Electrospun fibrous tissue engineering scaffolds: topographic cues and their influence on cell behavior

Theme of Conference: Research and Regulatory in Biomedical Engineering - Session B: Best Young Engineer's Paper Competitionpublished_or_final_versionThe International Conference and Pre-conference Workshop of Biomedical Engineering (BME2010), Hong Kong, China, 2-5 November 2010. In Proceedings of BME2010, 2010, p. B-

miR-9-5p, miR-675-5p and miR-138-5p Damages the Strontium and LRP5-Mediated Skeletal Cell Proliferation, Differentiation, and Adhesion

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An improved method for the measurement of mechanical properties of bone by nanoindentation

Nanoindentation is widely used to measure the mechanical properties of bio-tissues. However, viscoelastic effects during the nanoindentation are seldom considered rigorously, although they are in general very significant in bio-tissues. In this study, a recently developed method for correcting the viscoelastic effects during nanoindentation is applied to mice bone samples. This method is found to yield reliable elastic modulus and hardness results from forelimb and femur cortical bone samples of C57 BL/6N and ICR mice. The creep properties of the samples are also characterized by a novel procedure using nanoindentation. The measured mechanical properties correlate well with the calcium content of the bone samples. © 2007 Springer Science+Business Media, LLC.postprin

Low-dose versus high-dose fish oil for pain reduction and function improvement in patients with knee osteoarthritis

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Three-dimensional nanocomposite scaffolds for bone tissue engineering: from design to application

Selective laser sintering (SLS), a rapid prototyping technology, was investigated for producing bone tissue engineering scaffolds. Completely biodegradable osteoconductive calcium phosphate (Ca-P)/poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) scaffolds were successfully fabricated via SLS using Ca-P/PHBV nanocomposite microspheres. In the SLS manufacturing route, the architecture of tissue engineering scaffolds (pore shape, size, interconnectivity, etc.) can be designed and the sintering process can be optimized for obtaining scaffolds with desirable porous structures and mechanical properties. SLS was also shown to be very effective in producing highly complex porous structures using nanocomposite microspheres. To render SLS-formed Ca-P/PHBV scaffolds osteoinductive, recombinant human bone morphogenetic protein-2 (rhBMP-2) could be loaded onto the scaffolds. For achieving a controlled release of rhBMP-2 from scaffolds, surface modification of Ca-P/PHBV scaffolds by gelatin entrapment and heparin immobilization was needed. The immobilized heparin provided binding affinity for rhBMP-2. Surface modified Ca-P/PHBV nanocomposite scaffolds loaded with rhBMP-2 enhanced the proliferation of human umbilical cord derived mesenchymal stem cells (hUCMSCs) and also their alkaline phosphatase activity. In in vivo experiments using a rabbit model, surface modified Ca-P/PHBV nanocomposite scaffolds loaded with rhBMP-2 promoted ectopic bone formation, exhibiting their osteoinductivity. The strategy of combining advanced scaffold fabrication, nanocomposite material, and controlled growth factor delivery is promising for bone tissue regeneration.postprin

Electrospinning, characterization and in vitro biological evaluation of nanocomposite fibers containing carbonated hydroxyapatite nanoparticles

Poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) fibers containing carbonated hydroxyapatite (CHA) nanoparticles with different CHA amounts (5, 10 and 15 wt%) were electrospun with the aid of ultrasonic power for dispersing the nanoparticles. Scanning electron microscopy and energy-dispersive x-ray spectroscopy results showed that the distribution of CHA within the CHA/PHBV nanocomposite fibers was homogeneous when the CHA content was 10 wt%. Slight particle agglomeration occurred when the CHA content was 15 wt%. The diameters of the electrospun CHA/PHBV nanocomposite fibers and PHBV polymer fibers were around 3 μm. Fourier transform infrared spectroscopic analysis further confirmed the presence of CHA in CHA/PHBV nanocomposite fibers. Both PHBV and CHA/PHBV fibrous membranes exhibited similar tensile properties. Compared with PHBV solvent-cast film, the PHBV fibrous membrane was hydrophobic but the incorporation of CHA nanoparticles dramatically enhanced its wettability. In vitro studies revealed that both types of electrospun fibrous membranes (PHBV and CHA/PHBV) supported the proliferation of human osteoblastic cells (SaOS-2). The alkaline phosphatase activity of SaOS-2 cells seeded on the CHA/PHBV fibrous membranes was higher than that of the cells seeded on the PHBV fibrous membranes after 14 days of cell culture. The electrospun CHA/PHBV nanocomposite fibrous membranes show promises for bone tissue engineering applications. © 2010 IOP Publishing Ltd.postprin

Use of strontium-enriched bioactive bone cement in enhancing tendon osteointegration in a rabbit anterior cruciate ligament reconstruction model

Conference Theme: Defying the Aging Spine: Our Mission ContinuesConcurrent Free Papers 5 - Sports: no. 5.17Introduction: It was hypothesised that strontium led to accelerated healing of strontium-enriched calcium phosphate cement (Sr-CPC)–treated soft tissue tendon graft within the bone tunnel in anterior cruciate ligament (ACL) reconstruction. This hypothesis was tested in a rabbit ACL reconstruction model using Achilles tendon allograft. Methods: A total of 30 bilateral ACL reconstructions were performed in 15 rabbits. The graft on the tested limb was treated with Sr-CPC, while that on the contralateral limb was treated with CPC. Three were sacrificed for histomorphometric analysis respectively at 3, 6, 9, 12, and 24 weeks after the index operation. Histomorphometric analysis of the healing of graft was done by 2 independent observers in 42 histological zones per animal using a scoring system of 0 to 9. The data were analysed by Mann-Whitney U test. Results: Accelerated healing of the graft within bone tunnel was noted in the strontium-treated limb at 3, 6, 9, and 12 weeks after the operation (p < 0.001) when compared with the CPC-treated limb. Complete healing of the graft by Sharpey’s fibre formation at 9 weeks and early evidence of remodelling into normal ACL insertion site at 12 weeks were noted in the SrCPC group. The healing of the graft in the CPC-treated limb was noted 3 to 6 weeks slower than the Sr-CPC group. Conclusion: Strontium is the main contributing factor leading to accelerated healing of Sr-CPC–treated soft tissue tendon graft in a rabbit ACL reconstruction model.postprin

Local Application of Strontium in a Calcium Phosphate Cement System Accelerates Healing of Soft Tissue Tendon Grafts in Anterior Cruciate Ligament Reconstruction: Experiment Using a Rabbit Model

Background: The healing of soft tissue tendon graft within the bone tunnel in anterior cruciate ligament (ACL) reconstruction is known to be slower than that of bone-patellar tendon-bone graft. There are attempts in accelerating the healing of the graft within the bone tunnel. One of the methods is the use of strontium-enriched calcium phosphate bone cement (Sr-CPC). The early result in animal study was encouraging, though it was not known whether the accelerated healing was solely due to the effect of the strontium within the cement, or due to the calcium phosphate cement (CPC) itself. Hypothesis: There would be differences between a strontium-enriched calcium phosphate cement (Sr-CPC) and a conventional calcium phosphate cement (CPC) in terms of the effect on soft tissue tendon graft healing within the bone tunnels in anterior cruciate ligament (ACL) reconstruction. Study Design: Controlled laboratory study. Methods: Thirty single bundle ACL reconstruction procedures were performed in 15 rabbits with the use of an Achilles tendon allograft. The graft on the left limb was coated with Sr-CPC, while that on the right limb was coated with CPC. Three animals were sacrificed for histological and histomorphometric analysis at 3, 6, 9, 12 and 24 weeks post-operation. Results: In the Sr-CPC group, early Sharpey fiber formation was present at 6 weeks post-operation while early remodeling of a graft-fibrocartilage-bone junction was noted at 12weeks. In the CPC group, early Sharpey fiber formation was only found at 9 to 12 weeks post-operation. At 24 weeks, a direct enthesis was found in both groups. According to histomorphometric score, graft healing in the Sr-CPC group took place 3 weeks faster than that in the CPC group at and before 12 weeks, but there was no difference at 24 weeks. Conclusion: The local application of strontium in a CPC system leads to accelerated graft healing within the bone tunnels. Clinical Relevance: The use of Sr-CPC to enhance graft-bone healing may improve the clinical results of ACL reconstruction using soft tissue tendon graft. Keywords: anterior cruciate ligament (ACL); strontium; calcium phosphate cementpostprin

Using EMG to evaluate muscle functions in patients with low back pain (LBP) syndromes

Muscle function is relevant to the effective diagnosis and treatment of LBP, although the qualitative and quantitative measurement of muscle function remains problematic. The aims of this study is to evaluate the spinal musculature function and contraction profiles for patients with low back pain (LBP) syndromes both pre and post treatment, and to compare these results to those obtained from normal subjects. 20 normal subjects and 10 patients with LBP were asked to perform symmetrical and asymmetrical loading activities which simulated common industrial tasks. Surface EMG electrodes and video cameras were used to record muscular activity and spinal kinematics. In comparison with the normal group, subjects with LBP showed different muscle activations profiles. No change in the EMG patterns was seen pre and post-treatment.published_or_final_versionThe 20th IEEE Engineering in Medicine and Biology Society Conference Proceedings, Hong Kong, China, 29 October - 1 November 1998, v. 5, p. 2666-266

Rod-like trabeculae extraction from cancellous bone microstructure using topological analysis

The study of the microstructure in cancellous bone is important in osteoporosis research. In this paper, we focus in the extraction of rod-like trabeculae in cancellous hone, whose topological and geometrical properties are known to be strongly related to bone strength. Three dimensional (3D) cancellous bone volume data obtained from micro Computed Tomography (micro-CT) scans is used in our analysis. Because of the complexity of the cancellous bone microstructure, the mere use of existing 3D digital topology method's is unable to yield satisfactory results for trabeculae extraction. We devise several enhancements which are specific to the identification of rod-like trabeculae. Experimental results show that the accuracy of trabeculae extraction is greatly improved. This application study may help clinicians to solve problems in future. © 2005 IEEE.published_or_final_versio