scholarly journals Simulated-Physiological Loading Conditions Preserve Biological and Mechanical Properties of Caprine Lumbar Intervertebral Discs in Ex Vivo Culture

PLoS ONE ◽  
2012 ◽  
Vol 7 (3) ◽  
pp. e33147 ◽  
Author(s):  
Cornelis P. L. Paul ◽  
Hendrik A. Zuiderbaan ◽  
Behrouz Zandieh Doulabi ◽  
Albert J. van der Veen ◽  
Peter M. van de Ven ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Ex Vivo ◽  
Intervertebral Discs ◽  
Loading Conditions ◽  
Physiological Loading ◽  
Ex Vivo Culture

Determination of Real Time In-Vivo Cartilage Contact Deformation in the Ankle Joint

2007 ◽  
Author(s):  
Guoan Li ◽  
Lu Wan ◽  
Michal Kozanek
Keyword(s):  
Computational Models ◽  
Ex Vivo ◽  
Loading Conditions ◽  
Contact Deformation ◽  
Normal Cartilage ◽  
Physiological Loading ◽  
Contact Data ◽  
Biomechanical Responses

Knowledge of in-vivo articular cartilage contact deformation is critical for understanding normal cartilage function and the etiology of osteoarthritis (2,8). This knowledge is also instrumental for design of ex-vivo experiment to investigate the chondrocyte mechanotransductions under physiological loading conditions (7). Further, in-vivo cartilage contact data is necessary for validation of 3D computational models used to predict biomechanical responses of the articular joints (1,5). However, due to the complexity of in-vivo joint loading conditions as well as the complicated joint geometry, little information is available on in-vivo cartilage deformation in literature (9). In-vivo cartilage deformation as a function of loading history has not been delineated.

Nano-dispersed Particulate Ceramics in Poly-Lactide-Co-Glycolide Composites Improve Implantable Bone Substitute Properties

2007 ◽  
Vol 1056 ◽  
Author(s):  
Huinan Liu ◽  
Thomas J. Webster
Keyword(s):  
Mechanical Properties ◽  
Large Fraction ◽  
Critical Role ◽  
Tensile Modulus ◽  
Nano Particles ◽  
Loading Conditions ◽  
Ceramic Phase ◽  
Natural Bone ◽  
Physiological Loading ◽  
Orthopedic Applications

ABSTRACTMetallic materials widely used in orthopedic applications have much stronger mechanical properties (such as elastic modulus) than natural bone, which can weaken the newly formed bone interface due to stress-shielding. Because natural bone is under continuous physiological stresses (such as compression, tension, torsion, and/or bending), the mechanical properties of orthopedic implant materials should closely match those of living bone. This is necessary to minimize stress and strain imbalances during physiological loading conditions which will lead to implant failure. The objective of the present study was to characterize the mechanical properties of PLGA with well-dispersed nanophase titania. The dispersion of titania in PLGA was controlled by sonication and was characterized by field emission scanning electron microscopy and image analysis. For this purpose, two major stresses (compression and tension) that natural bone experiences under physiological loading conditions were characterized using an Instron Material Testing System. The results showed that nano-dispersed titania particles in PLGA increased the compressive and tensile modulus of such scaffolds compared to pure PLGA scaffolds and the more agglomerated ceramics in PLGA scaffolds. The mechanisms behind these results were also speculated. Since the predominant feature of nano-particles lies in their ultra-fine dimension, a large fraction of filler atoms can reside at the PLGA-ceramic interface which can lead to a stronger interfacial interaction, but only if the nano-particles are well dispersed at the nanometer level in the surrounding polymer matrix. As the interfacial PLGA-ceramic structure plays a critical role in determining the mechanical properties of composites, nano-composites with a great number of smaller interfaces could be expected to provide unusual properties, and the shortcomings induced by the heterogeneity of conventional (or micron) particle filled composites would also be avoided. Therefore, coupled with prior studies demonstrating greater osteoblast functions, the combination of PLGA with a strong and biocompatible well-dispersed nano-ceramic phase may provide better candidate materials for orthopedic applications.

Assessment of mechanical properties of porcine aortas under physiological loading conditions using vascular elastography

2016 ◽  
Vol 59 ◽  
pp. 185-196 ◽  
Author(s):  
Edgar J.S. Mascarenhas ◽  
Mathijs F.J. Peters ◽  
Jan Nijs ◽  
Marcel C.M. Rutten ◽  
Frans N. van de Vosse ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Loading Conditions ◽  
Physiological Loading

A regenerative approach towards recovering the mechanical properties of degenerated intervertebral discs: Genipin and platelet-rich plasma therapies

2016 ◽  
Vol 231 (2) ◽  
pp. 127-137 ◽  
Author(s):  
Mohammad Nikkhoo ◽  
Jaw-Lin Wang ◽  
Masoud Abdollahi ◽  
Yu-Chun Hsu ◽  
Mohamad Parnianpour ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Material Properties ◽  
Degenerative Disc Disease ◽  
Structural Changes ◽  
Ex Vivo ◽  
Platelet Rich Plasma ◽  
Element Model ◽  
Intervertebral Discs ◽  
Disc Disease ◽  
Degenerative Disc

Degenerative disc disease, associated with discrete structural changes in the peripheral annulus and vertebral endplate, is one of the most common pathological triggers of acute and chronic low back pain, significantly depreciating an individual’s quality of life and instigating huge socioeconomic costs. Novel emerging therapeutic techniques are hence of great interest to both research and clinical communities alike. Exogenous crosslinking, such as Genipin, and platelet-rich plasma therapies have been recently demonstrated encouraging results for the repair and regeneration of degenerated discs, but there remains a knowledge gap regarding the quantitative degree of effectiveness and particular influence on the mechanical properties of the disc. This study aimed to investigate and quantify the material properties of intact (N = 8), trypsin-denatured (N = 8), Genipin-treated (N = 8), and platelet-rich plasma–treated (N = 8) discs in 32 porcine thoracic motion segments. A poroelastic finite element model was used to describe the mechanical properties during different treatments, while a meta-model analytical approach was used in combination with ex vivo experiments to extract the poroelastic material properties. The results revealed that both Genipin and platelet-rich plasma are able to recover the mechanical properties of denatured discs, thereby affording promising therapeutic modalities. However, platelet-rich plasma–treated discs fared slightly, but not significantly, better than Genipin in terms of recovering the glycosaminoglycans content, an essential building block for healthy discs. In addition to investigating these particular degenerative disc disease therapies, this study provides a systematic methodology for quantifying the detailed poroelastic mechanical properties of intervertebral disc.

Phagocytosis of Liposome Particles by Rat Splenic Immature Monocytes Makes Them Transiently and Highly Immunosuppressive In Ex Vivo Culture Conditions

2011 ◽  
Vol 337 (1) ◽  
pp. 42-49 ◽  
Author(s):  
Daisuke Takahashi ◽  
Hiroshi Azuma ◽  
Hiromi Sakai ◽  
Keitaro Sou ◽  
Daiko Wakita ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Culture Conditions ◽  
Ex Vivo Culture

scholarly journals Mimicking of Blood Flow Results in a Distinct Functional Phenotype in Human Non-Adherent Classical Monocytes

Biology ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 748
Author(s):  
Elisa Wirthgen ◽  
Melanie Hornschuh ◽  
Ida Maria Wrobel ◽  
Christian Manteuffel ◽  
Jan Däbritz
Keyword(s):  
Blood Flow ◽  
Shear Flow ◽  
Ex Vivo ◽  
Culture Conditions ◽  
Inflammatory Signaling ◽  
Gm Csf ◽  
Beneficial Effects ◽  
Migratory Capacity ◽  
Ex Vivo Culture ◽  
Static Conditions

Ex vivo culture conditions during the manufacturing process impact the therapeutic effect of cell-based products. Mimicking blood flow during ex vivo culture of monocytes has beneficial effects by preserving their migratory ability. However, the effects of shear flow on the inflammatory response have not been studied so far. Hence, the present study investigates the effects of shear flow on both blood-derived naïve and activated monocytes. The activation of monocytes was experimentally induced by granulocyte-macrophage colony-stimulating factor (GM-CSF), which acts as a pro-survival and growth factor on monocytes with a potential role in inflammation. Monocytes were cultured under dynamic (=shear flow) or static conditions while preventing monocytes' adherence by using cell-repellent surfaces to avoid adhesion-induced differentiation. After cultivation (40 h), cell size, viability, and cytokine secretion were evaluated, and the cells were further applied to functional tests on their migratory capacity, adherence, and metabolic activity. Our results demonstrate that the application of shear flow resulted in a decreased pro-inflammatory signaling concurrent with increased secretion of the anti-inflammatory cytokine IL-10 and increased migratory capacity. These features may improve the efficacy of monocyte-based therapeutic products as both the unwanted inflammatory signaling in blood circulation and the loss of migratory ability will be prevented.

scholarly journals Stem cell integrins: Implications for ex-vivo culture and cellular therapies

2011 ◽  
Vol 6 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Andrew B.J. Prowse ◽  
Fenny Chong ◽  
Peter P. Gray ◽  
Trent P. Munro
Keyword(s):  
Stem Cell ◽  
Ex Vivo ◽  
Cellular Therapies ◽  
Ex Vivo Culture

Study on Multi-Axial Mechanical Properties of a Polyurethane Foam and Experimental Verification

2011 ◽  
Vol 311-313 ◽  
pp. 301-308
Author(s):  
Shou Hong Han ◽  
Zhen Hua Lu ◽  
Yong Jin Liu
Keyword(s):  
Mechanical Properties ◽  
Constitutive Model ◽  
Polyurethane Foam ◽  
Axial Compression ◽  
Axial Loading ◽  
Hydrostatic Compression ◽  
Model Parameters ◽  
Loading Conditions ◽  
Three Point Bending ◽  
Pu Foam

In order to investigate the multi-axial mechanical properties of a kind of PU (polyurethane) foam, some experiments in different loading conditions including uni-axial tension, uni-axial compression, hydrostatic compression and three-point bending were conducted. It is shown that the hydrostatic component influences yield behavior of PU foam, the yield strength and degree of strain hardening in hydrostatic compression exceed those for uni-axial compression. In terms of the differential hardening constitutive model, the evolution of PU foam yield surface and plastic hardening laws were fitted from experimental data. A finite element method was applied to analyze the quasi-static responses of the PU foam sandwich beam subjected to three-point bending, and good agreement was observed between experimental load-displacement responses and computational predictions, which validated the multi-axial loading methods and stress-strain constitutive model parameters. Moreover, effects of two foam models applied to uni-axial loading and multi-axial loading conditions were analyzed and compared with three-point bending tests and simulations. It is found that the multi-axial constitutive model can bring more accurate prediction whose parameters are obtained from the tests above mentioned.

scholarly journals Ex vivo culture of Fancc-/- stem/progenitor cells predisposes cells to undergo apoptosis, and surviving stem/progenitor cells display cytogenetic abnormalities and an increased risk of malignancy

Blood ◽  
2005 ◽  
Vol 105 (9) ◽  
pp. 3465-3471 ◽  
Author(s):  
Xiaxin Li ◽  
Michelle M. Le Beau ◽  
Samantha Ciccone ◽  
Feng-Chun Yang ◽  
Brian Freie ◽  
...  
Keyword(s):  
Progenitor Cells ◽  
Genome Stability ◽  
Bone Marrow Cells ◽  
Ex Vivo ◽  
Acquired Resistance ◽  
Intrinsic Defects ◽  
Cytogenetic Abnormalities ◽  
Increased Risk ◽  
Ex Vivo Culture ◽  
The Impact

AbstractCurrent strategies for genetic therapy using Moloney retroviruses require ex vivo manipulation of hematopoietic cells to facilitate stable integration of the transgene. While many studies have evaluated the impact of ex vivo culture on normal murine and human stem/progenitor cells, the cellular consequences of ex vivo manipulation of stem cells with intrinsic defects in genome stability are incompletely understood. Here we show that ex vivo culture of Fancc-/- bone marrow cells results in a time-dependent increase in apoptosis of primitive Fancc-/- progenitor cells in conditions that promote the proliferation of wild-type stem/progenitor cells. Further, recipients reconstituted with the surviving Fancc-/- cells have a high incidence of cytogenetic abnormalities and myeloid malignancies that are associated with an acquired resistance to tumor necrosis factor α (TNF-α). Collectively, these data indicate that the intrinsic defects in the genomic stability of Fancc-/- stem/progenitor cells provide a selective pressure for cells that are resistant to apoptosis and have a propensity for the evolution to clonal hematopoiesis and malignancy. These studies could have implications for the design of genetic therapies for treatment of Fanconi anemia and potentially other genetic diseases with intrinsic defects in genome stability.

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