scholarly journals Evaluation of Electrospun Nanofiber-Anchored Silicone for the Degenerative Intervertebral Disc

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
M. Khandaker ◽  
S. Riahanizad
Keyword(s):  
Intervertebral Disc ◽  
Viscoelastic Properties ◽  
Mechanical Stability ◽  
Ex Vivo ◽  
Electrospun Fiber ◽  
Mechanical Tests ◽  
Tissue Properties ◽  
Clinical Potential ◽  
Fiber Mesh ◽  
Mesh Anchoring

The nucleus pulposus (NP) substitution by polymeric gel is one of the promising techniques for the repair of the degenerative intervertebral disc (IVD). Silicone gel is one of the potential candidates for a NP replacement material. Electrospun fiber anchorage to silicone disc, referred as ENAS disc, may not only improve the biomechanical performances of the gel but it can also improve restoration capability of the gel, which is unknown. This study successfully produced a novel process to anchor any size and shape of NP gel with electrospun fiber mesh. Viscoelastic properties of silicone and ENAS disc were measured using standard experimental techniques and compared with the native tissue properties. Ex vivo mechanical tests were conducted on ENAS disc-implanted rabbit tails to the compare the mechanical stability between intact and ENAS implanted spines. This study found that viscoelastic properties of ENAS disc are higher than silicone disc and comparable to the viscoelastic properties of human NP. The ex vivo studies found that the ENAS disc restore the mechanical functionality of rabbit tail spine, after discectomy of native NP and replacing the NP by ENAS disc. Therefore, the PCL ENF mesh anchoring technique to a NP implant can have clinical potential.

Different Passive Viscoelastic Properties Between the Left and Right Ventricles in Healthy Adult Ovine

2021 ◽  
Author(s):  
Wenqiang Liu ◽  
Michael Nguyen-Truong ◽  
Matt Ahern ◽  
Kevin Labus ◽  
Christian Puttlitz ◽  
...  
Keyword(s):  
Stress Relaxation ◽  
Viscoelastic Properties ◽  
Healthy Adult ◽  
Ex Vivo ◽  
Longitudinal Direction ◽  
Mechanical Tests ◽  
Mortality And Morbidity ◽  
Linear Viscoelastic ◽  
Left And Right ◽  
Relaxation Curves

Abstract Ventricle dysfunction is the most common cause of heart failure, which leads to high mortality and morbidity. The mechanical behavior of the ventricle is critical to its physiological function. It is known that the ventricle is anisotropic and viscoelastic. However, the understanding of ventricular viscoelasticity is much less than that of its elasticity. Moreover, the left and right ventricles (LV&RV) are different in embryologic origin, anatomy, and function, but whether they distinguish in viscoelastic properties is unclear. We hypothesized that passive viscoelasticity is different between healthy LVs and RVs. Ex vivo cyclic biaxial tensile mechanical tests (1, 0.1, 0.01Hz) and stress relaxation (strain of 3, 6, 9, 12 15%) were performed for ventricles from healthy adult sheep. Outflow track direction was defined as the longitudinal direction. Hysteresis stress-strain loops and stress relaxation curves were obtained to quantify the viscoelastic properties. We found that the RV had more pronounced frequency-dependent viscoelastic changes than the LV. Under the physiological frequency (1Hz), the LV was more anisotropic in the elasticity and stiffer than the RV in both directions, whereas the RV was more anisotropic in the viscosity and more viscous than the LV in the longitudinal direction. The LV was quasi-linear viscoelastic in the longitudinal but not circumferential direction, and the RV was non-linear viscoelastic in both directions. This study is the first to investigate passive viscoelastic differences in healthy LVs and RVs, and the findings will deepen the understanding of biomechanical mechanisms of ventricular function.

Evaluation of Biomechanical Performances of Electrospun Fiber Anchored Silicone Disc As an Intervertebral Disc Implant

2017 ◽  
Author(s):  
Subhakar Tummala ◽  
Oguz Dogan ◽  
Fatih Karpat ◽  
Shahram Riahinezhad ◽  
M. Khandaker
Keyword(s):  
Finite Element ◽  
Intervertebral Disc ◽  
Annulus Fibrosus ◽  
Electrospun Fiber ◽  
Lumbar Vertebra ◽  
Element Model ◽  
Compressive Modulus ◽  
Test Results ◽  
Electrospun Nanofiber ◽  
Fiber Mesh

A tissue engineered intervertebral disc (IVD) anchor the circumference and top/bottom sides of nucleus pulposus (NP) implants with annulus fibrosus and endplates. The proper anchorage of a NP implant to annulus fibrosus and endplates is possible by enclosing the NP by electrospun fiber mesh that mimics the surrounding structures. The biomechanical performance of silicone based NP can be improved if electrospun fiber mesh can secure all sides of silicone NP. However, it is unknown whether silicone surrounded by an electrospun nanofiber matrix can better restore the biomechanical functions of the disc in compare to intact, IVD made with silicone only, and, IVD made with silicone anchored all sides by nanofiber. This study compared the compressive and viscoelastic properties of a silicone and electrospun nanofiber anchored silicone discs (ENAS) under compression and shear with the same properties of human NP. This study developed a nonlinear finite element model (FEM) for the intact and ENAS implanted human lumbar vertebra segments. The compression test results show that ENAS disc compressive modulus (87.47 ± 7.56 kPa, n = 3) is significantly higher in compare to silicone gel (38.75 ± 2.15 kPa, n = 3) and the value is within the range of the compressive modulus of human NP (64.9 ± 44.1 kPa). The rheological test results show that ENAS disc compressive modulus (16 ∼ 40 kPa) is significantly higher in compare to silicone gel (0.10 ∼ 0.16 kPa) and the value is within the range of the compressive modulus of human NP (7 ∼ 20 kPa). These results confirm the suitability of ENAS disc over silicone as NP implant. A finite element model has been developed based on the ENAS properties. The FEA results showed that ENAS can restore better the biomechanical motions of a lumbar vertebra segments in compare to silicone NP.

scholarly journals Marker for the pre-clinical development of bone substitute materials

2017 ◽  
Vol 3 (2) ◽  
pp. 711-715
Author(s):  
Michael de Wild ◽  
Simon Zimmermann ◽  
Marcel Obrecht ◽  
Michel Dard
Keyword(s):  
Bone Graft ◽  
Mechanical Stability ◽  
Clinical Performance ◽  
Ex Vivo ◽  
Region Of Interest ◽  
Defect Site ◽  
Novel Approach ◽  
Bone Substitute Materials ◽  
Clinical Experiments

AbstractThin mechanically stable Ti-cages have been developed for the in-vivo application as X-ray and histology markers for the optimized evaluation of pre-clinical performance of bone graft materials. A metallic frame defines the region of interest during histological investigations and supports the identification of the defect site. This standardization of the procedure enhances the quality of pre-clinical experiments. Different models of thin metallic frameworks were designed and produced out of titanium by additive manufacturing (Selective Laser Melting). The productibility, the mechanical stability, the handling and suitability of several frame geometries were tested during surgery in artificial and in ex-vivo bone before a series of cages was preclinically investigated in the female Göttingen minipigs model. With our novel approach, a flexible process was established that can be adapted to the requirements of any specific animal model and bone graft testing.

scholarly journals Annular Defects Impair the Mechanical Stability of the Intervertebral Disc

2021 ◽  
pp. 219256822110060
Author(s):  
Jun-Xin Chen ◽  
Yun-He Li ◽  
Jian Wen ◽  
Zhen Li ◽  
Bin-Sheng Yu ◽  
...  
Keyword(s):  
Intervertebral Disc ◽  
Degrees Of Freedom ◽  
Mechanical Stability ◽  
Biomechanical Testing ◽  
Bending Stiffness ◽  
Biomechanical Study ◽  
Torsional Stiffness ◽  
P Value ◽  
Lateral Bending ◽  
Flexion Extension

Study Design: A biomechanical study. Objectives: The purpose of this study was to investigate the effects of cruciform and square incisions of annulus fibrosus (AF) on the mechanical stability of bovine intervertebral disc (IVD) in multiple degrees of freedom. Methods: Eight bovine caudal IVD motion segments (bone-disc-bone) were obtained from the local abattoir. Cruciform and square incisions were made at the right side of the specimen’s annulus using a surgical scalpel. Biomechanical testing of three-dimensional 6 degrees of freedom was then performed on the bovine caudal motion segments using the mechanical testing and simulation (MTS) machine. Force, displacement, torque and angle were recorded synchronously by the MTS system. P value <.05 was considered statistically significant. Results: Cruciform and square incisions of the AF reduced both axial compressive and torsional stiffness of the IVD and were significantly lower than those of the intact specimens ( P < .01). Left-side axial torsional stiffness of the cruciform incision was significantly higher than a square incision ( P < .01). Neither incision methods impacted flexional-extensional stiffness or lateral-bending stiffness. Conclusions: The cruciform and square incisions of the AF obviously reduced axial compression and axial rotation, but they did not change the flexion-extension and lateral-bending stiffness of the bovine caudal IVD. This mechanical study will be meaningful for the development of new approaches to AF repair and the rehabilitation of the patients after receiving discectomy.

Establishment of a Novel Intervertebral Disc/Endplate Culture Model: Analysis of an Ex Vivo In Vitro Whole-Organ Rabbit Culture System

Spine ◽  
2006 ◽  
Vol 31 (25) ◽  
pp. 2918-2925 ◽  
Author(s):  
Daniel Haschtmann ◽  
Jivko V. Stoyanov ◽  
Ladina Ettinger ◽  
Lutz -P. Nolte ◽  
Stephen J. Ferguson
Keyword(s):  
Intervertebral Disc ◽  
Culture System ◽  
Ex Vivo ◽  
Model Analysis ◽  
Culture Model

Micromechanical poroelastic and viscoelastic properties of ex-vivo soft tissues

2020 ◽  
Vol 113 ◽  
pp. 110090
Author(s):  
Mohammad R. Islam ◽  
Jitka Virag ◽  
Michelle L. Oyen
Keyword(s):  
Viscoelastic Properties ◽  
Soft Tissues ◽  
Ex Vivo

scholarly journals Evaluation of bone formation on orthopedic implant surfaces using an ex-vivo bone bioreactor system

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rupak Dua ◽  
Hugh Jones ◽  
Philip C. Noble
Keyword(s):  
Culture System ◽  
Ex Vivo ◽  
Calcium Phosphates ◽  
Wire Mesh ◽  
Bioreactor Culture ◽  
Static Culture ◽  
Group 4 ◽  
The Matrix ◽  
Bioreactor System ◽  
Fiber Mesh

AbstractRecent advances in materials and manufacturing processes have allowed the fabrication of intricate implant surfaces to facilitate bony attachment. However, refinement and evaluation of these new design strategies are hindered by the cost and complications of animal studies, particularly during early iterations in the development process. To address this problem, we have previously constructed and validated an ex-vivo bone bioreactor culture system that can maintain the viability of bone samples for an extended period ex-vivo. In this study, we investigated the mineralization of a titanium wire mesh scaffold under both static and dynamic culturing using our ex vivo bioreactor system. Thirty-six cancellous bone cores were harvested from bovine metatarsals at the time of slaughter and divided into five groups under the following conditions: Group 1) Isolated bone cores placed in static culture, Group 2) Unloaded bone cores placed in static culture in contact with a fiber-mesh metallic scaffold, Group 3) Bone cores placed in contact with a fiber-mesh metallic scaffold under the constant pressure of 150 kPa, Group 4) Bone core placed in contact with a fiber-mesh metallic scaffold and exposed to cyclic loading with continuous perfusion flow of media within the ex-vivo culture system and Group 5) Bone core evaluated on Day 0 to serve as a positive control for comparison with all other groups at weeks 4 and 7. Bone samples within Groups 1–4 were incubated for 4 and 7 weeks and then evaluated using histological examination (H&E) and the Live-Dead assay (Life Technologies). Matrix deposits on the metallic scaffolds were examined with scanning electron microscopy (SEM), while the chemical composition of the matrix was measured using energy-dispersive x-ray spectroscopy (EDX). We found that the viability of bone cores was maintained after seven weeks of loading in our ex vivo system. In addition, SEM images revealed crystallite-like structures on the dynamically loaded metal coupons (Group 4), corresponding to the initial stages of mineralization. EDX results further confirmed the presence of carbon at the interface and calcium phosphates in the matrix. We conclude that a bone bioreactor can be used as an alternate tool for in-vivo bone ingrowth studies of new implant surfaces or coatings.

scholarly journals Unravelling the role of Mesenchymal Stem/Stromal Cells Secretome in intervertebral disc degeneration in a pro-inflammatory/degenerative ex vivo model

2020 ◽  
Author(s):  
JR Ferreira ◽  
GQ Teixeira ◽  
E Neto ◽  
C Ribeiro-Machado ◽  
AM Silva ◽  
...  
Keyword(s):  
Intervertebral Disc ◽  
Disc Degeneration ◽  
Stromal Cells ◽  
Intervertebral Disc Degeneration ◽  
Ex Vivo ◽  
Ex Vivo Model

Abstract The authors have withdrawn this preprint due to author disagreement.

scholarly journals Ex vivo Evaluation of the Dynamic Morphometry of the Caudal Cervical Intervertebral Disc Spaces of Small Dogs and Cats

2021 ◽  
Vol 8 ◽  
Author(s):  
Sebastian C. Knell ◽  
Lucas A. Smolders ◽  
Antonio Pozzi
Keyword(s):  
Body Weight ◽  
Intervertebral Disc ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Ex Vivo ◽  
Wedge Angle ◽  
Flexion Extension ◽  
Cervical Spondylomyelopathy ◽  
Vertebral Endplates ◽  
Small Breed

The objective of this study was to provide a morphometric description of the caudal cervical intervertebral disc (IVD) spaces of small-breed dogs and cats. Specimens consisting of C4 through C7 from five small-breed dogs and six cats were positioned in neutral, flexion, extension, and lateral bending positions; and CT images were acquired. Height and width of the cranial and caudal vertebral endplates (VEPs), angle between the VEPs (IVD wedge angle), and craniocaudal distance (IVD width) between VEPs for the four loading positions were measured and compared for three segments (C4–C5, C5–C6, and C6–C7). VEP size normalized to body weight from medium-sized dogs was retrieved from a previous study and compared with data from small dogs and cats. A linear mixed model was used to compare outcome measures. Significance was set to p &lt; 0.05. VEP size normalized to body weight was the largest in small dogs compared with cats (p = 0.0422) and medium-sized dogs (p = 0.0064). Cats and medium-sized dogs were similar (p = 0.2763) in this regard. Flexion and extension induced a reduction of IVD width in the ventral portion of the IVD and the area of the nucleus. The dorsal part of the IVD remained unchanged throughout loading conditions. Unique morphometric characteristics of the caudal cervical IVD space of small dogs and cats were detected that are different from those described in sizes of dogs (medium-sized) typically affected by caudal cervical spondylomyelopathy (CSM). These findings may help to understand the different pathomechanisms in cervical spinal disease between small- and medium-sized dogs, including caudal CSM.

Ex Vivo Genetic Studies of the Intervertebral Disc: Methods and Modeling

2013 ◽  
Vol 13 (9) ◽  
pp. S52-S53
Author(s):  
Dominic W. Pelle ◽  
Jacqueline D. Peacock ◽  
Scott S. Russo ◽  
Kenneth J. Easton ◽  
Matthew Steensma
Keyword(s):  
Intervertebral Disc ◽  
Ex Vivo ◽  
Genetic Studies
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