Development of poly(trimethylene carbonate) network implants for annulus fibrosus tissue engineering

Purpose: Intervertebral disk degeneration is the main cause of chronic back pain. Disk degeneration often leads to tearing of the annulus fibrosus (AF) and extrusion of the nucleus pulposus (NP), which compresses the nerves. Current treatment involves removing the herniated NP and suturing the damaged AF tissue. This surgical approach has several drawbacks. In this study, we designed a biodegradable AF closure system comprising a tissue engineering scaffold, a supporting membrane and an adhesive material, to not only restore the function of the herniated disc but also to promote tissue regeneration. 
Materials and Methods: Porous scaffolds with precisely defined architectures were built by stereolithography using resins based on poly(trimethylene carbonate) (PTMC) macromers functionalized with methacrylate endgroups. In addition, a porous photo-cross-linked PTMC membrane was developed that can be used to keep the scaffold in place in the AF tissue. Results: After synthesis and characterization, the components of the implant are glued together and to the AF tissue using a diisocyanate glue based on polyethylene glycol–PTMC triblock copolymers. The adhesion strengths of the materials to each other and to AF tissue were determined in lap-shear tests. 
 Conclusions: This study showed that a device for AF tissue engineering can be prepared from PTMC-based scaffolds, membranes and glues.