Characterization of bio-nanocapsule as a transfer vector targeting human hepatocyte carcinoma by disulfide linkage modification

Computation-Guided Rational Design of Cysteine-Less Protein Variants in Engineered hCGL

The engineered human cystathionine-γ-lyase (hCGL) resulting in enhanced activity toward both cysteine and cystine unveils a potential robust antitumor activity. However, the presence of cysteine residues has the potential to induce oligomerization or incorrect disulfide bonding, which may decrease the bioavailability of biopharmaceuticals. Through a meticulous design process targeting the cysteine residues within engineered hCGL, a set of potential beneficial mutants were obtained by virtual screening employing Rosetta and ABACUS. Experimental measurements have revealed that most of the mutants showed increased activity toward both substrates l-Cys and CSSC. Furthermore, mutants C109V and C229D demonstrated Tm value increases of 8.2 and 1.8 °C, respectively. After an 80 min incubation at 60 °C, mutant C229D still maintained high residual activity. Unexpectedly, mutant C109V, displaying activity approximately 2-fold higher than the activity of wild type (WT) for both substrates, showed disappointing instability in plasma, which suggests that computational design still requires further consideration. Analysis of their structure and molecular dynamics (MD) simulation revealed the impact of hydrophobic interaction, hydrogen bonds, and near-attack conformation (NAC) stability on activity and stability. This study acquired information about mutants that exhibit enhanced activity or thermal resistance and serve as valuable guidance for subsequent specific cysteine modifications.

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.

Synthesis and assembly of Hepatitis B virus envelope protein-derived particles in Escherichia coli

Hepatitis B virus (HBV) envelope particles have been synthesized in eukaryotic cells (e.g., mammalian cells, insect cells, and yeast cells) as an HB vaccine immunogen and drug delivery system (DDS) nanocarrier. Many researchers had made attempts to synthesize the particles in Escherichia coli for minimize the cost and time for producing HBV envelope particles, but the protein was too deleterious to be synthesized in E. coli. In this study, we generated deletion mutants of HBV envelope L protein (389 amino acid residues (aa)) containing three transmembrane domains (TM1, TM2, TM3). The ΔNC mutant spanning from TM2 to N-terminal half of TM3 (from 237 aa to 335 aa) was found as a shortest form showing spontaneous particle formation. After the N-terminal end of ΔNC mutant was optimized by the N-end rule for E. coli expression, the modified ΔNC mutant (mΔNC) was efficiently expressed as particles in E. coli. The molecular mass of mΔNC particle was approx. 670 kDa, and the diameter was 28.5 ± 6.2 nm (mean ± SD, N = 61). The particle could react with anti-HBV envelope S protein antibody, indicating the particles exhibited S antigenic domain outside as well as HBV envelope particles. Taken together, the E. coli-derived mΔNC particles could be used as a substitute of eukaryotic cell-derived HBV envelope particles for versatile applications.

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.

Nano-visualization of oriented-immobilized IgGs on immunosensors by high-speed atomic force microscopy

Oriented immobilization of sensing molecules on solid phases is an important issue in biosensing. In case of immunosensors, it is essential to scrutinize not only the direction and shape of immunoglobulin G (IgG) in solution but also the real-time movement of IgGs, which cannot be achieved by conventional techniques. Recently, we developed bio-nanocapsules (BNCs) displaying a tandem form of the IgG Fc-binding Z domain derived from Staphylococcus aureus protein A (ZZ-BNC) to enhance the sensitivity and antigen-binding capacity of IgG via oriented-immobilization. Here, we used high-speed atomic force microscopy (HS-AFM) to reveal the fine surface structure of ZZ-BNC and observe the movement of mouse IgG3 molecules tethered onto ZZ-BNC in solution. ZZ-BNC was shown to act as a scaffold for oriented immobilization of IgG, enabling its Fv regions to undergo rotational Brownian motion. Thus, HS-AFM could decipher real-time movement of sensing molecules on biosensors at the single molecule level.

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.

Drug delivery systems and liver targeting for the improved pharmacotherapy of the hepatitis B virus (HBV) infection

In spite of the progress made in vaccine and antiviral therapy development, hepatitis B virus (HBV) infection is still the most common cause of liver cirrhosis and hepatocellular carcinoma, with more than 400 million people chronically infected worldwide. Antiviral therapy with nucleos(t)ide analogues and/or immunomodulating peptides is the only option to control and prevent the progression of the disease in chronic hepatitis B (CHB)-infected patients. So far, the current antiviral monotherapy remains unsatisfactory because of the low efficacy and the development of drug resistance mutants. Moreover, viral rebound is frequently observed following therapy cessation, since covalent closed circular DNA (cccDNA) is not removed from hepatocytes by antiviral therapy. First, this review describes the current pharmacotherapy for the management of CHB and the new drug candidates being investigated. Then, the challenges in the development of drug delivery systems for the targeting of antiviral drugs to the liver parenchyma are discussed. Finally, perspectives in the design of a more efficient pharmacotherapy to eradicate the virus from the host are addressed.

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.

Bio-nanocapsule conjugated with liposomes for in vivo pinpoint delivery of various materials

Bio-nanocapsules (BNCs) consisting of hepatitis B virus (HBV) surface antigen (HBsAg) are approximately 50-nm hollow particles displaying a human hepatocyte-recognizing molecule (pre-S1 peptide). They have been used as an HB vaccine for the last two decades. Original BNC can incorporate various payloads (e.g., drugs, genes) by electroporation and deliver them to human hepatocytes specifically by utilizing the HBV infection mechanism. Here, we developed a new BNC conjugated with liposomes and succeeded in incorporating large materials (100-nm fluorescence-labeled polystyrene beads and >30 kbp plasmids) into the BNC-liposome complex. The complex delivered these large materials to human hepatocytes specifically ex vivo and in vivo. The transfection efficiency of the BNC-liposome complex was significantly higher than that of the original BNC. These results indicated that BNC confers the tissue- and cell-specificity on the conventional liposomes and raises new possibilities for drug delivery systems, gene delivery systems, and bio-imaging systems in vivo.