ABSTRACT
BACKGROUND:Al ogeneic bone has anatomical appearance and biological features similar to autogenous bone, which is an excel ent biological scaffold material. Mesenchymal stem cel s originating from autogenous bone marrow have mutli-lineage differentiation potential, can differentiate into osteoblasts and chondrocyte, and thus can accelerate the formation of bone tissue and cartilage tissue. OBJECTIVE:To establish the osteogenic ability of al ogeneic bone with autogenous bone marrow mesenchymal stem cel s for repairing major mandibular defects. METHODS:The left mandibular teeth of 24 beagles were extracted, and at 2 months after wound healing, mandibular defects were made artificial y. The beagles were divided into two groups:control group treated with lyophilized al ogeneic bone, and experimental group with autogenous bone marrow mesenchymal stem cel s and lyophilized al ogeneic bone. Densitometry with CT and Micro-CT was conducted 4, 12, and 24 weeks after surgery. RESULTS AND CONCLUSION:Compared with the control group, the bone density of the mandible was significantly higher in the experimental group at 12 weeks after transplantation (P<0.05). Over time, the bone densities in the two groups were both increased, but the bone density in the experimental group was always higher than that in the control group. Bone structure parameters were progressively increased or decreased in the two groups, especial y in the experimental group. At 24 weeks after surgery, the degree of trabecular separation in regions of interest was higher in the experimental group than the control group (P<0.05), but the bone volume fraction, number of trabecular bone, and bone trabecular thickness were significantly lower in the experimental group than the control group (P<0.05). These findings indicate that bone marrow mesenchymal stem cel s are capable of accelerating the reconstruction of al ogeneic bones.
ABSTRACT
BACKGROUND:The favorable structure and biological characteristics of al ogeneic temporomandibular joint become an effective solution for condylar defect, but immunologic rejection and slow ossification are the main problem for the presence of bone al ograft. OBJECTIVE:To meet the requirements of rebuilding mandible defect by lyophilizing canine mandible. METHODS:The periosteum, soft tissue, and cartilage of 12 canine mandibles were removed. 1 mm diameter hole was dril ed with 1 to 2 cm intervals in their cortical bones with a fissure bur. After washing, they were placed into a-4 ℃ refrigerator for 12 hours, and then stored at-80℃gradual y for 1 week. The mandibles were put in a drier. When the moisture content of osseous tissue decreased to 5%, the bones were packed in aseptic environment, radio pasteurized, and stored in vacuum container at atmosphere temperature. A biomechanical test was conducted after the lyophilization. RESULTS AND CONCLUSION:The maximum shifts of lyophilized mandibles in compression and bending tests were slight according to the steep load-shift curve. The plastic zone was insignificant and fractures appeared immediately when the pressure exceeded the plastic zone. The maximum load, maximum shift, and rigidity in the compression test were (5 163.10±730.16) N, (0.78±0.19) mm and (11 069.17±1 758.12) N/mm, respectively. The data in bending test were (486.67±134.12) N, (0.67±0.15) mm and (1 151.67±256.46) N/mm, respectively. It is concluded that the dehydrated and lyophilized canine mandibles have good shape and support ability and can meet the mechanical requirements in repairing and reconstructing mandibular defect.
ABSTRACT
<p><b>OBJECTIVE</b>To investigate the effect of segmental defects reconstruction of canine mandible with allogenenic bone marrow mesenchymal stem cells (BMSC) combined with lyophilized bone.</p><p><b>METHODS</b>A 30 mm segmental defect was created on the left mandibles of beagles. Beagles were randomly divided into three groups. Allogeneic bone marrow mesenchymal stem cells with lyophilized bone were used for segmental defects reconstruction in group A. Autologous bone marrow mesenchymal stem cells with freeze- dried bone were used for segmental defects reconstruction in group B. The defects of group C were repaired with lyophilized bone only. Every three beagles were sacrificed 4, 12, 24, and 48 weeks after surgery respectively. The reconstruction effect was evaluated by CT and histopathological examination.</p><p><b>RESULTS</b>CT examination showed that new bones formed in group A and group B 12 weeks after surgery, but not in group C. The form of the reconstructed mandibles in the three groups recovered in 48 weeks. The small pores on the bone graft were filled with new bones in group A and group B. In group C, the pores were still evident. Histopathological examination showed that bone trabecula between allogeneic bone and autogenous bone was completely joined in group A and group B. A large number of fibrous tissue appeared around the implanted bone and new bones were formed. In group C, the lyophilized bone resorption was still not obvious, the new bone formation was significantly slower than the other two groups. There was no difference between group A and group B.</p><p><b>CONCLUSIONS</b>Both allogeneic bone marrow mesenchymal stem cells and autologous mesenchymal stem cells could accelerate the bone formation.</p>