Optimizing mandibular bone defect reconstruction using adipose-derived stem cells on 3-dimensionally printed polycaprolactone/xenograft scaffolds in canine model.

BACKGROUND: Mandibular bone defects present significant challenges in reconstructive surgery due to their complex structure, and the body's limited ability to heal these areas naturally. Tissue engineering provides a promising solution, combined with stem cell therapy to overcome these obstacles. This study investigated the effects of adipose-derived mesenchymal stem cells (ADSCs) cultured on novel three-dimensional (3D)-printed polycaprolactone/xenograft scaffolds on the reconstruction and regeneration of segmental mandibular bone defects in canine models. METHODS: 3D-printed personalized PCL/xenograft scaffolds were designed and fabricated. After isolation and cultivation of canine ADSCs from their falciform tissues, they were seeded on 3D-printed scaffolds sterilized by gamma ray and implanted on 20 mm unilateral segmental mandibular bone defects of three dogs as the experimental group. Another three dogs received untreated scaffolds for their segmental defects. The defects were fixed with titanium plates. At 20 weeks post-implantation, the animals were sacrificed, the samples were harvested from all animals of both groups and three-dimensional microcomputed tomography (MicroCT), histopathological and immunohistochemistry analyses were performed. The parameters assessed included bone volume fraction, trabecular separation, trabecular number, trabecular thickness, new bone formation, amounts of connective tissue, remnants of scaffold and the detection of collagen type 1 and osteocalcin. Statistical analysis was performed using the unpaired Student's t test and Mann‒Whitney U test analysis of variance (P < 0.05). RESULTS: MicroCT analysis demonstrated that the mean bone volume fraction was significantly higher in the ADSC-seeded group compared to the control group, further indicating that ADSCs enhance bone regeneration and repair. Histopathological assessments showed that PCL/xenografts in the ADSC-seeded group were significantly more degraded than those in the scaffold-only group. Additionally, the connective tissue generation within the scaffold exhibited more maturation and extension in the ADSC-seeded PCL/xenografts. The tissue regeneration also showed that the PCL/xenograft scaffold supported the structural integrity of the mandible and facilitated the proper alignment of the defect edges. Immunohistochemical analysis revealed increased expression of collagen type I and osteocalcin in the ADSC-seeded PCL/xenografts, which supports the enhanced bone formation observed in the microCT and histological assessments. CONCLUSION: The cell-seeded 3D-printed PCL/xenograft scaffold group presented increased bone tissue regeneration and might be a promising way to reconstruct segmental maxillofacial defects.