Repair of Bone Defect in Caprine Tibia Using a Laminated Scaffold With Bone Marrow Stromal Cells Loaded Poly (L-Lactic Acid)/β-Tricalcium Phosphate

Abstract

Repair of bone defects of a critical size encounters many problems, and many efforts aim to build a porous scaffold loading bone marrow stromal cells (BMSCs) or bone morphogenetic protein (BMP2) to quickly repair bone defects. In this paper, a laminated scaffold was designed and tested for the repair of bone defects in a caprine tibia. Beta-tricalcium phosphate (β-TCP) and poly (L-lactic acid) (PLLA) were fabricated to a sandwich structured composite that was then rolled up to form a cylindrical shaped, porous scaffold. The porosity and bending strength of the PLLA/β-TCP laminated scaffold were around 70% and 1.7 MPa, respectively. Results from in vitro experiments showed that the pH value of the scaffold in water fluctuated between 4.9 and 7.0 during its degradation. When exposed to the simulated body fluid, the scaffold lost its strength after 11 weeks of degradation. After implantation in Chinese caprines' diaphyseal defects with loaded allogeneic BMSCs, the scaffold sped up the bone repair without collapse of the scaffold and the unwanted inflammatory response, and then rapidly degraded and finally disappeared at 12 weeks. Gross examinations and pullout tests showed that the experimental caprines walked normally and the implanted leg could be heavily loaded. X-ray examinations and histological analyses showed new bone tissues formed with similar structures to normal ones. It is suggested that the novel PLLA/β-TCP laminated scaffold with BMSCs loading can regenerate new bones quickly.