#$%^&*AU2013257540B220150611.pdf#####ABSTRACT Methods and compositions for the biological repair of cartilage using a hybrid construct combining both an inert structure and living core are described. The inert structure is intended to act not only as a delivery system to feed and grow a living core 5 component, but also as an inducer of cell differentiation. The inert structure comprises concentric internal and external and inflatable/expandable balloon-like bio-polymers. The living core comprises the cell-matrix construct comprised of HDFs, for example, seeded in a scaffold. The method comprises surgically removing a damaged cartilage from a patient and inserting the hybrid construct into the cavity generated after the 10 foregoing surgical intervention. The balloons of the inert structure are successively inflated within the target area, such as a joint, for example. Also disclosed herein are methods for growing and differentiating human fibroblasts into chondrocyte-like cells via mechanical strain.