Bio-nanocapsule conjugated with liposomes for in vivo pinpoint delivery of various materials. J Control Release. 2008;126:255-264. [PMID: 18207275 DOI: 10.1016/j.jconrel.2007.12.002]

In Vivo Evaluation of the ZHER2-BNC/LP Carrier Encapsulating an Anticancer Drug and a Radiosensitizer

Radiosensitizing therapy for cancer treatment that enhances the effect of existing radiation therapy and enables noninvasive therapy has attracted attention. In this study, to achieve target cell-specific noninvasive cancer treatment using a Z_HER2-bionanocapsule/liposome (BNC/LP), a carrier that binds to human epidermal growth factor receptor 2 (HER2), we evaluated the delivery of anticancer drugs and radiosensitizers and treatment effects in vitro and in vivo in mice. Target cell-specific cytotoxic activity and antitumor effects were confirmed following delivery of doxorubicin-encapsulated particles. In addition, cell damage due to radiosensitizing effects was confirmed in combination with X-ray irradiation following delivery of particles containing polyacrylic acid-modified titanium peroxide nanoparticles as a radiosensitizer. Furthermore, even when the particles were injected via the tail vein of mice, they accumulated in the tumor and exhibited an antitumor effect because of radiosensitization. Therefore, Z_HER2-BNC/LP is expected to be a carrier that releases small-molecule drugs into the target cell cytoplasm and delivers a radiosensitizer such as inorganic nanoparticles, enabling combination therapy with X-rays to the target tumor.

A Novel Hybrid Drug Delivery System for Treatment of Aortic Aneurysms

Ongoing aortic wall degeneration and subsequent aneurysm exclusion failure are major concerns after an endovascular aneurysm repair with a stent-graft. An ideal solution would be a drug therapy that targets the aortic wall and inhibits wall degeneration. Here, we described a novel drug delivery system, which allowed repetitively charging a graft with therapeutic drugs and releasing them to the aortic wall in vivo. The system was composed of a targeted graft, which was labeled with a small target molecule, and the target-recognizing nanocarrier, which contained suitable drugs. We developed the targeted graft by decorating a biotinylated polyester graft with neutravidin. We created the target-recognizing nanocarrier by conjugating drug-containing liposomes with biotinylated bio-nanocapsules. We successfully demonstrated that the target-recognizing nanocarriers could bind to the targeted graft, both in vitro and in blood vessels of live mice. Moreover, the drug released from our drug delivery system reduced the expression of matrix metalloproteinase-9 in mouse aortas. Thus, this hybrid system represents a first step toward an adjuvant therapy that might improve the long-term outcome of endovascular aneurysm repair.

[DDS Nanocarriers Mimicking Early Infection Machinery of Viruses]

Viruses are natural nanocarriers that deliver various biological cargos, such as DNA, RNA, and proteins. We are developing a new nanocarrier by mimicking the early mechanism of infection by hepatitis B virus (HBV). When the HBV envelope L protein is overexpressed in yeast cells, hollow nanoparticles displaying L proteins are synthesized. This nanoparticle, namely a bio-nanocapsule (BNC), can specifically attach to, and then internalize into, human hepatic cells by implementing the early mechanism of infection by HBV. In this review, we outlined the cellular uptake mechanism of HBV/BNC linking to L protein function. The L protein contains several functional domains in the pre-S1 region, including the fusogenic domain and the heparin-binding domain. The fusogenic domain corresponding to the pre-S1(9-24) region is responsible for the low pH-dependent membrane fusion of BNC. The heparin-binding domain corresponding to the pre-S1(30-42) region has a strong affinity to heparin as compared to that of known heparin-binding peptides, such as vitronectin and gp120 in human immunodeficiency virus-1. This heparin-binding domain binds to heparan sulfate proteoglycan (HSPG) at the cell surface of human hepatic cells. These functional domains are present in any virus, thus, these viral envelope proteins are very useful in designing novel DDS nanocarriers.

In vivo uterine local gene delivery system using TAT-displaying bionanocapsules

BACKGROUND

The uterus is an organ that is directly accessible via the transvaginal route, whereas the drug delivery system and the gene delivery system (GDS) for the uterus are very limited, even in animal models. In the present study, we optimized a bionanocapsule (BNC) comprising a hepatitis B virus envelope L-protein particle, for which a structurally similar particle has been used as an immunogen of a conventional HB vaccine worldwide for more than 30 years, as a local uterine GDS using a mouse model.

METHODS

To display various antibodies for re-targeting to different cells other than hepatic cells, the pre-S1 region of BNC was replaced with a tandem form of the protein A-derived immunoglobulin G Fc-interacting region (Z domain, ZZ-BNC). To induce strong cell adhesion after local administration into the uterine cavity, ZZ-BNC was modified with a transactivator of transcription (TAT) peptide.

RESULTS

Gene transfer using TAT-modified ZZ-BNC is approximately 5000- or 18-fold more efficient than the introduction of the same dose of naked DNAs or the use of the cationic liposomes, respectively. TAT-modified ZZ-BNC was rapidly eliminated from the uterus and had no effect on the pregnancy rate, litter size or fetal growth.

CONCLUSIONS

TAT-modified ZZ-BNC could be a useful GDS for uterine endometrial therapy via local uterine injection.

A hepatitis B virus-derived human hepatic cell-specific heparin-binding peptide: identification and application to a drug delivery system

Viruses are naturally evolved nanocarriers that can evade host immune systems, attach specifically to the surfaces of target cells, enter the cells through endocytosis, escape from endosomes efficiently, and then transfer their genomes to host cells. Hepatitis B virus (HBV) is a ∼42 nm enveloped DNA virus that can specifically infect human hepatic cells. To utilize the HBV-derived early infection machinery in synthetic nanocarriers, the human hepatic cell-binding site (i.e., the sodium taurocholate co-transporting polypeptide (NTCP)-binding site, with myristoylated pre-S1(2-47)) and the low pH-dependent fusogenic domain (pre-S1(9-24)) are indispensable for targeting and endosomal escape, respectively. However, cell-surface NTCP has recently been shown not to be involved in the initial attachment of HBV. In this study, we identified a novel heparin-binding site (pre-S1(30-42)) in the N-terminal half of the pre-S1 region, which presumably interacts with cell-surface heparan sulfate proteoglycan (HSPG) and plays a pivotal role in the initial attachment of HBV to human hepatic cells. The evolutionarily conserved amino acid residues Asp-31, Trp-32, and Asp-33 are indispensable for the heparin-binding activity. Liposomes (LPs) displaying the peptide were endocytosed by human hepatic cells in a cell-surface heparin-dependent manner and delivered doxorubicin to human hepatic cells more efficiently than myristoylated pre-S1(2-47)-displaying LPs. These results demonstrated that the pre-S1(30-42) peptide is the most promising HBV-derived targeting peptide for synthetic nanocarriers, and that this peptide exhibits high specificity for human hepatic cells and efficiently induces endocytosis.

Oriented immobilization to nanoparticles enhanced the therapeutic efficacy of antibody drugs

Antibody drugs have been important therapeutic agents for treating various diseases, such as cancer, rheumatism, and hypercholesterolemia, for the last three decades. Despite showing excellent therapeutic efficacy with good safety in vivo, they require high doses. We have developed a ∼30-nm bio-nanocapsule (ZZ-BNC) consisting of hepatitis B virus envelope L protein fused with the tandem form of protein A-derived IgG Fc-binding Z domain (ZZ-L protein), for tethering antibodies in an oriented immobilization manner. In this study, antibody drugs were spontaneously conjugated to ZZ-BNC, which displayed the IgG Fv regions outwardly. The anti-human epidermal growth factor receptor IgG conjugated to ZZ-BNC (α-hEGFR-ZZ-BNC) was endocytosed by the human epidermoid carcinoma A431 cells, with increases in cellular uptake by ∼1.5 fold, compared that of α-hEGFR IgG alone. The amount of α-hEGFR IgG in the late endosomes and lysosomes was increased from 4% to 33% by the conjugation to ZZ-BNC. The in vitro cytotoxicity of α-hEGFR-ZZ-BNC was higher by ∼10-fold than that of α-hEGFR IgG alone. Furthermore, in vivo tumor growth was significantly reduced by α-hEGFR-ZZ-BNC than by α-hEGFR IgG alone. Taken together, since endosomal EGFR, not cell surface EGFR, played a pivotal role in the EGFR-mediated signaling cascade, ZZ-BNC increased α-hEGFR IgG avidity by efficiently repressing the activation of hEGFR not only on the cell surface, but presumably also in the endosomes. These results strongly suggested that ZZ-BNC is a promising nano-scaffold for enhancing the therapeutic efficacy and reducing the dose of antibody drugs. STATEMENT OF SIGNIFICANCE: Antibody drugs are widely used for treating severe diseases, such as cancer, rheumatism, and hypercholesterolemia. These drugs are composed of naturally occurring biomaterials with low immunogenicity and toxicity, as well as long in vivo serum half-life. To achieve sufficient therapeutic efficacy, the dose of antibody drugs are unavoidably higher than those of conventional drugs. The present study shows an innovative way to reduce the dose of antibody drugs by using a nanocarrier-conjugated antibody. Oriented immobilization of the antibody enhanced its avidity, endocytosis efficiency, and therapeutic efficacy.

CD11c-specific bio-nanocapsule enhances vaccine immunogenicity by targeting immune cells

BACKGROUND

Various nanocarriers have been used to deliver subunit vaccines specifically to dendritic cells (DCs) for the improvement of immunogenicity. However, due to their insufficient DC priming ability, these vaccines could not elicit effective innate immunity. We have recently developed a DC-targeting bio-nanocapsule (BNC) by displaying anti-CD11c IgGs via protein A-derived IgG Fc-binding Z domain on the hepatitis B virus envelope L protein particles (α-DC-ZZ-BNC).

RESULTS

After the chemical modification with antigens (Ags), the α-DC-ZZ-BNC-Ag complex could deliver Ags to DCs efficiently, leading to effective DC maturation and efficient endosomal escape of Ags, followed by Ag-specific T cell responses and IgG productions. Moreover, the α-DC-ZZ-BNC modified with Japanese encephalitis virus (JEV) envelope-derived D3 Ags could confer protection against 50-fold lethal dose of JEV injection on mice.

CONCLUSION

The α-DC-ZZ-BNC-Ag platform was shown to induce humoral and cellular immunities effectively without any adjuvant.

Low immunogenic bio-nanocapsule based on hepatitis B virus escape mutants

Bio-nanocapsules (BNCs) consisting of hepatitis B virus surface antigen (HBsAg) L proteins and phospholipids are used as efficient non-viral carriers for liver-specific delivery of genes and drugs. Considering the administration to HB vaccinees and HB patients, endogenous anti-HBsAg immunoglobulins (HBIGs) may reduce the delivery efficacy and prevent repetitive administration. Therefore, low immunogenic BNCs were generated by inserting two point mutations in the HBsAg L protein, which were found in HBV escape mutants. Escape mutant-type BNC (emBNC) showed 50% lower HBIG binding capacity than that of parental BNC (wtBNC). It induced HBIG production to a lesser extent than that associated with wtBNC in BALB/c mice. The emBNC could accumulate into human hepatocyte-derived tumor in mice pre-treated with HBIGs. The complex of emBNC and cationic liposomes could deliver plasmid DNA to HepG2 cells efficiently in the presence of HBIGs. Thus, emBNC could evade HBIG-neutralizing antibodies, expanding the clinical utility of BNC-based nanomedicine.

Current Progress of Virus-mimicking Nanocarriers for Drug Delivery

Nanomedicines often involve the use of nanocarriers as a delivery system for drugs or genes for maximizing the therapeutic effect and/or minimizing the adverse effect. From drug administration to therapeutic activity, nanocarriers must evade the host's immune system, specifically and efficiently target and enter the cell, and release their payload into the cell cytoplasm by endosomal escape. These processes constitute the early infection stage of viruses. Viruses are a powerful natural nanomaterial for the efficient delivery of genetic information by sophisticated mechanisms. Over the past two decades, many virus-inspired nanocarriers have been generated to permit successful drug and gene delivery. In this review, we summarize the early infection machineries of viruses, of which the part has so far been utilized for delivery systems. Furthermore, we describe basics and applications of the bio-nanocapsule, which is a hepatitis B virus-mimicking nanoparticle harboring nearly all activities involved in the early infection machineries (i.e., stealth activity, targeting activity, cell entry activity, endosomal escaping activity).

Preclinical evaluation of cisplatin-incorporated bio-nanocapsules as chemo-radiotherapy for human hepatocellular carcinoma

The incidence of hepatocellular carcinoma (HCC) has continued to increase worldwide, and advanced HCC is difficult to treat using the currently available therapeutics. Chemoradiotherapy with cisplatin (cis-diamminedichloroplatinum, CDDP) is expected to confer a curative benefit on HCC patients; however, its application is limited due to side-effects such as acute nephrotoxicity as well as the conventionally limited application of chemoradiotherapy for HCC. For the practical application of this drug in the clinical setting, we formulated a novel drug carrier-comprising bio-nanocapsule (BNC) and liposomal CDDP (BNC-LP-CDDP) that recognizes the human liver and releases CDDP. BNC-LP-CDDP showed selectively high cytotoxicity for HCC cells, and markedly reduced the survival fractions of HCC when combined with ionizing radiation (IR) treatment in in vitro assays. In particular, the treatment of mice bearing human HCC with BNC-LP-CDDP and 3 Gy IR showed 95.68% growth inhibition, whereas IR treatment alone showed 65.6% growth inhibition. Moreover, BNC-LP-CDDP led to the withdrawal of CDDP-induced nephrotoxicity. These results indicate that BNC-LP-CDDP in combination with IR markedly enhanced the chemo-radiotherapeutic efficacy and eliminated CDDP induced nephrotoxicity, thus, suggesting the potential for its clinical application as human HCC therapy.

Elucidation of the early infection machinery of hepatitis B virus by using bio-nanocapsule

Currently, hepatitis B virus (HBV), upon attaching to human hepatocytes, is considered to interact first with heparan sulfate proteoglycan (HSPG) via an antigenic loop of HBV envelope S protein. Then, it is promptly transferred to the sodium taurocholate cotransporting polypeptide (NTCP) via the myristoylated N-terminal sequence of pre-S1 region (from Gly-2 to Gly-48, HBV genotype D), and it finally enters the cell by endocytosis. However, it is not clear how HSPG passes HBV to NTCP and how NTCP contributes to the cellular entry of HBV. Owing to the poor availability and the difficulty of manipulations, including fluorophore encapsulation, it has been nearly impossible to perform biochemical and cytochemical analyses using a substantial amount of HBV. A bio-nanocapsule (BNC), which is a hollow nanoparticle consisting of HBV envelope L protein, was efficiently synthesized in Saccharomyces cerevisiae. Since BNC could encapsulate payloads (drugs, genes, proteins) and specifically enter human hepatic cells utilizing HBV-derived infection machinery, it could be used as a model of HBV infection to elucidate the early infection machinery. Recently, it was demonstrated that the N-terminal sequence of pre-S1 region (from Asn-9 to Gly-24) possesses low pH-dependent fusogenic activity, which might play a crucial role in the endosomal escape of BNC payloads and in the uncoating process of HBV. In this minireview, we describe a model in which each domain of the HBV L protein contributes to attachment onto human hepatic cells through HSPG, initiation of endocytosis, interaction with NTCP in endosomes, and consequent provocation of membrane fusion followed by endosomal escape.

Bio-nanocapsules displaying various immunoglobulins as an active targeting-based drug delivery system

The bio-nanocapsule (BNC) is an approximately 30-nm particle comprising the hepatitis B virus (HBV) envelope L protein and a lipid bilayer. The L protein harbors the HBV-derived infection machinery; therefore, BNC can encapsulate payloads such as drugs, nucleic acids, and proteins and deliver them into human hepatocytes specifically in vitro and in vivo. To diversify the possible functions of BNC, we generated ZZ-BNC by replacing the domain indispensable for the human hepatotrophic property of BNC (N-terminal region of L protein) with the tandem form of the IgG Fc-binding Z domain of Staphylococcus aureus protein A. Thus, the ZZ-BNC is an active targeting-based drug delivery system (DDS) nanocarrier that depends on the specificity of the IgGs displayed. However, the Z domain limits the animal species and subtypes of IgGs that can be displayed on ZZ-BNC. In this study, we introduced into BNC an Ig κ light chain-binding B1 domain of Finegoldia magna protein L (protein-L B1 domain) and an Ig Fc-binding C2 domain of Streptococcus species protein G (protein-G C2 domain) to produce LG-BNC. The LL-BNC was constructed in a similar way using a tandem form of the protein-L B1 domain. Both LG-BNC and LL-BNC could display rat IgGs, mouse IgG1, human IgG3, and human IgM, all of which not binding to ZZ-BNC, and accumulate in target cells in an antibody specificity-dependent manner. Thus, these BNCs could display a broad spectrum of Igs, significantly improving the prospects for BNCs as active targeting-based DDS nanocarriers.

STATEMENT OF SIGNIFICANCE

We previously reported that ZZ-BNC, bio-nanocapsule deploying the IgG-binding Z domain of protein A, could display cell-specific antibody in an oriented immobilization manner, and act as an active targeting-based DDS nanocarrier. Since the Z domain can only bind to limited types of Igs, we generated BNCs deploying other Ig-binding domains: LL-BNC harboring the tandem form of Ig-binding domain of protein L, and LG-BNC harboring the Ig binding domains of protein L and protein G sequentially. Both BNCs could display a broader spectrum of Igs than does the ZZ-BNC. When these BNCs displayed anti-CD11c IgG or anti-EGFR IgG, both of which cannot bind to Z domain, they could bind to and then enter their respective target cells.

Study of the combined treatment of lung cancer using gene-loaded immunomagnetic albumin nanospheres in vitro and in vivo

Combination therapy for lung cancer has garnered widespread attention. Radiation therapy, gene therapy, and molecular targeted therapy for lung cancer have certain effects, but the disadvantages of these treatment methods are evident. Combining these methods can decrease their side effects and increase their curative effects. In this study, we constructed a pYr-ads-8-5HRE-cfosp-iNOS-IFNG plasmid (a gene circuit that can express IFNγ), which is a gene circuit, and used that plasmid together with C225 (cetuximab) to prepare gene-loaded immunomagnetic albumin nanospheres (IMANS). Moreover, we investigated the therapeutic effects of gene-loaded IMANS in combination with radiation therapy on human lung cancer in vitro and in vivo. The results showed that this gene circuit was successively constructed and confirmed that the expression of INFγ was increased due to the gene circuit. Gene-loaded IMANS combined with radiation therapy demonstrated improved results in vitro and in vivo. In conclusion, gene-loaded IMANS enhanced the efficacy of combination therapy, solved problems related to gene transfer, and specifically targeted lung cancer cells.

Development of a virus-mimicking nanocarrier for drug delivery systems: The bio-nanocapsule

As drug delivery systems, nanocarriers should be capable of executing the following functions: evasion of the host immune system, targeting to the diseased site, entering cells, escaping from endosomes, and releasing payloads into the cytoplasm. Since viruses perform some or all of these functions, they are considered naturally occurring nanocarriers. To achieve biomimicry of the hepatitis B virus (HBV), we generated the "bio-nanocapsule" (BNC)-which deploys the human hepatocyte-targeting domain, fusogenic domain, and polymerized-albumin receptor domain of HBV envelope L protein on its surface-by overexpressing the L protein in yeast cells. BNCs are capable of delivering various payloads to the cytoplasm of human hepatic cells specifically in vivo, which is achieved via formation of complexes with various materials (e.g., drugs, nucleic acids, and proteins) by electroporation, fusion with liposomes, or chemical modification. In this review, we describe BNC-related technology, discuss retargeting strategies for BNCs, and outline other virus-inspired nanocarriers.

Applications of human hepatitis B virus preS domain in bio- and nanotechnology

Human hepatitis B virus (HBV) is a member of the family Hepadnaviridae, and causes acute and chronic infections of the liver. The hepatitis B surface antigen (HBsAg) contains the large (L), middle (M), and small (S) surface proteins. The L protein consists of the S protein, preS1, and preS2. In HBsAg, the preS domain (preS1 + preS2) plays a key role in the infection of hepatocytic cells by HBV and has several immunogenic epitopes. Based on these characteristics of preS, several preS-based diagnostic and therapeutic materials and systems have been developed. PreS1-specific monoclonal antibodies (e.g., MA18/7 and KR127) can be used to inhibit HBV infection. A myristoylated preS1 peptide (amino acids 2-48) also inhibits the attachment of HBV to HepaRG cells, primary human hepatocytes, and primary tupaia hepatocytes. Antibodies and antigens related to the components of HBsAg, preS (preS1 + preS2), or preS1 can be available as diagnostic markers of acute and chronic HBV infections. Hepatocyte-targeting delivery systems for therapeutic molecules (drugs, genes, or proteins) are very important for increasing the clinical efficacy of these molecules and in reducing their adverse effects on other organs. The selective delivery of diagnostic molecules to target hepatocytic cells can also improve the efficiency of diagnosis. In addition to the full-length HBV vector, preS (preS1 + preS2), preS1, and preS1-derived fragments can be useful in hepatocyte-specific targeting. In this review, we discuss the literature concerning the applications of the HBV preS domain in bio- and nanotechnology.

Virosomes of hepatitis B virus envelope L proteins containing doxorubicin: synergistic enhancement of human liver-specific antitumor growth activity by radiotherapy

Bionanocapsules (BNCs) are hollow nanoparticles consisting of hepatitis B virus (HBV) envelope L proteins and have been shown to deliver drugs and genes specifically to human hepatic tissues by utilizing HBV-derived infection machinery. The complex of BNCs with liposomes (LPs), the BNC-LP complexes (a LP surrounded by BNCs in a rugged spherical form), could also become active targeting nanocarriers by the BNC function. In this study, under acidic conditions and high temperature, BNCs were found to fully fuse with LPs (smooth-surfaced spherical form), deploying L proteins with a membrane topology similar to that of BNCs (ie, virosomes displaying L proteins). Doxorubicin (DOX) was efficiently encapsulated via the remote loading method at 14.2%±1.0% of total lipid weight (mean ± SD, n=3), with a capsule size of 118.2±4.7 nm and a ζ-potential of -51.1±1.0 mV (mean ± SD, n=5). When mammalian cells were exposed to the virosomes, the virosomes showed strong cytotoxicity in human hepatic cells (target cells of BNCs), but not in human colon cancer cells (nontarget cells of BNCs), whereas LPs containing DOX and DOXOVES (structurally stabilized PEGylated LPs containing DOX) did not show strong cytotoxicity in either cell type. Furthermore, the virosomes preferentially delivered DOX to the nuclei of human hepatic cells. Xenograft mice harboring either target or nontarget cell-derived tumors were injected twice intravenously with the virosomes containing DOX at a low dose (2.3 mg/kg as DOX, 5 days interval). The growth of target cell-derived tumors was retarded effectively and specifically. Next, the combination of high dose (10.0 mg/kg as DOX, once) with tumor-specific radiotherapy (3 Gy, once after 2 hours) exhibited the most effective antitumor growth activity in mice harboring target cell-derived tumors. These results demonstrated that the HBV-based virosomes containing DOX could be an effective antitumor nanomedicine specific to human hepatic tissues, especially in combination with radiotherapy.

Intracellular trafficking of bio-nanocapsule-liposome complex: Identification of fusogenic activity in the pre-S1 region of hepatitis B virus surface antigen L protein

Bio-nanocapsules (BNCs) are a hollow nanoparticle consisting of about 100-nm liposome (LP) embedding about 110 molecules of hepatitis B virus (HBV) surface antigen (HBsAg) L protein as a transmembrane protein. Owing to the human hepatocyte-recognizing domains on the N-terminal region (pre-S1 region), BNCs have recently been shown to attach and enter into human hepatic cells using the early infection mechanism of HBV. Since BNCs could form a complex with an LP containing various drugs and genes, BNC-LP complexes have been used as a human hepatic cell-specific drug and gene-delivery system in vitro and in vivo. However, the role of BNCs in cell entry and intracellular trafficking of payloads in BNC-LP complexes has not been fully elucidated. In this study, we demonstrate that low pH-dependent fusogenic activity resides in the N-terminal part of pre-S1 region (NPLGFFPDHQLDPAFG), of which the first FF residues are essential for the activity, and which facilitates membrane fusion between LPs in vitro. Moreover, BNC-LP complexes can bind human hepatic cells specifically, enter into the cells via clathrin-mediated endocytosis, and release their payloads mostly into the cytoplasm. Taken together, the BNC portion of BNC-LP complexes can induce membrane fusion between LPs and endosomal membranes under low pH conditions, and thereby facilitate the endosomal escape of payloads. Furthermore, the fusogenic domain of the pre-S1 region of HBsAg L protein may play a pivotal role in the intracellular trafficking of not only BNC-LP complexes but also of HBV.

Specific delivery of microRNA93 into HBV-replicating hepatocytes downregulates protein expression of liver cancer susceptible gene MICA

Chronic hepatitis B virus (HBV) infection is a major cause of hepatocellular carcinoma (HCC). To date, the lack of efficient in vitro systems supporting HBV infection and replication has been a major limitation of HBV research. Although primary human hepatocytes support the complete HBV life cycle, their limited availability and difficulties with gene transduction remain problematic. Here, we used human primary hepatocytes isolated from humanized chimeric uPA/SCID mice as efficient sources. These hepatocytes supported HBV replication in vitro. Based on analyses of mRNA and microRNA (miRNA) expression levels in HBV-infected hepatocytes, miRNA93 was significantly downregulated during HBV infection. MiRNA93 is critical for regulating the expression levels of MICA protein, which is a determinant for HBV-induced HCC susceptibility. Exogenous addition of miRNA93 in HBV-infected hepatocytes using bionanocapsules consisted of HBV envelope L proteins restored MICA protein expression levels in the supernatant. These results suggest that the rescued suppression of soluble MICA protein levels by miRNA93 targeted to HBV-infected hepatocytes using bionanocapsules may be useful for the prevention of HBV-induced HCC by altering deregulated miRNA93 expression.

Nanomedicines in gastroenterology and hepatology

Nanoscale systems are currently under investigation for multiple different diagnostic and therapeutic applications. These systems can be used to identify pathologically changed tissues or to selectively deliver drugs to these sites; both applications have an extremely high potential to ameliorate therapeutic outcomes for patients. Tissues as well as single cells can be targeted because of the small size of these systems, which enables enhanced diagnosis and increased specificity of therapy. Drug loads can be delivered directly to the site of action, which can result in a reduction in incidence and severity of adverse systemic effects. Several nano-based platform technologies are currently under investigation for use in therapeutic approaches, mainly for anti-inflammatory and anti-cancer therapies. Although many nanoscale systems show promising therapeutic outcomes in preclinical studies, only a limited number are ready for clinical use. This Review will discuss the diverse nanomaterials currently available and the first specific uses for select gastroenterological and hepatological pathologies. The discussion of diagnostic and therapeutic applications will consider realities of market introduction of these sometimes very complex systems in light of remaining regulatory challenges and hurdles for industrial production.

A safe and efficient hepatocyte-selective carrier system based on myristoylated preS1/21-47 domain of hepatitis B virus

A safe and efficient liver targeted PEGylated liposome (PEG-Lip) based on N-terminal myristoylated preS1/21-47 (preS1/21-47(myr)) of hepatitis B virus was successfully developed. The study aimed to elucidate the cellular uptake mechanism of preS1/21-47(myr) modified PEG-Lip (preS1/21-47(myr)-PEG-Lip) in hepatogenic cells and the distribution behavior of preS1/21-47(myr)-PEG-Lip in Vr:CD1 (ICR) mice. The cellular uptake results showed that preS1/21-47(myr)-PEG-Lip was effectively taken up by hepatogenic cells (including primary hepatocytes and liver tumor cells) through a receptor-mediated endocytosis pathway compared with non-hepatogenic cells. After systemic administration to H22 hepatoma-bearing mice, preS1/21-47(myr)-PEG-Lip showed significant liver-specific delivery and an increase in the distribution of preS1/21-47(myr)-PEG-Lip in hepatic tumor. Furthermore, the antitumor effect of preS1/21-47(myr)-PEG-Lip loaded with paclitaxel (PTX) was remarkably stronger than that of PTX injection and PTX loaded liposomes (including common liposomes and PEG-Lip). In safety evaluation, no acute systemic toxicity and immunotoxicity were observed after intravenous injection of preS1/21-47(myr)-PEG-Lip. No liver toxicity was observed despite the dramatic increase of preS1/21-47(myr)-PEG-Lip in liver. Taken together, preS1/21-47(myr)-PEG-Lip represents a promising carrier system for targeted liver disease therapy and imaging.

Human tumor xenograft models for preclinical assessment of anticancer drug development

Xenograft models of human cancer play an important role in the screening and evaluation of candidates for new anticancer agents. The models, which are derived from human tumor cell lines and are classified according to the transplant site, such as ectopic xenograft and orthotopic xenograft, are still utilized to evaluate therapeutic efficacy and toxicity. The metastasis model is modified for the evaluation and prediction of cancer progression. Recently, animal models are made from patient-derived tumor tissue. The patient-derived tumor xenograft models with physiological characters similar to those of patients have been established for personalized medicine. In the discovery of anticancer drugs, standard animal models save time and money and provide evidence to support clinical trials. The current strategy for using xenograft models as an informative tool is introduced.

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

Background

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

Findings

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

Conclusion

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

Targeting cancer cell-specific RNA interference by siRNA delivery using a complex carrier of affibody-displaying bio-nanocapsules and liposomes

Background

Small interfering RNA (siRNA) has attracted attention in the field of nucleic acid medicine as a RNA interference (RNAi) application that leads to gene silencing due to specific messenger RNA (mRNA) destruction. However, since siRNA is unstable in blood and unable to cross the cell membrane, encapsulation of siRNA into a carrier is required.

Results

In this study, we used a carrier that combined Z_HER2-displaying bio-nanocapsule (derived from hepatitis B virus surface antigen) and liposomes in a complex in order to investigate the feasibility of effective and target-cell-specific RNAi applications. As a result, by observing RNAi only in HER2-expressing breast cancer cells, using our proposed methodology, we successfully demonstrated target-cell-specific delivery and effective function expression of siRNA.

Conclusions

These findings show that, in the field of nucleic acid medicine, Z_HER2-BNC/LP can be a useful carrier for siRNA delivery, and could also become a useful tool for gene silencing and to accomplish protein knock-down.

Developments in the use of nanocapsules in oncology

The application of nanotechnology to medicine can provide important benefits, especially in oncology, a fact that has resulted in the emergence of a new field called Nanooncology. Nanoparticles can be engineered to incorporate a wide variety of chemotherapeutic or diagnostic agents. A nanocapsule is a vesicular system that exhibits a typical core-shell structure in which active molecules are confined to a reservoir or within a cavity that is surrounded by a polymer membrane or coating. Delivery systems based on nanocapsules are usually transported to a targeted tumor site and then release their contents upon change in environmental conditions. An effective delivery of the therapeutic agent to the tumor site and to the infiltrating tumor cells is difficult to achieve in many cancer treatments. Therefore, new devices are being developed to facilitate intratumoral distribution, to protect the active agent from premature degradation and to allow its sustained and controlled release. This review focuses on recent studies on the use of nanocapsules for cancer therapy and diagnosis.

Complex carriers of affibody-displaying bio-nanocapsules and composition-varied liposomes for HER2-expressing breast cancer cell-specific protein delivery

A bio-nanocapsule (BNC), a hollow particle composed of hepatitis B virus (HBV) surface antigen (HBsAg), and liposome (LP) conjugation method (BNC/LP) has been recently developed by Jung et al. (2008) . The BNC/LP complex carrier could successfully deliver fluorescence-labeled beads (100 nm) into liver cells. In this study, we report the promising delivery of proteins incorporated in the complex carriers, which were prepared by the BNC/LP conjugation method with specificity-altered BNC and composition-varied LPs. The specificity-altered BNC, Z(HER2)-BNC was developed by replacing the hepatocyte recognition site of BNC with Z(HER2) binding to HER2 receptor specifically. Using green fluorescent protein (GFP; 27 kDa) and cellular cytotoxic protein (exotoxin A; 66 kDa) for the delivery, we herein present the impact of different charges attributed to the composition of the LP on specific cell targeting and cellular uptake of the complex carriers. In addition, we demonstrate that the mixture prepared by mixing LPs with helper lipid possessing endosomal escaping ability boosts the functional expression of the cellular cytotoxic exotoxin A activity specifically. Finally, we further show the blending ratio of the LP mixture and Z(HER2)-BNC is a critical factor in determining the highly-efficient expression of the cytotoxic activity of exotoxin A.

Nano-technology for targeted drug delivery to combat antibiotic resistance

Several microbes have evolved clinically significant resistance against almost every available antibiotic. Yet the development of new classes of antibiotics has lagged far behind our growing need. Frequent and suboptimal use of antibiotics particularly in developing countries aggravated the problem by increasing the rate of resistance. Therefore, developing new and multidimensional strategies to combat microbial infections is warranted. These include i) modification of existing antibiotics, ii) searching new and novel antibiotics, iii) development and improvement of antibiotics carrier system to reduce amount and frequency of antibiotic doses, iv) development of targeted antibiotic delivery systems. Here, the authors discuss trends and development of nano-materials and alternative antimicrobials to solve the problem of antibiotic resistance.

Engineered hepatitis B virus surface antigen L protein particles for in vivo active targeting of splenic dendritic cells

Dendritic cells (DCs) are key regulators of adaptive T-cell responses. By capturing exogenous antigens and presenting antigen-derived peptides via major histocompatibility complex molecules to naïve T cells, DCs induce antigen-specific immune responses in vivo. In order to induce effective host immune responses, active delivery of exogenous antigens to DCs is considered important for future vaccine development. We recently generated bionanocapsules (BNCs) consisting of hepatitis B virus surface antigens that mediate stringent in vivo cell targeting and efficient endosomal escape, and after the fusion with liposomes (LP) containing therapeutic materials, the BNC-LP complexes deliver them to human liver-derived tissues in vivo. BNCs were further modified to present the immunoglobulin G (IgG) Fc-interacting domain (Z domain) derived from Staphylococcus aureus protein A in tandem. When mixed with IgGs, modified BNCs (ZZ-BNCs) displayed the IgG Fv regions outwardly for efficient binding to antigens in an oriented-immobilization manner. Due to the affinity of the displayed IgGs, the IgG-ZZ-BNC complexes accumulated in specific cells and tissues in vitro and in vivo. After mixing ZZ-BNCs with antibodies against DCs, we used immunocytochemistry to examine which antibodies delivered ZZ-BNCs to mouse splenic DCs following intravenous injection of the ZZ-BNCs. ZZ-BNCs displaying anti-CD11c monoclonal antibodies (α-CD11c-ZZ-BNCs) were found to accumulate with approximately 62% of splenic DCs, and reside within some of them. After the fusion with liposomes containing antigens, the α-CD11c-ZZ-BNCs could elicit the respective antibodies more efficiently than other nontargeting control vaccines, suggesting that this DC-specific nanocarrier is promising for future vaccines.

Nanotechnology for therapy and imaging of liver diseases

Nanotechnology has been considered for the improved delivery of various therapeutic agents, including drugs and genes. Indeed, liposomes and nanoparticles equipped with homing devices for the targeting of receptors over-expressed on the hepatic tissue have improved the treatment of various liver diseases. In this review, various nanotechnology approaches employed for the treatment/imaging of liver disease, either in preclinical or in clinic are discussed.

Hepatitis B virus envelope L protein-derived bio-nanocapsules: mechanisms of cellular attachment and entry into human hepatic cells

A bio-nanocapsule (BNC) is a hollow nanoparticle consisting of an approximately 100-nm-diameter liposome with about 110 molecules of hepatitis B virus (HBV) surface antigen L protein embedded as a transmembrane protein. BNC can encapsulate various drugs and genes and deliver them specifically to human hepatic cells based on the ability of HBV to recognize human hepatocyte, which is integrated in the N-terminal region of L protein. However, it is elusive whether the cellular attachment and entry into hepatic cells of BNC utilize the early infection mechanism of HBV. In this study, we have found that while all human hepatic cells show distinct affinities for BNC compared to non-hepatic cells, primary hepatocytes shows the highest efficiency for cellular binding and incorporation of BNC. Amounts of BNCs bound weakly and strongly to cell membranes and those entered into the cells varied significantly depending on the types of human hepatic cells. The weak and strong binding modes of BNC are likely mediated through binding to two distinct HBV receptors (heparin-mediated low-affinity and unidentified high-affinity receptors), which play major roles in the early infection mechanism of HBV. The rates of cellular uptake of BNC are similar to those reported for HBV. The BNCs incorporated into the cells are swiftly sorted to either early endosomes or macropinosomes and then to late endosomes and/or lysosomes. These findings strongly suggest that BNC is bound to and incorporated into human hepatic cells according to the early infection mechanism of HBV.

Protein-encapsulated bio-nanocapsules production with ER membrane localization sequences

Bio-nanocapsules (BNCs) are hollow nanoparticles composed of the L protein of hepatitis B virus (HBV) surface antigen (HBsAg), which can specifically introduce genes and drugs into various kinds of target cells. Although the classic electroporation method has typically been used to introduce highly charged molecules such as DNA, it is rarely adopted for proteins due to its very low efficiency. In this study, a novel approach to the preparation of BNC was established whereby a target protein was pre-encapsulated during the course of nanoparticle formation. Briefly, because of the process of BNC formation in a budding manner on the endoplasmic reticulum (ER) membrane, the association of target proteins to the ER membrane with lipidation sequences (ER membrane localization sequences) could directly generate protein-encapsulating BNC in collaboration with co-expression of the L proteins. Since the membrane-localized proteins are automatically enveloped into BNCs during the budding event, this method can be protect the proteins and BNCs from damage caused by electroporation and obviate the need for laborious consideration to study the optimal conditions for protein encapsulation. This approach would be a useful method for encapsulating therapeutic candidate proteins into BNCs.

Efficient and rapid purification of drug- and gene-carrying bio-nanocapsules, hepatitis B virus surface antigen L particles, from Saccharomyces cerevisiae

Bio-nanocapsules (BNCs) are hollow particles (approx. 50 nm diameter) consisting of hepatitis B virus surface antigen (HBsAg) large (L, pre-S1+pre-S2+S) proteins embedded in a unilamellar liposome, sharing the same transmembrane S region with an immunogen of hepatitis B vaccine (i.e., HBsAg small (S) protein particle). BNCs can incorporate drugs and genes into the hollow space and systemic administration of the BNCs can deliver the products to human liver via the human hepatocyte-specific receptor within the pre-S (pre-S1+pre-S2) region displayed on BNC's surface. Thus, BNCs are expected to offer efficient and safe non-viral nanocarriers to deliver human liver-specific genes and drugs. To date, BNCs have been purified from the crude extract of BNC-overexpressing yeast cells by fractionation with polyethylene glycol followed by one CsCl equilibrium and two sucrose density gradient ultracentrifugation steps. However, the process was inefficient in terms of yield and time, and was not suitable for mass production because of the ultracentrifugation step. Furthermore, trace contamination with yeast-derived proteinases degraded the pre-S region, which is indispensable for liver-targeting, during long-term storage. In this study, we developed a new purification method involving heat treatment and sulfated cellulofine column chromatography to facilitate rapid purification, completely remove proteinases, and enable mass production. In addition, the BNCs were functional for at least 14 months after lyophilization with 5% (w/v) sucrose as an excipient. This new process will significantly contribute to the development of forthcoming BNC-based nanomedicines as well as hepatitis B vaccines.

Properties, engineering and applications of lipid-based nanoparticle drug-delivery systems: current research and advances

Lipid-based drug-delivery systems have evolved from micro- to nano-scale, enhancing the efficacy and therapeutic applications of these delivery systems. Production of lipid-based pharmaceutical nanoparticles is categorized into top-down (fragmentation of particulate material to reduce its average total dimensions) and bottom-up (amalgamation of molecules through chemical interactions creating particles of greater size) production methods. Selection of the appropriate method depends on the physiochemical properties of individual entities within the nanoparticles. The production method also influences the type of nanoparticle formulations being produced. Liposomal formulations and solid-core micelles are the most widely utilized lipid-based nanoparticles, with surface modifications improving their therapeutic outcomes through the production of long-circulating, tissue-targeted and/or pH-sensitive nanoparticles. More recently, solid lipid nanoparticles have been engineered to reduce toxicity toward mammalian cells, while multifunctional lipid-based nanoparticles (i.e., hybrid lipid nanoparticles) have been formulated to simultaneously perform therapeutic and diagnostic functions. This article will discuss novel lipid-based drug-delivery systems, outlining the properties and applications of lipid-based nanoparticles alongside their methods of production. In addition, a comparison between generations of the lipid-based nano-formulations is examined, providing insight into the current directions of lipid-based nanoparticle drug-delivery systems.

A gene-delivery system specific for hepatoma cells and an intracellular kinase signal based on human liver-specific bionanocapsules and signal-responsive artificial polymer

Recently, our group has proposed a novel gene-regulation system responding to cAMP-dependent protein kinase (PKA) that has been applied to living cells. In this study, human liver-specific bionanocapsules (BNCs) are used as a gene-delivery system to increase transfection efficiency and to target specific cell types. BNCs can efficiently deliver a target gene to human hepatocytes and hepatoma cells in vitro or in vivo. The combination of a signal-responsive gene-delivery system with BNCs led to an increase in the transfection efficiency and selectivity for hepatoma cells. Expression from the delivered gene was identified from PKA-activated hepatoma cells (HepG2), but not from colon tumor cells (WiDr). These results show that the combination of a gene-regulation system responding to an intracellular signal with BNC can be used for the selective treatment of human hepatoma cells.

Development and use of iron oxide nanoparticles (Part 1): Synthesis of iron oxide nanoparticles for MRI

Contrast agents, such as iron oxide, enhance MR images by altering the relaxation times of tissues in which the agent is present. They can also be used to label targeted molecular imaging probes. Unfortunately, no molecular imaging probe is currently available on the clinical MRI market. A promising platform for MRI contrast agent development is nanotechnology, where superparamagnetic iron oxide nanoparticles (SPIONS) are tailored for MR contrast enhancement, and/or for molecular imaging. SPIONs can be produced using a range of methods and the choice of method will be influenced by the characteristics most important for a particular application. In addition, the ability to attach molecular markers to SPIONS heralds their application in molecular imaging.There are many reviews on SPION synthesis for MRI; however, these tend to be targeted to a chemistry audience. The development of MRI contrast agents attracts experienced researchers from many fields including some researchers with little knowledge of medical imaging or MRI. This situation presents medical radiation practitioners with opportunities for involvement, collaboration or leadership in research depending on their level of commitment and their ability to learn. Medical radiation practitioners already possess a large portion of the understanding, knowledge and skills necessary for involvement in MRI development and molecular imaging. Their expertise in imaging technology, patient care and radiation safety provides them with skills that are directly applicable to research on the development and application of SPIONs and MRI.In this paper we argue that MRI SPIONs, currently limited to major research centres, will have widespread clinical use in the future. We believe that knowledge about this growing area of research provides an opportunity for medical radiation practitioners to enhance their specialised expertise to ensure best practice in a truly multi-disciplinary environment. This review outlines how and why SPIONs can be synthesised and examines their characteristics and limitations in the context of MR imaging.

Colloidal nanocarriers: a review on formulation technology, types and applications toward targeted drug delivery

Colloidal nanocarriers, in their various forms, have the possibility of providing endless opportunities in the area of drug delivery. The current communication embodies an in-depth discussion of colloidal nanocarriers with respect to formulation aspects, types, and site-specific drug targeting using various forms of colloidal nanocarriers with special insights to the field of oncology. Specialized nanotechnological approaches like quantum dots, dendrimers, integrins, monoclonal antibodies, and so forth, which have been extensively researched for targeted delivery of therapeutic and diagnostic agents, are also discussed. Nanotechnological patents, issued by the U.S. Patent and Trademark Office in the area of drug delivery, are also included in this review to emphasize the importance of nanotechnology in the current research scenario.

FROM THE CLINICAL EDITOR

Colloidal nanocarriers provide almost endless opportunities in the area of drug delivery. While the review mainly addresses potential oncological applications, similar approaches may be applicable in other conditions with a requirement for targeted drug delivery. Technologies including quantum dots, dendrimers, integrins, monoclonal antibodies are discussed, along with US-based patents related to these methods.

Nanoparticles for human liver-specific drug and gene delivery systems: in vitro and in vivo advances

A wide variety of nanoparticles (NPs) that can deliver incorporated therapeutic materials such as compounds, proteins, genes and siRNAs to the human liver have been developed to treat liver-related diseases. This review describes NP-based drug and gene delivery systems such as liposomes (including lipoplex), polymer micelles, polymers (including polyplex) and viral vectors. It focuses upon the modification of these NPs to enhance liver specificity or delivery efficiency in vitro and in vivo. We discuss recent advances in drug and gene delivery systems specific to the human liver utilizing bio-nanocapsules comprising hepatitis B virus (HBV) envelope L protein, which has a pivotal role in HBV infection. These NP-based medicines may offer novel strategies for the treatment of liver-related diseases and contribute to the development of nanomedicines targeting other tissues.

Chapter 8 - Bio-nanocapsule-liposome conjugates for in vivo pinpoint drug and gene delivery

A bio-nanocapsule (BNC) is an ~50-nm hepatitis B virus (HBV) subviral particle comprising HBV envelope L proteins and a lipid bilayer, and is synthesized in recombinant Saccharomyces cerevisiae. When BNCs are administered intravenously in a mouse xenograft model, they can accumulate specifically in human liver-derived tissues and enter cells efficiently by the HBV-derived human liver-specific infection machinery, localized at the outer-membrane pre-S region of the L protein. BNC specificity for the human liver can be altered to other tissues by substituting the pre-S region using targeting molecules (e.g., antibodies, lectins, cytokines). BNCs can spontaneously form complexes with liposomes (LPs) by the membrane fusogenic activity of the pre-S region. LPs containing various therapeutic materials (e.g., chemicals, proteins, DNA, RNA) can therefore be covered with BNCs to form an ~150-nm BNC-LP conjugate. BNC-LP conjugates injected intravenously can deliver incorporated materials to target tissues specifically and efficiently by utilizing the HBV-derived infection machinery. The stability of BNC-LP conjugates in the blood circulation is similar to that of PEGylated LPs. In this chapter, we describe the preparation and in vivo application of BNC-LP conjugates, and the potential of BNC-LP conjugates as in vivo pinpoint drug delivery systems.

Expression of squamous cell carcinoma antigen-1 in liver enhances the uptake of hepatitis B virus envelope-derived bio-nanocapsules in transgenic rats

We previously developed the bio-nanocapsule, which consists of hepatitis B virus envelope L proteins. The bio-nanocapsule can be used to deliver genes and drugs specifically to the human liver-derived tissues in xenograft models, presumably by utilizing the human liver-specific mechanism of hepatitis B virus infection. The hepatitis B virus tropism is highly restricted to humans and higher primates. Thus, to evaluate the in vivo therapeutic effects of forthcoming bio-nanocapsule-based medicines, it will be crucial to develop an animal model whose liver is susceptible to both bio-nanocapsule and hepatitis B virus. In the present study, we aimed to establish a bio-nanocapsule-susceptible animal model using transgenic rats expressing squamous cell carcinoma antigen-1 (SCCA1), which has been proposed to be a receptor for hepatitis B virus, interacting with the hepatitis B virus envelope protein and enhancing the cellular uptake of hepatitis B virus. We show that the recombinant SCCA1 protein interacts directly with bio-nanocapsule and inhibits its attachment to the cultured human liver-derived cells. Furthermore, we have established a transgenic rat that specifically expresses SCCA1 in the liver and also demonstrate that the amount of bio-nanocapsule accumulated in the liver is significantly increased by the SCCA1 expression. Histological analysis suggests that bio-nanocapsule is preferentially incorporated into the SCCA1-expressing hepatocytes but not into macrophages, such as Küppfer cells, nor into endothelial cells. Therefore, this animal model is expected to be useful for the development of bio-nanocapsule-based medicines.