Papers by Keyword: Controlled-Release

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Authors: Yasuhiko Tabata
Abstract: A new therapeutic trial based on the self-healing potential of cells to naturally induce tissue regeneration, has been recently noted. To realize this regenerative medical therapy, it is highly required to efficiently combine cells with their local environment which basically allows cells to survive and biologically function in vivo through the essential interaction. Tissue engineering is a biomedical technology or methodology to create the local environment which promotes the proliferation and differentiation of cells to induce tissue regeneration. There are some cases where tissue regeneration can be induced only by supplying a cell scaffold of biomaterials. Drug delivery system (DDS) with biomaterials enhanced the in vivo biological activities of un-stable growth factor and gene for cell-induced tissue regeneration. The controlled release technology enabled growth factors to achieve the regeneration of various tissues experimentally and clinically. The DDS technology also augmented the biological functions of plasmid DNA and small interference RNA. The cells genetically engineered by the DDS gene system showed an enhanced therapeutic efficacy in cell-based tissue regeneration (cell-gene hybrid therapy). By making use of DDS technology, it is possible to suppress the deterioration and proceeding of chronic fibrotic diseases based on the self-healing potential inherently equipped in the living body. This paper emphasizes significance of biomaterials in tissue engineering for regenerative medical therapy.
Authors: Masaya Yamamoto, Yoshitake Takahashi, Yasuhiko Tabata
Abstract: The objective of this study is to examine feasibility of biodegradable gelatin hydrogels incorporating bone morphogenetic protein (BMP)-2 in inducing bone regeneration at a bone defect of non-human primates and rabbits considering their BMP-2 release profiles. As a result, controlled release by the hydrogel system enabled BMP-2 to induce successful bone regeneration in non-human primates even at the BMP-2 dose as low as that for rabbit case (0.034 mg of BMP-2/cm3 of hydrogel).
Authors: Ling Fei Wei, Gang Wu, Li Quan Deng, Yue Lian Liu
Abstract: Although preclinical and clinical studies have shown the benefits of bone morphogenetic protein-2 (BMP2) in bone regeneration, there are increasing concerns about its side effects. These are mainly due to the high dosage of BMP2 which is necessary to obtain the desired clinical results. Previously our group has developed a novel controlled-release delivery system; the biomimetic calcium phosphate coating incorporated with BMP2. It can be used at much lower concentrations of BMP2 than those used in the commercially available product and still produce similar biological effects. In this study, we made a primarily biological evaluation of BMP2 incorporated beta-tricalcium phosphate (β-TCP) for bone regeneration in critical-sized bone defects. Critical-sized calvarial defects were created in rats. They were divided into four groups as follows: (1) empty defects (control), (2) defects filled with β-TCP, (3) defects filled with BMP2 incorporated β-TCP, (4) defects filled with autologous bone. Eight weeks after the operation, the efficiency of the materials was evaluated using histology and histomorphometry. Moreover, the safety of the materials was evaluated using routine blood examination, blood biochemistry examination and histopathological examination of viscera. BMP2 incorporated β-TCP demonstrated an efficiency of bone regeneration that was comparable with autologous bone, with the highest levels of new bone formation (38.3±8.4 mm3 versus 30.1±9.9 mm3, p < 0.05). All clinical lab index of blood in these four groups were within the normal range. Moreover, no change related to the treatment was noted in the histopathological examination of viscera. The results from the present study demonstrated that BMP2 incorporated β-TCP could be a promising substitute for autologous bone used for bone regeneration. Future clinical trials and preclinical trials with large animal models are necessary to investigate the safety and efficacy of BMP2 incorporated β-TCP.
Authors: Xin Liu, Yun Hui Xu, Wei Wei Zhang
Abstract: With science and standard of living progressing, functional textile become more and more popular. We reported that a new bamboo pulp fiber fabric with the chitosan modification (CMBPFF) was prepared by the selective oxidation of sodium periodate and then treatment with a solution of chitosan aqueous acetic acid. The resulting CMBPFF is a nonpolluting and eco-friendly fabric product through the method of natural raw materials and no additives, which not only increase the added value of the product but also achieve natural ecological fabrics. This research using Kjeldahl nitrogen analysis showed that the maximum percentage of chitosan crosslinked on bamboo pulp fiber fabric was 10.52% (w/w). FT-IR spectra characterization suggested that the imine covalent bond between the chitosan and the oxidized bamboo pulp cellulose was formed through a series of reaction. The breaking strength of the modified fabric remained basically unchanged when the concentration of sodium periodate was less than 2.0 mg/ml. Furthermore, the chitosan modified bamboo pulp fiber fabric had the good antibacterial property. The wrinkle recovery angle and moisture regain of the chitosan modified fabric were improved. Meanwhile, a model experiment for the controlled release the drug was investigated using cactus extracts, a component of a Chinese medicine, indicated the extensive applicability of CMBPFF as a carrier for the controlled release drugs.
Authors: D.H.R. Kempen, Chan Wook Kim, L. Lu, W.J.A. Dhert, B.L. Currier, M.J. Yaszemski
Authors: Stefan Lemke, Mont Kumpugdee-Vollrath
Abstract: In this project we have prepared the tablets with a coating of pH-sensitive polymer Kollicoat MAE 30DP. For this purpose the core tablets prepared from poorly water soluble model drug and other excipients were coated by a fluidized bed apparatus at the exhaust air temperature of 30°C and spraying rate of 0.55 g/min. The highest coating time was 384 min which leads to the film thickness of 648 µm. The coated tablets were gastric resistant for one hour and resistant against intestinal fluid pH 6.8 up to 70 min. The coating film has a good quality with smoothness and dense packing. However, if the thickness was high e.g. 600 µm the film surface had more wavy structure. The results served to formulate the colon delivery system.
Authors: T. Kushibiki, K. Matsumoto, T. Nakamura, Yasuhiko Tabata
Abstract: NK4, composed of the NH2-terminal hairpin and subsequent four-kringle domains of hepatocyte growth factor (HGF), acts as a potent angiogenesis inhibitor. This study is an investigation to evaluate the feasibility of controlled release of NK4 plasmid DNA in suppressing tumor growth. Controlled release by a biodegradable hydrogel enabled the NK4 plasmid DNA to enhance the tumor suppression effects. Biodegradable microspheres of cationized gelatin were prepared for the controlled release of a NK4 plasmid DNA. The cationized gelatin microspheres incorporating NK4 plasmid DNA were subcutaneously injected to tumor-bearing mice to evaluate the suppressive effects on tumor angiogenesis and growth. The cationized gelatin microspheres incorporating NK4 plasmid DNA could release over 28 days. When the cationized gelatin microspheres incorporating NK4 plasmid DNA were injected into the subcutaneous tissue of mice intraperitoneally inoculated with pancreatic cancer cells, their survival time period was prolonged. Tumor growth was suppressed to a significantly greater extent than free NK4 plasmid DNA. The controlled release of NK4 plasmid DNA suppressed angiogenesis and increased cell apoptosis in the tumor tissue, while it enhanced and prolonged the serum level of NK4 protein. We conclude that the controlled release technology was promising to enhance the tumor suppression effects of NK4 plasmid DNA.
Authors: J. Papangkorn, C. Isaraphan, S. Phinhongthong, Mantana Opaprakasit, Pakorn Opaprakasit
Abstract: Urea fertilizer is a major source of nitrogen, which is one of the essential nutrients for plant growth. Due to its uncontrollable release, this chemical can be wasted easily by leaching and volatilization that can adversely cause the contamination to the environment. In this work, a controlled-release material for urea fertilizer has been prepared by using degradable polylactic acid. Unlike other conventional controlled-release system, the resulting material is able to provide an efficient supply of urea fertilizer, without causing further contamination to the environment from residue material, as polylactic acid can be degraded in the environment. Micron-size particles of polylactic acid coated urea were prepared by employing atomizing technique. Effect of the preparation conditions; urea/PLA composition, PLA concentration, and pressure of atomizing gun on the particle size of material are investigated. The urea release rate of these samples is then studied by employing UV-Visible spectrophotometer. In addition, the effect of preparation conditions on shape and morphology of sample is determined by using Scanning Electron Microscope (SEM).
Authors: N. Jintakanon, Pakorn Opaprakasit, Atitsa Petchsuk, Mantana Opaprakasit
Abstract: ontrolled-release materials for urea are prepared by spray coating urea granulates with lactic acid based homo- and co-polymers solutions. Percent coating as a function of polymer types, molecular weight, polymer concentration, and dose applications are examined by gravimetric analysis. Percentage of urea dissolution in water of the coated fertilizer is measured by monitoring refractive index of the solutions. Morphology of the polymer coating surfaces is revealed by Scanning Electron Microscopy (SEM). It was found that an amount of cracks and pin-holes, which is dependent on polymer types and molecular weight, plays a significant role in controlling the rate of urea release. Results from urea dissolution test also suggests that the synthesized poly(lactic acid-co-ethylene terephthalate) show urea-holding efficiency comparable to that of commercial PLA, despite its much lower molecular weight, indicating that the copolymer is potentially suitable for this specific application.
Authors: Chong Wang, Sze Nga Tong, Yuk Hang Tse, Min Wang
Abstract: Over the past decade, intensive research has been conducted on electrospinning of fibrous tissue engineering scaffolds and their applications in body tissue regeneration. For providing multifunctions and/or enhancing the biological performance, drugs or biomolecules can be incorporated in electrospun fibers using normally one of these techniques: (1) direct dissolution, (3) emulsion electrospinning, and (3) coaxial electrospinning. In this investigation, for constructing nanofibrous delivery vehicles, conventional electrospinning using polymer solutions with directly dissolved drugs or biomolecules and emulsion electrospinning were studied and compared. Bovine serum albumin (BSA) was used as a model protein and the drug was rifamycin, a hydrophobic antibiotic. A poly (lactic-co-glycolic acid) containing the protein or drug was electrospun into fibers. In these two routes of fabricating drug-or biomolecule-loaded nanofibers, different polymer concentrations and emulsion formulations were investigated. Various aspects of the fibrous delivery vehicles were investigated using several techniques and the in vitro release behaviour was studied.
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