Intervertebral discs (IVD) are soft tissues that have viscoelastic behavior. Under cyclic loading, viscoelastic tissues dissipate the mechanical loading through the production of heat. In IVD, it is hypothesized that heat cannot be convected from the nucleus pulposus (NP), since it is not perfused by the cardio-vascular system. This may result in local increase of temperature in the NP, and therefore may affect the metabolism of cells present in NP or its mechanical behavior. The overall goal of the project is to study the only thermal contribution on NP cells metabolism, without any mechanical effect. A screening of potential effects, due to different temperatures, will be performed on fetal cells and on cells extracted from bovine NP.