Determination of biomechanical properties. Biomechanical properties of the newly formed ECM at day 28 of BMSC, mixed cultures and chondrocytes co- or tricultured with OAB explants were analyzed and calculated to 100% of monocultured controls (dotted lines at 100). Young’s modulus of (A) 0 to 10% and (B) 40 to 50% strain were determined using unconfined compression. Aggregate modulus at equilibrium (C) and hydraulic permeability (D) were determined using confined compression performed at 50% compression. N =4. BMSC, bone marrow-derived mesenchymal stem cells; ECM, extracellular matrix; OAB, osteoarthritic subchondral bone.