The fabrication and characterization of a multi-laminate, angle-ply collagen patch for annulus fibrosus repair.

One major limitation of intervertebral disc (IVD) repair is that no ideal biomaterial has been developed that effectively mimics the angle-ply collagen architecture and mechanical properties of the native annulus fibrosus (AF). Furthermore, it would be beneficial to devise a simple, scalable process by which to manufacture a biomimetic biomaterial that could function as a mechanical repair patch to be secured over a large defect in the outer AF that will support AF tissue regeneration. Such a biomaterial would: (1) enable the employment of early-stage interventional strategies to treat IVD degeneration (i.e. nucleus pulposus arthroplasty); (2) prevent IVD re-herniation in patients with large AF defects; and (3) serve as a platform to develop full-thickness AF and whole IVD tissue engineering strategies. Due to the innate collagen fibre alignment and mechanical strength of pericardium, a procedure was developed to assemble multi-laminate angle-ply AF patches derived from decellularized pericardial tissue. Patches were subsequently assessed histologically to confirm angle-ply microarchitecture, and mechanically assessed for biaxial burst strength and tensile properties. Additionally, patch cytocompatibility was evaluated following seeding with bovine AF cells. This study demonstrated the effective removal of porcine cell remnants from the pericardium, and the ability to reliably produce multi-laminate patches with angle-ply architecture using a simple assembly technique. Resultant patches demonstrated their inherent ability to resist biaxial burst pressures reminiscent of intradiscal pressures commonly borne by the AF, and exhibited tensile strength and modulus values reported for native human AF. Furthermore, the biomaterial supported AF cell viability, infiltration and proliferation.