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Magnesium alloy based interference screw developed for ACL reconstruction attenuates peri-tunnel bone loss in rabbits

Biomaterials - Sat, 2017-12-16 09:50
Publication date: March 2018
Source:Biomaterials, Volume 157

Author(s): Jiali Wang, Yuanhao Wu, Huafang Li, Yang Liu, Xueling Bai, Wingho Chau, Yufeng Zheng, Ling Qin

Peri-tunnel bone loss after anterior cruciate ligament (ACL) reconstruction is often observed clinically, which may detrimentally affect tendon graft integration with surrounding bone tissue. Biodegradable magnesium (Mg) based fixators in terms of interference screws may be suitable for fixation of the tendon graft due to their favorable effects on promotion of new bone formation. However, the poor mechanical strength of Mg is still one of the major challenges for its clinical applications. The addition of alloying elements into Mg is one of the strategies to improve their mechanical properties. Here, we prepared magnesium (Mg)-(4 and 6 wt%) zinc (Zn)-(0.2, 0.5, 1 and 2 wt%) strontium(Sr) alloys and tested their potential for attenuating peri-tunnel bone loss in ACL reconstruction. The optimal (6 wt%) Zn and (0.5 wt%) Sr contents were screened with respect to the microstructures, mechanical properties and corrosion behavior of these alloys. As compared to pure Mg, Mg-6Zn-0.5Sr rods and screws showed significantly higher torque and torsional stiffness in both numerical and experimental analysis. The in vitro cyto-compatibility of Mg-6Zn-0.5Sr alloy was assessed with MTT test and fluorescence assay. The Mg-6Zn-0.5Sr interference screw was designed for fixation of the tendon graft to the femoral tunnel in a rabbit model of ACL reconstruction, with a commercially available poly-lactide (PLA) screw for comparison. In vivo high resolution peripheral quantitative computed tomography (HR-pQCT) scanning was performed to measure the degradation behavior of Mg-6Zn-0.5Sr interference screws and peri-tunnel bone quality at 0, 6, 12 and 16 weeks post-surgically. Mg-6Zn-0.5Sr interference screw was completely degraded within 12 weeks after surgery. The peri-tunnel bone loss was significantly attenuated in the Mg-6Zn-0.5Sr group when compared to the PLA group. Importantly, the bony ingrowth rapidly filled the cavity left by the complete degradation of Mg-6Zn-0.5Sr screws at 16 weeks. In histological analysis, more bone formation was observed in peri-tunnel region in the Mg-6Zn-0.5Sr group in comparison to the PLA group at 6 and 16 weeks after surgery. The femur-tendon graft-tibia complex was harvested at the end of week 6 and 16 post-operation for tensile testing. The maximum load to failure was significantly improved in the Mg-6Zn-0.5Sr group at week 16 post-operation. Therefore, our results indicate the potential clinical application of MgZnSr based interference screws in ACL reconstruction.





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Editorial Board

Biomaterials - Sat, 2017-12-16 09:50
Publication date: February 2018
Source:Biomaterials, Volume 155









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A nephron model for study of drug-induced acute kidney injury and assessment of drug-induced nephrotoxicity

Biomaterials - Sat, 2017-12-16 09:50
Publication date: February 2018
Source:Biomaterials, Volume 155

Author(s): Yueyang Qu, Fan An, Yong Luo, Yao Lu, Tingjiao Liu, Weijie Zhao, Bingcheng Lin

In this study, we developed a multilayer microfluidic device to simulate nephron, which was formed by “glomerulus”, “Bowman's capsule”, “proximal tubular lumen” and “peritubular capillary”. In this microdevice, artificial renal blood flow was circulating and glomerular filtrate flow was single passing through, mimicking the behavior of a nephron. In this dynamic artificial nephron, we observed typical renal physiology, including the glomerular size-selective barrier, glomerular basement membrane charge-selective barrier, glucose reabsorption and para-aminohippuric acid secretion. To demonstrate the capability of our microdevice, we used it to investigate the pathophysiology of drug-induced acute kidney injury (AKI) and give assessment of drug-induced nephrotoxicity, with cisplatin and doxorubicin as model drugs. In the experiment, we loaded the doxorubicin or cisplatin in the “renal blood flow”, recorded the injury of primary glomerular endothelial cells, podocytes, tubular epithelial cells and peritubular endothelial cells by fluorescence imaging, and identified the time-dependence, dose-dependence and the death order of four types of renal cells. Then by measuring multiple biomarkers, including E-cadherin, VEGF, VCAM-1, Nephrin, and ZO-1, we studied the mechanism of cell injuries caused by doxorubicin or cisplatin. Also, we investigated the effect of BSA in the “renal blood flow” on doxorubicin-or-cisplatin-induced nephrotoxicity, and found that BSA enhanced the tight junctions between cells and eased cisplatin-induced nephrotoxicity. In addition, we compared the nephron model and traditional tubule models for assessment of drug-induced nephrotoxicity. And it can be inferred that our biomimetic microdevice simulated the complex, dynamic microenvironment of nephron, yielded abundant information about drug-induced-AKI at the preclinical stage, boosted the drug safety evaluation, and provided a reliable reference for clinical therapy.





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Theranostic 2D ultrathin MnO2 nanosheets with fast responsibility to endogenous tumor microenvironment and exogenous NIR irradiation

Biomaterials - Sat, 2017-12-16 09:50
Publication date: February 2018
Source:Biomaterials, Volume 155

Author(s): Zhuang Liu, Shengjian Zhang, Han Lin, Menglong Zhao, Heliang Yao, Linlin Zhang, Weijun Peng, Yu Chen

The fabrication of functional nanoparticles with unique ultra-sensitivity to endogenous tumor microenvironment (TME) is of great significance for their improved theranostic performance and easy excretion out of the body, which has not been realized among diverse nano-sized photothermal agents for photothermal therapy (PTT) of tumor. In this work, we report on the synthesis of 2D ultrathin MnO2 nanosheets for highly efficient PTT against tumor with ultra-sensitivity to endogenous TME. These ultrathin 2D MnO2 nanosheets show the intriguing characteristic of disintegration and releasing of Mn2+ in response to the mild acidic condition and elevated reducing microenvironment of TME, which has successfully realized the pH- and reducing-responsive T1-weighted magnetic resonance imaging of tumor. Importantly, the high PTT efficiency of 2D MnO2 nanosheets responsive to exogenous NIR irradiation has been systematically demonstrated both in vitro and in vivo for suppressing the tumor growth. This first report on the exploring of TME-sensitive photothermal agents with concurrent diagnostic and therapeutic (theranostic) functions significantly broadens the biomedical application of 2D functional biomaterials, which also promotes the further potential clinical translations of nano-sized photothermal agents.
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Fabrication of Ellipsoidal Mesostructures in Block Copolymers via a Step-Shear Deformation

Macromolecules - Fri, 2017-12-15 11:33

MacromoleculesDOI: 10.1021/acs.macromol.7b02060
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Mechanism of a Class C Radical S-Adenosyl-l-methionine Thiazole Methyl Transferase

Journal of the American Chemical SocietyDOI: 10.1021/jacs.7b10203
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Size Effect on Lipid Nanocapsule-Mediated GLP-1 Secretion from Enteroendocrine L Cells

Molecular Pharmaceutics - Fri, 2017-12-15 10:36

Molecular PharmaceuticsDOI: 10.1021/acs.molpharmaceut.7b00742
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How Solid-Electrolyte Interphase Forms in Aqueous Electrolytes

Journal of the American Chemical SocietyDOI: 10.1021/jacs.7b10688
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Small-Band-Offset Perovskite Shells Increase Auger Lifetime in Quantum Dot Solids

ACS Nano - Fri, 2017-12-15 07:08

ACS NanoDOI: 10.1021/acsnano.7b06363
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Biocompatible Amphiphilic Hydrogel–Solid Dimer Particles as Colloidal Surfactants

ACS Nano - Fri, 2017-12-15 06:49

ACS NanoDOI: 10.1021/acsnano.7b03110
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