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See detailNew use of VEGF in therapeutics: application in tendon lesions
Kaux, Jean-François ULg; Le Goff, Caroline ULg; Drion, Pierre ULg et al

in Clinical Chemistry (2010, July), 56(S6), 111

Introduction: As demonstrated in previous studies, mechanical overload, injury and inflammation, hypoxic condition or any combination of the above could lead to increased expression of VEGF in the tendon ... [more ▼]

Introduction: As demonstrated in previous studies, mechanical overload, injury and inflammation, hypoxic condition or any combination of the above could lead to increased expression of VEGF in the tendon. Thus, VEGF could participate in the healing of pathological tendons. Indeed, some authors are convinced that this neovascularization is the sign of a chronic tendinopathy while others plead in favour of it being a sign of healing processes. The VEGF111, which is a biologically active and proteolysis-resistant VEGF-A isoform, was recently identified. It is induced by ultraviolet B and genotoxic drugs. Experimentation shows that, in nude mice, tumors formed by HEK293 cells expressing VEGF111 develop a more widespread peritumoral neovascularisation than those expressing other VEGF isoforms. Good angiogenic activity and resistance to proteolysis makes VEGF111 a potential beneficial therapeutic option for ischemic diseases. The aim of our study was to determine whether if VEGF111 could have a therapeutic interest in the framework of tendinous pathology. Methods (*): A 5mm defect was surgically induced in Achilles tendon of 60 rats. Rats were divided into 2 groups of 30: A: a control group (no injection) and B: with a VEGF111 injection. The rats of group B received an injection of 100 ng of VEGF111 in situ 1 hour after surgery on the site of the tendon lesion. Afterwards, rats of both groups were placed in their cages without immobilization. After 5, 15 and 30 days, 10 rats of each group were euthanized. The traumatized Achilles tendon of each rat was dissected and removed. Immediately after sampling, tendons were submitted to a biomechanical tensile test up to rupture, using a tensile machine with “Cryo-jaw”. Statistical analyses were made with an ANOVA. Results: A significant increase over time of the force necessary to induce tendon rupture was observed for tendons which had been submitted to an injection of VEGF111 (p=0.016). The force required to break the tendon is always greater for the VEGF111 group (p<0.05). Discussion: We demonstrated that the force necessary to induce the rupture of a rat’s Achilles tendon during biomechanical tensile testing was greater for tendons which had been submitted to an injection of VEGF111. Thus, this experimentation showed that VEGF111 injections could accelerate the tendon healing process and increase the force needed to break tendons in their healing process. Conclusion: VEGF111 could be a new therapy for tendon lesions. However, other experimentation using a rat model with different concentrations of VEGF111 should be made to ascertain the best concentration for this healing process. Acknowledgement: This experimentation was partially financed by “Standard de Liège” and “Lejeune-Lechien” grants. (*) All experimental procedures and protocols used in this investigation were reviewed and approved by the Institutional Animal Care and Use Committee of the University of Liège. [less ▲]

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See detailComparison between platelet-rich plasma (PRP) and vascular endothelial growth factor-111 (VEGF-111) as a therapeutic tool in tendon healing process
Kaux, Jean-François ULg; Drion, Pierre ULg; Libertiaux, Vincent ULg et al

Poster (2010, March 20)

Introduction In spite of the availability of various treatments for tendinopathy, this pathology often becomes chronic. For this reason, it is of interest to develop new treatments. Among them, the ... [more ▼]

Introduction In spite of the availability of various treatments for tendinopathy, this pathology often becomes chronic. For this reason, it is of interest to develop new treatments. Among them, the injection of platelet-rich plasma (PRP) seems to be a promising one. Indeed, several animal models have demonstrated that injection of blood platelets can initiate and stimulate tendon and ligament repair by releasing growth factors (GF) locally. Among all the GF released by activated platelets, the vascular endothelial growth factor-A (VEGF-A) is known to induce positive effects on vascular function and angiogenesis, and could be implicated in the healing process of tendons. Recently, a novel VEGF-A isoform was identified, the VEGF-111, a biologically active and proteolysis-resistant VEGF-A isoform, also known to present beneficial effects on ischemic diseases. This prompted us to evaluate whether VEFF-111 would have a therapeutic interest within the framework of the tendon pathology. Aim of the study: We hypothesized that the healing of ruptured Achilles tendons, which is the last stage of the Blazina’s classification, could be improved by injection of VEGF-111 that was compared to the potential effect of PRP injections using a rat model. Methods: A 5mm defect was surgically induced in rat Achilles tendon after resection of plantaris tendon. Rats were divided into 3 groups: A: control (no injection), B: PRP treatment and C: VEGF-111 treatment. Rats received a local injection of PRP (50µL) or VEGF-111 (100ng) in situ after the surgery and were placed in their cage without immobilization. After 5, 15 and 30 days, the rats were euthanized in each group. The traumatized Achilles tendon of each rat was removed and dissected during the healing process. Immediately after sampling, tendons were submitted to a biomechanical tensile test up to rupture, using a “Cryo-jaw”. Results: Our results show that developed force necessary to induce tendon rupture during biomechanical tensile test was more important for tendons which had received an injection of PRP or VEGF-111. Moreover, the tensile force necessary to break tendons is higher with PRP than with VEGF-111. These results were already noticed from day 5 onwards. Conclusion: This experimentation has shown that both PRP and VEGF-111 injections stimulated tendon healing process as suggested by the increased force needed to break tendons during its healing process. Furthermore, this acceleration of the cicatrisation process was more significant with PRP than with VEGF-111. This could be explained by the release from platelets of a “cocktail” of growth factors acting in synergy on the healing process. Acknowledgement This experimentation was partially financed by “Standard de Liège 2007” and “Lejeune-Lechien 2008” grants. [less ▲]

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See detailPlatelet-rich plasma (PRP) increases healing process of rats' Achilles tendons
Kaux, Jean-François ULg; Drion, Pierre ULg; Pascon, Frédéric ULg et al

Conference (2010, March 20)

Introduction Some tendinopathies (epicondylitis, jumper’s knee or Achilles tendinopathy) are frequently considered as rebel to “classic” treatments such as rest, orthotics, NSAIs, electrotherapy ... [more ▼]

Introduction Some tendinopathies (epicondylitis, jumper’s knee or Achilles tendinopathy) are frequently considered as rebel to “classic” treatments such as rest, orthotics, NSAIs, electrotherapy, physiotherapy, corticosteroid infiltrations, extracorporeal shock waves… Recently, several studies, essentially in vitro, demonstrated the positive effects of platelets on the healing process of different tissues: bones, muscles and tendons. Objectives The aim of our experiment was to ascertain whether the use of platelet-rich plasma (PRP) was of interest for accelerating the healing process of Achilles tendon after surgical induced lesion. Methods A 5mm defect was surgically induced in rat Achilles tendon after resection of plantaris tendon. Rats were divided into 2 groups: A: control (no injection) and B: PRP injection. Rats of group B received a PRP injection in situ after the surgery. Afterwards, rats of both groups were placed in their cage without immobilization. After 5, 15 and 30 days, rats were euthanized. The traumatized Achilles tendon of each rat was removed and dissected during this healing process. Immediately after sampling, tendons were submitted to a biomechanical tensile test up to rupture, using a “Cryo-jaw”. Results We demonstrated that the force necessary to induce tendon rupture during biomechanical tensile test study was more important for tendons which had been submitted to an injection of PRP. These results were noticed from day 5 onwards. Discussion – Conclusion This experimentation has shown that PRP injections could accelerate tendons healing process and increase the force needed to break tendons in their healing process. This “accelerating” process can be observed as early as day 5. Acknowledgement This experimentation was partially financed by “Standard de Liège 2007” and “Lejeune-Lechien 2008” grants. [less ▲]

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See detailLe PRP (Platelet-Rich Plasma) peut-il favoriser la régénération tendineuse ?
Kaux, Jean-François ULg; Drion, Pierre ULg; Pascon, Frédéric ULg et al

in Annales de Réadaptation et de Médecine Physique (2009, October), 52(Sup. 1), 109-110

Introduction : Certaines tendinopathies (l’épicondylite, la tendinopathie rotulienne supérieure ou encore la tendinopathie d’Achille) demeurent rebelles malgré un traitement « classique » bien conduit ... [more ▼]

Introduction : Certaines tendinopathies (l’épicondylite, la tendinopathie rotulienne supérieure ou encore la tendinopathie d’Achille) demeurent rebelles malgré un traitement « classique » bien conduit : repos, orthèse, AINS, électrothérapie, kinésithérapie, infiltrations de corticoïdes, ondes de choc... Certains travaux, essentiellement in vitro, soulignent les potentialités réparatrices des plaquettes qui présentent la capacité d’accélérer la cicatrisation de différents tissus : os, muscles et tendons. Objectifs : Le but de notre étude préliminaire est d’objectiver l’effet « accélérateur » sur la réparation tendineuse suite à l’emploi d’injection de plasma enrichi en plaquettes (platelet-rich plasma ou PRP) car cette technique pourrait représenter une thérapeutique d’avenir en médecine physique et en traumatologie du sport. Méthodes : Nous avons sectionné et réalisé un défect de 5mm dans le tendon d’Achille de rats (N = 12). Quatre rats ont bénéficié d’une injection in loco de PRP et remis en liberté comme les autres dans leur cage. Trois rats (2 sans PRP et 1 avec PRP) sont euthanasiés à J5, J10, J20 et J30 et le tendon d’Achille en cours de régénération est disséqué et prélevé. Une étude biomécanique de traction jusqu’à rupture est réalisé à l’aide de « Cryo-jaw ». Résultats : L’analyse des résultats montre que la force développée pour obtenir la rupture tendineuse doit être plus importante pour les tendons ayant bénéficié d’une injection de PRP et ce dès J5. Discussion – Conclusion : Cette série préliminaire permet de montrer que les injections de PRP permettent une accélération de la cicatrisation tendineuse et une augmentation des valeurs de résistances à la traction. Une étude avec un plus grand nombre de sujets est en cours. [less ▲]

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See detailViscoelastic Modeling of Brain Tissue: A Fractional Calculus-Based Approach
Libertiaux, Vincent ULg; Pascon, Frédéric ULg

in Ganghoffer, Jean-François; Pastrone, Franco (Eds.) Mechanics of Microstructured Solids Cellular Materials, Fibre Reinforced Solids and Soft Tissues (2009)

In recent years, the mechanical study of the brain has become a major topic in the field of biomechanics. A global biomechanical model of the brain could find applications in neurosurgery and haptic ... [more ▼]

In recent years, the mechanical study of the brain has become a major topic in the field of biomechanics. A global biomechanical model of the brain could find applications in neurosurgery and haptic device design. It would also be useful for car makers, who could then evaluate the possible trauma due to impact. Such a model requires the design of suitable constitutive laws for the different tissues that compose the brain (i.e. for white and for gray matters, among others). Numerous constitutive equations have already been proposed, based on linear elasticity, hyperelasticity, viscoelasticity and poroelasticity. Regarding the strong strain-rate dependence of the brain’s mechanical behaviour, we decided to describe the brain as a viscoelastic medium. The design of the constitutive law was based on the Caputo fractional derivation operator. By definition, it is a suitable tool for modeling hereditary materials. Indeed, unlike integer order derivatives, fractional (or real order) operators are non-local, which means they take the whole history of the function into account when computing the derivative at current time t. The model was calibrated using experimental data on simple compression tests performed by Miller and Chinzei. A simulated annealing algorithm was used to ensure that the global optimum was found. The fractional calculus-based model shows a significant improvement compared to existing models. This model fits the experimental curves almost perfectly for natural strains up to − 0.3 and for strain-rates from 0.64s − 1 to 0.64 10− 2 s − 1. [less ▲]

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See detailProblems and Challenges of Image-Guided Neurosurgical Navigation and Intervention
Verly, Jacques ULg; Kavec, Martin; Vigneron, Lara et al

in Lecture Notes in Computer Science (2006, November), 4263

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