1,721,001 research outputs found
VEGF-overexpressed Human Tonsil-derived Mesenchymal Stem Cells with PEG/HA-based Cryogels for Therapeutic Angiogenesis
No full textTherapeutic neovascularization through cell transplantation has widely been investigated as a cure for ischemia. However, there are several limitations to this technique, including low survival rate of the therapeutic cells and inflammation at the transplanted sites. Polyethylene glycol (PEG)/hyaluronic acid (HA)-based cryogels are used to overcome these problems as they provide cell adhesion sites owing to their interconnected macroporous structure, which increases cell viability in combination with the cryogel's intrinsic biocompatibility. Furthermore, vascular endothelial growth factor (VEGF) plays a significant role in pro-angiogenesis of endothelial cells (ECs) and it has been demonstrated that injection of VEGF-secreting cells could enhance neovascularization at the sites of injection. In the present study, we developed a PEG diacrylate (PEGDA)/glycidyl methacrylate-HA (GMHA)-based cryogel system seeded with VEGF-transfected human tonsil-derived mesenchymal stem cells to induce enhanced neovascularization in murine hind-limb ischemia. Addition of GMHA allowed the PEGDA cryogel to enhance cell metabolism, including attachment and proliferation. The secreted VEGF affected human umbilical vein endothelial cells by enhancing in vitro angiogenesis. Finally, our cell-seeded cryogel successfully facilitated regeneration of blood flow and damaged tissue in a hind-limb ischemia model.N
Partially Digested Osteoblast Cell Line-Derived Extracellular Matrix Induces Rapid Mineralization and Osteogenesis
No full textAn extracellular matrix (ECM) utilized as a biomaterial can be obtained from organs of living organisms. Therefore, it has some limitations in its supply because of insufficient organs. Furthermore, therapeutic efficacy of ECMs varies depending on factors such as donor's health condition and age. For this reason, ECMs obtained from a cell line could be a good alternative because they can be produced under a controlled environment with uniform quality. Thus, the purpose of this study was to investigate the potential of the MC3T3-E1 cell line-derived ECM as bone graft. The optimized decellularization process was developed to separate the ECM from MC3T3-E1, osteoblast cell line, using Trypsin-EDTA and Triton X-100. The decellularized ECM was partially digested using pepsin. Also, human bone marrow-derived mesenchymal stem cells induced faster osteogenesis on the ECM-coated surface than on the collagen-coated surface. Partially digested ECM fragments were embedded on the polyethylene glycol scaffold without additional chemical modification or crosslinking. Micro-computed tomography and histological analysis results showed that the ECM in the scaffold promoted actual bone regeneration after in vivo implantation to a mouse calvarial defect model. This study suggests that the bone-specific ECM derived from the cell line can replace the ECM from organs for application in tissue engineering and regenerative medicine.N
Protein-based direct reprogramming of fibroblasts to neuronal cells using 30Kc19 protein and transcription factor Ascl1
No full textDirect reprogramming of non-neural lineages to functional neurons holds great potential for neural development, neurological disease modeling, and regenerative medicine. Recent work has shown that single transcription factor Ascl1 can directly reprogram fibroblasts into neuronal cells under co-culture system with glial cells. It is confirmed that Ascl1 is the key driver in the reprogramming of induced neuronal cells (iNCs). However, most reprogramming methods use genetic materials and/or potentially mutagenic molecules to generate iNCs.,Herein, we used 30Kc19 protein as a novel fusion partner of transcription factor Ascl1 to induce direct reprogramming of fibroblasts to neuronal cells. We demonstrated soluble expression and stability of Ascl1 protein was increased and maintained by co-expression with 30Kc19 protein, respectively. We confirmed that intracellular delivery of the fusion protein resulted in iNC generation. Protein-induced neuronal cells (p-iNCs) expressed neuronal protein markers (MAP2, Tuj1) and transcriptional genes (Ascl1, Brn2, and Myt1l. Protein-based direct reprogramming system eliminates the potential risk associated with the use of genetic materials. This method is anticipated to be useful for safe generation of patient-specific human neuronal cells for future applications in regenerative medicine.N
Functional-hydrogel-based electronic-skin patch for accelerated healing and monitoring of skin wounds
No full textConductive hydrogels feature reasonable electrical performance as well as tissue-like mechanical softness, thus positioning them as promising material candidates for soft bio-integrated electronics. Despite recent advances in materials and their processing technologies, however, facile patterning and monolithic integration of functional hydrogels (e.g., conductive, low-impedance, adhesive, and insulative hydrogels) for all-hydrogel-based soft bioelectronics still poses significant challenges. Here, we report material design, fabrication, and integration strategies for an electronic-skin (e-skin) patch based on functional hydrogels. The e-skin patch was fabricated by using photolithography-compatible functional hydrogels, such as poly(2-hydroxyethyl acrylate) (PHEA) hydrogel (substrate), Ag flake hydrogel (interconnection; conductivity: similar to 571.43 S/cm), poly(3,4-ethylenedioxythiophene:polystyrene) (PEDOT:PSS) hydrogel (working electrode; impedance: similar to 69.84 Omega @ 1 Hz), polydopamine (PDA) hydrogel (tissue adhesive; shear strength: similar to 725.1 kPa), and poly(vinyl alcohol) (PVA) hydrogel (encapsulation). The properties of these functional hydrogels closely resemble those of human tissues in terms of water content and Young's modulus, enabling stable tissue-device interfacing in dynamically changing physiological environments. We demonstrated the efficacy of the e-skin patch through its application to accelerated healing and monitoring of skin wounds in mouse models- efficient fibroblast migration, proliferation, and differentiation promoted by electric field (EF) stimulation and iontophoretic drug delivery, and monitoring of the accelerated healing process through impedance mapping. The all-hydrogel-based e-skin patch is expected to create new opportunities for various clinically-relevant tissue interfacing applications.N
Modulation of BMP-2-Induced Chondrogenic Versus Osteogenic Differentiation of Human Mesenchymal Stem Cells by Cell-Specific Extracellular Matrices
No full textBone morphogenetic protein-2 (BMP-2) is known to induce both osteogenic and chondrogenic commitment of human mesenchymal stem cells (hMSCs). However, factors influencing BMP-2-dependent chondrogenic and osteogenic differentiation have not been investigated. In this study, we demonstrated that extracellular micro-environments, in the form of cell-derived matrices, play important roles in determining the specific lineage commitment of hMSCs in the presence of BMP-2. Extracellular matrices (ECMs) derived from osteoblasts and chondrocytes were utilized to regulate cell differentiation. Osteogenic and chondrogenic differentiation of hMSCs cultured on the two different cell-derived ECMs were assessed by quantitative real-time-polymerase chain reaction, immunocytochemistry, and western blot analysis. To minimize the effects of the cell-adhesion proteins contained in serum on the ECMs, hMSCs were cultured in serum-free osteogenic or chondrogenic differentiation medium. Fibronectin-, collagen type I-, or collagen type II-coated substrates were utilized as ECM controls. The ECM specific to each cell type promoted lineage-specific commitment of hMSCs in the presence of BMP-2, that is, osteoblast-and chondrocyte-derived ECM promoted osteogenic and chondrogenic commitment, respectively. Therefore, cell-specific ECMs are capable of modulating the BMP-2-induced osteogenic and chondrogenic differentiation of hMSCs.Y
Dual action of a tyrosinase-mesoporous silica nanoparticle complex for synergistic tissue adhesion
No full textBridging biological tissues for immediate adhesion and long-term sustainability was accomplished using a combination of mesoporous silica nanoparticles (MSNs) and tyrosinase. Tyrosinase-loaded MSNs provided rapid physical adsorption, while tyrosinase within MSNs induced enzymatic chemical bond gluing of tissues. This synergistic strategy has robust potential in tissue adhesives for clinical settings.11Nsciescopu
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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