Jiewen Dai

The effect of co-culturing costal chondrocytes and dental pulp stem cells combined with exogenous FGF9 protein on chondrogenesis and ossification in engineered cartilage

Dental pulp stem cells (DPSCs), which arise from cranial neural crest cells, are multipotent, making them a candidate for use in tissue engineering that may be especially useful for craniofacial tissues. Costal chondrocytes (CCs) can be easily obtained and demonstrate higher initial cell yields and expansion than articular chondrocytes. CCs have been found to retain chondrogenic capacity that can effectively repair articular defects. In this study, human CCs were co-cultured with human DPSCs, and the results showed that the CCs were able to supply a chondro-inductive niche that promoted the DPSCs to undergo chondrogenic differentiation and to enhance the formation of cartilage. Although CCs alone could not prevent the mineralization of chondro-differentiated DPSCs, CCs combined with exogenous FGF9 were able to simultaneously promote the chondrogenesis of DPSCs and partially inhibit their mineralization. Furthermore, FGF9 may activate this inhibition by binding to FGFR3 and enhancing the phosphorylation of ERK1/2 in DPSCs. Our results strongly suggest that the co-culture of CCs and DPSCs combined with exogenous FGF9 can simultaneously enhance chondrogenesis and partially inhibit ossification in engineered cartilage.

The effect of overexpression of Dlx2 on the migration, proliferation and osteogenic differentiation of cranial neural crest stem cells

Craniofacial skeleton mainly originate from the cranial neural crest stem cells (CNCCs), which is a subpopulation of neural crest stem cells (NCCs). Dlx2, a member of the homeodomain family of transcription factors, plays crucial roles in the development of the CNCCs derived craniofacial skeleton. Previous reports reveal that Dlx2-targeted null mutation resulted in anomalies in the skeletal derivatives of CNCCs in mice. Dlx2 overexpression in ova disturbed the migration and differentiation of affected CNCCs and induced the development of ectopic skeleton elements. However, whether Dlx2 overexpression can impair the morphogenesis of CNCCs derived craniofacial skeleton in vivo has not been explored. Here, we generated a transgenic mouse overexpressing Dlx2 in NCCs (Wnt1Cre::iZEG-Dlx2). The Wnt1Cre::iZEG-Dlx2 embryos showed decreased cell proliferation, increased cell apoptosis, abnormal chondrogenesis and impaired osteogenesis within the CNCCs population, resulting in obvious craniofacial defects that ranged from a cleft lip and midfacial clefts to neural tube defects and exencephaly. Adult Wnt1Cre::iZEG-Dlx2 mice showed nasal and premaxillary hypoplasia and spinal deformities. These findings reveal that Dlx2 overexpression in NCCs may be a new pathogenesis of facial cleft and spinal kyphosis in mammals, and may offer us a useful model organism to find suitable therapy methods for these genetic defects that may be different from the traumatic defect and resected defect.

Effect of fibroblast growth factor 9 on the osteogenic differentiation of bone marrow stromal stem cells and dental pulp stem cells

The role of fibroblast growth factor 9 (FGF9) in bone formation may depend on gene dosage, developmental stage, cell type or interactions with other cytokines. In the present study bone marrow stromal stem cells (BMSCs) and dental pulp stem cells (DPSCs) were cultured and osteogenically induced in vitro, treated with exogenous FGF9 at varying concentrations. Alkaline phosphatase staining, alizarin red S staining, reverse transcription quantitative polymerase chain reaction and western blot analyses were performed in order to investigate the gene expression levels of osteogenic markers. The results of the present study demonstrated that FGF9 enhanced the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) during osteogenic induction in BMSCs and DPSCs, which are derived from different tissues. FGF9 also inhibited the osteogenic differentiation of BMSCs and DPSCs through the activation of ERK1/2. These findings suggested that FGF9 may be an inhibitor of osteogenesis in mesenchymal stem cells in vitro and its application in vivo requires investigation in the future.

Comparative Investigation of Human Amniotic Epithelial Cells and Mesenchymal Stem Cells for Application in Bone Tissue Engineering

Emerging evidence suggests amniotic epithelial cells (AECs) as a promising source of progenitor cells in regenerative medicine and bone tissue engineering. However, investigations comparing the regenerative properties of AECs with other sources of stem cells are particularly needed before the feasibility of AECs in bone tissue engineering can be determined. This study aimed to compare human amniotic epithelial cells (hAECs), human bone marrow mesenchymal stem cells (hBMSCs), and human amniotic fluid derived mesenchymal stem cells (hAFMSCs) in terms of their morphology, proliferation, immunophenotype profile, and osteogenic capacity in vitro and in vivo. Not only greatly distinguished by cell morphology and proliferation, hAECs, hAFMSCs, and hBMSCs exhibited remarkably different signature regarding immunophenotypical profile. Microarray analysis revealed a different expression profile of genes involved in ossification along the three cell sources, highlighting the impact of different anatomical origin and molecular response to osteogenic induction on the final tissue-forming potential. Furthermore, our data indicated a potential role of FOXC2 in early osteogenic commitment.

Finite element analysis of type B condylar head fractures and osteosynthesis using two positional screws

OBJECTIVE The aim of this study was to explore the cause of type B condylar head fracture after parasymphyseal impact, and evaluate the biomechanics of osteosynthesis using two positional screws for the repair of this type of fractures. METHODS A finite element model of the mandible was created, and a parasymphyseal impact was simulated using Mimics 10.01 and Abaqus 6.10 software. The type B condylar head fracture was simulated in the right condyle using a mimics simulation cut with polyplane module according to the analyzed results together with clinical experience, and the left condyle was used as a control. Two positional screws were used for rigid internal fixation of the fracture. von Mises stress distributions in the condyles and screws were analyzed. RESULTS The von Mises stress generated in parasymphyseal trauma simulation showed a significant concentration in the sagittal direction of the condyle. In two-positional-screw osteosynthesis of the condylar head fractures, stress concentration appeared within the screws in the gap area between the two fractured segments and the area around the screw head. A small amount of stress was distributed in the screw holes and on the posterior surfaces of both segments. The von Mises stress was negligible in the fractured sagittal surfaces. CONCLUSION It is reasonable to attribute the cause of type B condylar head fracture to the anatomical features of the condyle. The biomechanics of two-positional-screw osteosynthesis revealed that the stress can transmit through the screws to the medial fragments, and the stresses on both sagittal fractured surfaces are minimal.

Two- and Three-dimensional Models for the Visualization of Jaw Tumors Based on Ct–mri Image Fusion

PurposeThe objective of this study was to demonstrate the feasibility of two- and three-dimensional (2D and 3D) models based on computed tomography–magnetic resonance imaging (CT-MRI) image fusion for the visualization of jaw tumors. MethodsSeven patients with proved jaw tumors were involved in this study. Both preoperative CT and MRI image data were acquired in DICOM format and imported into Surgicase CMF software, respectively. Then, the structures of interest, including tumor, muscle, and vascular, and so on, were segmented based on different thresholds and reconstructed in 3D texture. Finally, CT-MRI image fusion was semiautomatically performed to obtain the fused 2D images and 3D models for the visualization of jaw tumors. The qualities of the fused 2D images and 3D models together with their potential applications in surgical management of jaw tumors were qualitatively assessed. Besides, the importance of this imaging technique in terms of training junior surgeons was also discussed in detail. ResultsComputed tomography–MRI image fusion clearly showed the relationship between tumors and adjacent structures. The qualitative assessment of fused images was satisfied. ConclusionsAlthough there are some limitations, the 2D images and 3D models based on CT-MRI image fusion can provide a powerful tool for the visualization of jaw tumors. It may offer surgeons an assisted tool for the subject-specific preoperative planning, surgical simulation, and intraoperative guidance for jaw tumors. Furthermore, it also may offer valuable 2D and 3D models for training junior surgeons or provide a useful tool for surgeons to communicate well with patients.

Irf6-Related Gene Regulatory Network Involved in Palate and Lip Development.

AbstractNumerous genes including Irf6 have been revealed to contribute to cleft lip with or without cleft palate (CL/P). In this study, we performed a systematic bioinformatics analysis of Irf6-related gene regulatory network involved in palate and lip development by using GeneDecks, DAVID, STRING, and GeneMANIA database. Our results showed that many CL/P candidate genes have relation with Irf6, and 9 of these genes, including Msx1, Pvrl1, Pax9, Jag2, Irf6, Tgfb3, Rara, Gli2, and Tgfb2, were enriched into the CL/P gene group. Some of these 9 genes also were commonly involved in different signaling pathways and different biological processes, and they also have protein-protein interactions with Irf6. These findings make us analyze the intricate function of Irf6 in a CL/P gene regulatory network, followed by guiding us to perform further functional studies on these genes in the future. This method also offers us a simple, cheap, but useful method to analyze the relationship with a gene regulatory network of a certain disease such as CL/P.

An excellent navigation system and experience in craniomaxillofacial navigation surgery: a double-center study

Numerous problems regarding craniomaxillofacial navigation surgery are not well understood. In this study, we performed a double-center clinical study to quantitatively evaluate the characteristics of our navigation system and experience in craniomaxillofacial navigation surgery. Fifty-six patients with craniomaxillofacial disease were included and randomly divided into experimental (using our AccuNavi-A system) and control (using Strker system) groups to compare the surgical effects. The results revealed that the average pre-operative planning time was 32.32 mins vs 29.74 mins between the experimental and control group, respectively (p > 0.05). The average operative time was 295.61 mins vs 233.56 mins (p > 0.05). The point registration orientation accuracy was 0.83 mm vs 0.92 mm. The maximal average preoperative navigation orientation accuracy was 1.03 mm vs 1.17 mm. The maximal average persistent navigation orientation accuracy was 1.15 mm vs 0.09 mm. The maximal average navigation orientation accuracy after registration recovery was 1.15 mm vs 1.39 mm between the experimental and control group. All patients healed, and their function and profile improved. These findings demonstrate that although surgeons should consider the patients’ time and monetary costs, our qualified navigation surgery system and experience could offer an accurate guide during a variety of craniomaxillofacial surgeries.

Le Fort I osteotomy combined with endoscopic assistance for treatment of compound fracture of maxilla, zygoma, and orbital floor.

PurposeThe traditional surgery to reconstruct the compound fracture of the zygoma, maxilla, and orbital floor was usually open reduction and internal fixation using miniplate, and surgeons now can perform the endoscopic repair of relatively simple zygoma or orbital blowout fracture. In this study, we try to reconstruct midfacial complex fracture by combined application of intraoral approach and endoscopic-assisted minimally invasive method. MethodsSix patients with traumatic midfacial fracture, including maxilla, zygoma, and orbital floor fracture, were selected. Intraoral Le Fort I osteotomy approach and endoscopic-assisted minimally invasive method were combined and applied to treat this complex midfacial fracture. ResultsThe intraoral incision combined with endoscope offered suitable approach for reduction and fixation of fractured zygoma. The Le Fort I osteotomy could help to effectively reduce the fractured maxilla and offered useful operative approach for endoscope. The endoscope combined with a balloon catheter could successfully reconstruct the orbital floor fracture, and no intraoperative complications were encountered. The balloon catheter was removed 4 to 8 weeks after operation and did not lead to infection and obviously disrupt the healing of bone segments. The postoperative eye and occlusion function, evaluated by clinical examination, was satisfactory at 3 months. ConclusionsAlthough there are some limitations and strict indications, the advantages of this method may offer alternative choice for reconstruction of compound midfacial fracture.

Le Fort II midfacial distraction combined with orthognathic surgery in the treatment of nasomaxillary hypoplasia.

AbstractPatients with nasomaxillary hypoplasia have severe facial concavity and compromised skeletal class III malocclusion. Its treatment is still a challenge to surgeons. Our aim was to evaluate the combination of midfacial distraction and orthognathic surgery in the treatment of nasomaxillary hypoplasia. Four patients with nasomaxillary hypoplasia were enrolled in this study. After Le Fort II osteotomy, the rotational distraction of nasomaxillary complex was performed to rehabilitate facial convexity. Then bilateral sagittal split ramus osteotomy with or without Le Fort I osteotomy was used to correct malocclusion. All patients healed uneventfully, and the maxillae moved forward conspicuously. No obvious pain and severe discomfort were complained during distraction. A significant advancement and downward movement of the maxilla were shown by cephalometric analysis. The combination of midfacial distraction and orthognathic surgery provides us an ideal alternative in the treatment of nasomaxillary hypoplasia.