Effect of enzymatic digestion on the transverse mechanical properties of annulus fibrosus lamellae

Intervertebral disc (IVD) degeneration is associated with changes in the major biomolecular components in the disc as well as changes in enzymatic activity in the IVD. Collagen, elastin, and proteoglycans in the disc are primarily responsible for mechanical and structural support as well as disc recovery after loading. In order to investigate the effects of the loss of these biomolecules, a single annulus fibrosus (AF) lamellar model has been developed. Isolated segments of human AF were digested with elastase, collagenase and chondroitinase ABC to selectively degenerate collagen, elastin, and proteoglycan respectively. Samples were then mechanically tested to determine the contribution of these components to the mechanical properties. Understanding the effects of biomolecular changes in the IVD will promote understanding of the relationship between composition and mechanical behavior.