of both gene silencing and tumor inhibition was achieved by UA-GT NCs at a low siRNA dose. Moreover, neither histological nor hematological toxicity was detected following repeated intravenous administration. Therefore, UA-GT NCs potentially served as an efficient and safe candidate in the treatment of hepatocellular carcinoma through knocking down the overall barriers for siRNA delivery.