Design and Ex Vivo Evaluation of a PCLA Degradable Device To Improve Annulus Fibrosus Repair

With a prevalence of over 90% in people over 50, intervertebral disc degeneration (IVDD) is a major health concern. This weakening of the intervertebral discs can lead to herniation, where the nucleus pulpus (NP) leaks through the surrounding Annulus Fibrosus (AF). Considering the limited self-healing capacity of AF tissue, an implant is needed to restore its architecture and function. Here, we developed a biomimetic electrospun nanofibrous biodegradable scaffold that could be potentially used to repair AF defects. To that aim, we synthesized copolymers and blends of epsilon-caprolactone and lactide to create poly(epsilon-caprolactone-co-lactide) (PCLA) and PCL/PLA scaffolds with 10, 20, or 30% PLA. Properties of the initial nanofibrous scaffolds and the impact of gamma irradiation sterilization on the mechanical, thermal, and in vitro degradation properties are assessed and discussed with respect to the AF application. It was shown that ovine AF cells colonize the nanofibrous layers with increased metabolic activity over time. As an outcome of these studies, two copolymers were chosen to design a device composed of a 3D nanofibrous stacked scaffold associated with a degradable anchoring system to maintain the scaffold in an AF defect. The implantability of this device was tested in a cadaveric sheep lumbar IVD.