3D-Printed Poly(ε-caprolactone) Scaffold Augmented With Mesenchymal Stem Cells for Total Meniscal Substitution: A 12-and 24-Week Animal Study in a Rabbit Model

Background: Total meniscectomy leads to knee osteoarthritis in the long term. The poly(epsilon-caprolactone) (PCL) scaffold is a promising material for meniscal tissue regeneration, but cell-free scaffolds result in relatively poor tissue regeneration and lead to joint degeneration. Hypothesis: A novel, 3-dimensional (3D)-printed PCL scaffold augmented with mesenchymal stem cells (MSCs) would offer benefits in meniscal regeneration and cartilage protection. Study Design: Controlled laboratory study. Methods: PCL meniscal scaffolds were 3D printed and seeded with bone marrow-derived MSCs. Seventy-two New Zealand White rabbits were included and were divided into 4 groups: cell-seeded scaffold, cell-free scaffold, sham operation, and total meniscectomy alone. The regeneration of the implanted tissue and the degeneration of articular cartilage were assessed by gross and microscopic (histological and scanning electron microscope) analysis at 12 and 24 weeks postoperatively. The mechanical properties of implants were also evaluated (tensile and compressive testing). Results: Compared with the cell-free group, the cell-seeded scaffold showed notably better gross appearance, with a shiny white color and a smooth surface. Fibrochondrocytes with extracellular collagen type I, II, and III and proteoglycans were found in both seeded and cell-free scaffold implants at 12 and 24 weeks, while the results were significantly better for the cell-seeded group at week 24. Furthermore, the cell-seeded group presented notably lower cartilage degeneration in both femur and tibia compared with the cell-free or meniscectomy group. Both the tensile and compressive properties of the implants in the cell-seeded group were significantly increased compared with those of the cell-free group. Conclusion: Seeding MSCs in the PCL scaffold increased its fibrocartilaginous tissue regeneration and mechanical strength, providing a functional replacement to protect articular cartilage from damage after total meniscectomy. Clinical Relevance: The study suggests the potential of the novel 3D PCL scaffold augmented with MSCs as an alternative meniscal substitution, although this approach requires further improvement before being used in clinical practice.