In vivo comparison of the degradation and osteointegration properties of micro-arc oxidation—coated Mg–Sr and Mg–Ca alloy scaffolds

2021 ◽  
pp. 1-11
Author(s):  
Hongyu Sun ◽  
Yuefei Wang ◽  
Chu Sun ◽  
Haiming Yu ◽  
Zheng Xi ◽  
...  
Keyword(s):  
Histological Examination ◽  
Bone Defects ◽  
Mg Alloy ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Implantable Medical Devices ◽  
X Ray ◽  
Post Surgery ◽  
Micro Arc Oxidation

BACKGROUND: Magnesium (Mg) alloy have biodegradation and mechanical properties that are similar to those of human bone, making it a promising candidate material for inclusion in implantable medical devices. OBJECTIVE: The osteointegration effect of Mg alloy scaffolds with different corrosion rates were studied and evaluated in large bone defect models. METHOD: Mg–Sr and Mg–Ca alloy scaffolds with a 20-μm Micro-arc oxidation (MAO) coating were used to repair critical bone defects for subsequent assessment of each alloy’s degradation and osteointegration by X-ray, Micro-CT, fluorescence and histological examination. RESULTS: At 12 weeks post-implantation, each defect was found to be effectively reconstructed by either of the Mg alloys based on X-ray and Micro-CT images. The corrosion rate (CR) of each Mg alloy – as calculated based on micro-computed tomography information – demonstrated that the MAO coating could provide effective protection for only 4 weeks post-surgery. From weeks 8 to 12, the CR of the Mg–Ca alloy scaffold increased from 1.34 ± 0.23 mm/y to 1.57 ± 0.16 mm/y. In contrast, the CR of the Mg–Sr alloy scaffold decreased from 0.58 ± 0.14 mm/y to 0.54 ± 0.16 mm/y. However, fluorescence and histological examination revealed more mature, closely and regularly arranged newborn osteocytes at the Mg–Ca scaffold-fracture interface e from weeks 8 to 12 after surgery. RESULTS: The Mg–Sr scaffold was more corrosion resistant and the Mg–Ca scaffold yielded a better overall repair, which indicates that the CR of magnesium alloys matches the rate of new bone formation and is the key to repair bone defects as a bone substitute.

scholarly journals X-ray-based virtual slicing of TB-infected lungs

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Ana Ortega-Gil ◽  
Juan José Vaquero ◽  
Mario Gonzalez-Arjona ◽  
Joaquín Rullas ◽  
Arrate Muñoz-Barrutia
Keyword(s):  
Contrast Agent ◽  
Contrast Agents ◽  
3D Visualization ◽  
Post Mortem ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Preclinical Research ◽  
X Ray ◽  
The Right

AbstractHollow organs such as the lungs pose a considerable challenge for post-mortem imaging in preclinical research owing to their extremely low contrast and high structural complexity. The aim of our study was to enhance the contrast of tuberculosis lesions for their stratification by 3D x-ray–based virtual slicing. Organ samples were taken from five control and five tuberculosis-infected mice. Micro-Computed Tomography (CT) scans of the subjects were acquired in vivo (without contrast agent) and post-mortem (with contrast agent). The proposed contrast-enhancing technique consists of x-ray contrast agent uptake (silver nitrate and iodine) by immersion. To create the histology ground-truth, the CT scan of the paraffin block guided the sectioning towards specific planes of interest. The digitalized histological slides reveal the presence, extent, and appearance of the contrast agents in lung structures and organized aggregates of immune cells. These findings correlate with the contrast-enhanced micro-CT slice. The abnormal densities in the lungs due to tuberculosis disease are concentrated in the right tail of the lung intensity histograms. The increase in the width of the right tail (~376%) indicates a contrast enhancement of the details of the abnormal densities. Postmortem contrast agents enhance the x-ray attenuation in tuberculosis lesions to allow 3D visualization by polychromatic x-ray CT, providing an advantageous tool for virtual slicing of whole lungs. The proposed contrast-enhancing technique combined with computational methods and the diverse micro-CT modalities will open the doors to the stratification of lesion types associated with infectious diseases.

Micro-Computed Tomography to Finite Element Analysis of In Vivo Biodegradable Magnesium-Alloy Screw and Surrounding Bone in Rabbit Femurs

2015 ◽  
Author(s):  
Adrienne F. O. Williams ◽  
Matthew B. A. McCullough
Keyword(s):  
Computed Tomography ◽  
Finite Element ◽  
Mg Alloy ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Element Analysis ◽  
Animal Modeling ◽  
Finite Element Software ◽  
Over Time

Magnesium (Mg) and its alloys are attractive orthopedic biomaterials because of their degradability and mechanical properties, which are similar to bone’s. Characterizing the mechanical changes and interactions of these promising degradable biomaterials and the host environment (bone) is essential to their success in orthopedic devices. The objective of this study was to develop a protocol to evaluate in vivo biodegradable Mg-alloy screws and surrounding new and cancellous bone in rabbit femurs over time, using high resolution micro-computed tomography (micro-CT) images and the finite element method. Micro-CT was used to visually evaluate bone remodeling and degradation of Mg-alloy screws that were implanted in rabbit femoral condyles for 2, 4, 12, 24, 36 and 52 weeks. Over time, the degradation product around the device and the remainder of the intact core was observed. Scans were segmented into bone, degradation/corrosion products and non-degraded device, then reconstructed into 3D volumes. These volumes were meshed and assigned material properties based on CT data. The meshed volumes were exported to finite element software and analyzed in a virtual environment. Several foundational observations were made about animal modeling of in vivo degrading magnesium devices with a micro-CT to FEA protocol.

Tissue transformation mold design and stereolithography fabrication

2017 ◽  
Vol 23 (1) ◽  
pp. 162-168 ◽  
Author(s):  
Yihao Zheng ◽  
Yancheng Wang ◽  
Roland K. Chen ◽  
Sagar Deshpande ◽  
Noah S. Nelson ◽  
...  
Keyword(s):  
Bone Graft ◽  
Autologous Bone Graft ◽  
Bone Reconstruction ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Content Type ◽  
X Ray ◽  
Rat Mandible ◽  
Vascularized Bone

Purpose To obtain a vascularized autologous bone graft by in-vivo tissue transformation, a biocompatible tissue transformation mold (TTM) is needed. An ideal TTM is of high geometric accuracy and X-ray radiolucent for monitoring the bone tissue formation. The purpose of this study is to present the TTM design and fabrication process, using 3D reconstruction, stereolithography (SLA) and silicone molding. Design/methodology/approach The rat mandible, the targeted bone graft, was scanned by micro-computed tomography (CT). From the micro-CT images, the 3D mandible model was identified and used as the cavity geometry to design the TTM. The TTM was fabricated by molding the biocompatible and radiolucent silicone in the SLA molds. This TTM was implanted in a rat for in vivo tests on its biocompatibility and X-ray radiolucency. Findings SLA can fabricate the TTM with a cavity shape that accurately replicates that of the rat mandible. The bone formation inside of the silicone TTM can be observed by X-ray. The TTM is feasible for in vivo tissue transformation for vascularized bone reconstruction. Research limitations/implications Research of the dimensional and geometrical accuracy of the TTM cavity is required in the future study of this process. Practical implications The TTM fabricated in this presented approach has been used for in-vivo tissue transformation. This technique can be implemented for bone reconstruction. Originality/value The precision fabrication of the TTMs for in-vivo tissue transformation into autogenous vascularized bone grafts with complex structures was achieved by using SLA, micro-CT and silicone molding.

scholarly journals Longitudinal in vivo evaluation of bone regeneration by combined measurement of multi-pinhole SPECT and micro-CT for tissue engineering

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Philipp S. Lienemann ◽  
Stéphanie Metzger ◽  
Anna-Sofia Kiveliö ◽  
Alain Blanc ◽  
Panagiota Papageorgiou ◽  
...  
Keyword(s):  
Computed Tomography ◽  
High Resolution ◽  
Bone Formation ◽  
Bone Regeneration ◽  
Bone Defects ◽  
Histological Evaluation ◽  
Biological Processes ◽  
Micro Ct ◽  
Pinhole Spect

Abstract Over the last decades, great strides were made in the development of novel implants for the treatment of bone defects. The increasing versatility and complexity of these implant designs request for concurrent advances in means to assess in vivo the course of induced bone formation in preclinical models. Since its discovery, micro-computed tomography (micro-CT) has excelled as powerful high-resolution technique for non-invasive assessment of newly formed bone tissue. However, micro-CT fails to provide spatiotemporal information on biological processes ongoing during bone regeneration. Conversely, due to the versatile applicability and cost-effectiveness, single photon emission computed tomography (SPECT) would be an ideal technique for assessing such biological processes with high sensitivity and for nuclear imaging comparably high resolution (<1 mm). Herein, we employ modular designed poly(ethylene glycol)-based hydrogels that release bone morphogenetic protein to guide the healing of critical sized calvarial bone defects. By combined in vivo longitudinal multi-pinhole SPECT and micro-CT evaluations we determine the spatiotemporal course of bone formation and remodeling within this synthetic hydrogel implant. End point evaluations by high resolution micro-CT and histological evaluation confirm the value of this approach to follow and optimize bone-inducing biomaterials.

scholarly journals Endogenous Production of n-3 Polyunsaturated Fatty Acids Promotes Fracture Healing in Mice

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Yuhui Chen ◽  
He Cao ◽  
Dawei Sun ◽  
Changxin Lin ◽  
Liang Wang ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
Fracture Healing ◽  
Histological Analysis ◽  
Callus Formation ◽  
Healing Process ◽  
Proximal Femoral Fracture ◽  
Fracture Repair ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
X Ray

Bone fracture is a global healthcare issue for high rates of delayed healing and nonunions. Although n-3 polyunsaturated fatty acid (PUFA) is considered as a beneficial factor for bone metabolism, only few studies till date focused on the effects of n-3 PUFAs on fracture healing. In this study, we investigated the effect of endogenous n-3 PUFAs on fracture healing by measuring femur fracture repair in bothfat-1transgenic mice and WT mice. Proximal femoral fracture model was established infat-1transgenic mice and WT mice, respectively, and then the fracture was analyzed by using X-ray, micro-computed tomography (micro-CT), and histological assessment at 7, 14, 21, 28, and 35 days after fixation. The results showed that compared with WT mice,fat-1mice exhibited acceleration in fracture healing through radiographic and histological analysis (18–21 days versus 21–28 days postfracture). Meanwhile, X-ray and micro-CT analysis that showed better remodeling callus formation were in thefat-1group compared to WT group. Furthermore, histological analysis revealed that endogenous n-3 PUFAs promoted local endochondral ossification and accelerated the remodeling of calcified calluses after fracture. In conclusion, the present study indicated that endogenously produced n-3 PUFAs promote fracture healing process and accelerate bone remodeling in mice, and supplementation of n-3 PUFAs was positively associated with fracture healing.

Radiographic and Micro—Computed Tomographic Imaging of Lipopolysaccharide-Mediated Bone Resorption

2009 ◽  
Vol 118 (5) ◽  
pp. 391-396 ◽  
Author(s):  
Robert Nason ◽  
Dong H. Lee ◽  
Jae Y. Jung ◽  
Richard A. Chole
Keyword(s):  
Bone Resorption ◽  
Chronic Otitis Media ◽  
Plain Radiography ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Gram Negative ◽  
Successful Model ◽  
Computed Tomographic ◽  
Myeloid Differentiation Factor

Objectives: Chronic otitis media and cholesteatomas cause hearing loss as a result of bony erosion. This bone resorption is known to be more aggressive when cholesteatomas become infected. The most common organism isolated from both diseases is the gram-negative bacterium Pseudomonas aeruginosa. Lipopolysaccharide (LPS), a major virulence factor found in the gram-negative bacterial cell wall, is well known to incite inflammatory bone resorption. The mechanisms underlying this process, however, are poorly understood. In this study, we developed a mouse model of calvarial osteolysis in which resorption was reliably imaged by plain radiography and micro–computed tomography (micro-CT). Methods: A murine calvarial model was developed to study bone resorption induced by P aeruginosa LPS. Calvariae from wild-type and knockout mice used in this model were imaged by plain radiography and micro-CT. Results: A high degree of correlation between plain radiography and micro-CT was identified (R2 = 0.8554). Furthermore, maximal LPS-induced bone resorption required functioning toll-like receptor (TLR) 2, TLR4, and myeloid differentiation factor 88 (MyD88). Conclusions: We have developed a successful model of inflammatory osteolysis in which plain radiography can reliably delineate induced bone resorption. In vivo, we have shown that P aeruginosa LPS signals via TLR2, as well as TLR4 through MyD88.

scholarly journals 0349 : Comparison of bioimpedance and X-ray micro-computed tomography (μCT) for total fat volume measurement in mice in vivo

2015 ◽  
Vol 7 (2) ◽  
pp. 139
Author(s):  
Gaëlle Aubertin-Kirch ◽  
Amira Sayeh ◽  
Christian Goetz ◽  
Jean-Philippe Dillenseger ◽  
Isabelle Chery ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Volume Measurement ◽  
Micro Computed Tomography ◽  
X Ray ◽  
Total Fat ◽  
Fat Volume

Ceramic Coatings of Magnesium Alloy for Biomaterial Applications

2010 ◽  
Vol 434-435 ◽  
pp. 634-637 ◽  
Author(s):  
Pu Liang Zhang ◽  
Bin Liu ◽  
Dong Zhang ◽  
Yong Wei Tao ◽  
Sheng Rong Yang ◽  
...  
Keyword(s):  
Body Fluid ◽  
Ceramic Coatings ◽  
Alkaline Treatment ◽  
Mg Alloy ◽  
X Ray Diffraction ◽  
Electrodeposition Technique ◽  
Corrosion Properties ◽  
X Ray ◽  
Micro Arc Oxidation ◽  
Porous Oxide

Ceramic coatings were produced on magnesium (Mg) alloy of AZ91D for biomaterial applications by micro-arc oxidation (MAO) and electrodeposition methods. The morphology, microstructure, phase composition and corrosion properties of the prepared coatings were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and potentiodynamic polarization tester, etc. The results indicated that a porous oxide layer was grown on the Mg alloy sheets after MAO process and the compositions of oxides were mainly Mg2SiO4 and MgO. After further electrodeposition and alkaline treatment, a flake-like structure diverging from centre to periphery was grown on the MAO coating and the coating was mainly made up of hydroxyapatite (HA). Moreover, the corrosion resistance of the Mg alloy after being treated with MAO and electrodeposition technique increases obviously, which was evaluated in stimulated body fluid (SBF).

scholarly journals Longitudinal in vivo micro-CT-based approach allows spatio-temporal characterization of fracture healing patterns and assessment of biomaterials in mouse femur defect models

2020 ◽  
Author(s):  
Esther Wehrle ◽  
Duncan C Tourolle né Betts ◽  
Gisela A Kuhn ◽  
Erica Floreani ◽  
Malavika H Nambiar ◽  
...  
Keyword(s):  
Bone Regeneration ◽  
Healing Process ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Collagen Scaffolds ◽  
Non Union ◽  
Spatio Temporal ◽  
Large Bone

AbstractThorough preclinical evaluation of novel biomaterials for treatment of large bone defects is essential prior to clinical application. Using in vivo micro-computed tomography (micro-CT) and mouse femoral defect models with different defect sizes, we were able to detect spatio-temporal healing patterns indicative of physiological and impaired healing in three defect sub-volumes and the adjacent cortex. The time-lapsed in vivo micro-CT-based approach was then applied to evaluate the bone regeneration potential of biomaterials using collagen and BMP-2 as test materials. Both collagen and BMP-2 treatment led to distinct changes in bone turnover in the different healing phases. Despite increased periosteal bone formation, 87.5% of the defects treated with collagen scaffolds resulted in non-unions. Additional BMP-2 application significantly accelerated the healing process and increased the union rate to 100%. This study further shows potential of time-lapsed in vivo micro-CT for capturing spatio-temporal deviations preceding non-union formation and how this can be prevented by application of biomaterials.This study therefore supports the application of longitudinal in vivo micro-CT for discrimination of normal and disturbed healing patterns and for the spatio-temporal characterization of the bone regeneration capacity of biomaterials.

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