Toshimasa Kagawa

Osteogenic potential of primed periosteum graft in the rat calvarial model.

Repair of bone defects remains a major concern in plastic and maxillofacial surgery. Based on modern concepts of tissue engineering, periosteum has gained attention as a suitable osteogenic material. We tested the hypothesis that surgically released and immediately repositioned periosteum would exhibit high osteogenic capacity upon grafting in a rat calvarial defect. Seven days after periosteum was released from the tibia and immediately repositioned, the “primed periosteum graft” (PPG; n = 15) was placed into a critical-sized defect of rat calvaria and the process of bone formation was evaluated histologically, immunohistologically, and radiographically at 7, 14, and 21 days after grafting. Findings were compared with a nonprimed periosteal graft (NPG; n = 15). Endochondral ossification was observed in both the PPG and NPG. The PPG showed higher expression of proliferative cell nuclear antigen, bone morphogenetic protein, and vascular endothelial growth factor than the NPG. Three-dimensional radiographic examination revealed significantly increased bone formation in the PPG than in the NPG (P < 0.01). These findings suggested that surgical stimulation of the periosteum enhanced the osteogenic potential of periosteal cells. This method may be suitable for the clinical repair of bone defects.

Regeneration of the mandibular head from grafted periosteum.

Grafted periosteum has a rich potential to induce heterotopic bone formation. In the current study the authors investigate whether autogenous periosteal grafts can regenerate the mandibular head in a rabbit model. They removed the mandibular head of Japanese white rabbits and grafted tibial periosteum to the cut surface of the mandible. Grafted periosteum was observed histologically and radiographically at day 7, 14, 21, and 45 after surgery. At day 7 after grafting, grafted tissue showed remarkable cell proliferation. By 14 days these cells had differentiated into chondrocytes to form cartilage, and endochondral ossification took place after 21 days. At 45 days after surgery, soft X-ray findings showed a newly formed mandibular head, which was similar histologically to that of a normal mandibular head. The cut mandible without periosteal graft showed no regeneration. These findings indicate that grafted periosteum can regenerate the mandibular head without special procedures such as bone fixation in a rabbit model, and suggest that this technique may be useful clinically.

Evaluation of osteogenic/chondrogenic cellular proliferation and differentiation in the xenogeneic periosteal graft.

To determine whether grafted young periosteum can induce new bone formation in elderly patients, this preliminary study evaluated cell proliferation and differentiation in xenogeneic periosteal grafts in old rats radiographically, histologically, and immunohistochemically. Periosteum harvested from the tibia of young Japanese white rabbits were grafted into old Sprague–Dawley rats with or without administration of 1.0 mg per kilogram per day immunosuppressant FK506. Autogenous old periosteal tissue grafts were also evaluated as a control. Grafted tissue was extirpated after 7, 14, 21, and 45 days. In the xenogeneic group, proliferative cell nuclear antigen-positive cells were observed 7 days after surgery, which differentiated into chondroblasts with bone morphogenetic protein-2 expression and finally formed cartilage by 14 days. Endochondral ossification was observed at 21 days, and bone replacement was completed by 45 days. No osteogenic cell activity was observed in the two other groups. Xenogeneic young periosteum thus maintained its osteogenic/chondrogenic potentiality in older rats.

Immunolocalization of vascular endothelial growth factor during heterotopic bone formation induced from grafted periosteum

Vessel invasion is an important step in cartilage replacement that leads to bone formation, and vascular endothelial growth factor (VEGF) has been implicated as a key player in this process. Although grafted periosteum undergoes endochondral ossification, little is known about the role of VEGF in this process. In the current study the authors investigated by immunohistochemical, histochemical, and ultrastructural techniques the localization of VEGF during bone formation in periosteal grafts. At day 14 after grafting the tibias of Japanese white rabbits, periosteal cells in the grafted tissue had differentiated into chondrocytes to form cartilage. Some chondrocytes were immunopositive for VEGF expression, and subsequent vessel invasion occurred predominantly in these VEGF-positive areas. At day 45, the cartilage invaded by blood vessels had been replaced by newly formed bone. These findings suggest that VEGF is associated with the process of blood vessel invasion into cartilage before bone replacement in endochondral ossification from grafted periosteum.

The Evaluation of Bone Formation of the Whole-Tissue Periosteum Transplantation in Combination With β-Tricalcium Phosphate (TCP)

We investigated the osteogenic potential of a combination graft of β-tricalcium phosphate (TCP) and periosteum in the rat calvarial defect model. The combination β-TCP and periosteum graft was grafted into rat calvarial defects; the newly formed bone in the defect was studied histologically and radiographically and compared with periosteum grafts and TCP grafts. Ten days after combination grafting, the grafted periosteum showed cell proliferation and Runx2 immunoreaction; 20 days after grafting, new bone formation was seen around the β-TCP; and 30 days after grafting, new bone developed and actively replaced β-TCP, while radiography showed calcified areas. Total bone formation of the combination periosteum and β-TCP graft was significantly increased compared with single grafts of β-TCP or periosteum (P < 0.01). The combination graft of periosteum and β-TCP showed marked bone formation in rat calvarial defects. This result suggests that combination grafts may be effective for repairing bone defects.

Pathology of the temporomandibular joint of patients with rheumatoid arthritis–case reports of secondary amyloidosis and macrophage populations

INTRODUCTION The pathogenetic features of rheumatoid arthritis of the temporomandibular joint (TMJ) are not well defined. In this paper the histological features of TMJs affected by rheumatoid arthritis, and the detection of secondary amyloidosis and macrophage populations in the TMJs of two patients with progressive rheumatoid arthritis are described. METHODS In two patients (64-year-old man and 61-year-old woman) with rheumatoid arthritis total TMJ replacement were performed. The surgical specimens were studied histologically. RESULTS It was found that the articular cartilage had been completely replaced by proliferating fibrous tissue. Congo red staining and polarizing microscopy revealed amyloid deposition in the connective tissue of the joint space. Immunohistochemical staining showed CD 68 positive macrophages around the amyloid deposition in the proliferating soft tissue. CONCLUSION TMJ involvement in rheumatoid arthritis followed the same destructive pathway as in other joints. Amyloid deposition and macrophage populations were detected in two TMJs affected by rheumatoid arthritis.

Expression of Transcription Factor Sox9 in Cartilage Formation from Grafted Periosteal Cells

Abstract Objective : To investigate the expression of Sox9 protein in the process of cartilage formation after periosteal grafting using the rat periosteum graft model. Materials and Methods : Periostea taken from twenty 7-week-old rats were immediately grafted into the suprahyoid muscles. Grafted tissues were harvested 0, 7, 14, and 21 days after grafting and examined by microscopy and immunohistochemistry using CD44, type 2 collagen, and Sox9 antibodies as markers. Results : Periosteal cells expressed CD44 after 7 days and Sox9 after 14 days. The Sox9-positive cells showed chondrogenic differentiation with type 2 collagen expression by 21 days after grafting. Endochondral ossification was also seen 21 days after grafting. Sox9 was not detected in hypertrophic chondrocytes. Conclusion : These findings suggested that Sox9 may be related to chondrogenic differentiation of periosteal cells in grafted periosteum.

Osteoblastoma of the Mandible: Report of a Case with Immunohistochemical Analysis

Abstract An osteoblastoma of the mandible in a 19-year-old woman is reported. By means of immunohistochemical analysis, the expression of bone morphogenetic proteins, osteopontin, and osteocalcin are described and illustrated.