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Kazunori Kataoka

Publications and source records attributed to Kazunori Kataoka.

At least 19 recordsLinked to original sources
PubMed2007

Preparation and characterization of polyion complex micelles with a novel thermosensitive poly(2-isopropyl-2-oxazoline) shell via the complexation of oppositely charged block ionomers.

Novel thermosensitive polyion complex (PIC) micelles were prepared in an aqueous medium based on the complexation of a pair of oppositely charged block ionomers, poly(2-isopropyl-2-oxazoline)-b-poly(amino acid)s (PiPrOx-b-PAA), containing thermosensitive PiPrOx segments. The controlled synthesis of PiPrOx-b-PAA was achieved via the ring-opening anionic polymerization of N-carboxyanhydrides (NCA) of either eta-benzyloxycarbonyl-l-lysine (Lys(Z)-NCA) or beta-benzyl-l-aspartate (BLA-NCA) with omega-amino-functionalized PiPrOx macroinitiators and the subsequent deprotection reaction under acidic or basic conditions. Gel permeation chromatography (GPC) and 1H NMR spectroscopy revealed that the syntheses of two block ionomers, poly(2-isopropyl-2-oxazoline)-b-poly(l-lysine) [PiPrOx-P(Lys)] and poly(2-isopropyl-2-oxazoline)-b-poly(aspartic acid) [PiPrOx-P(Asp)], proceeded almost quantitatively to give samples with a narrow molecular weight distribution (Mw/Mn </= 1.2). The mixing of these two oppositely charged block ionomers in an aqueous medium led to the spontaneous formation of PIC micelles, which was confirmed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The PIC micelles were spherical particles with a narrow distribution in the range of the measured concentration (0.125-1 mg/mL) and were stable without any secondary aggregates. Furthermore, the PIC micelles had a constant cloud-point temperature (Tcp) of approximately 32 degrees C under physiological conditions regardless of the total concentration, suggesting that the concentration factor is almost negligible with respect to the Tcp of the micelles presumably because of the increased local concentration of the PiPrOx segments in the shell layer. These PIC micelles have a promising application as a size-regulated smart nanocontainer loading charged compounds as well as bearing a thermosensitive outer shell that is useful for physical affinity control.

Hot Temperature↗
PubMed2006

Activation of lymphocyte proliferation by boronate-containing polymer immobilised on substrate: the effect of boron content on lymphocyte proliferation.

This study demonstrates that boronic acid-containing polymers coated onto solid support function as synthetic mitogens for mouse lymphocytes. The polymer was synthesized by radical copolymerization of 3-acrylamidophenylboronic acid with dimethylacrylamide (poly(AAPBA-DMAA)). The boronic acid in the trigonal form in the copolymer activated lymphocytes, probably by crosslinkage to glycoprotein moieties on the plasma membrane surface, as in the case of lectin stimulation. A higher concentration of phenylboronic acid on the copolymer surface resulted in greater activation of lymphocytes, suggesting that the number of phenylboronic acid residues per unit area may be a crucial factor in lymphocyte proliferation. The proliferative response of lymphocytes was also affected by the surface wettability, probably due to a difference in the flexibility of polymer strands at the cell-polymer interface.

Acrylic Resins↗
PubMed2006

PEGylated gene nanocarriers based on block catiomers bearing ethylenediamine repeating units directed to remarkable enhancement of photochemical transfection.

The therapeutic usefulness of macromolecular drugs such as plasmid DNA is often limited by the inefficient transfer of macromolecules to the cytosol. Photochemical internalization (PCI) technology, in which the endosomal escape of DNA or its complex is assisted by co-incubated photosensitizers that photodamage endosome membrane, offers a solution for this problem. A series of poly(ethylene glycol) (PEG)-based block polycatiomers with increasing number of ethylenediamine repeating unit at side chain of polycatiomers were complexed with pDNA to form the PEGylated polyplexes as a biocompatible gene carrier. Dendrimeric phthalocyanine (DPc)-incorporated micelle was used to assist the gene transfer of these polyplexes in a light-inducible manner. As a result, the light-inducible transfection activity was significantly enhanced as the number of amino group at the side chain of PEG-b-polycatiomer increased. The polyplex from PEG-b-polycatiomer having the longest ethylenediamine structure achieved approximately 1000-fold enhancement of transfection upon photoirradiation. This result supports the underlying hypothesis that photochemical transfection and proton sponge effect of polycations can work synergistically to enhance the transfection efficiency. With careful balance between photochemical transfection enhancement and cytotoxicity, PEG-b-polycatiomers used in this study might be a potential candidate for in vivo PCI-mediated gene transfer.

Algorithms↗
PubMed2006

Current state, achievements, and future prospects of polymeric micelles as nanocarriers for drug and gene delivery.

Polymeric micelles, self-assemblies of block copolymers, are promising nanocarrier systems for drug and gene delivery. Until now, several micellar formulations of antitumor drugs have been intensively studied in preclinical and clinical trials, and their utility has been demonstrated. Even compared with long-circulating liposomes, polymeric micelles might have several advantages, such as controlled drug release, tissue-penetrating ability and reduced toxicity such as hand-foot syndrome and hypersensitivity reaction. Importantly, critical features of the polymeric micelles as drug carriers, including particle size, stability, and loading capacity and release kinetics of drugs, can be modulated by the structures and physicochemical properties of the constituent block copolymers. Also, nano-engineering of block copolymers might allow the preparation of polymeric micelles with integrated smart functions, such as specific-tissue targetability, as well as chemical or physical stimuli-sensitivity. Thus, polymeric micelles are nanotechnology-based carrier systems that might exert the activity of potent bioactive compounds in a site-directed manner, ensuring their effectiveness and safety in the clinical use.

Animals↗
PubMed2006

Development of a fitting model suitable for the isothermal titration calorimetric curve of DNA with cationic ligands.

A novel curve fitting model was developed for the isothermal titration calorimetry (ITC) of a cationic ligand binding to DNA. The ligand binding often generates a DNA conformational change from an elongated random coil into a compact collapsed form that is referred to as "DNA condensation". The ligand binding can be classified into two regimes having different binding constants Ki, i.e., the binding to an elongated DNA chain with a binding constant K1 and with K2 that occurred during the conformational transition. The two-variable curve fitting models are usually bound by a strict regulation on the difference in the values of the binding constants K1 > K2. For the DNA condensation, however, the relationships for K1 and K2 are still unclear. The novel curve fitting model developed in this study takes into account this uncertainty on the relationship of the binding constants and is highly flexible for the two-variable binding constant system.

Calorimetry↗
PubMed2006

Polyion complex micelles for photodynamic therapy: incorporation of dendritic photosensitizer excitable at long wavelength relevant to improved tissue-penetrating property.

A polymeric micelle (DPcZn/m) system, which is formed via an electrostatic interaction of anionic dendrimer phthalocyanine (DPcZn) and poly(ethylene glycol)-poly(l-lysine) block copolymers (PEG-b-PLL), was prepared for use as an effective photosensitizer for photodynamic therapy. DPcZn/m exhibited strong Q band absorption around 650 nm, a useful wavelength for high tissue penetration. Dynamic light scattering studies indicated that the DPcZn/m system has a relevant size of 50 nm for intravenous administration. Under light irradiation, either DPcZn or DPcZn/m exhibited efficient consumption of dissolved oxygen in a medium to generate reactive oxygen species and an irradiation-time-dependent increase in photocytotoxicity. The photodynamic efficacy of the DPcZn was drastically improved by the incorporation into the polymeric micelles, typically exhibiting more than two orders of magnitude higher photocytotoxicity compared with the free DPcZn at 60-min photoirradiation.

Cell Culture Techniques↗
PubMed2006

Semipermeable polymer vesicle (PICsome) self-assembled in aqueous medium from a pair of oppositely charged block copolymers: physiologically stable micro-/nanocontainers of water-soluble macromolecules.

A new entity of polymer vesicle with a polyion complex (PIC) membrane, a PICsome, was prepared by simple mixing of a pair of oppositely charged block copolymers, composed of biocompatible PEG and poly(amino acid)s, in an aqueous medium. Flow particle image analysis revealed the formation of spherical particles with a size range up to 10 mum. Observation by dark-field and confocal laser scanning microscopes clearly confirmed that the PICsome has a hollow structure with an inner-water phase, in which FITC-dextran emitting green fluorescence was successfully encapsulated simply by the simultaneous mixing with the block copolymers. Confocal laser scanning microscopic observation and spectral analysis revealed the smooth penetration of a low molecular weight fluorescent dye (TRITC; MW = 443.5) emitting red fluorescence into the FITC-dextran encapsulated PICsome to give the PICsome image with a merged color of yellows, indicating the semipermeable nature of the PICsome membrane. The PICsomes showed appreciable physiological stability even in the presence of serum proteins, suggesting their feasibility in biomedical fields such as carriers of therapeutic compounds and compartments for diagnostic enzymes.

Biocompatible Materials↗
PubMed2006

Organic-inorganic hybrid-nanocarrier of siRNA constructing through the self-assembly of calcium phosphate and PEG-based block aniomer.

The development of siRNA delivery systems is a major key for practical RNA therapy that holds promise for the treatment of life-threatening human diseases, yet there still exists significant difficulties in their construction because of the various requirements including high transfection efficacy, tolerability in the biological medium, and low toxicity. Here we report the novel preparation route of organic-inorganic hybrid-nanocarriers entrapping siRNA based on the self-assembly of the block aniomer, poly(ethylene glycol)-block-poly(methacrylic acid), with calcium phosphate crystals. The nanocarriers have diameters in the range of several hundreds of nanometers and revealed excellent colloidal stability due to the steric stabilization effect of the PEG palisade. The biological activity of siRNA loaded in nanocarriers was assessed using 293 cells stably expressing luciferase gene, showing the remarkably high gene silencing-efficacy without the use of any adjuvant molecules such as chroloquin. Further advantage of the system is the serum tolerability, which is of a critical issue in in vivo application.

Calcium Phosphates↗
PubMed2006

A PEG-based biocompatible block catiomer with high buffering capacity for the construction of polyplex micelles showing efficient gene transfer toward primary cells.

Nonviral gene vectors from synthetic catiomers (polyplexes) are a promising alternative to viral vectors. In particular, many recent efforts have been devoted to the construction of biocompatible polyplexes for in vivo nonviral gene therapy. A promising approach in this regard is the use of poly(ethylene glycol) (PEG)-based block catiomers, which form a nanoscaled core-shell polyplex with biocompatible PEG palisades. In this study, a series of PEG-based block catiomers with different amine functionalities were newly prepared by a simple and affordable synthetic procedure based on an aminolysis reaction, and their utility as gene carriers was investigated. This study revealed that the block catiomers carrying the ethylenediamine unit at the side chain are capable of efficient and less toxic transfection even toward primary cells, highlighting critical structural factors of the cationic units in the construction of polyplex-type gene vectors. Moreover, the availability of the polyplex micelle for transfection with primary osteoblasts will facilitate its use for bone regeneration in vivo mediated by nonviral gene transfection.

Animals↗
PubMed2006

Photochemical enhancement of transgene expression by polymeric micelles incorporating plasmid DNA and dendrimer-based photosensitizer.

The development of synthetic gene carriers has recently received much attention; however, they might lack the ability to control the transgene expression. The use of external stimuli for enhancement of the transgene expression may be a promising approach for the site-directed transfection in vivo. In this regard, a new technology of "photochemical internalization (PCI)" has recently been reported, in which the endosomal escape of gene carriers is assisted by photodamage of the endosomal membrane with co-incubating photosensitizers. To apply this technology for systemic gene delivery, the development of appropriate carrier systems for both the plasmid DNA (pDNA) and photosensitizer is of crucial importance. Also, the photocytotoxicity accompanied by the photochemical enhancement of the gene expression may need to be reduced. In this study, the combinational formulation of polymeric micelles incorporating pDNA and a dendrimer-based photosensitizer (DP) (dendrimer phthalocyanine (DPc)) was applied in the PCI-mediated transfection in vitro and then, estimating its potential utility for in vivo applications. The PCI using the polymeric micelle system achieved a remarkable photochemical enhancement of the transgene expression while maintaining an approximate 80% cell viability over a wide range of the DPc concentrations and light doses. Thus, this system may be promising for in vivo PCI-mediated gene delivery.

Cell Survival↗
PubMed2006

The state of the art of nanobioscience in Japan.

This paper reviews a part of the state of the art of nanobioscience in Japan. The importance of combination and integration of interdisciplinary principles is emphasized for the development of nanobioscience. Biomagnetics, biomechanics, nanomachining, self-replicating cell model, neuronal network, drug delivery system, and tissue engineering are discussed.

Biological Science Disciplines↗
PubMed2006

Sendai virus-mediated gene delivery into hepatocytes via isolated hepatic perfusion.

The recombinant Sendai virus vector is a promising tool for human gene therapy, capable of inducing high-level expression of therapeutic genes in tissue cells in situ. The target tissues include airway epithelium, blood vessels, skeletal muscle, retina and the central nervous system, but application to hepatic tissues has not yet been achieved, because direct intraportal injection of the vector is not feasible. We report an efficient and harmless procedure of gene delivery by recombinant Sendai virus into rat parenchymal hepatocytes, based on isolated hepatic perfusion with controlled inflow. Critical parameters for successful hepatic gene delivery are a brief preperfusion period (25 degrees C, 5 min); appropriate vector concentration in the perfusate (10(7) pfu/ml); moderate portal vein pressure (12 mmHg) and a brief hyperthermic postperfusion period (42 degrees C, 5 min). Under these optimized conditions, marker genes were expressed in most parenchymal hepatocytes without significant damage to hepatic tissues. Furthermore, expression of the marker genes was undetectable in nonhepatic tissues, including the gonads, indicating that this approach strictly targets hepatic tissues and thus offers good clinical potential for human gene therapy.

Animals↗
PubMed2006

[Nano-engineering for biomedical applications].

Recently, medical applications of nanotechnology have received much attention. Among them, advances in polymer chemistry have significantly contributed to this field. Here, we review nano-engineering of functional polymers for diagnostic and therapeutic purposes, which have been carried out mainly by our group. Functional polymer-coated nanoparticles can be used for quick detection of biomarkers and DNA separation. Multiarray of hepatocyte spheroids on a microfabricated polymer-brush surface can maintain the hepatocyte viability and liver-specific functions, offering a new high-throughput screening method of pharmacologically and toxicologically active compounds for drug discovery. Polymeric micelles are promising drug carriers, of which the critical parameters such as the size, drug loading and release can be controlled by engineering the constituent block copolymers. Thus, polymeric nano-device will be the leading technology in this field.

Biomedical Engineering↗
PubMed2006

[Supramolecular nanocarrier for gene and siRNA delivery].

In this review article, supramolecular nanocarriers for gene and siRNA delivery were introduced. They were formed through the multimolecular assembly of block copolymers, containing the DNA or siRNA inside the core of the micelle structure. Due to the excellent stability under the physiological conditions, low toxic effect, and controllable gene functions, this system should be a promising candidate for in vivo therapeutic applications including the non-lethal diseases and the tissue engineering.

DNA↗
PubMed2005

Light-induced gene transfer from packaged DNA enveloped in a dendrimeric photosensitizer.

The control of gene transfection in the body is a core issue in gene therapy. Photochemical internalization is a technology that allows light-induced delivery of DNA, drugs or other biological factors directly inside cells. Usually it requires that a photosensitizer be added to the drug-delivery system to photochemically destabilize the endosomal membrane. Here we present a system for in vivo DNA delivery in which these two components are assembled into one structure. This is a ternary complex composed of a core containing DNA packaged with cationic peptides and enveloped in the anionic dendrimer phthalocyanine, which provides the photosensitizing action. The ternary complex showed more than 100-fold photochemical enhancement of transgene expression in vitro with reduced photocytotoxicity. In an animal experiment, subconjuctival injection of the ternary complex followed by laser irradiation resulted in transgene expression only in the laser-irradiated site. This work demonstrates a new biomedical application for dendrimers, and the first success in the photochemical-internalization-mediated gene delivery in vivo.

Animals↗
PubMed2005

Freeze-dried formulations for in vivo gene delivery of PEGylated polyplex micelles with disulfide crosslinked cores to the liver.

A stable, freeze-dried formulation consisting of a core-shell-type polyplex with a poly(ethylene glycol) (PEG) shell (polyplex micelles) was prepared from a polyion complex of plasmid DNA (pDNA) and thiolated PEG-poly(L-lysine) block copolymers. The use of lyoprotectants was avoided by crosslinking the core with disulfide bonds. The crosslinked polyplex micelles (CPMs) showed excellent stability during freeze-drying and reconstitution processes, which is in sharp contrast with the formation of visible agglomerates from the non-crosslinked polyplex micelles (NCPMs) after a similar process. A thiolation degree higher than 13% of the lysine residues was required to achieve sufficient tolerability of the CPMs during the freeze-drying/reconstitution cycle. Dynamic light scattering measurements and atomic force microscopy observations demonstrated that the original size and shape of the CPMs with a thiolation degree of higher than 13% were maintained even after the freeze-drying. Furthermore, the CPMs reconstituted from the freeze-dried state achieved a transfection efficiency as high as that of the original samples. The intravenous injection of the CPM with a thiolation degree of 37% into mice via the orbital vein led to an appreciably uniform gene expression of a yellow fluorescence protein variant (Venus) in the liver, while no gene expression was observed in the case of the free pDNA injection. The procedure of disulfide crosslinking of the polyplex micell core allows the preparation of non-viral gene vectors as a powder formulation without the use of any lyoprotectants. This achievement is certainly useful for pharmaceutical applications and exhibits many advantages, including easy concentration adjustments of dosing samples, long-term storage stability, and large-scale production reproducibility.

Animals↗