Runa M.J.,University of Minho |
Runa M.J.,Rush University Medical Center |
Runa M.J.,Institute of Biomaterials |
Mathew M.T.,Rush University Medical Center |
And 5 more authors.
Acta Biomaterialia | Year: 2015
In uncemented Ti6Al4V hip implants, the bone-stem interface is subjected to cyclic loading motion driven by the daily activities of the patients, which may lead to the complete failure of the implant in the long term. It may also compromise the proliferation and differentiation processes of osteoblastic cells (bone-forming cells). The main objective of this work is to approach for the first time the role of these organic materials on the bio-tribocorrosion mechanisms of cultured Ti6Al4V alloys. The colonized materials with MG63 osteoblastic-like cells were characterized through cell viability/proliferation and enzymatic activity. Tribocorrosion tests were performed under a reciprocating sliding configuration and low contact pressure. Electrochemical techniques were used to measure the corrosion kinetics of the system, under free potential conditions. All tests were performed at a controlled atmosphere. The morphology and topography of the wear scar were evaluated. The results showed that the presence of an osteoblastic cell layer on the implant surface significantly influences the tribocorrosion behavior of Ti6Al4V alloy. It was concluded that the cellular material was able to form an extra protective layer that inhibits further wear degradation of the alloy and decreases its corrosion tendency. © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Rath S.N.,Indian Institute of Technology Hyderabad |
Nooeaid P.,Institute of Biomaterials |
Arkudas A.,Zhejiang Provincial Key Laboratory of Tissue Engineering and Regenerative Medicine |
Beier J.P.,Zhejiang Provincial Key Laboratory of Tissue Engineering and Regenerative Medicine |
And 6 more authors.
Journal of Tissue Engineering and Regenerative Medicine | Year: 2013
Mesenchymal stem cells can be isolated from a variety of different sources, each having their own peculiar merits and drawbacks. Although a number of studies have been conducted comparing these stem cells for their osteo-differentiation ability, these are mostly done in culture plastics. We have selected stem cells from either adipose tissue (ADSCs) or bone marrow (BMSCs) and studied their differentiation ability in highly porous three-dimensional (3D) 45S5 Bioglass®-based scaffolds. Equal numbers of cells were seeded onto 5×5×4mm3 scaffolds and cultured in vitro, with or without osteo-induction medium. After 2 and 4weeks, the cell-scaffold constructs were analysed for cell number, cell spreading, viability, alkaline phosphatase activity and osteogenic gene expression. The scaffolds with ADSCs displayed osteo-differentiation even without osteo-induction medium; however, with osteo-induction medium osteogenic differentiation was further increased. In contrast, the scaffolds with BMSCs showed no osteo-differentiation without osteo-induction medium; after application of osteo-induction medium, osteo-differentiation was confirmed, although lower than in scaffolds with ADSCs. In general, stem cells in 3D bioactive glass scaffolds differentiated better than cells in culture plastics with respect to their ALP content and osteogenic gene expression. In summary, 45S5 Bioglass-based scaffolds seeded with ADSCs are well-suited for possible bone tissue-engineering applications. Induction of osteogenic differentiation appears unnecessary prior to implantation in this specific setting. © 2013 John Wiley & Sons, Ltd.
Heise S.,Institute of Biomaterials |
Virtanen S.,Chair for Surface Science and Corrosion |
Boccaccini A.R.,Institute of Biomaterials
Journal of Biomedical Materials Research - Part A | Year: 2016
The field of protective coatings for magnesium and its alloys (e.g., AZ31) using natural polymers is reviewed. Polymers utilized are broadly divided into polysaccharides and proteins. For both polymer classes examples are given focusing on coating processing and characterization. Several analysing methods reported in literature are summarized highlighting the different characterization approaches applied in different studies, which makes difficult a direct comparison of the outcomes. In most cases, the protective behavior of coatings was determined using electrochemical impedance spectroscopy or by assessing hydrogen evolution in different fluids. Mechanical tests and in vitro cell culture studies have been also carried out on selected coating systems. Overall, the results show the possibility of applying protective coatings based on natural polymers on magnesium and its alloys, however, in vivo investigations are scarce so that long-term results in relevant conditions are not yet available. A comparison with the use of synthetic polymers is presented and current challenges and areas for future research are discussed, highlighting the need for further investigations in the field, which should enable broadening the applications of Mg and Mg alloys in medicine. © 2016 Wiley Periodicals, Inc.
Qi X.,University of Toronto |
Fraser A.R.,University of Toronto |
Munce N.,Institute of Biomaterials |
Wright G.A.,Institute of Biomaterials |
Strauss B.H.,University of Toronto
EuroIntervention | Year: 2013
Aims: Percutaneous revascularisation of chronic total occlusions (CTO) is limited by failure of guidewire crossing. Neovascularisation within the proximal CTO segment may be important for guidewire crossing and dramatically declines in CTO beyond six weeks of age. The aims of the current study were to determine whether local delivery of a pro-angiogenic growth factor increases neovascularisation in mature CTO and facilitates guidewire crossings. Methods and results: CTO (n=51) were created in the femoral arteries of 44 New Zealand white rabbits using the thrombin injection model. At 12 weeks, CTO were treated with poly-lactic-glycolic-acid (PLGA) microspheres containing either bovine serum albumin (BSA) (n=15) or recombinant mouse VEGF164 (n=14), or received no intervention (controls, n=12). Contrast-enhanced magnetic resonance angiography (CEMRA) was performed prior to treatment and at three weeks post treatment. Animals were sacrificed at three weeks post treatment and arterial samples were excised for micro-computed tomography imaging (μCT) and histologic morphometric analysis. Guidewire crossing was assessed at three weeks post treatment in an additional 10 VEGF164-treated CTO. In comparison to BSA-treated and control non-intervened CTO, VEGF 164-treated 164 164 CTO showed a significant increase in relative blood volume index in the proximal segment of the CTO lesion as determined by CEMRA and by μCT Histologic measurements of microvessel area were also higher in VEGF164-treated CTO. Guidewire crossing across the proximal fibrous cap was successful in eight out of 10 VEGF164-treated CTO. 164 Conclusions: Angiogenic therapy appears to be a promising strategy to improve neovascularisation and guidewire crossing rates in CTO. © Europa Digital & Publishing 2013. All rights reserved.
News Article | April 27, 2016
Targeting cancer cells for destruction while leaving healthy cells alone—that has been the promise of the emerging field of cancer nanomedicine. But a new meta-analysis from U of T's Institute of Biomaterials & Biomedical Engineering (IBBME) indicates that progress so far has been limited and new strategies are needed if the promise is to become reality.
Shirdar M.R.,University of Technology Malaysia |
Taheri M.M.,University of Illinois at Chicago |
Taheri M.M.,Institute of Biomaterials |
Moradifard H.,University of Technology Malaysia |
And 5 more authors.
Ceramics International | Year: 2016
Inadequate mechanical properties of pure hydroxyapatite (HA) coating layers make it an unsuitable candidate for many load-bearing orthopedic implants. In this study, Titania nanotubes (TNT) and HA were synthesized using Rapid Breakdown Adonization (RBA) and sol-gel methods, respectively. The sintering process at different temperatures was then conducted for the phase transformation of titanium. HA-TNT mixtures in different quantities and phases were prepared for coating on Co-Cr-based substrates. To optimize the coated HA-TNT composite layer in term of hardness, bonding strength and corrosion potential, empirical models based on Response Surface Methodology (RSM) were developed. The synthesized TNT and HA-TNT coated samples were characterized using X-ray diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM) and Transmission Electron Microscopy (TEM). The predicted models generated by RSM were compared with the experimental results, and close agreement was observed. While the models demonstrate that TNT quantity is a more significant factor than sintering temperature in improving hardness (H), bonding strength (P) and the corrosion potential (Ecorr) of a coated substrate, sintering temperature still has a considerable effect on H and Ecorr. The optimum HA-TNT composite coating layer in terms of the mechanical and electrochemical properties were obtained with a TNT ratio of 1.07 (wt%) at a sintering temperature of 669.11 °C. © 2016 Elsevier Ltd and Techna Group S.r.l.
Grotberg J.,University of Illinois at Chicago |
Grotberg J.,Institute of Biomaterials |
Hamlekhan A.,Institute of Biomaterials |
Hamlekhan A.,Michigan Technological University |
And 15 more authors.
Materials Science and Engineering C | Year: 2016
The negative impact of in vivo corrosion of metallic biomedical implants remains a complex problem in the medical field. We aimed to determine the effects of electrochemical anodization (60 V, 2 h) and thermal oxidation (600 °C) on the corrosive behavior of Ti-6Al-4V, with serum proteins, at physiological temperature. Anodization produced a mixture of anatase and amorphous TiO2 nanopores and nanotubes, while the annealing process yielded an anatase/rutile mixture of TiO2 nanopores and nanotubes. The surface area was analyzed by the Brunauer-Emmett-Teller method and was estimated to be 3 orders of magnitude higher than that of polished control samples. Corrosion resistance was evaluated on the parameters of open circuit potential, corrosion potential, corrosion current density, passivation current density, polarization resistance and equivalent circuit modeling. Samples both anodized and thermally oxidized exhibited shifts of open circuit potential and corrosion potential in the noble direction, indicating a more stable nanoporous/nanotube layer, as well as lower corrosion current densities and passivation current densities than the smooth control. They also showed increased polarization resistance and diffusion limited charge transfer within the bulk oxide layer. The treatment groups studied can be ordered from greatest corrosion resistance to least as Anodized + Thermally Oxidized > Anodized > Smooth > Thermally Oxidized for the conditions investigated. This study concludes that anodized surface has a potential to prevent long term implant failure due to corrosion in a complex in-vivo environment. © 2015 Elsevier B.V.
Tansaz S.,Institute of Biomaterials |
Durmann A.-K.,Institute of Biomaterials |
Detsch R.,Institute of Biomaterials |
Boccaccini A.R.,Institute of Biomaterials
Journal of Applied Polymer Science | Year: 2016
Alginate hydrogels are combined with soy protein isolate (SPI), a plant derived protein with low immunogenicity, appropriate biodegradability and low cost, to produce biocompatible films, and microcapsules. The cell-material interaction is assessed through the use of mouse embryotic fibroblast cells (MEF cells) on films, and the results illustrate that the alginate/SPI hydrogel films support cell attachment, spreading, and proliferation. Cell biology results combined with degradation studies suggest that such hydrogels are promising biomaterials for soft tissue regeneration or as wound dressing materials. © 2016 Wiley Periodicals, Inc.