Multi-laminate Annulus Fibrosus Repair Scaffold with an Interlamellar Matrix Enhances Impact Resistance, Prevents Herniation and Assists in Restoring Spinal Kinematics
Focal defects in the annulus fibrosus (AF) of the intervertebral disc (IVD) from herniation or surgical injury have detrimental impacts on IVD mechanical function. Thus, biomaterial-based repair strategies, which can restore the mechanical integrity of the AF and support long-term tissue regeneration are needed. Accordingly, a collagen-based multi-laminate scaffold with an underlying \"angle-ply\" architecture has been previously reported demonstrating similar mechanical properties to native AF tissue. The objectives of this work were to: 1) enhance the biomaterials impact strength, 2) define its contribution to spinal kinematics, and 3) assess its ability to prevent IVD herniation. First, AFRPs were enriched with a glycosaminoglycan-based (GAG) interlamellar matrix (ILM), and then tested for its radially-directed impact resistance under physiological stresses. Subsequent kinematic testing was conducted using a characterized GAG-enriched AFRP as an AF focal defect closure device. In summary, AFRPs demonstrated 1) incorporation of a GAG-based ILM significantly increased radial impact strength, 2) restoration of axial FSU kinematics and 3) ability to prevent herniation of native IVD tissues. Together, these results suggest that the AFRP demonstrates the mechanical robustness and material properties to restore an IVDs physiological mechanical function through the adequate closure of an AF focal defect.