In Vivo Biocompatibility Study of Electrospun Chitosan Microfiber for Tissue Engineering

In this work, we examined the biocompatibility of electrospun chitosan microfibers as a scaffold. The chitosan microfibers showed a three-dimensional pore structure by SEM. The chitosan microfibers supported attachment and viability of rat muscle-derived stem cells (rMDSCs). Subcutaneous implantation of the chitosan microfibers demonstrated that implantation of rMDSCs containing chitosan microfibers induced lower host tissue responses with decreased macrophage accumulation than did the chitosan microfibers alone, probably due to the immunosuppression of the transplanted rMDSCs. Our results collectively show that chitosan microfibers could serve as a biocompatible in vivo scaffold for rMDSCs in rats

Transgenic tomatoes expressing human beta-amyloid for use as a vaccine against Alzheimer’s disease

Human β-amyloid (Aβ) is believed to be one of the main components of Alzheimer’s disease, so reduction of Aβ is considered a key therapeutic target. Using Agrobacterium-mediated nuclear transformation, we generated transgenic tomatoes for Aβ with tandem repeats. Integration of the human Aβ gene into the tomato genome and its transcription were detected by PCR and Northern blot, respectively. Expression of the Aβ protein was confirmed by western blot and ELISA, and then the transgenic tomato line expressing the highest protein level was selected for vaccination. Mice immunized orally with total soluble extracts from the transgenic tomato plants elicited an immune response after receiving a booster. The results indicate that tomato plants may provide a useful system for the production of human Aβ antigen

Plant Body Weight-Induced Secondary Growth in Arabidopsis and Its Transcription Phenotype Revealed by Whole-Transcriptome Profiling

Wood is an important raw material and environmentally cost-effective renewable source of energy. However, the molecular biology of wood formation (i.e. secondary growth) is surprisingly understudied. A novel experimental system was employed to study the molecular regulation of secondary xylem formation in Arabidopsis. First, we demonstrate that the weight carried by the stem is a primary signal for the induction of cambium differentiation and the plant hormone, auxin, is a downstream carrier of the signal for this process. We used Arabidopsis whole-transcriptome (23 K) GeneChip analysis to examine gene expression profile changes in the inflorescent stems treated for wood formation by cultural manipulation or artificial weight application. Many of the genes up-regulated in wood-forming stems had auxin responsive cis-acting elements in their promoter region, indicating auxin-mediated regulation of secondary growth. We identified 700 genes that were differentially expressed during the transition from primary growth to secondary growth. More than 40% of the genes that were up-regulated (>5×) were associated with signal transduction and transcriptional regulation. Biological significance of these regulatory genes is discussed in light of the induction and development of secondary xylem

Review Article N-Glycosylation Modification of Plant-Derived Virus-Like Particles: An Application in Vaccines

Plants have been developed as an alternative system to mammalian cells for production of recombinant prophylactic or therapeutic proteins for human and animal use. Effective plant expression systems for recombinant proteins have been established with the optimal combination of gene expression regulatory elements and control of posttranslational processing of recombinant glycoproteins. In plant, virus-like particles (VLPs), viral "empty shells" which maintain the same structural characteristics of virions but are genome-free, are considered extremely promising as vaccine platforms and therapeutic delivery systems. Unlike microbial fermentation, plants are capable of carrying out N-glycosylation as a posttranslational modification of glycoproteins. Recent advances in the glycoengineering in plant allow human-like glycomodification and optimization of desired glycan structures for enhancing safety and functionality of recombinant pharmaceutical glycoproteins. In this review, the current plant-derived VLP approaches are focused, and N-glycosylation and its in planta modifications are discussed. Plant-Derived Virus-Like Particle (VLP) Viruses are able to form the quaternary structure of viral capsids through molecular self-assembly of repetitive building blocks In general, bacteria, yeast, insect, and animal cells have been applied as cell-based systems to produce VLPs. The bacterial cell cultures have been explored as a VLP production platform with advantages in terms of scalability and production cost Virus-Like Particles in Plant Expression Systems Glycosylation of VLP Vaccines Even though virus-like particles-(VLPs-) based vaccines have shown promising results, commercial production systems are currently limited to eukaryotic cells such as yeast, insect, and mammalian core 1,3-fucose, and Le a containing epitopes have been considered as immunogenic glycan epitopes found in plantspecific N-glycans. Such glycan residues are not present in humans, and thus proteins could cause immune rejection inducing plant-glycan specific antibodies causing protein clearance in blood stream as well as potential allergenic effects N-Glycomodification in Plants Targeted Expression to the ER. N-glycan structures influence biofunctionality and stability of therapeutic proteins and even directly affect immunogenicity of glycosylated subunit vaccines displayed on VLP surfaces. In plants, thus, N-glycosylation pathway has been modified in order to humanize the glycan structures of glycoproteins A commonly used approach to express recombinant glycoproteins in plants is their accumulation in ER by addition of C-terminal signal H/KDEL ER retention motif Knockout of Plant-Specific Glycosyltransferases. Gene inactivation or silencing may be used to reduce or eliminate the activity of plant-specific glycosyltransferases. In a plant cell, the specific enzymes are 1,2-xylosyltransferase and core 1,3-fucosyltransferase, which are responsible for transfer of the plant-specific xylose and fucose onto the attached N-glycan. Such glycan residues are not present in humans and are thus unwanted on proteins intended for therapeutic use. The knockout of the genes that are responsible for the synthesis of these glycan epitopes 1,2-xylosyltransferase and core 1,3-fucosyltransferase provides an easy strategy to solve this problem. The feasibility of this strategy has been proven by the generation of knockout Arabidopsis thaliana plant lacking xylosyltransferase and fucosyltransferase Humanization of Plant N-Glycosylation. The immunogenic and allergenic reactions of the 1,2-xylose and core 1,3-fucose N-glycan epitopes on plant-derived glycoproteins have been a problem for application of therapeutic proteins produced from plant expression system Conclusions Taken together, plant-derived VLPs are considered safe because plants do not bear human pathogens and promising in terms of cost-effective scalability and speed of production. In fact, as far as upstream and downstream processing are concerned, plant-derived VLPs can take advantage of what has been done so far in the broader field of plantmade pharmaceuticals. Also compared to prokaryotes host cells, plants host guarantees the appropriate posttranslational modifications, such as glycosylation, often needed for proper protein function. In plants, glycoengineering has been improved to create plants able to perform the ideal glycosylation enhancing efficacy and potency of VLPs-based therapeutics. As described in this review, several strategies, focused on the inactivation and/or addition of key enzymes, can be adopted to decorate tailor-made glycoforms of VLPs in plants. Thus, plant expression systems will be further improved for production of VLPs-based vaccines with respect to their proper glycomodification and the rapid and cost-effective expression

Current Understanding of the Genetics and Molecular Mechanisms Regulating Wood Formation in Plants

Unlike herbaceous plants, woody plants undergo volumetric growth (a.k.a. secondary growth) through wood formation, during which the secondary xylem (i.e., wood) differentiates from the vascular cambium. Wood is the most abundant biomass on Earth and, by absorbing atmospheric carbon dioxide, functions as one of the largest carbon sinks. As a sustainable and eco-friendly energy source, lignocellulosic biomass can help address environmental pollution and the global climate crisis. Studies of Arabidopsis and poplar as model plants using various emerging research tools show that the formation and proliferation of the vascular cambium and the differentiation of xylem cells require the modulation of multiple signals, including plant hormones, transcription factors, and signaling peptides. In this review, we summarize the latest knowledge on the molecular mechanism of wood formation, one of the most important biological processes on Earth

N-Glycosylation Modification of Plant-Derived Virus-Like Particles: An Application in Vaccines

Plants have been developed as an alternative system to mammalian cells for production of recombinant prophylactic or therapeutic proteins for human and animal use. Effective plant expression systems for recombinant proteins have been established with the optimal combination of gene expression regulatory elements and control of posttranslational processing of recombinant glycoproteins. In plant, virus-like particles (VLPs), viral “empty shells” which maintain the same structural characteristics of virions but are genome-free, are considered extremely promising as vaccine platforms and therapeutic delivery systems. Unlike microbial fermentation, plants are capable of carrying out N-glycosylation as a posttranslational modification of glycoproteins. Recent advances in the glycoengineering in plant allow human-like glycomodification and optimization of desired glycan structures for enhancing safety and functionality of recombinant pharmaceutical glycoproteins. In this review, the current plant-derived VLP approaches are focused, and N-glycosylation and its in planta modifications are discussed

Electron Transport through Nano-aperture in Ferroelectric Thin Film of Metal/Insulator(Stack of Ferroelectric and Non-ferroelectric)/Metal Junction

The electron energy band profile through a nm-scale circular aperture in ferroelectric thin film of metal/insulator(stack of ferroelectric and non-ferroelectric)/metal junction was calculated by performing finite-element electrostatic modeling. It is found that the energy band profile through the circular aperture alters significantly near the boundary of aperture depending on the polarization direction of ferroelectric thin film. The energy band profile shows pinch-off when the interface bound charge at Ferroelectric/Non-ferroelectric interface is negative while it shows a valley-like shape when the interface bound charge is positive. The change of the energy band profile depending on ferroelectric polarization was confirmed to result in a drastic change of electron tunneling probability through the non-ferroelectric insulating film inside the circular aperture by using WKB method. It is believed that this switching of electron tunneling resistance through the circular aperture opens a way to develop non-volatile ferroelectric memory devices using non-destructive read-out

The Arabidopsis GRF-INTERACTING FACTOR Gene Family Performs an Overlapping Function in Determining Organ Size as Well as Multiple Developmental Properties1[C][W][OA]

Previously, the GRF-INTERACTING FACTOR1 (GIF1)/ANGUSTIFOLIA3 (AN3) transcription coactivator gene, a member of a small gene family comprising three genes, was characterized as a positive regulator of cell proliferation in lateral organs, such as leaves and flowers, of Arabidopsis (Arabidopsis thaliana). As yet, it remains unclear how GIF1/AN3 affects the cell proliferation process. In this study, we demonstrate that the other members of the GIF gene family, GIF2 and GIF3, are also required for cell proliferation and lateral organ growth, as gif1, gif2, and gif3 mutations cause a synergistic reduction in cell numbers, leading to small lateral organs. Furthermore, GIF1, GIF2, and GIF3 overexpression complemented a cell proliferation defect of the gif1 mutant and significantly increased lateral organ growth of wild-type plants as well, indicating that members of the GIF gene family are functionally redundant. Kinematic analysis on leaf growth revealed that the gif triple mutant as well as other strong gif mutants developed leaf primordia with fewer cells, which was due to the low rate of cell proliferation, eventually resulting in earlier exit from the proliferative phase of organ growth. The low proliferative activity of primordial leaves was accompanied by decreased expression of cell cycle-regulating genes, indicating that GIF genes may act upstream of cell cycle regulators. Analysis of gif double and triple mutants clarified a previously undescribed role of the GIF gene family: gif mutants had small vegetative shoot apical meristems, which was correlated with the development of small leaf primordia. gif triple mutants also displayed defective structures of floral organs. Taken together, our results suggest that the GIF gene family plays important roles in the control of cell proliferation via cell cycle regulation and in other developmental properties that are associated with shoot apical meristem function