An “in vitro” experimental model to predict the mechanical behavior of macroporous scaffolds implanted in articular cartilage

A model is proposed to assess mechanical behavior of tissue engineering scaffolds and predict their performance “in vivo” during tissue regeneration. To simulate the growth of tissue inside the pores of the scaffold, the scaffold is swollen with a Poly (Vinyl alcohol) solution and subjected to repeated freezing and thawing cycles. In this way the Poly (Vinyl alcohol) becomes a gel whose stiffness increases with the number of freezing and thawing cycles. Mechanical properties of the construct immersed in water are shown to be determined, in large extent, by the water mobility constraints imposed by the gel filling the pores. This is similar to the way that water mobility determines mechanical properties of highly hydrated tissues, such as articular cartilage. As a consequence, the apparent elastic modulus of the scaffold in compression tests is much higher than those of the empty scaffold or the gel. Thus this experimental model allows assessing fatigue behavior of the scaffolds under long-term dynamic loading in a realistic way, without recourse to animal experimentation.