In Vivo Efficacy of Bone Marrow Stromal Cells Coated with Beta-Tricalcium Phosphate for the Reconstruction of Orbital Defects in Canines

Abstract

To repair the segmental orbital rim defects of dogs with three-dimensional (3D) tissue-engineered constructs derived from culturing autogenous bone marrow stromal cells (BMSCs) on β-tricalcium phosphate (β-TCP) scaffolds. A 25-mm segmental defect on the canine inferior orbital rim was created. BMSCs were isolated and osteogenically induced in vitro, then were seeded onto 3D β-TCP scaffolds and implanted to repair the orbital defects after 5 days of cultivation. The group of noninduced BMSC/β-TCP, β-TCP alone, and the normal inferior orbital rim were set as controls. The orbits of all groups had spiral computed tomography (CT) scans 1, 4, 8, and 12 weeks after surgery. Gross examination, bone density, microCT, and histologic measurements were performed 12 weeks after surgery. The results were analyzed to evaluate the extent of bone repair. Twelve weeks after surgery, CT examination revealed good inferior orbital rim recovery in the induced BMSC/β-TCP group, and the bone density was 0.30 ± 0.03 g/cm(2) with no dominant variance, compared with the normal control (P > 0.05). MicroCT and histologic examination confirmed that the implantations led to good repair of the defects. Pore-like spongy bone surrounded the implants through the section plane, with some residue remaining in the center. In contrast, the noninduced BMSC/β-TCP implants were not fully repaired, and nonunion was evident. The bony density for this group was 0.23 ± 0.07 g/cm(2), which was significantly lower than that of the control group (P < 0.05). The β-TCP group was largely held by fibrous tissues. Engineered bone from induced BMSCs and 3D biodegradable β-TCP can efficiently repair critical-sized segmental orbital defects in dogs.