DLP-based bioprinting of void-forming hydrogels for enhanced stem-cell-mediated bone regeneration.

The integration of 3D bioprinting and stem cells is of great promise in facilitating the reconstruction of cranial defects. However, the effectiveness of the scaffolds has been hampered by the limited cell behavior and functions. Herein, a therapeutic cell-laden hydrogel for bone regeneration is therefore developed through the design of a void-forming hydrogel. This hydrogel is prepared by digital light processing (DLP)-based bioprinting of the bone marrow stem cells (BMSCs) mixed with gelatin methacrylate (GelMA)/dextran emulsion. The 3D-bioprinted hydrogel can not only promote the proliferation, migration, and spreading of the encapsulated BMSCs, but also stimulate the YAP signal pathway, thus leading to the enhanced osteogenic differentiation of BMSCs. In addition, the in vivo therapeutic assessments reveal that the void-forming hydrogel shows great potential for BMSCs delivery and can significantly promote bone regeneration. These findings suggest that the unique 3D-bioprinted void-forming hydrogels are promising candidates for applications in bone regeneration.

Nanoparticle-Stabilized Emulsion Bioink for Digital Light Processing Based 3D Bioprinting of Porous Tissue Constructs.

A challenge for bioprinting tissue constructs is enabling the viability and functionality of encapsulated cells. Rationally designed bioink that can create appropriate biophysical cues shows great promise for overcoming such challenges. Here, a nanoparticle-stabilized emulsion bioink for direct fabrication of porous tissue constructs by digital light processing based 3D bioprinting technology is introduced. The emulsion bioink is integrated by the mixture of aqueous dextran microdroplets and gelatin methacryloyl solution and is further rendered stable by ß-lactoglobulin nanoparticles. After bioprinting, the printed tissue constructs create the macroporous structure via removal of dextran, thereby providing favorable biophysical cues to promote the viability, proliferation, and spreading of the encapsulated cells. Moreover, a trachea-shaped construct containing chondrocytes is bioprinted and implanted in vivo. The results demonstrate that the generated macroporous construct is of benefit to cartilage tissue rebuilding. This work offers an advanced bioink for the fabrication of living tissue constructs by activating the cell behaviors and functions in situ and can lead to the development of 3D bioprinting.

Additively Manufactured Lattice-like Subperiosteal Implants for Rehabilitation of the Severely Atrophic Ridge.

Subperiosteal implants represent an alternative implant approach for cases with severe bone atrophy. Although some successful clinical cases have been reported, the biomechanical stability of subperiosteal implants remains unclear, and more data are needed to confirm the feasibility of this approach. Therefore, this study investigated the biomechanical characteristics of subperiosteal implants based on histological observation, clinical cases, and finite element analysis. Finite element analysis indicated that subperiosteal implants with a lattice-like structure could better disperse the stress to the underlying bone surface. A novel customized subperiosteal implant was then digitally designed and fabricated using an additive manufacturing technology. Six beagle dogs received such customized subperiosteal implants. Histological and microcomputed tomography examination showed new bone growth into and around the implant. Patient-specific subperiosteal implants were placed into the edentulous mandibular bone, with immediate loading. The implant was functional, without pain or infection, over a 12 month observation period. Images taken 12 months post-operatively showed new bone formation and osseointegration of the device. This indicated that 3D-printed lattice-like subperiosteal implants have sufficient stability for the rehabilitation of severely atrophic ridges.

Application of digital immediate implant restoration and angle screw channel abutment in the aesthetic area:case report and literature review / 口腔疾病防治

Objective @# To investigate the application of digital immediate implant and angle screw channel abutment in the aesthetic area and the related influencing factors by reviewing the data of one case of immediate implant repair of the upper anterior teeth and related literature. @*Methods@#One case of refractory chronic apicitis of the upper anterior teeth involved immediate implantation after extraction. The digital information of the patient was obtained by CBCT and intraoral scanning. According to the information from the patients, a preoperative evaluation was performed; a treatment scheme was formulated; a minimally invasive extraction was performed; implants were placed under a digital guide plate; and temporary restoration was immediately performed. Six months after the operation, the patients underwent individualized mold removal, and angle screw channel fixation was completed. We observed the cosmetic effects and soft and hard tissue and gingival contour maintenance effects after restoration and reexamined the patients 6 months after restoration. In addition, the relevant literature was reviewed. @*Results @#The height of the gingival margin and gingival papilla and gingival contour of this patient were well maintained. The red and white aesthetic effect was good. There was no redness or swelling of the gingiva nor obvious changes in the soft and hard tissues around the implant 6 months after restoration, and the patient was satisfied. The results in the literature review show that a preoperative design based on CBCT and intraoral scanning data combined with digital software and a whole digital guide plate make the procedure more accurate and safer. These factors can not only avoid important anatomical structures and serious surgical complications but can also result in implantation in the best three-dimensional position. In addition, the application of digital impression technology and CAD/CAM increases the efficiency, speed, accuracy, simplicity, and comfort of oral impressions and the construction of temporary and final prostheses more precise and faster, greatly improving clinical efficiency. @*Conclusion@#Digital immediate implant and angle screw channel abutment is a good method to restore the aesthetics and function of missing teeth and to avoid the complications caused by adhesive residue.

Oxysophocarpine Retards the Growth and Metastasis of Oral Squamous Cell Carcinoma by Targeting the Nrf2/HO-1 Axis.

BACKGROUND/AIMS: Nuclear factor erythroid 2-related factor 2 (Nrf2) is an oncogene in various types of cancers, including oral squamous cell carcinoma (OSCC). Oxysophocarpine (OSC) is a natural alkaloid that has multiple pharmacological activities. However, the biological functions and molecular mechanism underlying the effects of OSC on the growth and metastasis of OSCC are unclear. METHODS: Nrf2 levels were determined in OSCC tissues and non-cancerous specimens by quantitative real-time PCR, western blotting, and immunohistochemistry (IHC) assays. The effects of OSC on OSCC cell growth and metastasis were explored (1) using 5-ethynyl-20-deoxyuridine staining and Cell Counting Kit-8, colony formation, flow cytometry, wound-healing, Transwell, and tube formation assays in vitro; and (2) by establishing a xenograft nude mouse model in vivo. The molecular mechanisms underlying the effects of OSC on the growth and metastasis of OSCC were investigated in vitro by western blotting, caspase-3 activity, and enzyme-linked immunosorbent assays, and in vivo by western blotting and IHC assays. RESULTS: The expression levels of Nrf2 in OSCC tissues and in cell lines were much higher than in non-cancerous tissues and normal oral keratinocytes. The upregulation of Nrf2 was positively correlated with a high incidence of lymph node metastasis and advanced histological grade and TNM stage, but inversely associated with differentiation and survival of OSCC patients. OSC reduced the expression of Nrf2 and heme oxygenase 1 (HO-1) in OSCC cells. OSC also inhibited proliferation, migration, invasion, and pro-angiogenesis of OSCC cells. Moreover, OSC induced cell cycle arrest, enhanced apoptosis of OSCC cells in vitro, and decreased OSCC tumor growth in vivo. Mechanically, OSC reduced the aggressive behavior of OSCC cells by inactivation of the Nrf2/HO-1 signaling pathway. CONCLUSION: Our findings provide evidence that OSC inhibits the growth and metastasis of OSCC by targeting the Nrf2/ HO-1 axis, suggesting that OSC may be a potential therapeutic agent for OSCC.

[The intercellular communication condition of alveolar bone with traumatic occlusion at early stage in rats].

OBJECTIVE: To study the intercellular communication of alveolar bone during traumatic occlusion at early stage in rats. METHODS: The occlusal surface of the upper left first molar of rat was raised by placing a stainless steel wire to induce occlusal trauma in the lower left first molar. After 24 hours, the alveolar bone tissues of the lower jaws first molars at the both sides were taken out under anesthesia The various 27 000 genes were identified with genome-wide microarray, and further were investigated with reverse transcription-polymerase chain reaction (RT-PCR) and Pathway analysis. RESULTS: Total 586 gene were found to be changed, 106 different signal pathways got involved with Pathway analysis, including cell adhesion molecules(CAMS), adhesions junction, gap junction, focal adhesion and tight junction, and the cytokines associated with bone metabolism in above 5 signal pathways were all down-regulated. CONCLUSION: At the early phase of the occlusal trauma, intercellular communication in rat's alveolar bone were inhibited.

[The primary study on the gene expression profiles of alveolar bone with traumatic occlusion in early stage in rats].

OBJECTIVE: To study the gene expression profiles of traumatic occlusion in early stage with the animal model of rats. METHODS: The occlusal surface of the upper left first molar of rat was raised by placing a stainless steel wire to induce occlusal trauma in the lower left first molar. After 24 hours, the alveolar bone tissue of the first molars at the both sides of rats' lower jaws were taken out under anesthesia. The different expressive genes were shown by genome-wide microarray, which comprises about 27 000 genes and analyzed the different expressive genes with Pathway and GO analysis, finally the results of the microarray were examined by real time-polymerase chain reaction (RT-PCR). RESULTS: In the results of the study, 586 different expressions were found, of which the expressions of 166 genes increased and 420 genes decreased. 106 different pathways were involved with Pathway analysis and 270 different functional classification related to GO analysis. CONCLUSION: The balance of the lower alveolar bone is destroyed after 24 hours of traumatic occlusion. At early phase of the occlusal trauma, osteogenesis and bone formation in alveolar bone are inhibited, yet osteoblast genesis and bone resorption are not significant.

The early phase response of rat alveolar bone to traumatic occlusion.

OBJECTIVES: Occlusal trauma is an important factor to influence alveolar bone remodelling, the effect of which includes many cytokines and signalling pathways. However, the exact mechanism of the traumatic stimulus for alveolar remodelling is still unclear. The purpose of the present study was to investigate the early responses of alveolar osteocytes to occlusal trauma through genome-wide microarray. METHODS: The occlusal surface of the upper left first molar of rat was raised by placing a stainless steel wire to induce occlusal trauma in the lower left first molar. After 24 h, we took out the alveolar bone tissue of the first molars at the both sides of rats' lower jaws under anaesthesia. The different gene expressions were showed by genome-wide microarray, which comprises about 27,000 genes and the results were examined by quantitative RT-PCR. RESULT: Of the approximately 27,000 genes, the expression of 586 genes was strongly changed. These findings clearly demonstrated that in the early response of the alveolar bone to occlusal trauma, the expression of osteoblast, collagens, bone mineralization, bone remodelling and WNT, TGF-ß pathway related cytokines decreased, and osteoclast-specific cytokines have no significant changes in expression. CONCLUSION: These results suggested that at early phase of the occlusal trauma, osteogenesis in rat's alveolar bone was inhibited, and osteoclastogenesis was not significant.