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See detailEccentric training improves tendon biomechanical properties: a rat model
Kaux, Jean-François ULg; Drion, Pierre ULg; Libertiaux, Vincent et al

in British Journal of Sports Medicine (2014, April), 48(7), 155

Background: Even if eccentric exercises appear favourable in primary prevention of tendons lesions and, especially, in secondary prevention after tendinopathy, the biomechanical changes to the tissue are ... [more ▼]

Background: Even if eccentric exercises appear favourable in primary prevention of tendons lesions and, especially, in secondary prevention after tendinopathy, the biomechanical changes to the tissue are not yet clear. Objective: We aimed to better define the biomechanical changes that affect healthy tendon after eccentric and concentric training. Design: Randomised controlled trial. Participants: Eighteen Sprague-Dawley rats of 2 months. Interventions: The six rats in the control group (U) were not subjected to physical exercise. The 12 remaining rats (6 in each group) ran on a treadmill set at a +15° incline for concentric training (C) or a -15° incline for eccentric training (E), at a speed of 17 m/min for 1 h, three times per week for 5 weeks. Main Outcome Measurements: The tricipital, patellar and Achilles tendons were subsequently removed to perform a traction test until rupture, and a histological analysis was performed. Results: There was a significant improvement in the rupture force of the patellar and tricipital tendons between the U and E groups. The tricipital tendons in the control group presented a significantly smaller cross-section than the E- and C-trained groups, but none between E and C groups. No significant difference was observed for the mechanical stress at rupture per surface unit between the three groups for all three tendons. However, a tendency towards improvement these values was observed between the trained and the U groups for the patellar tendon. Histological studies demonstrated the tendency of the development of a greater number of blood vessels and a larger quantity of collagen in the eccentric group. Conclusions: The mechanical properties of tendons in rats improve after specific training, especially following eccentric training. Our results partly explained how mechanical loading, especially in eccentric mode, could improve the tendon structure. [less ▲]

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See detailVascular Endothelial Growth Factor-111 (VEGF-111) and tendon healing: preliminary results in a rat model of tendon injury
Kaux, Jean-François ULg; Janssen, Lauriane ULg; Drion, Pierre ULg et al

in Muscles, Ligaments and Tendons Journal (2014), 4(1), 25-28

Tendon lesions are among the most frequent musculoskeletal pathologies. Vascular endothelial growth factor (VEGF) is known to regulate angiogenesis. VEGF-111, a biologically active and proteolysis ... [more ▼]

Tendon lesions are among the most frequent musculoskeletal pathologies. Vascular endothelial growth factor (VEGF) is known to regulate angiogenesis. VEGF-111, a biologically active and proteolysis-resistant splice variant of this family, was recently identified. This study aimed at evaluating whether VEGF-111 could have a therapeutic interest in tendon pathologies. Surgical section of one Achilles tendon of rats was performed before a local injection of either saline or VEGF-111. After 5, 15 and 30 days, the Achilles tendons of 10 rats of both groups were sampled and submitted to a biomechanical tensile test. The force necessary to induce tendon rupture was greater for tendons of the VEGF-111 group (p<0.05) while the section areas of the tendons were similar. The mechanical stress was similar at 5 and 15 days in the both groups but was improved for the VEGF-111 group at day 30 (p <0.001). No difference was observed in the mRNA expression of collagen III, tenomodulin and MMP-9. In conclusion, we observed that a local injection of VEGF-111 improves the early phases of the healing process of rat tendons after a surgical section. Further confirmatory experimentations are needed to consolidate our results. [less ▲]

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See detailEccentric training improves tendon biomechanical properties: a rat model
Kaux, Jean-François ULg; Drion, Pierre ULg; Libertiaux, Vincent et al

in Journal of Orthopaedic Research (2013), 31(1), 119-124

Introduction: The treatment of choice for tendinopathies is eccentric reeducation. Although the clinical results appear favourable, the biomechanical changes to the tissue are not yet clear. Even if the ... [more ▼]

Introduction: The treatment of choice for tendinopathies is eccentric reeducation. Although the clinical results appear favourable, the biomechanical changes to the tissue are not yet clear. Even if the mechanotransduction theory is commonly accepted, the physiology of tendons is not clearly understood. We aimed to better define the biomechanical and histological changes that affect healthy tendon after eccentric and concentric training. Materiel and Methods: This study compared the effects of 2 methods of training (eccentric (E) training and concentric (C) training) with untrained (U) rats. The animals were trained over a period of 5 weeks. The tricipital, patellar and Achilles tendons were removed, measured and a tensile test until failure was performed. A histological analysis (hematoxylin and eosin and Masson's trichrome stains) was also realized. Results: There was a significant increase in the rupture force of the patellar and tricipital tendons between the U and E groups. The tricipital tendons in the control group presented a significantly smaller cross-sectional area than the E- and C-trained groups, but none was constated between E and C groups. No significant difference was observed for the mechanical stress between the three groups for all three tendons. Histological studies demonstrated the development of a greater number of blood vessels and a larger quantity of collagen in the E group. Discussion and conclusion: The mechanical properties of tendons in rats improve after specific training, especially following eccentric training. Our results partly explained how mechanical loading, especially in eccentric mode, could improve the healing of tendon. [less ▲]

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See detailEffects of platelet-rich plasma (PRP) on the healing of Achilles tendons of rats
Kaux, Jean-François ULg; Drion, Pierre ULg; Colige, Alain ULg et al

in Wound Repair & Regeneration : Official Publication of the Wound Healing Society and the European Tissue Repair Society (2012), 20(5), 748-756

Platelet-Rich Plasma (PRP) contains growth factors involved in the tissular healing process. The aim of the study was to determine if an injection of PRP could improve the healing of sectioned Achilles ... [more ▼]

Platelet-Rich Plasma (PRP) contains growth factors involved in the tissular healing process. The aim of the study was to determine if an injection of PRP could improve the healing of sectioned Achilles tendons of rats. After surgery, rats received an injection of PRP (n=60) or a physiological solution (n=60) in situ. After 5, 15 and 30 days, 20 rats of both groups were euthanized and 15 collected tendons were submitted to a biomechanical test using cryo-jaws before performing transcriptomic analyses. Histological and biochemical analyses were performed on the 5 remaining tendons in each group. Tendons in the PRP group were more resistant to rupture at 15 and 30 days. The mechanical stress was significantly increased in tendons of the PRP group at day 30. Histological analysis showed a precocious deposition of fibrillar collagen at day 5 confirmed by a biochemical measurement. The expression of tenomodulin was significantly higher at day 5. The mRNA level of type III collage, matrix metalloproteinase 2, 3 and 9 was similar in the 2 groups at all time points whereas type I collagen was significantly increased at day 30 in the PRP group. In conclusion, an injection of PRP in sectioned rat Achilles tendon influences the early phase of tendons healing and results in an ultimate stronger mechanical resistance. [less ▲]

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See detailEffects of platelet-rich plasma on the healing of tendons: animal model
Kaux, Jean-François ULg; Drion, Pierre ULg; Colige, Alain ULg et al

in Biomedica 2012 (2012, April)

Introduction: Platelet-Rich Plasma (PRP) contains lot of growth factors which could enhance the healing process of different tissues. We aimed to determine if a single injection of PRP could improve the ... [more ▼]

Introduction: Platelet-Rich Plasma (PRP) contains lot of growth factors which could enhance the healing process of different tissues. We aimed to determine if a single injection of PRP could improve the cicatrisation of ruptured Achilles tendons of rats. Material and Methods: A 5mm defect was surgically made in the Achilles tendon of 120 rats. A few hours after surgery, 45 rats received a PRP or PBS injection in situ. After 5, 15 and 30 days, 20 rats of both groups were euthanized and 15 collected tendons were immediately submitted to a biomechanical tensile strength test until rupture using a “cryo-jaw” device. After, theses samples were used for transcriptomic analyses. Histological and biochemical analyses were performed on the five remained tendons in each group. Results: Tendons in the PRP group were more resistant to rupture at 15 and 30 days than those in the control group. The transverse area of tendons in the PRP group was significantly higher at day 5 and 15. The constraint was significantly increased in tendons of the PRP group in the late phase of the healing (day 30). Histological and immunohistological analysis showed an increased staining for fibrillar collagen at day 5 confirmed by a biochemical analysis showing an increased collagen concentration in the callus. The expression of tenomodulin, a tenocyte differentiation marker, was significantly higher in the PRP-treated tendons at day 5. No significant difference in terms of mRNA for type III collagen and matrix metalloproteinase 9 was observed at any time between the 2 groups. Conclusion: A single injection of PRP in sectioned Achilles tendon of rats few hours after surgery influences the early phase of tendons healing, resulting in an ultimate stronger mechanical resistance. [less ▲]

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See detailInjection de concentrés plaquettaires et régénération tendineuse : modèle animal
Kaux, Jean-François ULg; Drion, Pierre ULg; Renouf, Julien et al

in 3ème Congrès Commun SFMS - SFTS (2010, October 01)

Introduction : La régénération tendineuse en traumatologie du sport demeure un processus actuellement difficile à gérer et de nouvelles voies thérapeutiques sont en cours d’exploration. La littérature ... [more ▼]

Introduction : La régénération tendineuse en traumatologie du sport demeure un processus actuellement difficile à gérer et de nouvelles voies thérapeutiques sont en cours d’exploration. La littérature récente fait état d’effets bénéfiques sur la régénération tendineuse de concentrés plaquettaires (platelet-rich plasma ou PRP), administrés in situ, dus au relargage de facteurs de croissance par activation des plaquettes et à leur activité stimulante au cours de la cicatrisation. Dès lors, nous avons souhaité tester l’effet bénéfique de ce traitement sur des rats préalablement lésés au niveau de leur tendon d’Achille. Matériel et Méthode : Une section unilatérale du tendon d’Achille a été réalisée chez 60 rats Sprague Dawley adultes. De ces 60 rats, 30 ont subi une cicatrisation naturelle (rats contrôles) et 30 rats ont bénéficié d’une injection in situ de PRP le jour de la lésion. Diverses études biomécaniques, biochimiques et histologiques ont été réalisées sur ces tendons d’Achille en cours de cicatrisation à respectivement J5, J15 et J30 après lésion. Dix rats supplémentaires ont servi de témoins sains (sans lésion tendineuse). L’étude biomécanique appréciait la résistance maximale des tendons à la traction à l’aide de mors type « cryo-jaws ». L’étude histologique évaluait l’évolution cellulaire pendant la phase de cicatrisation. L’analyse transcriptomique étudiait l’expression de gènes codant pour le collagène de type III, les métalloprotéases matricielles (MMP-9) et la ténomoduline (TNMD), ainsi qu’un dosage d’hydroxyproline permettant d’évaluer la quantité de collagène présente dans le tendon au cours de la cicatrisation. Résultats : L’étude biomécanique démontre la meilleure résistance des tendons traités avec du PRP par rapport aux tendons contrôles à J5 (+19%), J15 (+30%) et significativement à J30 (+43%). L’étude histologique suggère qu’une injection de PRP stimule la prolifération cellulaire, favorise l’organisation tissulaire, stimule l’angiogenèse et la réorganisation architectural du collagène. L’étude biochimique ne permet pas d’expliquer les effets bénéfiques puisqu’il n’y a pas de différence dans l’expression des gènes des différentes molécules matricielles (collagène de type III, MMP-9 et TNMD) ni dans la quantité d’hydroxyproline qui s’accroit au cours du temps de la cicatrisation de façon similaire dans les deux groupes. Conclusion : L’injection de PRP améliore et accélère la cicatrisation tendineuse et augmente la résistance aux contraintes mécaniques du tendon en cours de cicatrisation. [less ▲]

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