Comparison Capacity of Collagen Hydrogel and Collagen/Strontium Bioglass Nanocomposite Scaffolds With and Without mesenchymal Stem Cells in Regeneration of Critical Sized Bone Defect in a Rabbit Animal Model.

Bone self-healing is limited and requires additional or external intervention to promote and accelerate bone regeneration. Therefore, the aim of this study was to investigate the potential capacity of hydrogel collagen (Co) nanocomposite alone, and in combination with 2% strontium (Co/BGSr2%) in presence of mesenchymal stem cells (MSCs) in full-thickness bone defect regeneration in the rabbit animal model. A total of 72 New Zealand white rabbits were randomly divided in 6 groups of 12 rabbits with full-thickness bone defect. In five groups, the bone defect was treated with MSC, Co, Co/BGSr2%, Co + MSCs, and Co/BGSr2% + MSCs. No treatment was done in the control group. The treatments were assessed radiographically, histopathologically, and immunohistochemically on days 14, 28, 42, and 56 post-treatment. The highest radiographical and histological scores were belonged to the Co/BGSr2% + MSC followed by Co + MSCs, Co/BGSr2%, Co, MSC, and the control groups. The highest and lowest mean expression level of osteocalcin was detected in the Co/BGSr2% + MSC and control groups by 28th dayof post-implantation, respectively. In contrast, the highest and lowest mean expression level of osteocalcin on day 56 post-implantation was belonged to the control and Co/BGSr2% + MSC, respectively. The Co/BGSr2% nanocomposite scaffold seeded with MSC can accelerate bone regeneration resulted from osteoblastic production of osteocalcin protein. Therefore, collagen hydrogel combined with 2% strontium in nanocomposite form is a suitable candidate scaffold for bone tissue engineering.