MORPHO-FUNCTIONAL INTERACTION BETWEEN MUSCLE AND TENDON IN HYPERTROPHIC MLC/MIGF-1 MICE

摘要

Tendons and ligaments are uniaxial viscoelastic connective tissues and, during normal activity, tendons transmit forces from muscles to bones, while ligaments stabilize the joints. Many experiments have been carried out to study ligaments and tendons mechanical properties [1], and the effects of training protocols [2] or specific pathologies. Recently, different transgenic mice models have been proposed as a new way to study in depth tendons' function and development [3]. Within this context, we made use of pathological and transgenic animal models to investigate the morpho-functional interaction between muscles with an altered functionality and their tendons. In a previous work, by using the animal model of human Duchenne dystrophy, mdx, we found out that tendons connected to muscles with functional defects present reduced mechanical properties and an altered balance between alive and dead cells [4]. Here, we evaluated whether hypertrophic muscles would also involve alterations in tendon biomechanical properties. To do this, we used the transgenic animal model MLC/mlgf-1, were the local form of Igf-1 is over-expressed under a muscle specific promoter [5] inducing an increase in skeletal muscle mass and a proportional increment of force. To determine tendons' elastic and viscous response separately, complex compliance has been computed with a new experimental method [6] which uses a pseudorandom Gaussian noise (PGN) to stimulate all the frequencies of interest within its bandwidth. Elasticity determines the tissue response to loading while viscous dissipation affects the likelihood of injuries to tendons. Indeed, knowing tendinous tissue viscoelasticity is central to better understand the mechanism between energy dissipation and tissue injuries. Finally, the hypothesis that changes in tendons' mechanical properties could be correlated with alterations in the balance between alive and dead cells has been tested with an in situ cellular analysis