|  |  |  | | | | | pubmed: "regenerative medici... | | | | | | | | | | | | | | | | | | | Cytocompatibility of bio-inspired silicon carbide ceramics. J Biomed Mater Res B Appl Biomater. 2010 Aug 24; Authors: López-Ãlvarez M, de Carlos A, González P, Serra J, León B Due to its good mechanical and biochemical properties and, also, because of its unique interconnected porosity, bio-inspired silicon carbide (bioSiC) can be considered as a promising material for biomedical applications, including controlled drug delivery devices and tissue engineering scaffolds. This innovative material is produced by molten-Si infiltration of carbon templates, obtained by controlled pyrolysis of vegetable precursors. The final SiC ceramic presents a porous-interconnected microstructure that mimics the natural hierarchical structure of bone tissue and allows the internal growth of tissue, as well as favors angiogenesis. In the present work, the in vitro cytocompatibility of the bio-inspired SiC ceramics obtained, in this case, from the tree sapelli (Entandrophragma cylindricum) was evaluated. The attachment, spreading, cytoskeleton organization, proliferation, and mineralization of the preosteoblastic cell line MC3T3-E1 were analyzed for up to 28 days of incubation by scanning electron microscopy, interferometric profilometry, confocal laser scanning microscopy, MTT assay, as well as red alizarin staining and quantification. Cells seeded onto these ceramics were able to attach, spread, and proliferate properly with the maintenance of the typical preosteoblastic morphology throughout the time of culture. A certain level of mineralization on the surface of the sapelli-based SiC ceramics is observed. These results demonstrated the cytocompatibility of this porous and hierarchical material. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010. PMID: 20737554 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Fabrication of polyvinyl alcohol/gelatin nanofiber composites and evaluation of their material properties. J Biomed Mater Res B Appl Biomater. 2010 Aug 24; Authors: Linh NT, Min YK, Song HY, Lee BT Electrospinning of polyvinyl alcohol (PVA), gelatin (GE), and a PVA/GE blend was conducted with the aim of fabricating biodegradable scaffolds for tissue engineering. The process parameters including the concentration of GE in PVA/GE blends, electrical field, and tip-to-collector distance (TCD) were investigated. Electrospinning processes were conducted at three different GE concentrations (PVA/GE = 2/8, 6/4, and 8/2), and the voltage and TCD were varied from 18 to 24 kV and 7 to 20 cm, respectively. The average diameter of the electrospun PVA, GE, and PVA/GE blend fibers ranged from 50 to 150 nm. The TCD had significant effects on the average diameter of the PVA/GE nanofiber, while changes in the voltage did not significantly affect the diameter of the PVA/GE nanofiber. The miscibility of the PVA/GE blend fibers was examined by differential scanning calorimetry, and X-ray diffraction was used to determine the crystallinity of the membrane. Tensile strength was measured to evaluate the physical properties of the membrane. Based on the combined results of this study, the PVA/GE membrane holds great promise for use in tissue engineering applications, especially in bone or drug delivery systems. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010. PMID: 20737434 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | In Vitro Evaluation of Magnetic Resonance Imaging Contrast Agents for Labeling Human Liver Cells: Implications for Clinical Translation. Mol Imaging Biol. 2010 Aug 25; Authors: Raschzok N, Muecke DA, Adonopoulou MK, Billecke N, Werner W, Kammer NN, Zielinski A, Behringer PA, Ringel F, Huang MD, Neuhaus P, Teichgräber U, Sauer IM PURPOSE: Magnetic resonance imaging (MRI) is a promising approach for non-invasive monitoring after liver cell transplantation. We compared in vitro labeling of human liver cells with nano-sized (SPIO) and micron-sized iron oxide particles (MPIO). PROCEDURES: The cellular iron load was quantified and phantom studies were performed using 3.0-T MRI. Transferrin receptor and ferritin gene expression, reactive oxygen species (ROS) formation, transaminase leakage, and urea synthesis were investigated over 6 days. RESULTS: Incubation with MPIO produced stronger signal extinctions in MRI at similar iron loads within shorter labeling time. MPIO had no negative effects on the cellular iron homeostasis or cell performance, whereas SPIO caused temporary ROS formation and non-physiologic activation of the iron metabolic pathway. CONCLUSIONS: Our findings suggest that MPIO are suited for clinical translation of strategies for cellular imaging with MRI. Attention should be paid to iron release and oxidative stress caused by biodegradable contrast agents. PMID: 20737221 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Live celloidosome structures based on the assembly of individual cells by colloid interactions. Phys Chem Chem Phys. 2010 Aug 25; Authors: Fakhrullin RF, Brandy ML, Cayre OJ, Velev OD, Paunov VN A new class of colloid structures, celloidosomes, has been developed which represent hollow microcapsules whose membranes consist of a single monolayer of living cells. Two routes for producing these structures were designed based on templating of: (i) air bubbles and (ii) anisotropic microcrystals of calcium carbonate with living cells, which allowed us to fabricate celloidosomes of spherical, rhombohedral and needle-like morphologies. Air microbubbles were templated by yeast cells coated with poly(allylamine hydrochloride) (PAH), then coated with carboxymethylcellulose and rehydrated resulting in the formation of spherical multicellular structures. Similarly, calcium carbonate microcrystals of anisotropic shapes were coated with several consecutive layers of oppositely charged polyelectrolytes to obtain a positive surface charge which was used to immobilise yeast cells coated with anionic polyelectrolyte of their surfaces. After dissolving of sacrificial cores, hollow multicellular structures were obtained. The viability of the cells in the produced structures was confirmed by using fluorescein diacetate. In order to optimize the separation of celloidosomes from free cells magnetic nanoparticles were immobilised onto the surface of templates prior to the cells deposition, which greatly facilitated the separation using a permanent magnet. Two alternative approaches were developed to form celloidosome structures using magnetically functionalised core-shell microparticles which resulted in the formation of celloidosomes with needle-like and cubic-like geometries which follows the original morphology of the calcium carbonate microcrystals. Our methods for fabrication of celloidosomes may found applications in the development of novel symbiotic bio-structures, artificial multicellular organisms and in tissue engineering. The unusual structure of celloidosomes resembles the primitive forms of multicellular species, like Volvox, and other algae and could be regarded as one possible mechanism of the evolutionary development of multicellularity. PMID: 20737085 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Local antibiotic delivery using tailorable chitosan sponges: the future of infection control? J Orthop Trauma. 2010 Sep;24(9):592-7 Authors: Stinner DJ, Noel SP, Haggard WO, Watson JT, Wenke JC OBJECTIVES:: Local antibiotic delivery is a viable and attractive option for preventing infection. Unfortunately, the current options are limited and often necessitate surgical removal. This study evaluates the ability of a biodegradable and biocompatible chitosan sponge to minimize infection by delivering local antibiotics within the wound. METHODS:: A complex musculoskeletal wound was created on the hindlimb of goats and contaminated with Pseudomonas aeruginosa (lux) or Staphylococcus aureus (lux) bacteria. These bacteria are genetically engineered to emit photons, allowing for quantification with a photon-counting camera system. The wounds were closed and similarly débrided and irrigated with 9 L normal saline using bulb-syringe irrigation 6 hours after inoculation. Goats were assigned to different treatment groups: a control group with no adjunctive treatment and an experimental group using a chitosan sponge loaded with either amikacin (for wounds contaminated with P. aeruginosa) or vancomycin (for wounds contaminated with S. aureus). The wounds were closed after the procedure and evaluated 48 hours after initial contamination. Serum levels of the antibiotics were also measured at 6, 12, 24, 36, and 42 hours after treatment was initiated. RESULTS:: The wounds treated with the antibiotic-loaded chitosan sponge had significantly less bacteria than the untreated wounds (P < 0.05). The highest serum levels were 6 hours after treatment but remained less than 15% of target serum levels for systemic treatment. At study end point, all sponges were between 60% and 100% degraded. CONCLUSIONS:: The chitosan sponges are effective delivering the antibiotic and reducing the bacteria within the wounds. PMID: 20736801 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Potential applications of natural origin polymer-based systems in soft tissue regeneration. Crit Rev Biotechnol. 2010 Sep;30(3):200-21 Authors: Silva SS, Mano JF, Reis RL Despite the many advances in tissue engineering approaches, scientists still face significant challenges in trying to repair and replace soft tissues. Nature-inspired routes involving the creation of polymer-based systems of natural origins constitute an interesting alternative route to produce novel materials. The interest in these materials comes from the possibility of constructing multi-component systems that can be manipulated by composition allowing one to mimic the tissue environment required for the cellular regeneration of soft tissues. For this purpose, factors such as the design, choice, and compatibility of the polymers are considered to be key factors for successful strategies in soft tissue regeneration. More recently, polysaccharide-protein based systems have being increasingly studied and proposed for the treatment of soft tissues. The characteristics, properties, and compatibility of the resulting materials investigated in the last 10 years, as well as commercially available matrices or those currently under investigation are the subject matter of this review. PMID: 20735324 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Mineralization of Hydrogels for Bone Regeneration. Tissue Eng Part B Rev. 2010 Aug 25; Authors: Gkioni C, Leeuwenburgh S, Douglas T, Mikos AG, Jansen J Hydrogels are an important class of highly hydrated polymers that are widely investigated for potential use in soft tissue engineering. Generally, however, hydrogels lack the ability to mineralize, preventing the formation of chemical bonds with hard tissues such as bone. A recent trend in tissue engineering involves the development of hydrogels that possess the capacity to mineralize. The strategy that has attracted most interest has been the incorporation of inorganic phases such as calcium phosphate ceramics and bioglasses into hydrogel matrices. These inorganic particles act as nucleation sites that enable further mineralization, thus improving the mechanical properties of the composite material. A second route to create nucleation sites for calcification of hydrogels involves the use of features from the physiological mineralization process. Examples of these biomimetic mineralization strategies include i) soaking of hydrogels in solutions that are saturated with respect to calcium phosphate, ii) incorporation of enzymes that catalyze deposition of bone mineral and iii) incorporation of synthetic analogues to matrix vesicles that are the initial sites of biomineralization. Functionalization of the polymeric hydrogel backbone with negatively charged groups is a third mechanism to promote mineralization in otherwise inert hydrogels. This review summarizes the main strategies that have been developed in the past decade to calcify hydrogel matrices and render these hydrogels suitable for applications in bone regeneration. PMID: 20735319 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Minimally invasive sinus augmentation. J Oral Implantol. 2010;36(4):295-304 Authors: Steiner GG, Steiner DM, Herbias MP, Steiner R Abstract Sinus lift surgery has become more common as patients choose dental implants for tooth replacement. The recent development of a graft material that stimulates osteogenesis coupled with the application of tissue engineering principles has allowed for refinement of this surgical modality. A simple nontraumatic subantral sinus lift microsurgery is presented. This sinus lift microsurgery resulted in a 97% implant success rate. PMID: 20735266 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | The Effects of 17-beta Estradiol on Enhancing Proliferation of Human Bone Marrow Mesenchymal Stromal Cells in vitro. Stem Cells Dev. 2010 Aug 24; Authors: Hong L, Zhang G, Sultana H, Yu Y, Wei Z Human bone marrow mesenchymal stromal cells (MSCs) with self-renewal and multiple differentiation potentials are considered a possible cell source for tissue engineering and regenerative medicine. However, the limited amount of MSCs in bone marrow and the loss of differentiation capacity following in vitro expansion restrict their practical application. Effective improvement of MSC proliferation is necessary for the clinical application of MSCs-based tissue engineering. The effects of estrogen supplements on proliferation and characterizations of human MSCs were investigated at the present study. Supplements of 17-beta estradiol (E2) significantly increase the proliferation of human MSCs in vitro. The dose range of E2 to significantly increase MSC proliferation differs in the gender of MSC donor. E2 supplementation in cell proliferation maintains characterizations of MSCs including cell surface markers, and osteogenic and adipogenic differentiation capacities. These data indicate that estrogen treatment can play an important role in improving human MSCs' expansion in vitro, which will effectively facilitate MSCs' function in the practical application of tissue engineering and regeneration. PMID: 20735179 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Defining the risks of mesenchymal stromal cell therapy. Cytotherapy. 2010 Sep;12(5):576-8 Authors: Prockop DJ, Brenner M, Fibbe WE, Horwitz E, Le Blanc K, Phinney DG, Simmons PJ, Sensebe L, Keating A Abstract We address the issue of the potential for malignant transformation of cultured mesenchymal stromal cells (MSC) commonly used in clinical cell-therapy protocols and describe the culture conditions under which tumorigenesis is likely to be an extremely uncommon event. PMID: 20735162 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Heparin-binding-affinity-based delivery systems releasing nerve growth factor enhance sciatic nerve regeneration. J Biomater Sci Polym Ed. 2010;21(6):771-87 Authors: Wood MD, Hunter D, Mackinnon SE, Sakiyama-Elbert SE The controlled delivery of nerve growth factor (NGF) to the peripheral nervous system has been shown to enhance nerve regeneration following injury, although the effect of release rate has not been previously studied with an affinity-based delivery system (DS). The goal of this research was to determine if the binding site affinity of the DS affected nerve regeneration in vivo using nerve guidance conduits (NGCs) in a 13-mm rat sciatic nerve defect. These DSs consisted of bi-domain peptides that varied in heparin-binding affinity, heparin and NGF, which binds to heparin with moderate affinity. Eight experimental groups were evaluated consisting of NGF with DS, control groups excluding one or more components of the DS within silicone conduits and nerve isografts. Nerves were harvested 6 weeks after treatment for analysis by histomorphometry. These DSs with NGF resulted in a higher frequency of nerve regeneration compared to control groups and were similar to the nerve isograft group in measures of nerve fiber density and percent neural tissue, but not in total nerve fiber count. In addition, these DSs with NGF contained a significantly greater percentage of larger diameter nerve fibers, suggesting more mature regenerating nerve content. While there were no differences in nerve regeneration due to varying peptide affinity with these DSs, their use with NGF enhanced peripheral nerve regeneration through a NGC across a critical nerve gap. PMID: 20482984 [PubMed - indexed for MEDLINE] | | | | | | | | | |  | |  | |  |
No comments:
Post a Comment