The role of the lateral pterygoid muscle in the sagittal fracture of mandibular condyle (SFMC) healing process.

The aim of this study was to examine the role of the lateral peterygoid muscle in the reconstruction of the shape of the condyle during healing of a sagittal fracture of the mandibular condyle. Twenty adult sheep were divided into 2 groups: all had a unilateral operation on the right side when the anterior and posterior attachments of the discs were cut, and an oblique vertical osteotomy was made from the lateral pole of the condyle to the medial side of the condylar neck. Ten sheep had the lateral pterygoid muscle cut, and the other 10 sheep did not. Sheep were killed at 4 weeks (n=2 from each group), 12 weeks (n=4), and 24 weeks (n=4) postoperatively. Computed tomograms (CT) were taken before and after operations. We dissected the joints, and recorded with the naked eye the shape, degree of erosion, and amount of calcification of the temporomandibular joint (TMJ). In the group in which the lateral peterygoid muscle had not been cut the joints showed overgrowth of new bone and more advanced ankylosis. Our results show that the lateral pterygoid muscle plays an important part in reconstructing the shape of the condyle during the healing of a sagittal fracture of the mandibular condyle, and combined with the dislocated and damaged disc is an important factor in the aetiology of traumatic ankylosis of the TMJ.

Prefabrication of axial vascularized tissue engineering coral bone by an arteriovenous loop: a better model.

The most important problem for the survival of thick 3-dimensional tissues is the lack of vascularization in the context of bone tissue engineering. In this study, a modified arteriovenous loop (AVL) was developed to prefabricate an axial vascularized tissue engineering coral bone in rabbit, with comparison of the arteriovenous bundle (AVB) model. An arteriovenous fistula between rabbit femoral artery and vein was anastomosed to form an AVL. It was placed in a circular side groove of the coral block. The complex was wrapped with an expanded-polytetrafluoroethylene membrane and implanted beneath inguinal skin. After 2, 4, 6 and 8 weeks, the degree of vascularization was evaluated by India ink perfusion, histological examination, vascular casts, and scanning electron microscopy images of vascular endangium. Newly formed fibrous tissues and vasculature extended over the surfaces and invaded the interspaces of entire coral block. The new blood vessels robustly sprouted from the AVL. Those invaginated cavities in the vascular endangium from scanning electron microscopy indicated vessel's sprouted pores. Above indexes in AVL model are all superior to that in AVB model, indicating that the modified AVL model could more effectively develop vascularization in larger tissue engineering bone.

Surgical treatment of a giant neurofibroma.

Neurofibromatosis type 1, an autosomal dominant inherited disease, presents pathologic symptoms of multiple systems, including neurofibromatosis, skeletal dysplasia, café-au-lait spots in skins, and so on. A 45-year-old man with neurofibromatosis type 1 was reported in this article. The patient presented a giant neurofibroma in his head and neck, dysplasia of skull, facial bones and spinal columns, and multiple café-au-lait spots in systematic skins. Satisfactory curative effects were obtained in this case after tumor resection and prosthesis implantation.

Enhanced treatment of articular cartilage defect of the knee by intra-articular injection of Bcl-xL-engineered mesenchymal stem cells in rabbit model.

Direct intra-articular injection of mesenchymal stem cells (MSCs) has been proposed as a potential cell therapy for cartilage defects. This cell therapy relies on the survival of the implanted MSCs. However, the arduous local environment may limit cell viability after implantation, which would restrict the cells' regenerative capacity. Thus, it is necessary to reinforce the implanted cells against the unfavourable microenvironment in order to improve the efficacy of cell therapy. We examined whether the transduction of an anti-apoptotic protein, Bcl-xL, into MSCs could prevent cell death and improve the implantation efficiency of MSCs in a rabbit model. Our current findings demonstrate that the group treated with Bcl-xL-engineered MSCs could improve cartilage healing both morphologically and histologically when compared with the controls. These results suggest that intra-articular injection of Bcl-xL-engineered MSCs is a potential non-invasive therapeutic method for effectively treating cartilage defects of the knee.

Modified approach to construct a vascularized coral bone in rabbit using an arteriovenous loop.

The most important factor for the survival of thick three-dimensional tissues is the degree of vascularization. In this study, a modified arteriovenous loop (AVL) model was developed to prefabricate an axial vascularized tissue-engineered coral bone. In group A (n = 28), an arteriovenous fistula between rabbit femoral artery and vein was anastomosed to form an AVL. The AVL was placed in a coral block (6 x 8 x 10 mm (3)) as a vascular carrier. The complex was wrapped with polytetrafluoroethylene membrane and implanted subcutaneously. In group B (n = 20), there was no vascular carrier, and the same dimensional coral was directly implanted beneath inguinal skin. After 2, 4, 6, and 8 weeks, the rabbits were perfused with heparinized saline (for scanning electron microscopy), India ink (for histological examination), and ethylene perchloride (for vascular casts) via the abdominal aorta. In group A, histology showed that newly formed vasculature extended over the surfaces and invaded the entire coral blocks. The vascular density was significantly superior to that in group B. Vascular casts showed that new blood vessels robustly sprouted from the AVL. Scanning electron microscopy demonstrated that there were minute sprouting cavities in the vascular endangium. In this model, an axial vascularized coral bone could be effectively constructed.

[Constructing tissue engineered trachea-like cartilage graft in vitro by using bone marrow stromal cells sheet and PLGA internal support: experimental study in bioreactor].

OBJECTIVE: To explore the feasibility of constructing tissue engineered trachea-like cartilage graft in vitro by using bone marrow stromal cells (BMSCs) sheet and PLGA internal support. METHODS: Rabbit BMSCs were expanded and induced by transforming growth factor-1 to improve chondrocyte phenotype of BMSCs. BMSCs sheets were obtained by continuous culture and wrapped the PGLA scaffold in the shape of cylinder. The constructs were incubated in spinner flask for 8 weeks and cartilage formation was investigated by gross inspection, histology, glycosaminoglycan and mechanical strength content. RESULTS: After in vitro culture, cartilage like tissue in cylindrical shape had been regenerated successfully. Stiff, shiny, pearly opalescence tissues were observed. Histological analysis showed engineered trachea cartilage consisted of evenly spaced lacunae embedded in matrix, cells stationed in the lacunae could be noticed clearly. Safranin-O staining on the sections showed homogenous and positive red staining, which demonstrated that the engineered tissue was rich in proteoglycans. CONCLUSIONS: Based on the cell sheet and internal support strategy, trachea-like cartilage in cylindrical shape could be successfully fabricated which provided a highly effective cartilage graft substitute and could be useful in many situations of trachea-cartilage loss encountered in clinical practice.

A novel strategy for prefabrication of large and axially vascularized tissue engineered bone by using an arteriovenous loop.

The repair of bone defects remains a major clinical challenge because none available reconstruction methods and biomaterials have been proved completely satisfactory. As a promising approach for bone regeneration, tissue engineered bone has become a technically feasible method to repair small to moderate sized bone defects in clinical practice, but it is difficult to repair large one, particularly when the recipient site is scarred by infection or radiation injury. Construction of large and vascularized tissue engineered bone may overcome the problems since vascularization is an essential prerequisite for the constructs to survive and integrate with existing host tissue. On the other hand, prefabrication large artificial bone in vivo bioreactor and axial vascularization by means of arteriovenous loop model in soft tissue have been proved to be feasible. Therefore, we hypothesize that combination of cells, solid scaffold, growth factors, and arteriovenous loop may eventually generate a large and vascularized tissue engineered bone flap in vivo bioreactor. Like vascularized autologous bone grafts, the new constructs could be transferred to the defect site by using microsurgical techniques. The strategy would facilitate clinical translation in bone tissue engineering and offer new therapeutic strategies for reconstruction of extended bone defects if the hypothesis proved to be practical.

[The preparation of series of the controllable degradation coral-hydroxyapatite (SCHA-200R) and the on its application as the scaffold in bone tissue-engineering].

OBJECTIVE: Fabricate series of the controllable degradation coral-hydroxyapatite. METHODS: The natural coral undergo a chemical reaction with (NH4)2 HPO4 at high temperature and pressure for different time-lengths. After getting the products, the components and the special structures were analyzed. Observe the biologic degradation of the reaction products and analyze the metal elements and their contents. Haemolysis tests, cytotoxity tests and bone compatibility tests were performed to assess the biocompatibility of the products. RESULTS: When hydrothermal reactions happened under different conditions, the different gradients of CaCO3/hydroxyapatite materials were produced. These types of materials kept the characteristic of interconnected micro-porous network structures. A thin layer of compact material can be seen on the surface of its trabecula ultra-micro structure. The SCHA-200R has a good biocompatibility. CONCLUSIONS: Gradient HA (SCHA-200R) materials can be formed by adjusting the same temperature, same pressure and different time-length of the reaction. This kind of gradient material keeps the quality of micro-porous network structures. The SCHA-200R is a potential candidate scaffold for bone tissue engineering.

Regulation of skeletal muscle differentiation in fibroblasts by exogenous MyoD gene in vitro and in vivo.

MyoD of the myogenic regulatory factors (MRFs) family regulates the skeletal muscle differentiation program. In this study, stably transfected NIH3T3-derived cell lines were established, in which exogenous MyoD was expressed at high levels. Transcriptional activation of endogenous muscle regulatory gene and induction towards the skeletal muscle lineages were observed with phase-contrast microscopy when continuously cultured in vitro. Moreover, to determine their ability of myogenic formation in vivo, the transfected cells were implanted in nude mice subcutaneously for up to 10 weeks. The morphological characterization of inductive cells was observed using transmission electron microscope and histological staining. Myogenesis of fibroblasts incubated in the medium was activated by overexpression of MyoD, and the cells were accumulated and fused into multinucleated myotubes. Correlatively, RT-PCR and immunohistochemistry confirmed the increased expression of characteristic downstream molecule myogenin and mysion heavy chains during myogenic differentiation. Ecoptic myogenesis was found and remained stable phenotype when the transfected cells were seeded in vivo. Our results suggest that MyoD can be considered to be a determining factor of myogenic lineages, and it may play an important role in the cell therapy and cell-mediated gene therapy of the skeletal muscle.

[Repair of peripheral nerve defect by a scroll of amnion derivative compound with cultured autogenous Schwann cell in a rat model].

OBJECTIVE: To test a nerve bridge substitute for peripheral nerve repair by tissue-engineering approach. METHODS: An artificial nerve fabricated with a scroll of amnion derivative (ZQ membrane) and cultured autogenous Schwann cell was sutured to bridge sciatic nerve defect of 2.5 cm in length in rats. The specimens were assessed with tracking study, histology, electrophysiological technique, NF200, and synaptophysin-38 (SYP) immuno histochemical staining 3 months postoperatively. RESULTS: The regenerated nerve sprouted 3 months after the operation. The regenerated nerve fibers were plentiful and could grow into the recipient nerve and target muscle's motor end plate (MEP) areas to reinnervate target muscle, and reconstruct function of nerve-muscle junction. Functional recovery could reach to 40%-60% of normal control. Nerve-muscle conduction velocity (N-MCV) arrived at 21.77 +/- 1.15 m/s. CONCLUSIONS: A tissue engineering material fabricated with a scroll of ZQ membrane and cultured autologous Schwann cell may be a useful substitute for nerve repair.

Reconstruction of caprine mandibular segmental defect by tissue engineered bone reinforced by titanium reticulum.

OBJECTIVE: To investigate the feasibility of using natural poritos as scaffolds in bone tissue engineering (TE) and repair of caprine mandibular segmental defect with titanium reticulum reinforced. METHODS: Natural poritos with a pore of 190-230 microm in size and porosity of about 50percent-65percent was molded into the shape of granules 5 mm x 5 mm x 5 mm in size. Expanded autologous caprine marrow mesenchymal stem cells were induced by recombinant human morphogenetic protein-2 (rhBMP2) to improve osteoblastic phenotype. Then marrow derived osteoblasts were seeded into poritos in density of 4 x 10(7)/ml and incubated in vitro for 48 hours prior to implantation. Then osteoblastic cells/poritos complexes were implanted into mandibular defect and the defect was reinforced by titanium reticulum. Implantation of poritos alone acted as the control. Bone regeneration was assessed 4, 8, 16 weeks after implantation using roentgenographic analysis and histological observation was done after 16 weeks. RESULTS: New bone could be observed histologically on the surface and in the pores of natural coral in all specimens in the cell-seeding group, whereas in the control group there was no evidence of osteogenesis process in the center of the construction. The results showed that new bone grafts were successfully restored 16 weeks after implantation. CONCLUSIONS: This study suggests the feasibility of using porous coral as scaffold material transplanted with marrow derived osteoblasts by TE method. By means of titanium reticulum reinforcement, mandibular defect could be successfully restored. It shows the potentiality of using this method for the reconstruction of bone defect in clinic.

[Surgical orthodontic technique for the treatment of maxillofacial deformities and dysfunction of occlusion after maxillofacial fractures].

OBJECTIVE: To evaluate a new technique to treat severe maxillofacial deformity and dysfunction of occlusion after the maxillofacial fractures. METHODS: Thirty-four consecutive patients, with delayed maxillofacial deformities and dysfunction of occlusion after the maxillofacial fractures, were treated by the use of x-ray cephalometric analysis, model surgery, open reduction and rigid internal fixation. RESULTS: Thirty-three patients were successfully corrected the maxillofacial deformities, facilitated normal occlusal relationship. Only one patient with severe damage of the brain was presented a mild occlusion dysfunction one year after the operation. CONCLUSIONS: The above-mentioned technique may be a viable and effective option for the management of the deformities of the face and dentition after the maxillofacial fractures.

[Bone formation by seeding bone marrow stromal cells on the sodium calcium phosphate/beta tricalcium phosphate scaffold].

PURPOSE: To observe the osteogenesis of sodium calcium phosphate/beta-tricalcium phosphate scaffold loaded with marrow stromal cells in a nude mice subcutaneous model. METHODS: To transform the sintered bovine cancellous bone into NaCaPO(4)/beta-TCP biphasic calcium phosphate ceramic by physical and chemical methods. Bone marrow stromal cells (BMSCs) were obtained by harvesting the cancellous bone from the iliac crest of a rabbit. Then the BMSCs were isolated, expanded and induced in vitro and seeded in the NaCaPO(4)/beta-TCP ceramic scaffolds. The scaffold/BMSCs composites were implanted subcutaneously into the backs of nude mice. Implantation of NaCaPO(4)/beta-TCP ceramic alone was acted as control. At 4 and 8 weeks after implantation, the specimens were harvested and the osteogenetic activity were evaluated by gross and histologic observation. RESULTS: At 4 weeks after implantation, the relatively mature bone were seen on the surface of the material, the inner part of the material were mainly cartilaginous bone. At 8 weeks after implantation, A large amount of trabecula bone had formed and the medullary cavity, medullary cells and lipocytes could be seen. Osteoblasts and osteoclasts were seen between the scaffolds and the local bone in the transition area. The endochondral bone formation pattern were observed. CONCLUSIONS: The NaCaPO(4)/beta-TCP scaffold/BMSCs composites showed good osteogenetic activity and could promote mineralization of the immature bone. It can be used as the bone tissue engineering scaffolds.

[The long-term effects of rhBMP-2 and rhbFGF on alkaline phosphatase of bone mesenchymal stem cells].

PURPOSE: To evaluate the long-term effects of rhBMP-2 and rhbFGF on alkaline phosphatase(ALP) of rabbit bone mesenchymal stem cells by using them alone, associatedly and sequentially. METHODS: Under cell culture technique, ALP kits were used to evaluate ALP level of bone mesenchymal stem cells so as to reflect differentiation of the cells on the 2nd, 5th, 7th, and 10th day by adding rhBMP-2 and rhbFGF on different ways. RESULTS: Statistical analysis showed that rhBMP-2 could enhance while rhbFGF could inhibit the ALP level of rabbit bone mesenchymal stem cells significantly in long term, and also in a dose-dependent manner. The effects of using rhBMP-2 alone was similar to that of using the two growth factors associatedly, and they were significantly higher than that of using rhbFGF alone and using them sequentially. CONCLUSION: Different growth factor has different long-term effect on differentiation of bone mesenchymal stem cells by adding them on different ways.

[Transforming the sintered ostrich cancellous bone to multiphasic calcium phosphate ceramic].

OBJECTIVE: To transform the sintered ostrich cancellous bone(ostrich true bone ceramic, OTBC) to multiphasic calcium phosphate ceramic and study its components and characterization. METHODS: The OTBC blocks were soaked in different concentration of sodium pyrophosphate (Na(4)P(2)O(7).H(2)O,NP) solution and heated to 1100 degrees C to transform its constitution from HAP into multiphasic calcium phosphate ceramics. Then the surface configuration of the material was observed by SEM and the following properties of the material:porosity,bending strength,mineral composition and element ratio were analyzed. RESULTS: The prepared material was a kind of porous calcium phosphate ceramic composed of beta-TCP, HAP and NaCaPO(4). With increase of the NP concentration,the content of HAP decreased while beta-TCP and NaCaPO(4) increased. The average bending strength of the material was (1.95+/-0.46)Mpa,the Ca/P element ratio was 1.511 and the average porosity was(60.71+/-6.9)%. The pore size was uneven. CONCLUSION: The OTBC could be transformed into beta-TCP /HAP /NaCaPO(4) multiphasic calcium phosphate ceramic by heating with NP. With characteristic porous structure, the prepared OTBC could become a new type of bone graft.

[A study of injectable autogenous tissue-engineered bone].

OBJECTIVE: To investigate the utilization of carrier for delivering osteoblasts and creating autogenous bone tissue in ectopic site of animal via injection. METHODS: Bone marrow cells harvested from iliac bone of New Zealand rabbits were induced to differentiate into marrow stromal osteoblasts. The osteoblasts were mixed with 1.5% alginate sodium solution to generate osteoblasts/alginate composites with final cellular density of 4 x 10(9)/L. Calcium chloride was used as cross-linking agent to gel aqueous alginate solution. The marrow stromal osteoblasts/alginate composites were injected into the dorsal subcutaneous tissue of rabbits with autogenous cells transplantation. The samples were examined with X-ray and histological analysis. RESULTS: Four, eight and twelve weeks after injection, the hard knobbles were easily palpated under the dorsal skin of animals. On X-ray photograph the samples showed calcified image with more density than surrounding soft tissue, new bone formation was observed in the osteoblasts/alginate composites in histological analysis. The osteogenesis was in association with regenerated hematopoietic bone marrow. CONCLUSIONS: These results demonstrate that new bone tissue could be created through the injection of alginate sodium treated with autogenous marrow stromal osteoblasts.