Abstract
The unique properties of mesenchymal stem cells (MSCs) and their natural presence within the bone marrow make them an attractive source of cells for novel cartilage repair strategies. As mechanics play a critical role in vivo, a more physiological loading regime in vitro would be more appropriate to test novel therapies, and this can be achieved using bioreactors. Using a multiaxial load bioreactor system, we have investigated the effect of mechanical stimulation on human stem cell differentiation in the absence of growth factors, specifically transforming growth factor β (TGFβ). Our bioreactor system allows for the application of shear, compression or a combination of both stimuli to establish the phenotypic changes induced within MSCs. Neither compression alone, nor shear alone induces a change in MSC phenotype with a fibrin-based scaffold. However, we have demonstrated that a combination of compression and shear is able to induce chondrogenic differentiation and this is due to increased endogenous expression and activation of TGFβ. Using this multiaxial load bioreactor system, we can search for novel markers and potential therapeutic targets that only occur under physiological loads. In addition, potential rehabilitation protocols to be used after cell therapy in cartilage repair can also be investigated.
