Healing of Large Segmental Bone Defect after Implantation of Autogenous Cancellous Bone Graft in Comparison to Hydroxyapatite and 0.5% Collagen Scaffold Combined with Mesenchymal Stem Cells

At present, attention is focused on research into possibilities of healing large bone defects by the method of mini-invasive osteosynthesis, using implantation of biomaterials and mesenchymal stem cells (MSCs). This study evaluates the healing of segmental femoral defects in miniature pigs based on the radiological determination of the callus: cortex ratio at 16 weeks after ostectomy. The size of the formed callus was significantly larger (p < 0.05) in animals after transplantation of an autogenous cancellous bone graft (group A, callus : cortex ratio of 1.77 +/- 0.33) compared to animals after transplantation of cylindrical scaffold from hydroxyapatite and 0.5% collagen (group S, callus : cortex ratio of 1.08 +/- 0.13), or in animals after transplantation of this scaffold seeded with MSCs (group S + MSCs, callus: cortex ratio of 1.15 +/- 0.18). No significant difference was found in the size of callus between animals of group S and animals of group S + MSCs. Unlike a scaffold in the shape of the original bone column, a freely placed autogenous cancellous bone graft may allow the newly formed tissue to spread more to the periphery of the ostectomy defect. Implanted cylindrical scaffolds (with and without MSCs) support callus formation directly in the center of original bone column in segmental femoral ostectomy, and can be successfully used in the treatment of large bone defects.