A Combination of a Polycaprolactone Fumarate Scaffold with Polyethylene Terephthalate Sutures for Intra-Articular Ligament Regeneration

Intra-articular ligamentous injuries are typically unrepairable and have limited outcomes after graft reconstruction. A combination of porous polycaprolactone fumarate (PCLF) scaffolds with polyethylene terephthalate (PET) sutures was developed with the goal of regenerating intra-articular ligaments. Scaffolds were fabricated by injecting PCLF over three-dimensional-printed molds containing two strands of PET suture down its central pore followed by cross-linking. Scaffolds were seeded with human mesenchymal stem cells (MSCs) from adipose tissue. To demonstrate cell attachment and proliferation in culture, we performed live/dead staining and cell proliferation assays. These experiments showed that MSCs remain viable and continue to proliferate on the scaffolds in culture for at least 2 weeks. Bare scaffolds were then used to reconstruct the rabbit anterior-cruciate ligament (ACL), while control rabbits underwent semitendinosus autograft reconstruction. The specimens underwent micro-computed tomography (CT) imaging, histological examination, and biomechanical testing at 8 weeks. The ultimate pull-out strength of the PCLF-PET scaffolds and tendon autografts was initially 72 ± 30 N and to 45 ± 10 N, respectively (p < 0.06). On inspection after 8 weeks in vivo, the intra-articular portion of the PCLF-PET scaffolds was fragmented while the tendon autografts remained intact. Cross-sectional areas of bone tunnels in the PCLF-PET scaffolds (11.3 ± 1 mm²) were enlarged compared to tendon autografts (3.8 ± 0.5 mm²) (p < 0.004) as measured by micro-CT. These studies show that PET-reinforced PCLF scaffolds are capable of initial ACL reconstruction and supports stem cell growth. The intra-articular portion of the scaffold may need to be re-engineered to support their use in ligament regeneration.