Effects of confinement on the mechanical properties of self-assembled articular cartilage constructs in the direction orthogonal to the confinement surface.

This study examined the effects of radial confinement and passive axial compression-induced vertical confinement, on the biomechanical, biochemical, and histological properties of self-assembled chondrocyte constructs. The self-assembled constructs, engineered without the use of an exogenous scaffold, exhibited significant increases in stiffness in the direction orthogonal to that of the confinement surface. With radial confinement, the significantly increased aggregate modulus was accompanied by increased collagen organization in the direction perpendicular to the articular surface, with no change in collagen or glycosaminoglycan (GAG) content. Additionally, radial confinement was most beneficial when applied before 2 weeks. With passive axial compression, the significantly increased Young's modulus and ultimate tensile strength were accompanied by a significant increase in collagen production. This study is the first to demonstrate the beneficial effects of confinement on tissue engineered constructs in the direction orthogonal to that of the confinement surface. (c) 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.