Bone tissue engineering with bone marrow-derived stromal cells integrated with concentrated growth factor in Rattus norvegicus calvaria defect model.

Concentrated growth factor (CGF) is an autologous leukocyte-rich and platelet-rich fibrin (L-PRF) biomaterial termed "second-generation platelet concentrate". CGF contains autologous osteoinductive platelet growth factors and an osteoconductive fibrin matrix. The purpose of this study was to assess the ability of CGF combined with bone marrow stromal cells (BMSCs) to heal critical-size rat calvaria defects in vivo and to modulate the proliferation and osteogenic differentiation of mesenchymal stem cells (MSCs) in vitro. In the in-vivo study, the CGF group regenerated bone better than the control group, and combined therapy with CGF and BMSCs almost completely repaired critical-size bone defects within 12 weeks after surgery. In the in-vitro study, the CGF extract, at concentrations between 1 and 10%, promoted proliferation, osteogenic maturation, and mineralization of hTERT-E6/E7 human MSCs in a dose-dependent manner but had an inhibitory effect at higher concentrations. In conclusion, a CGF extract promoted the proliferation, osteogenic maturation, and mineralization of mesenchymal stem cells in vitro, and combination therapy with CGF and BMSCs resulted in excellent healing of critical-size bone defects in vivo.

Nkx3.2-induced suppression of Runx2 is a crucial mediator of hypoxia-dependent maintenance of chondrocyte phenotypes.

Hypoxia is a key factor in the maintenance of chondrocyte identity. However, crucial chondrogenic transcription factors in the Sox families are not activated in this phenomenon, indicating that other pathways are involved. Nkx3.2 is a well-known chondrogenic transcription factor induced by Sonic hedgehog (Shh); it suppresses a key osteogenic transcriptional factor, Runt-related transcription factor 2 (Runx2), to maintain the chondrogenic phenotype in mesenchymal lineages. The purpose of this study was to examine the function of Nkx3.2 in hypoxia-dependent maintenance of chondrocyte identity. C3H10T1/2 pluripotent mesenchymal cells were cultured with rh-BMP2 (300 ng/ml) to induce chondrogenesis under normoxic (20% O(2)) or hypoxic (5% O(2)) conditions. Immunohistological detection of Nkx3.2 in a micromass cell culture system revealed that hypoxia promoted expression of the Nkx3.2 protein. Real-time RT-PCR analysis revealed that hypoxia promoted Nkx3.2 mRNA expression and suppressed Runx2 mRNA expression; however, Sox9 mRNA expression was not altered by oxygen conditions, as previously described. Over-expression of exogenous Nkx3.2 promoted glycosaminoglycan (GAG) production and inhibited Runx2 mRNA expression and, based on a dual luciferase assay, Runx2 promoter activity. Interestingly, downregulation of Nkx3.2 using RNAi abolished hypoxia-dependent GAG production and restored Runx2 mRNA expression and promoter activity. These results demonstrated that Nkx3.2-dependent suppression of Runx2 was a crucial factor in hypoxia-dependent maintenance of chondrocyte identity.

Radio-sensitization of the murine osteosarcoma cell line LM8 with parthenolide, a natural inhibitor of NF-κB.

Nuclear factor (NF)-κB has been shown to be associated with cancer resistance to radiotherapy (RT), and is constitutively active in the murine osteosarcoma cell line, LM8. Parthenolide has been reported to show antitumor activity through inhibition of the NF-κB pathway. In this study, we investigated the radio-sensitizing activity of parthenolide. We established Luc-LM8, a stable transfectant reporter construct of NF-κB transcriptional activity into LM8. Luc-LM8 maintained the malignancy observed with LM8. In vitro, Luc-LM8 cells were cultured with or without parthenolide treatment, irradiated, and subjected to cell viability and apoptosis assays. In vivo, to investigate whether parthenolide enhances radio-sensitivity of tumors, a tumor growth assay was conducted. Parthenolide enhanced the growth inhibitory effect of RT and induced the apoptosis of Luc-LM8 cells with RT in vitro. The in vivo tumor growth was significantly suppressed in the mice treated with parthenolide and RT. The present study suggests that parthenolide sensitizes Luc-LM8 cells to irradiation. Thus, parthenolide is a potential candidate for use as a potent radio-sensitizing drug for use in cancer RT.

A case of giant squamous cell carcinoma of the buttock possibly arose from syringocystadenoma and invaded to the rectum.

We report a rare case of giant squamous cell carcinoma of the buttock infiltrated to the rectum. The tumor may have arisen from syringocystadenoma papilliferum. Since there was no sign of metastasis, radical operation including rectal amputation was performed after successful neoadjuvant therapies. Afterwards, the patient has been alive free from disease for 15 months with no lymph node and distant organ metastasis.

Novel fully interconnected porous hydroxyapatite ceramic in surgical treatment of benign bone tumor.

BACKGROUND: Large bone defects remaining after curettage of benign bone tumors should be filled with a substitute to restore mechanical strength. In 2000, we developed a fully interconnected porous calcium hydroxyapatite ceramic (IPCHA, NEOBONE) and have utilized it as a bone substitute. IP-CHA has a finely organized, three-dimensional interconnecting pore structure. The large interconnecting channels (average diameter 40 microm) permit easy penetration of tissue into the deep pores, so IP-CHA can itself induce local bone repair processes. The purpose of this study was to evaluate the clinical outcomes with the use of IP-CHA as bone substitute after curettage of benign bone tumors. METHODS: We reviewed the results of 71 patients with benign bone tumors sequentially treated by curettage followed by implantation of IP-CHA between 2000 and 2006. There were 29 women and 42 men, with a mean age of 28 years. Assessment was based on radiography at each time point during the follow-up. Radiographic findings were classified into five stages: stage 0, no change; stage 1, slight bone formation; stage 2, moderate bone formation; stage 3, consolidation; stage 4, absorption. RESULTS: In 70 of 74 operated lesions, radiographs showed that implanted IP-CHA proceeded to stage 2 or more within an average of 8 months after the surgery. In addition, 17 lesions proceeded to stage 4 within 35 months after surgery, on average. However, there were 10 local recurrences, which is similar to the recurrence rate for such tumors treated with or without implantation of CHAs and reflects the biological nature of each tumor. CONCLUSIONS: In this study, we utilized IP-CHA as a bone substitute after curettage of benign bone tumors and demonstrated its usefulness in the clinical situation. IP-CHA comparatively exhibited excellent bone formation at an early stage although the problem of recurrence of the tumor remained. We conclude that IP-CHA is a useful bone substitute for the treatment of benign bone tumors.

Kaposiform hemangioendothelioma arising in the deltoid muscle without the Kasabach-Merritt phenomenon.

Kaposiform hemangioendothelioma (KHE) is a rare tumor that occurs nearly exclusively during infancy and childhood. It has features common to both capillary hemangioma and Kaposi sarcoma and for that reason many terms have been used for these tumors including "Kaposi-like infantile hemangioendothelioma" and "hemangioma with Kaposi sarcoma-like features." KHE typically presents as an ill-defined, red to purple, indurated plaque and is often complicated by the Kasabach-Merritt phenomenon (KMP), a condition of severe thrombocytopenia and consumptive coagulopathy. Knowledge of the radiological findings of this uncommon tumor might be helpful for diagnosis. We present the MRI features of a case of KHE with neither typical skin lesions nor the Kasabach-Merritt phenomenon.

A comparative assessment of synthetic ceramic bone substitutes with different composition and microstructure in rabbit femoral condyle model.

Various bone substitutes with improved biocompatibility have been developed. Because these products vary in composition and microstructure, it is difficult to understand each feature and make an appropriate selection. Three recently developed highly porous ceramic bone substitutes were evaluated, including two made of hydroxyapatite with different structures (Apaceram-AX: 85%-porosity with micropores, NEOBONE: 75%-porosity without micropores) and one composed of beta-tricalcium phosphate (OSferion: 75%-porosity with micropores) in a rabbit model. Apaceram-AX showed gradual degradation, while NEOBONE remaining intact. OSferion was almost completely degraded at 24 weeks. Numerous osteoclasts were detected in materials with micropores, whether Apaceram-AX or OSferion, but not in NEOBONE. These differences of biodegradability seemed to be related to the presence of micropores. The compressive strength of OSferion increased for several weeks and decreased at a level of cancellous bone. The strength of NEOBONE gradually increased and remained at the highest level among three. The strength of Apaceram-AX increased two to three times that of cancellous bone. Surprisingly, the strength of all materials declined during the initial 1 week, suggesting that great care should be taken in the early period after implantation. These findings may help surgeons to select an appropriate porous substitute based on understanding of their features.

Use of hydroxyapatite ceramics for treatment of nonunited osseous defect after open fracture of lower limbs.

INTRODUCTION: Osseous defects in nonunited open fracture of the lower limbs are difficult to treat. Autogenous bone grafting is a promising treatment options, but a finite amount of autogenous bone graft is available from each individual and donor site morbidity remains a problem. These limitations have prompted the development and use of synthetic biomaterials such as hydroxyapatite (HA) ceramics. However, little information is available regarding the challenging cases such as nonunited open fractures The purpose of the present study is to evaluate the outcomes associated with the treatment of osseous defects in nonunited open fracture using novel HA ceramics. METHODS: Twelve bones (4 femora and 8 tibias) in 11 patients (10 men and 1 woman), with an average age of 49.1 (range 19-71) years, with nonunited osseous defects after open fracture were treated by the grafting of HA ceramics alone or with autogenous iliac bone followed by internal or external fixation. RESULTS: The patients were followed for an average of 25.2 months in average (range 10.3 -58.1 months). Finally, 11 of 12 fractures united clinically and radiographically, while one fracture required a second procedure for additional autogenous iliac bone grafting. The average time to union from the index surgery was 5.6 months (median 5.3 months, range 2.3-11 months.). Radiographs showed good incorporation of grafted HA into the host bone in most of the united cases. As a complication, transient wound drainage was found in two cases. CONCLUSION: The current protocol using the HA ceramics appears to be safe and efficacious for the treatment of osseous defects after the open fractures.

Interconnected porous hydroxyapatite ceramics for bone tissue engineering.

Several porous calcium hydroxyapatite (HA) ceramics have been used clinically as bone substitutes, but most of them possessed few interpore connections, resulting in pathological fracture probably due to poor bone formation within the substitute. We recently developed a fully interconnected porous HA ceramic (IP-CHA) by adopting the 'foam-gel' technique. The IP-CHA had a three-dimensional structure with spherical pores of uniform size (average 150 microm, porosity 75%), which were interconnected by window-like holes (average diameter 40 microm), and also demonstrated adequate compression strength (10-12 MPa). In animal experiments, the IP-CHA showed superior osteoconduction, with the majority of pores filled with newly formed bone. The interconnected porous structure facilitates bone tissue engineering by allowing the introduction of mesenchymal cells, osteotropic agents such as bone morphogenetic protein or vasculature into the pores. Clinically, we have applied the IP-CHA to treat various bony defects in orthopaedic surgery, and radiographic examinations demonstrated that grafted IP-CHA gained radiopacity more quickly than the synthetic HA in clinical use previously. We review the accumulated data on bone tissue engineering using the novel scaffold and on clinical application in the orthopaedic field.

(18)F-FDG PET analysis of schwannoma: increase of SUVmax in the delayed scan is correlated with elevated VEGF/VPF expression in the tumors.

OBJECTIVE: In order to clarify the increased 2-deoxy-2-fluoro-(18)F-D: -glucopyranose ((18)F-FDG) accumulation in schwannoma by positron emission tomography (PET) analysis, immunohistochemical analysis for the factors involved in glucose transportation and vascular formation was performed. MATERIALS AND METHODS: Twenty-six patients with schwannoma (13 men and 13 women) with ages ranging from 27 to 75 years, who received whole body (18)F-FDG PET scan, were enrolled for the present study. The retention index (RI) was calculated by dividing the increase in the standardized uptake value (SUVmax) at the delayed scan by the SUVmax in the early scan. SUVmax and RI were compared with the histologic variables, including the expression of glucose transporters 1 and 3, hexokinase II, vascular endothelial growth factor/vascular permeability factor (VEGF/VPF), and microvascular density shown by CD31 immunohistochemistry. RESULTS: Mean SUVmax values in the early and delayed scans were 2.64 +/- 1.47 and 2.71 +/- 1.57 (mean +/- SD), respectively. RI was -2.5 +/- 21 (percentage). SUVmax showed a positive correlation with the tumor size (tumor size <5 cm, 2.06 +/- 0.72; >5 cm, 3.95 +/- 1.89; p < 0.05) and the microvascular density (negative density, 2.16 +/- 1.12; positive density, 3.56 +/- 1.67; p < 0.05). RI correlated with VEGF/VPF expression in the tumors (negative expression, -11 +/- 6.1; positive expression, 13 +/- 8.1; p < 0.05). Other factors showed no correlation with SUVmax or RI. CONCLUSIONS: Microvascular density and vascular permeability of the tumor are suggested to affect the enhanced (18)F-FDG accumulation in schwannoma.

Oxygen tension regulates chondrocyte differentiation and function during endochondral ossification.

Cartilage functions at a lower oxygen tension than most other tissues. To determine the role of oxygen tension in chondrocyte differentiation and function, we investigated the influence of oxygen tension in the pluripotent mesenchymal cell line C3H10T1/2 and 14.5E mice embryo forelimb organ culture. 10T1/2 cells and embryo forelimbs were cultured under normoxia (20% O2) or hypoxia (5% O2) in the presence of recombinant human bone morphogenetic protein 2. To elucidate the mechanism by which oxygen tension influences chondrocyte differentiation, the Smad pathway was examined using Smad6 overexpression adenovirus and Smad6 transgenic mice embryo forelimbs. The p38 MAPK pathway was examined using dominant-negative MKK3 and FR167653, a specific p38 MAPK inhibitor. The transcriptional activities of Sox9 and Runx2 were also investigated. Hypoxia promoted bone morphogenetic protein 2-induced glycosaminoglycan production and suppressed alkaline phosphatase activity and mineralization of C3H10T1/2. Thus, hypoxia promoted chondrocytic commitment rather than osteoblastic differentiation. In the mice embryo forelimb organ culture, hypoxia increased cartilaginous matrix synthesis. These effects were primarily mediated by p38 MAPK activation, independent of Sox9. Hypoxia inhibited Col10a1 (type X collagen alpha1) expression via down-regulation of Runx2 activity by Smad suppression and histone deacetylase 4 activation. In conclusion, hypoxia promotes chondrocytic differentiation and cartilage matrix synthesis and suppresses terminal chondrocyte differentiation. These hypoxia-induced phenomena may act on chondrocytes to enhance and preserve their phenotype and function during chondrocyte differentiation and endochondral ossification.

False positive 18F-FDG PET in an ischial chondroblastoma; an analysis of glucose transporter 1 and hexokinase II expression.

We report a rare case of chondroblastoma arising from the ischium which showed an increased (18)F-FDG uptake. Chondroblastoma is an uncommon lesion and usually involves the epiphysis of long bones. However, in this case, the tumor appeared as a well-defined osteolytic lesion in the ischium on radiographs. MR imaging demonstrated two components in the tumor: a solid one and a multilobular cystic component. (18)F-FDG PET imaging revealed an increased uptake in the ischium. The (18)F-FDG uptake resembled the results observed in malignant bone tumors. A histological diagnosis of chondroblastoma was obtained from tissue of an open biopsy. An immunohistochemical analysis demonstrated weak expression of both Glut-1 and HK-II. These findings suggest that Glut-1 and HK-II expression are not strongly related to FDG uptake in chondroblastoma.

Leptin regulates chondrocyte differentiation and matrix maturation during endochondral ossification.

Leptin has been suggested to mediate a variety of actions, including bone development, via its ubiquitously expressed receptor (Ob-Rb). In this study, we investigated the role of leptin in endochondral ossification at the growth plate. The growth plates of wild-type and ob/ob mice were analyzed. Effects of leptin on chondrocyte gene expression, cell cycle, apoptosis and matrix mineralization were assessed using primary chondrocyte culture and the ATDC5 cell differentiation culture system. Immunohistochemistry and in situ hybridization showed that leptin was localized in prehypertrophic chondrocytes in normal mice and that Ob-Rb was localized in hypertrophic chondrocytes in normal and ob/ob mice. Growth plates of ob/ob mice were more fragile than those of wild-type mice in a mechanical test and were broken easily at the chondro-osseous junction. The growth plates of ob/ob mice showed disturbed columnar structure, decreased type X collagen expression, less organized collagen fibril arrangement, increased apoptosis and premature mineralization. Leptin administration in ob/ob mice led to an increase in femoral and humeral lengths and decrease in the proportional length of the calcified hypertrophic zone to the whole hypertrophic zone. In primary chondrocyte culture, the matrix mineralization in ob/ob chondrocytes was stronger than that of wild-type mice; this mineralization in both types of mice was abolished by the addition of exogenous leptin (10 ng/ml). During ATDC5 cell differentiation culture, exogenous leptin at a concentration of 1-10 ng/ml (equivalent to the normal serum concentration of leptin) altered type X collagen mRNA expression and suppressed apoptosis, cell growth and matrix calcification. In conclusion, we demonstrated that leptin modulates several events associated with terminal differentiation of chondrocytes. Our finding that the growth plates of ob/ob mice were fragile implies a disturbance in the differentiation/maturation process of growth plates due to depletion of leptin signaling in ob/ob mice. These findings suggest that peripheral leptin signaling plays an essential role in endochondral ossification at the growth plate.

A new biotechnology for articular cartilage repair: subchondral implantation of a composite of interconnected porous hydroxyapatite, synthetic polymer (PLA-PEG), and bone morphogenetic protein-2 (rhBMP-2).

OBJECTIVE: Articular cartilage repair remains a major obstacle in tissue engineering. We recently developed a novel tool for articular cartilage repair, consisting of a triple composite of an interconnected porous hydroxyapatite (IP-CHA), recombinant human bone morphogenetic protein-2 (rhBMP-2), and a synthetic biodegradable polymer [poly-d,l-lactic acid/polyethylene glycol (PLA-PEG)] as a carrier for rhBMP-2. In the present study, we evaluated the capacity of the triple composite to induce the regeneration of articular cartilage. METHODS: Full-thickness cartilage defects were created in the trochlear groove of 52 New Zealand White rabbits. Sixteen defects were filled with the bone morphogenetic protein (BMP)/PLA-PEG/IP-CHA composite (group I), 12 with PLA-PEG/IP-CHA (group II), 12 with IP-CHA alone (group III), and 12 were left empty (group IV). The animals were killed 1, 3, and 6 weeks after surgery, and the gross appearance of the defect sites was assessed. The harvested tissues were examined radiographically and histologically. RESULTS: One week after implantation with the BMP/PLA-PEG/IP-CHA composite (group I), vigorous repair had occurred in the subchondral defect. It contained an agglomeration of mesenchymal cells which had migrated from the surrounding bone marrow either directly, or indirectly via the interconnecting pores of the IP-CHA scaffold. At 6 weeks, these defects were completely repaired. The regenerated cartilage manifested a hyaline-like appearance, with a mature matrix and a columnar organization of chondrocytes. CONCLUSIONS: The triple composite of rhBMP-2, PLA-PEG, and IP-CHA promotes the repair of full-thickness articular cartilage defects within as short a period as 3 weeks in the rabbit model. Hence, this novel cell-free implant biotechnology could mark a new development in the field of articular cartilage repair.

FDG-PET imaging for chronic expanding hematoma in pelvis with massive bone destruction.

Chronic expanding hematoma is a rare presentation of a hematoma characterized by a persistent increase in size for more than a month after the initial hemorrhage. We present a 65-year-old man with a chronic expanding hematoma in his ilium who was receiving anticoagulant treatment. The patient had a delayed manifestation of a femoral neuropathy with massive bone destruction. 2-Deoxy-[18F]fluoro-D: -glucose (FDG) positron emission tomography (PET) imaging revealed an increased uptake in the rim of the mass in images acquired 1 h after FDG injection. FDG-PET scans were performed using a dedicated PET scanner (HeadtomeV/SET2400 W, Shimadzu, Kyoto, Japan), and the PET data for the most metabolically active region of interest (ROI) were analyzed. The maximum standardized uptake value (SUVmax) was set to a cut-off point of 3.0 to distinguish between benign and malignant lesions. The SUVmax of the patient's lesion was 3.10, suggesting a malignant lesion. The characteristics of FDG-PET images of chronic expanding hematomas, including the uptake of FDG in the peripheral rim of the mass as a result of inflammation, should be recognized as a potential interpretive pitfall in mimicking a sarcoma.

Macro-structural effect of metal surfaces treated using computer-assisted yttrium-aluminum-garnet laser scanning on bone-implant fixation.

Porous coatings have been applied to the surface of prosthetic devices to foster stable device fixation. The coating serves as a source of mechanical interlocking and may stimulate healthy bone growth through osseointegrated load transfer in cementless arthroplasty. Joint arthroplasty by porous-coated prostheses is one of the most common surgical treatments, and has provided painless and successful joint mobility. However, long-term success is often impaired by the loss of fixation between the prosthesis and bone. Porous-coated prostheses are associated with several disadvantages, including metal debris from porous coatings (third body wear particles) and irregular micro-texture of metal surfaces. Consequently, quantitative histological analysis has been very difficult. These issues arise because the porous coating treatment is based on addition of material and is not precisely controllable. We recently developed a precisely controllable porous texture technique based on material removal by yttrium-aluminum-garnet laser. Free shapes can be applied to complex, three-dimensional hard metal surfaces using this technique. In this study, tartan check shapes made by crossing grooves and dot shapes made by forming holes were produced on titanium (Ti6A14V) or cobalt chrome (CoCr) and evaluated with computer-assisted histological analysis and measurement of bone-metal interface shear strength. Width of grooves or holes ranged from 100 to 800 mum (100, 200, 500, and 800 microm), with a depth of 500 microm. When the cylindrical porous-texture-treated metal samples (diameter, 5 mm; height, 15 mm) were implanted into a rabbit femoral condyle, bone tissue with bone trabeculae formed in the grooves and holes after 2 or 4 weeks, especially in 500-microm-wide grooves. Abundant osteoconduction was consistently observed throughout 500-microm-wide grooves in both Ti6A14V and CoCr. Speed of osteoconduction was faster in Ti6A14V than in CoCr, especially in the tartan check shape made of 500-microm-wide grooves. In pushout testing, the tartan check shape made of 500-microm-wide grooves had significantly higher bone-metal interface shear strength than the dot shape or commercial porous coating. These results indicate that the tartan check shape made of 500-microm-wide grooves on metal surfaces has potential for clinical application in artificial prosthesis design.

Potentiation of the activity of bone morphogenetic protein-2 in bone regeneration by a PLA-PEG/hydroxyapatite composite.

Bone morphogenetic proteins (BMPs) are biologically active molecules capable of inducing new bone formation, and show potential for clinical use in bone defect repair. However, an ideal system for delivering BMPs that can potentiate their bone-inducing ability and provide initial mechanical strength and scaffold for bone ingrowth has not yet been developed. In this study, to construct a carrier/scaffold system for BMPs, we combined two biomaterials: interconnected-porous calcium hydroxyapatite ceramics (IP-CHA), and the synthetic biodegradable polymer poly D,L,-lactic acid-polyethyleneglycol block co-polymer (PLA-PEG). We used a rabbit radii model to evaluate the bone-regenerating efficacy of rhBMP-2/PLA-PEG/IP-CHA composite. At 8 weeks after implantation, all bone defects in groups treated with 5 or 20 microg of BMP were completely repaired with sufficient strength. Furthermore, using this carrier scaffold system, we reduced the amount of BMP necessary for such results to about a tenth of the amount needed in previous studies, probably due to the superior osteoconduction ability of IP-CHA and the optimal drug delivery system provided by PLA-PEG, inducing new bone formation in the interconnected pores. The present findings indicate that the synthetic biodegradable polymer/IP-CHA composite is an excellent combination carrier/scaffold delivery system for rhBMP-2, and that it strongly promotes the clinical effects of rhBMP-2 in bone tissue regeneration.

The effect of simulated microgravity by three-dimensional clinostat on bone tissue engineering.

Evidence suggests that mechanical stress, including gravity, is associated with osteoblast differentiation and function. To examine effects of microgravity on bone tissue engineering, we used a three-dimensional (3D) clinostat manufactured by Mitsubishi Heavy Industries (Kobe, Japan). A 3D clinostat is a device that generates multidirectional G force. By controlled rotation on two axes, it cancels the cumulative gravity vector at the center of the device. We cultured rat marrow mesenchymal cells (MMCs) in the pores of interconnected porous calcium hydroxyapatite (IP-CHA) for 2 weeks in the presence of dexamethasone using the 3D clinostat (clinostat group). MMCs cultured using the 3D clinostat exhibited a 40% decrease in alkaline phosphatase activity (a marker of osteoblastic differentiation), compared with control static cultures (control group). SEM analysis revealed that although there was no difference between the two groups in number or distribution of cells in the pores, the clinostat group exhibited less extensive extracellular matrix formation than the control group. Cultured IP-CHA/MMC composites were then implanted into subcutaneous sites of syngeneic rats and harvested 8 weeks after implantation. All implants showed bone formation inside the pores, as indicated by decalcified histological sections and microfocus computed tomography. However, the volume of newly formed bone was significantly lower for the clinostat group than for the control group, especially in the superficial pores close to the implant surface. These results indicate that new bone formation in culture was inhibited by use of the 3D clinostat, and that this inhibition was mainly due to suppression of osteoblastic differentiation of MMCs.

Peripheral nerve schwannoma: two cases exhibiting increased FDG uptake in early and delayed PET imaging.

We present two cases of peripheral nerve schwannoma which showed an increased accumulation of 2-deoxy-[(18)F] fluoro-D-glucose (FDG) in the tumors on positron emission tomography (PET) imaging acquired at both 1 h (early phase) and 2 h (delayed phase) after FDG injection. FDG-PET scans were performed with a dedicated PET scanner (HeadtomeV/ SET2400 W, Shimadzu, Kyoto, Japan) and the PET data analyzed the most metabolically active region of interest (ROI). We set the maximum standardized uptake value (SUV max) with a cut-off point of 3.0 to distinguish benign and malignant lesions. Although the mechanism responsible for the increased FDG uptake in benign schwannomas remains unknown, we discuss our findings in the context of tumor cellularity and briefly review other studies on the subject.