bluuebunny/crossref_metadata_2025_split huggingface dataset:
Highly superporous cholesterol‐modified poly(2‐hydroxyethyl methacrylate) scaffolds for spinal cord injury repair
Authors: Kubinová Šárka , Horák Daniel , Hejčl Aleš , Plichta Zdeněk , Kotek Jiří , Syková Eva 
Published: September 2011

AbstractModifications of poly(2‐hydroxyethyl methacrylate) (PHEMA) with cholesterol and the introduction of large pores have been developed to create highly superporous hydrogels that promote cell–surface interactions and that can serve as a permissive scaffold for spinal cord injury (SCI) treatment. Highly superporous cholesterol‐modified PHEMA scaffolds have been prepared by the bulk radical copolymerization of 2‐hydroxyethyl methacrylate (HEMA), cholesterol methacrylate (CHLMA), and ethylene dimethacrylate (EDMA) cross‐linking agent in the presence of ammonium oxalate crystals to establish interconnected pores in the scaffold. Moreover, 2‐[(methoxycarbonyl)methoxy]ethyl methacrylate (MCMEMA) was incorporated in the polymerization recipe and hydrolyzed, thus introducing carboxyl groups in the hydrogel to control its swelling and softness. The hydrogels supported thein vitroadhesion and proliferation of rat mesenchymal stem cells. In anin vivostudy of acute rat SCI, hydrogels were implanted to bridge a hemisection cavity. Histological evaluation was done 4 weeks after implantation and revealed the good incorporation of the implanted hydrogels into the surrounding tissue, the progressive infiltration of connective tissue and the ingrowth of neurofilaments, Schwann cells, and blood vessels into the hydrogel pores. The results show that highly superporous cholesterol‐modified PHEMA hydrogels have bioadhesive properties and are able to bridge a spinal cord lesion. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011.
Macrophage response to high number of titanium particles is cytotoxic and COX‐2 mediated and it is not affected by the particle's endotoxin content or the cleaning treatment
Authors: Schwab Luciana P. , Marlar Justin , Hasty Karen A. , Smith Richard A. 
Published: September 2011

AbstractPeriprosthetic osteolysis is a progressive deterioration of bone around prostheses resulting primarily from the presence of wear debris. Particulate material, number, and their interactions with environmental factors play important roles in macrophage activation around implants. We have previously shown that macrophages cultured in the presence of high numbers of cleaned titanium (Ti) particles released significant amounts of PGE2 that is potentially detrimental for bone. Cleaning of particles has become routine in most studies of macrophage/particle interactions as contaminating endotoxin elicits a macrophage cytokine response and since numerous studies have suggested that endotoxins may be present on implant materials. However, the strenuous cleaning procedure itself represents a possible source of other contaminants (such as material by‐products) that may be relevant to the prostanoid response of macrophages. To analyze this hypothesis, the macrophage response to high numbers of cleaned Ti particles was compared to that of unclean particles and to particles that were subjected to a short version of the cleaning procedure. It was found that neither the high amount of endotoxin on the unclean particles nor the duration of the cleaning procedure had an effect on the release of PGE2 and the decrease in cell viability in response to high number of Ti particles. Evidence of a possible relationship between these two variables is presented. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011.
Autologous fibrin scaffolds cultured dermal fibroblasts and enriched with encapsulated bFGF for tissue engineering
Authors: de la Puente Pilar , Ludeña Dolores , Fernández Ana , Aranda Jose L. , Varela Gonzalo , Iglesias Javier 
Published: September 2011

AbstractAutologous fibrin scaffolds (AFSs) enriched with cells and specific growth factors represent a promising biocompatible scaffold for tissue engineering. Here, we analyzed the in vitro behavior of dermal fibroblasts (DFs) (cellular attachment, distribution, viability and proliferation, histological and immunohistochemical changes), comparing AFS with and without alginate microcapsules loaded with basic fibroblast growth factor (bFGF), to validate our scaffold in a future animal model in vivo. In all cases, DFs showed good adhesion and normal distribution, while in scaffolds with bFGF at 14 days, the cell counts detected in proliferation and viability assays were greatly improved, as was the proliferative state, and there was a decrease in muscle specific actin expression and collagen synthesis in comparison with the scaffolds without bFGF. In addition, the use of plasma without fibrinogen concentration methods, together with the maximum controlled release of bFGF at 14 days, favored cell proliferation. To conclude, we have been able to create an AFS enriched with fully functional DFs and release‐controlled bFGF that could be used in multiple applications for tissue engineering © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011.
Characterization and behavior of anesthetic bioactive textile complex in vitro condition
Authors: Simovic Lj. , Skundric P. , Baralic A. Medovic , Pajic‐Lijakovic I. , Milutinovic‐Nikolic A. 
Published: September 2011

AbstractIn this study, a bioactive complex containing nonwoven textile material (polypropilene (PP)/viscose), chitosan hydrogel, and lidocaine hydrochloride, was designed. The purpose of such biomedical textile was in the treatment of painful sites. Mercury intrusion porosimetry was used in order to estimate the influence of medical impregnation on porous structure of nonwoven material. It was estimated that more than 97% of pores in untreated nonwoven sample were larger than 15 μm. Anesthetic treatment of nonwoven reduced total pore volume of ultramacropores and macropores, while total pore volume of mesopores slightly increased. Lidocaine hydrochloride release from the anesthetic/chitosan hydrogel/nonwoven complex was measured in vitro by Franz diffusion cell technique. Mathematical model was developed to estimate the release of the lidocaine from obtained bioactive textile material. The diffusive transport of lidocaine hydrochloride through three connected layers, i.e., polymer hydrogel, membrane, and solution is modeled based on Fick's second law. Taking all the relevant conditions, regarding this experiment, into consideration, the coefficient of lidocaine diffusion through the polymer hydrogel, as well as the concentration ratio parameter were determined by the mathematical model. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2012.
Crosslinking of poly(L‐lactide) nanofibers with triallyl isocyanutrate by gamma‐irradiation for tissue engineering application
Authors: He Chuanglong , Feng Wei , Cao Lijun , Fan Linpeng 
Published: September 2011

AbstractThe radiation crosslinked poly(L‐lactide) (PLLA) electrospun nanofibers have been developed with improved thermal stability and mechanical properties. Trially isocyanurate (TAIC) were added into PLLA solution at different weight ratios (1, 3, and 5%) and electrospun into nanofibrous mats, the mats were then irradiated by gamma ray at different radiation doses (5, 10, and 25 kGy) to crosslink the PLLA chains. Their surface morphology, thermal properties, mechanical properties, and biodegradation properties were investigated and compared before and after gamma irradiation. Furthermore, the in vitro biocompatibilities were also evaluated by using mouse L929 fibroblasts. The results indicated that the efficient crosslinking networks can be generated when the TAIC content is higher than 3%. The thermal stability and tensile mechanical properties were significantly increased at higher irradiation dose of 10 and 25 kGy. However, radiation dose at 25 kGy have an adverse effect on the thermal stability of crosslinked samples due to thermal degradation induced by irradiation, the crosslinked samples irradiated at 10 kGy exhibited the best enzymatic degradation. The in vitro results also revealed that the crosslinked PLLA/TAIC composite nanofibers did not induce cytotoxic effects and are suitable for cell growth. Therefore, the crosslinked PLLA nanofibers are one of the promising materials for future tissue engineering applications. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011.
Osteogenic gene expression of canine bone marrow stromal cell and bacterial adhesion on titanium with different nanotubes
Authors: Yu Wei‐Qiang , Jiang Xing‐Quan , Xu Ling , Zhao Yan‐Fang , Zhang Fu‐Qiang , Cao Xin 
Published: September 2011

AbstractBacterial infection and osseointegration of implant‐biomaterials all play important roles in the success of an orthopedic prosthesis or a dental‐implant. In this work, we evaluated the osteogenic gene expression of canine bone marrow stromal cells (CBMSCs) and the adhesion ofStaphylococcus aureus(ATCC 12598) on different diameter TiO2nanotube layers. The CBMSCs cultured on 30 and 70 nm nanotubes displayed polygon shape, but obviously elongated when the diameter of nanotubes turned to 120 nm. A significant increase in CBMSCs proliferation by as much as about ∼300%, and osteogenic gene (RUNX‐2, OPN, COL‐1, and OCN) expression were observed on the 120 nm diameter nanotubes when compared to the smooth Ti. However, the adhesion of bacteria also increased with an increased tube diameter and reached highest value on 120 nm nanotubes after 4 h of incubation. ∼300–400% increase in bacterial attached to 120 nm nanotubes in contract to the smooth Ti. These data suggested reducing bacteria colonization should be considered when larger diameter nanotubes with better osteogenic property would be used as orthopedic implants or dental implants. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2011.
The role of vascular calcification in inducing fatigue and fracture of coronary stents
Authors: Halwani Dina O. , Anderson Peter G. , Brott Brigitta C. , Anayiotos Andreas S. , Lemons Jack E. 
Published: September 2011

AbstractTraditional approaches for in‐vitro pulsatile and fatigue testing of endovascular stents do not take into consideration the pathologies of the stented vessel and their associated biomechanical effects. One important pathology is calcification, which may be capable of inducing changes in the vessel wall leading to inhomogeneous distribution of stresses combined with wall motion during the cardiac cycle. These local property changes in the region adjacent to stents could directly influence in‐vivo stent performance. Seven cases containing a total of 18 stents were obtained from autopsy. Radiographs were evaluated and vessels were sectioned for histology and stent topographical analysis. Stents were retrieved by chemical removal of surrounding tissue and surfaces were evaluated using 3D digital optical and scanning electron microscopy for biomechanical abrasion and fracture features. Pathologic complications such as restenosis and thrombus formation were assessed from histological sections. Direct evidence of fracture was found in 6 of the 7 cases (in 12 out of 18 stents; 9 drug eluting and 3 bare metal). The degree of stent alterations was variable, where separation of segments due to fracture occurred mostly in drug‐eluting stents. All fracture surfaces were representative of a high cycle fatigue mechanism. These fractures occurred in complex lesions involving the presence of diffuse calcification alone, or in combination with vessel angulations and multiple overlapping stents. Morphologic analysis of tissue at or near some fracture sites showed evidence of thrombus formation and/or neointimal tissue growth. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012.
Calcium phosphate bioceramics fabricated from extracted human teeth for tooth tissue engineering
Authors: Lim Ki‐Taek , Suh Je Duck , Kim Jangho , Choung Pill‐Hoon , Chung Jong Hoon 
Published: September 2011

AbstractBioceramic tooth powders were prepared via heat treatment of extracted human teeth using sintering temperatures between 600°C and 1200°C, and their properties were investigated for potential tooth tissue engineering. The sintered human tooth powders were characterized using thermal analysis (thermogravimetric analysis (TG) and differential thermal analysis (DTA)), field emission scanning electron microscopy, X‐ray diffraction, energy dispersive X‐ray spectroscopy, and Fourier transformed infrared (FTIR) spectroscopy. Additionally, the phase constitutions and chemical homogeneities of the composite samples were examined using a quantitative chemical analysis with inductively coupled plasma spectroscopy. The results revealed that the annealing process produced useful hydroxyapatite‐based bioceramic biomaterials when annealed above 1000°C. The FTIR spectra and the TG/DTA thermograms of the tooth powders indicated the presence of organic compounds, which were completely removed after annealing at temperatures above 1000°C. The tooth powders annealed between 1000°C and 1200°C had good characteristics as bioceramic biomaterials. Furthermore, the biocompatibility of each tooth powder was evaluated using in vitro and in vivo techniques; our results indicate that the prepared human tooth powders have great potential for tooth tissue engineering applications. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2011.
Reinforced nanohydroxyapatite/polyamide66 scaffolds by chitosan coating for bone tissue engineering
Authors: Huang Di , Zuo Yi , Zou Qin , Wang Yanying , Gao Shibo , Wang Xiaoyan , Liu Haohuai , Li Yubao 
Published: September 2011

AbstractHigh porosity of scaffold is always accompanied by poor mechanical property; the aim of this study was to enhance the strength and modulus of the highly porous scaffold of nanohydroxyapatite/polyamide66 (n‐HA/PA66) by coating chitosan (CS) and to investigate the effect of CS content on the scaffold physical properties and cytological properties. The results show that CS coating can reinforce the scaffold effectively. The compress modulus and strength of the CS coated n‐HA/PA66 scaffolds are improved to 32.71 and 2.38 MPa, respectively, being about six times and five times of those of the uncoated scaffolds. Meanwhile, the scaffolds still exhibit a highly interconnected porous structure and the porosity is approximate about 78%, slightly lower than the value (84%) of uncoated scaffold. The cytological properties of scaffolds were also studied in vitro by cocultured with osteoblast‐like MG63 cells. The cytological experiments demonstrate that the reinforced scaffolds display favorable cytocompatibility and have no significant difference with the uncoated n‐HA/PA66 scaffolds. The CS reinforced n‐HA/PA66 scaffolds can meet the basic mechanical requirement of bone tissue engineering scaffold, presenting a potential for biomedical application in bone reconstruction and repair. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2012.
Highly packed and aligned fluoride substituted hydroxyapatite via a surfactant‐free process
Authors: Xia Wei , Lausmaa Jukka , Thomsen Peter , Engqvist Håkan 
Published: September 2011

AbstractBiomolecules and surfactants are believed to be the key factors for reconstruction of tooth enamel and preparation of fluoride hydroxyapatite coating with enamel‐like structure on dental implants. We have developed an alternative surfactant‐free biomimetic method to stimulate growth of fluoride substituted hydroxyapatite coatings with highly packed and aligned structure on metallic substrates. Oxidized titanium plates were chosen as the substrates. The biomimetic fluoride hydroxyapatite was prepared by immersing the pretreated Ti plates into the phosphate‐buffered solution with Ca2+, H2PO4−, HPO42−, and F−. The pH value was controlled at 7.4 at the beginning. Every titanium plate (10 mm × 10 mm × 1 mm) was soaked into 20 mL of ion doped phosphate buffered solution in sealed plastic bottles, kept at 37°C or 60°C without stirring for time periods of 1 day to 2 weeks. After immersion, the samples were removed from the solution, rinsed with deionized water and allowed to dry in air. The fluoride substituted hydroxyapatite layer, composed of needle‐like crystallites with the diameter of 10–20 nm, was well‐organized and tightly packed. XRD results showed a sharper and stronger (002) peak, which could be used to explain that there was a preferable orientation along the c axis. The coating could be reconstructed on the former layer if the mineralization process was repeated, and the structure of the coating could be preserved. The method could be used to construct well organized fluoride substitute hydroxyapatite coating on metal implants. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012.
Mesoporous titanium dioxide coating for metallic implants
Authors: Xia Wei , Grandfield Kathryn , Hoess Andreas , Ballo Ahmed , Cai Yanling , Engqvist Håkan 
Published: September 2011

AbstractA bioactive mesoporous titanium dioxide (MT) coating for surface drug delivery has been investigated to develop a multifunctional implant coating, offering quick bone bonding and biological stability. An evaporation induced self‐assembly (EISA) method was used to prepare a mesoporous titanium dioxide coating of the anatase phase with BET surface area of 172 m2/g and average pore diameter of 4.3 nm. Adhesion tests using the scratch method and an in situ screw‐in/screw‐out technique confirm that the MT coating bonds tightly with the metallic substrate, even after removal from bone. Because of its high surface area, the bioactivity of the MT coating is much better than that of a dense TiO2 coating of the same composition. Quick formation of hydroxyapatite (HA) in vitro can be related to enhance bonding with bone. The uptake of antibiotics by the MT coating reached 13.4 mg/cm3 within a 24 h loading process. A sustained release behavior has been obtained with a weak initial burst. By using Cephalothin as a model drug, drug loaded MT coating exhibits a sufficient antibacterial effect on the material surface, and within millimeters from material surface, against E.coli. Additionally, the coated and drug loaded surfaces showed no cytotoxic effect on cell cultures of the osteoblastic cell line MG‐63. In conclusion, this study describes a novel, biocompatiblemesoporous implant coating, which has the ability to induce HA formation and could be used as a surface drug‐delivery system. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012.
Delayed short-course treatment with teriparatide (PTH1–34) improves femoral allograft healing by enhancing intramembranous bone formation at the graft–host junction
Authors: Takahata Masahiko , Schwarz Edward M , Chen Tony , O'Keefe Regis J , Awad Hani A 
Published: September 2011

Abstract
Clinical management of critical bone defects remains a major challenge. Despite preclinical work demonstrating teriparatide (PTH1–34) effectiveness in small animals, inconclusive data from clinical trials have raised questions of dose and regimen. To address this, we completed a comprehensive study in the murine femoral allograft model, to assess the effects of dose (0.4, 4, and 40 µg/kg/day) and various treatment regimens on radiographic, histologic, and biomechanical healing at 2, 4, and 9 weeks. Only the high dose (40 µg/kg) of PTH1–34 demonstrated significant effects when given daily over 9 weeks. Remarkably, equivalent biomechanical results were obtained with delayed, short treatment from 2 to 6 weeks that did not induce a significant increase in endochondral bone formation and callus volume. In contrast, PTH1–34 treatment from 1 to 5 weeks postop demonstrated similar osteogenic effects as immediate daily treatment for 9 weeks, but failed to achieve a significant increase in biomechanics at 9 weeks. MicroCT and histologic analyses demonstrated that the 2-week delay in treatment allowed for timely completion of the endochondral phase, such that the prominent effects of PTH1–34 were enhanced intramembranous bone formation and remodeling at the graft–host junction. These findings support the potential use of PTH1–34 as an adjuvant therapy for massive allograft healing, and suggest that there may be an ideal treatment window in which a short course is administered after the endochondral phase to promote osteoblastic bone formation and remodeling to achieve superior union with modest callus formation. © 2012 American Society for Bone and Mineral Research
Osteoblast extracellular Ca2+-sensing receptor regulates bone development, mineralization, and turnover
Authors: Dvorak-Ewell Melita M , Chen Tsui-Hua , Liang Nathan , Garvey Caitlin , Liu Betty , Tu Chialing , Chang Wenhan , Bikle Daniel D , Shoback Dolores M 
Published: September 2011

Abstract
The extracellular Ca2+-sensing receptor (CaR), a G protein-coupled receptor responsible for maintenance of calcium homeostasis, is implicated in regulation of skeletal metabolism. To discern the role of the osteoblast CaR in regulation of bone development and remodeling, we generated mice in which the CaR is excised in a broad population of osteoblasts expressing the 3.6-kb a1(I) collagen promoter. Conditional knockouts had abnormal skeletal histology at birth and developed progressively reduced mineralization secondary to retarded osteoblast differentiation, evident by significantly reduced numbers of osteoblasts and decreased expression of collagen I, osteocalcin, and sclerostin mRNAs. Elevated expression of ankylosis protein, ectonucleotide pyrophosphatase/phosphodiesterase 1, and osteopontin mRNAs in the conditional knockout indicate altered regulation of genes important in mineralization. Knockout of the osteoblast CaR also resulted in increased expression of the receptor activator of NF-κB ligand (RANKL), the major stimulator of osteoclast differentiation and function, consistent with elevated osteoclast numbers in vivo. Osteoblasts from the conditional knockouts exhibited delayed differentiation, reduced mineralizing capacity, altered expression of regulators of mineralization, and increased ability to promote osteoclastogenesis in coculture experiments. We conclude that CaR signaling in a broad population of osteoblasts is essential for bone development and remodeling and plays an important role in the regulation of differentiation and expression of regulators of bone resorption and mineralization. © 2011 American Society for Bone and Mineral Research