[Study on bone marrow mesenchymal stem cells derived osteoblasts and endothelial cells compound with...

To explore the osteogenesis and angiogenesis effect of bone marrow mesenchymal stem cells (BMSCs) derived osteoblasts and endothelial cells compound with chitosan/hydroxyapatite (CS/HA) scaffold in repairing radial defect in rats.

The BMSCs were isolated from Sprague Dawley rats and the 3rd generation of BMSCs were induced into osteoblasts and endothelial cells. The endothelial cells, osteoblasts, and mixed osteoblasts and endothelial cells (1:1) were compound with CS/HA scaffold in groups A, B, and C respectively to prepare the cell-scaffold composites. The cell proliferation was detected by MTT. The rat radial segmental defect model was made and the 3 cell-scaffolds were implanted, respectively. At 4, 8, and 12 weeks after transplantation, the graft was harvested to perform HE staining and CD34 immunohistochemistry staining. The mRNA expressions of osteopontin (OPN) and osteoprotegerin (OPG) were detected by RT-PCR.

Alkaline phosphatase staining of osteoblasts showed that there were blue grains in cytoplasm at 7 days after osteogenic induction and the nuclei were stained red. CD34 immunocytochemical staining of the endothelial cells showed that there were brown grains in the cytoplasm at 14 days after angiogenesis induction. MTT test showed that the proliferation level of the cells in 3 groups increased with the time. HE staining showed that no obvious osteoid formation, denser microvessel, and more fibrous tissue were seen at 12 weeks in group A; homogeneous osteoid which distributed with cord or island, and many osteoblast-like cells were seen in groups B and C. The microvessel density was significantly higher in groups A and C than group B at 3 time points (P < 0.05), and in group A than in group C at 12 weeks (P < 0.05). The OPN and OPG mRNA expressions of group A were significantly lower than those of groups B and C at 3 time points (P < 0.05). In groups B and C, the OPN mRNA expressions reached peak at 8 and 12 weeks, respectively, and OPG mRNA expressions reached peak at 4 weeks.

BMSCs derived osteoblasts and endothelial cells (1:1) compound with CS/HA porous scaffold can promote bone formation and vascularization in bone defect and accelerate the healing of bone defect.