Toshihiro Kushibiki

Regeneration of Defects in Articular Cartilage in Rat Knee Joints by CCN2 (Connective Tissue Growth Factor)

CTGF/CCN2, a hypertrophic chondrocyte‐specific gene product, possessed the ability to repair damaged articular cartilage in two animal models, which were experimental osteoarthritis and full‐thickness defects of articular cartilage. These findings suggest that CTGF/CCN2 may be useful in regeneration of articular cartilage.

In vivo release and gene expression of plasmid DNA by hydrogels of gelatin with different cationization extents

The objective of this paper is to investigate the in vivo release and gene expression of lacZ plasmid DNA (pSV-lacZ) by the hydrogels of cationized gelatin. Gelatin with different cationization extents was prepared by changing the amount of ethylenediamine added to aminize the carboxyl groups of gelatin with a water-soluble carbodiimide. The cationized gelatin prepared was crosslinked by various concentrations of glutaraldehyde (GA) to obtain cationized gelatin hydrogels with different cationization extents as the release carrier of plasmid DNA. When the cationized gelatin hydrogels incorporating 125I-labeled pSV-lacZ were implanted into the femoral muscle of mice, the radioactivity remaining decreased with time and the retention period was prolonged with an increase in the concentration of GA used for hydrogel preparation. In vivo experiments with 125I-labeled cationized gelatin hydrogels revealed that the higher the GA concentration, the longer the in vivo retention period of radioactivity remaining for every cationized gelatin hydrogel. Only for the hydrogels prepared from gelatin with the aminized percentages of 29.7, 41.6, and 47.8 mol.%, the time profile of pSV-lacZ retention correlated well with that of hydrogel retention. The gene expression by the cationized gelatin hydrogels incorporating pSV-lacZ depended on the aminized percentage of gelatin and was significant at the percentage of 41.6 mol.% or higher. It is possible that the pSV-lacZ was complexed with the degraded fragments of cationized gelatin and released with a positive charge, resulting in enhanced gene expression. We conclude that gelatin with a cationization extent of at least 41.6 mol.% is needed for the enhanced in vivo gene expression of plasmid DNA by the hydrogel release system.

Cationized gelatin delivery of a plasmid DNA expressing small interference RNA for VEGF inhibits murine squamous cell carcinoma

Double‐stranded RNA (dsRNA) plays a major role in RNA interference (RNAi), a process in which segments of dsRNA are initially cleaved by the Dicer into shorter segments (21–23 nt) called small interfering RNA (siRNA). These siRNA then specifically target homologous mRNA molecules causing them to be degraded by cellular ribonucleases. RNAi downregulates endogenous gene expression in mammalian cells. Vascular endothelial growth factor (VEGF) is a key molecule in vasculogenesis as well as in angiogenesis. Tumor growth is an angiogenesis‐dependent process, and therapeutic strategies aimed at inhibiting angiogenesis are theoretically attractive. To investigate the feasibility of using siRNA for VEGF in the specific knockdown of VEGF mRNA, thereby inhibiting angiogenesis, we have performed experiments with a DNA vector based on a siRNA system that targets VEGF (siVEGF). It almost completely inhibited the expression of three different isoforms (VEGF120, VEGF164 and VEGF188) of VEGF mRNA and the secretion of VEGF protein in mouse squamous cell carcinoma NRS‐1 cells. The siVEGF released from cationized gelatin microspheres suppressed tumor growth in vivo. A marked reduction in vascularity accompanied the inhibition of a siVEGF‐transfected tumor. Fluorescent microscopic study showed that the complex of siVEGF with cationized gelatin microspheres was still present around the tumor 10 days after injection, while free siVEGF had vanished by that time. siVEGF gene therapy increased the fraction of vessels covered by pericytes and induced expression of angiopoietin‐1 by pericytes. These data suggest that cationized‐gelatin microspheres containing siVEGF can be used to normalize tumor vasculature and inhibit tumor growth in a NRS‐1 squamous cell carcinoma xenograft model. (Cancer Sci 2006; 97: 313u2003–u2003321)

Suppression of tumor metastasis by NK4 plasmid DNA released from cationized gelatin

NK4, composed of the NH2-terminal hairpin and subsequent four-kringle domains of hepatocyte growth factor (HGF), acts as an HGF-antagonist and angiogenesis inhibitor. This study is an investigation to evaluate the feasibility of controlled release formulation of NK4 plasmid DNA in suppressing the tumor growth, and lung metastasis. Biodegradable cationized gelatin microspheres were prepared for the controlled release of an NK4 plasmid DNA. The cationized gelatin microspheres incorporating NK4 plasmid DNA could continuously release plasmid DNA over 28 days as a result of microspheres degradation following the subcutaneous injection. The injection of cationized gelatin microspheres incorporating NK4 plasmid DNA into the subcutaneous tissue significantly prolonged the survival time period of the mice bearing Lewis lung carcinoma tumor. Increases in the tumor volume and the number of lung metastatic nodules of NK4 plasmid DNA release group were suppressed to a significantly greater extent than that of solution-injected group (77.4 and 64.0%, respectively). The number of blood vessels and the apoptosis cells in the tumor tissue were significantly suppressed (80.4%) and increased (127.3%) against free NK4 plasmid DNA-injected group. Thus, the controlled release of NK4 plasmid DNA augmented angiogenesis suppression and apoptosis of tumor cells, which resulted in suppressed tumor growth. We conclude that this controlled release technology is promising to enhance the tumor suppression achieved by gene expression of NK4.

A new gene delivery system based on controlled release technology.

The recent rapid development of molecular biology together with the steady progress of genome projects has given us some essential and revolutionary informations of gene to elucidate all the biological phenomena at the molecular level. Under these circumstances, gene transfection has become a fundamental technology indispensable to the basic research of medicine and biology. On the other hand, the technology of gene transfection is also important for gene therapy of several diseases. Some human gene therapies have been performed with a plasmid DNA alone or virus vectors but are clinically limited by the poor gene expression of plasmid DNA and the adverse effects of virus itself, such as immunogenicity and toxicity or the possible mutagenesis of cells transfected. Therefore, several non-viral vectors of synthetic materials have been explored to enhance the transfection efficiency of gene into mammalian cells both in vitro and in vivo. In this paper, the researches about non-viral vectors and recent research trials about the controlled release of plasmid DNA are briefly reviewed to emphasize the significance of gene delivery technology in basic biology and medicine as well as clinical medicine. A new system of gene release based on biodegradable hydrogel is introduced.

SEM Observation of Wet Biological Specimens Pretreated with Room‐Temperature Ionic Liquid

A facile pretreatment process for SEM: The use of room temperature ionic liquids (RTILs) provides an interesting method for SEM of biological specimens. We used a novel and concise method of pretreatment, excluding fixation or Au sputtering steps. Fine and smooth-textured SEM images of a wide variety of biological specimens treated in this way were observed without artefacts.

Enhanced angiogenesis by gelatin hydrogels incorporating basic fibroblast growth factor in rabbit model of hind limb ischemia

Recently we have developed new sustained release system of basic fibroblast growth factor (bFGF) using gelatin hydrogel as a carrier. Using this system, we examined the effect of topical sustained release of bFGF on angiogenesis and tissue blood perfusion in a rabbit model of hind limb ischemia. Thirty-two rabbits underwent excision of right femoral artery under general anesthesia. Two weeks later the rabbits were randomized into four groups (n = 8 each): no treatment, intramuscular injection of gelatin hydrogel alone, and intramuscular injection of gelatin hydrogel incorporating 30u2009µg and 100u2009µg of bFGF. Four weeks after each treatment, selective angiography, tissue blood flowmetry using laser Doppler perfusion imaging, and histological examination of thigh muscle were performed. In groups treated with bFGF incorporating gelatin hydrogel, tissue blood flow, number of arterioles, and vascular density were significantly increased in a dose-dependent manner 4 weeks after the treatment. Serum concentrations of bFGF and vascular endothelial growth factor were not elevated 4 weeks after the treatment. In conclusion, sustained release of bFGF using gelatin hydrogel augmented angiogenesis and improved tissue blood flow after excision of the femoral artery.

Gelatin Hydrogel Microspheres Enable Pinpoint Delivery of Basic Fibroblast Growth Factor for the Development of Functional Collateral Vessels

Background—Various growth factors promote collateral vessel development and are regarded as promising for the treatment of vascular occlusive diseases. However, an efficacious delivery system for them has yet to be established. We devised a strategy to augment functional collateral vessels by using acidic gelatin hydrogel microspheres (AGHMs) incorporating basic fibroblast growth factor (bFGF). The aim of the present study was to investigate the hypothesis that by intra-arterial (IA) administration of bFGF-impregnated AGHMs, bFGF could be delivered from AGHMs trapped in distal small-diameter vessels and thereby induce functional collateral vessels with an assured blood supply through the process of arteriogenesis. Methods and Results—Various sizes of AGHMs (3 mg) incorporating 125I-labeled bFGF were injected into the left internal iliac artery of a rabbit model of hindlimb ischemia. Less than 50% of radioactivity accumulated in the ischemic hindlimb after injection of AGHMs that were 10 &mgr;m in diameter, whereas ≈80% of radioactivity was counted in the ischemic limb after administration of 29- or 59-&mgr;m-diameter AGHMs. Calf blood pressure ratio and the ratio of regional blood flow of the bilateral hindlimbs immediately before and after IA administration of 29-&mgr;m–diameter AGHMs showed no significant change. Then we evaluated the function of the developed collateral vessels 28 days after IA administration of bFGF-impregnated, 29-&mgr;m-diameter AGHMs. IA administration of bFGF-impregnated AGHMs induced marked collateral vessel improvement compared with IA administration of phosphate buffered saline–treated AGHMs and intramuscular administration of bFGF-impregnated AGHMs. Conclusions—IA administration of bFGF-impregnated, 29-&mgr;m-diameter AGHMs strongly induced functional collateral vessels without worsening ischemia, indicating the possible therapeutic usefulness of this approach.

Enhanced suppression of tumor growth using a combination of NK4 plasmid DNA-PEG engrafted cationized dextran complex and ultrasound irradiation

This investigation aims to determine experimentally whether or not ultrasound (US) irradiation is effective in enhancing the in vivo gene expression of NK4 plasmid DNA and suppressing tumor growth. NK4, composed of the NH2-terminal hairpin and subsequent four-kringle domains of hepatocyte growth factor (HGF), acts as an HGF-antagonist and angiogenesis inhibitor. Dextran was cationized by introducing spermine to the hydroxyl groups to allow for polyionic complexation with NK4 plasmid DNA. The cationized dextran was additionally modified with poly(ethylene glycol) (PEG) molecules giving PEG engrafted cationized dextran. Significant suppression of tumor growth was observed when PEG engrafted cationized dextran–NK4 plasmid DNA complexes were intravenously injected into mice carrying a subcutaneous Lewis lung carcinoma tumor mass with subsequent US irradiation when compared with the cationized dextran–NK4 plasmid DNA complex and naked NK4 plasmid DNA with or without US irradiation. We conclude that complexation with PEG-engrafted cationized dextran in combination with US irradiation is a promising way to target the NK4 plasmid DNA to the tumor for gene expression.

Tissue Regeneration Using Macrophage Migration Inhibitory Factor-Impregnated Gelatin Microbeads in Cutaneous Wounds

Migration inhibitory factor (MIF) responds to tissue damage and regulates inflammatory and immunological processes. To elucidate the function of MIF in cutaneous wound healing, we analyzed MIF knockout (KO) mice. After the excision of wounds from the dorsal skin of MIF KO and wild-type (WT) mice, healing was significantly delayed in MIF KO mice compared to WT mice. Lipopolysaccharide treatment significantly increased [(3)H]thymidine uptake in WT mouse fibroblasts compared to MIF KO mouse fibroblasts. Furthermore, there was a significant reduction in fibroblast and keratinocyte migration observed in MIF KO mice after 1-oleoyl-2-lysophosphatidic acid treatment. We subsequently examined whether MIF-impregnated gelatin slow-release microbeads could accelerate skin wound healing. Injection of more than 1.5 microg/500 microl of MIF-impregnated gelatin microbeads around a wound edge accelerated wound healing compared to a single MIF injection without the use of microbeads. MIF-impregnated gelatin microbeads also accelerated skin wound healing in C57BL/6 mice and diabetic db/db mice. Furthermore, incorporating MIF-impregnated gelatin microbeads into an artificial dermis implanted into MIF KO mice accelerated procollagen production and capillary formation. These findings suggest that MIF is crucial in accelerating cutaneous wound healing and that MIF-impregnated gelatin microbeads represent a promising treatment to facilitate skin wound healing.