Novel approach to engineer implantable nasal alar cartilage employing marrow precursor cell sheet and biodegradable scaffold.

PURPOSE: Repair of nasal and auricular malformation remains an obstacle for clinicians because of poor regenerative capacity of cartilage and limitation of donor sites. In the current study, we developed a novel approach to regenerate implantable nasal alar cartilage by using marrow precursor cell (MPC) sheet and biodegradable scaffold of polylactic acid-polyglycolic acid copolymer (PLGA). MATERIALS AND METHODS: Rabbit MPCs were expanded and induced by transforming growth factor-beta to improve chondrocyte phenotype. MPC sheets were obtained by continuous culture and used to wrap PLGA scaffold in the shape of the human nasal alar. The constructs were incubated in a spinner flask for 4 weeks, and cartilage formation was investigated by gross inspection and histological examination. The constructs were then implanted subcutaneously into a nude mouse. Specimens were harvested and analyzed 4 weeks after implantation. RESULTS: The results showed that cartilaginous tissue formed and PLGA absorbed during in vitro incubation. Histological analysis showed engineered cartilage consisted of evenly spaced lacunae embedded in a matrix rich in proteoglycans, and kept the initial shape of the nasal alar. Based on this "MPC sheet combining polymer strategy," implantable nasal alar could be successfully regenerated. CONCLUSION: This strategy has the advantage of high cell transplantation efficiency and great potential for clinical application.

Engineering of human tracheal tissue with collagen-enforced poly-lactic-glycolic acid non-woven mesh: a preliminary study in nude mice.

The purpose of the current study is to fabricate tissue engineered trachea with poly-lactic-glycolic acid (PLGA) non-woven mesh enforced by collagen type I. PLGA fibres coated with collagen solution were put together and fabricated into the shape of a human trachea, after drying and cross-linking treatment, a non-woven mesh with "C" shape formed. Chondrocytes from sheep nasal septum cartilage were expanded in vitro and seeded into PLGA/collagen non-woven mesh in the density of 5.0 x 10(7)mL(-1). After 5 days of in vitro incubation, six Cell-PLGA/collagen composites were implanted subcutaneously into the back of 6 nude mice to prefabricate a tissue engineering trachea. Eight weeks later, the cartilage formation was observed by gross inspection and histological examination. Cartilage-like tissue in the shape of the initial PLGA/collagen scaffold had been regenerated successfully without obvious inflammatory response. The tissue engineered trachea cartilage consisted of evenly spaced lacunae embedded in matrix stained red with safranin-O staining. The amount of GAGs in tissue engineered trachea cartilage reached 71.42% of normal value in native cartilage. This study demonstrated that collagen-enforced PLGA non-woven mesh facilitated the adhesion and proliferation of chondrocytes, it also owned adequate mechanical strength to serve as an ideal scaffold for trachea tissue engineering without internal support.

Bone marrow-derived osteoblasts seeded into porous beta-tricalcium phosphate to repair segmental defect in canine's mandibula.

BACKGROUND: Bone regeneration is often needed for many aesthetic and reconstructive procedures. Tissue engineering provided a promising approach to supplement existing treatment strategies. In this study, we aimed to evaluate the effect of reconstructing mandibular defect by using bioceramics seeded with bone marrow derived osteoblasts. METHODS: Canine's autologous marrow stromal cells were Culture-expanded and induced to osteoblastic phenotype, then were seeded into prepared porous beta-tricalcium phosphate, after being incubated in vitro. The cell/ scaffold complexes were implanted into the prepared defect in canines' mandibula and fixed by internal rigid fixation. In control groups, beta-tricalcium phosphate alone and autologous iliums were implanted into the prepared defects. Twelve weeks after implantation, the specimens were examined macroscopically and histologically. RESULTS: In experimental group and autologous iliums group, new bone grafts were successfully developed at 12 weeks after implantation and repaired the continuity of the mandibula. Histologically, newly formed bone could be observed on the surface and in the pores of beta-tricalcium phosphate in the cell/scaffold group, whereas incomplete bone repair was found in pure beta-tricalcium phosphate group. CONCLUSION: The harvested bone marrow derived osteoblasts possess the ability to form new bone tissue when seeded onto porous beta-tricalcium phosphate, which shows the potential of using this method to repair large segmental mandibular defect clinically.

Fundamental study of application of umbilical cord mesenchymal stem cells to the periodontium to aid healing after autotransplantation of teeth.

After autotransplantation of teeth the healing of periodontal tissue regulates the patient's prognosis. Umbilical cord mesenchymal stem cells (UCMSC) have shown excellent pluripotent and proliferation potential. In the present study we investigated the characteristics and developmental capability of osteogenic differentiation to find out whether human UCMSC promote periodontal healing. UCMSC were obtained by primary culture and identified using flow cytometry. Flow cytometry, real-time polymerase chain reaction (PCR), Western blotting, assays of alkaline phosphatase activity, and alizarin red staining were used to assess the potential for hUCMSC to proliferate and differentiate in vitro. Both dentine and predifferentiated or undifferentiated cells were transplanted subcutaneously onto the backs of immunodeficient mice to mimic periodontal tissue healing in vivo. The result showed that hUCMSC were readily obtained, and expressed numerous mesenchymal stem cell markers. Expression of stemness markers decreased notably during osteogenic differentiation. Through investigation of different time points, we found that the osteogenic procedure could be activated and detected at day 7. In the in vivo experiments, the predifferentiated hUCMSC showed increased ability to form cementum-like deposits surrounded by fibroblast-like tissue on the surface of the dentine. In conclusion, the potential for proliferation and differentiation, and the ability to form cementum-like tissue, suggest that hUCMSC are promising candidates as a source of mesenchymal stem cell for sources of periodontal healing after autotransplantation of teeth.

[Establishment of palatal organ culture in vitro].

OBJECTIVE: The purpose of this study was to establish a palatal organ culture method and to investigate the palatogenesis in vitro. METHODS: 20 pregnant 14-day mice were killed, embryos were separated ascetically, and palatal shelves were dissected and placed on a modified Trowell's system. All explants were cultured 24 h and 48 h respectively. Finally, all explants were embedded and stained by Hematoxylin and Eosin. RESULTS: All explants grew healthy. After incubation for 24 h, medial edge epithelium maintained, whereas after 48 h, medial edge epithelium disappeared, bilateral mesenchymal cells contacted, palates fused. CONCLUSION: This method provides an effective way for investigating the etiology of cleft palate in vitro.

A rare bilateral Tessier no. 6 and 7 clefts.

The authors describe a patient with bilateral Tessier no. 6 and no. 7 clefts. The case consists of macrostomia combined with maxillary, zygomatico-orbito-temporal deformities, dental anomalies and mandibular retrusion. In addition, the cleft is located bilaterally in the maxillary arch with a double deciduous posterior dentition. This is rare. The clinical and radiological features are reported and the treatment plans are discussed.

[Correction of progressive hemifacial atrophy using dermis-fat graft and Medpor implant shaped by reverse engineering technique].

OBJECTIVE: To evaluate the therapeutic effect of dermis-fat graft combined with Medpor implant shaped by reverse engineering technique in the correction of the progressive hemifacial atrophy. METHODS: A skull model was made by rapid prototyping and the bony deficiency model was acquired with reverse engineering technique. The Medpor implant was shaped precisely based on the deficiency model and implanted with dermis-fat graft at the same stage. RESULTS: 11 cases were treated successfully without infection, necrosis and rejection. The patients were followed up for six months to one year with satisfactory cosmetic improvement. The dermis-fat graft survived without obvious absorption. CONCLUSION: The technique can correct both the bony and soft tissue deficiency for progressive hemifacial atrophy. It is very practical and easily performed with reliant results and less morbidity.

[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.

[Fabrication of collagen/sodium hyaluronate scaffold and its biological characteristics for cartilage tissue engineering].

OBJECTIVE: To develop a scaffold material containing collagen 1 and sodium hyaluronate for the cartilage tissue engineering and to evaluate its biocompatibility by using the rabbit chondrocytes derived from a mandibular condylar process. METHODS: The porous matrices containing collagen 1 and sodium hyaluronate were fabricated by the freeze-drying technique and were crosslinked by using 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC). The microstructure of the scaffold was observed under the scanning electron microscope (SEM), and the enzymatic degradation test was performed to compare the ability of the scaffold resistance to collagenase before and after the crosslinking. The chondrocytes from the rabbits' condylar process were isolated and cultured before they were seeded into the scaffold, and cell attachment and proliferation were measured by the cell count 1, 3, 5, 7 and 10 days after the cell being seeded; then, the biocompatibility of the scaffold was evaluated by the light microscopic examination, histological examination, and the SEM exmination. RESULTS: The porous structure of the scaffold facilitated the penetration and attachment of the seeded cells. The porosity was 83.7% and the pore size was 100-120 microm. The cell number increased from 3.7 x 10(4) per scaffold 1 day after the cell being seeded to 8.2 x 10(4) per scaffold 10 days after the cell being seeded. The crosslinking treatment could significantly enhance the scaffold resistance to the collagenase activity. The examinations under the light microscope and SEM indicated that the chondrocyte adhered and spread well on the scaffold, and the extracellular matrices were also observed around the chondrocytes. CONCLUSION: The porous scaffold composed of collagen I and hyaluronan has an appropriate structure and a good biocompatibility for the attachment and proliferation of the chondrocytes, which can facilitate it to become a useful scaffold in the cartilage tissue engineering.

[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.