Mechanical loading using a multimodal bioreactor enhances mesenchymal stem cell chondrogenesis. (A) The bioreactor can apply both compression and shear to the cell-seeded construct through rotation of the ceramic hip ball in contact with the surface of the construct and through vertical movement of the ball perpendicular to the construct surface. Relative (B) Sox9 and (C) Col2 mRNA expression of human mesenchymal stem cells after culture for 21 days in fibrin/polyurethane constructs without exogenous growth factors. Although either compression or shear loading alone increased these chondrogenic markers above free swelling levels, the combination of shear and compression loading further enhanced the response. #P <0.05, ##P <0.01, ###P <0.001. Reproduced from  with kind permission from eCM journal .