Hiroyuki Yoshitake

Establishment of tendon-derived cell lines exhibiting pluripotent mesenchymal stem cell-like property.

Development of the musculoskeletal system requires coordinated formation of distinct types of tissues, including bone, cartilage, muscle, and tendon. Compared to muscle, cartilage, and bone, cellular and molecular bases of tendon development have not been well understood due to the lack of tendon cell lines. The purpose of this study was to establish and characterize tendon cell lines. Three clonal tendon cell lines (TT-E4, TT-G11, and TT-D6) were established using transgenic mice harboring a temperature-sensitive mutant of SV40 large T antigen. Proliferation of these cells was significantly enhanced by treatment with bFGF and TGF-beta but not BMP2. Tendon phenotype-related genes such as those encoding scleraxis, Six1, EphA4, COMP, and type I collagen were expressed in these tendon cell clones. In addition to tendon phenotype-related genes, expression of osteopontin and Cbfal was observed. These clonal cell lines formed hard fibrous connective tissue when implanted onto chorioallantoic membrane in ovo. Furthermore, these cells also formed tendon-like tissues when they were implanted into defects made in patella tendon in mice. As these tendon cell lines also produced fibrocartilaginous tissues in tendon defect implantation experiments, mesenchymal stem cell properties were examined. Interestingly, these cells expressed genes related to osteogenic, chondrogenic, and adipogenic lineages at low levels when examined by RT-PCR. TT-G11 and TT-E4 cells differentiated into either osteoblasts or adipocytes, respectively, when they were cultured in cognate differentiation medium. These observations indicated that the established tendon cell line possesses mesenchymal stem cell-like properties, suggesting the existence of mesenchymal stem cell in tendon tissue.

Osteopontin Deficiency Reduces Experimental Tumor Cell Metastasis to Bone and Soft Tissues

Osteopontin has been implicated in the metastasis of tumors, and human tumors with high metastatic activity often express osteopontin at high levels. Osteopontin contains an arginine‐glycine‐aspartate (RGD) motif that is recognized by integrin family members to promote various cell activities including attachment to substrate and it is abundant in bone, to which certain tumors preferentially metastasize. Therefore, we investigated the role of osteopontin in the experimental metastasis of tumor cells using recently established osteopontin‐deficient mice. B16 melanoma cells, which produce little osteopontin, were injected into the left ventricle of osteopontin‐deficient mice or wild‐type mice. Animals were killed 2 weeks after injection. The number of tumors was reduced in the bones of osteopontin‐deficient mice compared with the bones in wild‐type mice. The number of tumors in the adrenal gland also was reduced. To investigate the osteopontin effect on metastases via a different route, we injected B16 melanoma cells into the femoral vein. Through this route, the number of lung tumors formed was higher than in the intracardiac route and was again less in osteopontin‐deficient mice compared with wild‐type mice. In conclusion, in an experimental metastasis assay, the number of tumors found in bone (after intracardiac injection) and lung (after left femoral vein injection) was significantly reduced in osteopontin‐deficient mice compared with wild‐type mice. Tumor numbers in other organs examined were small and not significantly different in the two situations.

Retardation in Bone Resorption after Bone Marrow Ablation in Klotho Mutant Mice

The klotho gene mutant mice exhibit both osteopetrotic phenotype, including elongation of trabeculae in the epiphyses of long bones and vertebral bodies, and osteopenic phenotype, such as thin cortical bones in the diaphyses of these bones. These diverse features raise the question of whether the klotho gene defect results in alteration in bone resorption in vivo. Therefore, we examined the effect of the klotho gene defect on bone resorption by using bone marrow ablation model. At 1 week after bone marrow ablation, trabecular bones were formed in the ablated marrow cavity to levels higher than those in unablated bones in both klotho mutant and wild-type mice. At 2 weeks postsurgery, newly formed trabecular bones were resorbed in wild-type mice to resume normal bone marrow and trabecular bone volume fraction as reported previously. In contrast, the newly formed trabecular bones in the ablated marrow in klotho mutant mice remained at levels similar to those at 1 week. The defect in the bone resorption phase...

Bone morphogenetic proteins are involved in the pathobiology of synovial chondromatosis.

Synovial chondromatosis is characterized by the formation of osteocartilaginous nodules (free bodies) under the surface of the synovial membrane in joints. Free bodies and synovium isolated from synovial chondromatosis patients expressed high levels of BMP-2 and BMP-4 mRNAs. BMP-2 stimulated the expression of Sox9, Col2a1, and Aggrecan mRNAs in free-body and synovial cells and that of Runx2, Col1a1, and Osteocalcin mRNAs in the synovial [corrected] cells only. BMP-2 increased the number of alcian blue-positive colonies in the free-body cell culture but not in the synovial cell culture. Noggin suppressed the expression of Sox9, Col2a1, Aggrecan, and Runx2 mRNAs in both the free-body and synovial cells. Further, it inhibited Osteocalcin expression in the synovial cells. These results suggest that BMPs are involved in the pathobiology of cartilaginous and osteogenic metaplasia observed in synovial chondromatosis.

Complications and Outcome of Free Flap Transfers for Oral and Maxillofacial Reconstruction: Analysis of 213 Cases

Abstract Microvascular free flap transfers have become a preferred reconstructive technique; however, rare complications may still prove devastating. This study reviewed 213 consecutive freetissue transfers in order to assess the incidence and causes of complications in patients undergoing microvascular free flap reconstruction in the oral and maxillofacial region. In most cases, reconstruction was undertaken after resection of a malignant tumor. The flap donor sites were the radial forearm (n=111), rectus abdominis (n=88), scapula (n=13), and latissimus dorsi (n=1). The superior thyroid artery and the external jugular vein were commonly used as recipient vessels for anastomosis. The overall flap success rate was 99%. There were 7 cases of postoperative vascular thrombosis (6 venous and 1 arterial), constituting 3.3% of the entire series. Five flaps were salvaged, representing a 71.4% successful salvage rate in cases of vascular complications. Most of the successful salvage attempts were made within 24 hours of the end of the initial operation, and the successful salvage rate for re-exploration was 100%. Finally, the total flap loss rate was 0.9% and the partial flap loss rate was 2.3%. We conclude that early re-exploration should be the first choice for management of vascular compromised flaps. Complications at the donor site occurred in 17 cases (8.0%), the most common complication of which was partial skin graft loss after harvesting a radial forearm flap (n=10; 9.0%). Recipient and donor site morbidity was limited and considered acceptable.

Synovial chondromatosis of the right side temporomandibular joint extending to the middle cranial fossa: A case report with 7-year postoperative follow up and expression of a biomarker of cell proliferative activity

Highlights • Neoplastic disease of the TMJ is a rare condition.• We report a case of Synovial chondromatosis of the right side temporomandibular joint extending to the middle cranial fossa.• We evaluated the cell proliferative activity by immunohistochemical analysis.• Then, we confirmed the growth activity of the lesion and it was thought to be a cause of the tumor expansion.• This is a case report with 7-year postoperative follow up without reoccurrence.

Expression of CD90 decreases with progression of synovial chondromatosis in the temporomandibular joint.

Objectives: The aim of the present study was to investigate the factors that contribute to the progression of synovial chondromatosis in the temporomandibular joint (TMJ). Methods: The authors investigated the expression of CD105 and CD90 in specimens from 17 patients with synovial chondromatosis in the TMJ, using immunohistochemical staining, and expression of CD105 and CD90 in cartilaginous nodules was scored semiquantitatively. Results: The expression of CD105 and CD90 was found in almost all the cases. In particular, the expression of CD90 in cartilaginous nodules significantly decreased with the progression of synovial chondromatosis. Discussion: The factors that determine progression of synovial chondromatosis are not fully understood. The results of this study suggest that CD90 may play an important role in the progression of synovial chondromatosis in the TMJ.

Pseudotumor in the temporomandibular joint: A case report.

Highlights • Neoplastic disease of the TMJ is a rare condition.• We report a case of pseudotumor of the TMJ.• This case was difficult to differentiate from synovial chondromatosis.

Instrument for lateral release in temporomandibular joint hypomobility

mandibular joint (TMJ) by Ohnishi,1 intervention by arthroscopic examination and surgery have become popular worldwide for treating TMJ disorders. The investigators of many studies have reported that arthroscopic sweep, lysis, and lavage improve joint function and relieve the pain caused by persistent closed lock of the TMJ.2 There are a few reports of lateral release and stretching of the capsule. Ohnishi1 was the first to report the use of arthroscopy to show adhesive tissue in the lateral region of the upper joint cavity. Murakami et al3 and Moses and Poker4 suggested the importance of the capsular stretch procedure or capsular release for joint mobility. Although previous reports suggested that lateral lysis and stretching of the lateral capsule

Use of a new instrument for lateral release in arthroscopic surgery of the temporomandibular joint: a preliminary study.

We developed a new instrument, which we call a lateral releaser, to improve the safety of either a blind lateral release or lateral stretching within the TMJ We used it during arthroscopic surgery in patients with chronic painful hypomobility of the temporomandibular joint (TMJ). We operated on 24 TMJs in 17 patients (15 women and 2 men). At operation, the mean increase in the interincisal distance was 22 mm (range 10-32). No instruments were broken. No serious surgical complications were reported during or after operation. Many of the patients currently have an interincisal distance exceeding 38 mm.