A xenogeneic extracellular matrix-based 3D printing scaffold modified by ceria nanoparticles for craniomaxillofacial hard tissue regeneration via osteo-immunomodulation.

Hard tissue engineering scaffolds especially 3D printed scaffolds were considered an excellent strategy for craniomaxillofacial hard tissue regeneration, involving crania and facial bones and teeth. Porcine treated dentin matrix (pTDM) as xenogeneic extracellular matrix has the potential to promote the stem cell differentiation and mineralization as it contains plenty of bioactive factors similar with human-derived dentin tissue. However, its application might be impeded by the foreign body response induced by the damage-associated molecular patterns of pTDM, which would cause strong inflammation and hinder the regeneration. Ceria nanoparticles (CNPs) show a great promise at protecting tissue from oxidative stress and influence the macrophages polarization. Using 3D-bioprinting technology, we fabricated a xenogeneic hard tissue scaffold based on pTDM xenogeneic TDM-polycaprolactone (xTDM/PCL) and we modified the scaffolds by CNPs (xTDM/PCL/CNPs). Through series ofin vitroverification, we found xTDM/PCL/CNPs scaffolds held promise at up-regulating the expression of osteogenesis and odontogenesis related genes including collagen type 1, Runt-related transcription factor 2 (RUNX2), bone morphogenetic protein-2, osteoprotegerin, alkaline phosphatase (ALP) and DMP1 and inducing macrophages to polarize to M2 phenotype. Regeneration of bone tissues was further evaluated in rats by conducting the models of mandibular and skull bone defects. Thein vivoevaluation showed that xTDM/PCL/CNPs scaffolds could promote the bone tissue regeneration by up-regulating the expression of osteogenic genes involving ALP, RUNX2 and bone sialoprotein 2 and macrophage polarization into M2. Regeneration of teeth evaluated on beagles demonstrated that xTDM/PCL/CNPs scaffolds expedited the calcification inside the scaffolds and helped form periodontal ligament-like tissues surrounding the scaffolds.

Personalized 3D-Printed Scaffolds with Multiple Bioactivities for Bioroot Regeneration.

Recent advances in 3D printing offer a prospective avenue for producing transplantable human tissues with complex geometries; however, the appropriate 3D-printed scaffolds possessing the biological compatibility for tooth regeneration remain unidentified. This study proposes a personalized scaffold of multiple bioactivities, including induction of stem cell proliferation and differentiation, biomimetic mineralization, and angiogenesis. A brand-new bioink system comprising a biocompatible and biodegradable polymer is developed and reinforced with extracellular matrix generated from dentin tissue (treated dentin matrix, TDM). Adding TDM optimizes physical properties including microstructure, hydrophilicity, and mechanical strength of the scaffolds. Proteomics analysis reveals that the released proteins of the 3D-printed TDM scaffolds relate to multiple biological processes and interact closely with each other. Additionally, 3D-printed TDM scaffolds establish a favorable microenvironment for cell attachment, proliferation, and differentiation in vitro. The 3D-printed TDM scaffolds are proangiogenic and facilitate whole-thickness vascularization of the graft in a subcutaneous model. Notably, the personalized TDM scaffold combined with dental follicle cells mimics the anatomy and physiology of the native tooth root three months after in situ transplantation in beagles. The remarkable in vitro and in vivo outcomes suggest that the 3D-printed TDM scaffolds have multiple bioactivities and immense clinical potential for tooth-loss therapy.

3D-bioprinted Recombination Structure of Hertwig's Epithelial Root Sheath Cells and Dental Papilla Cells for Alveolar Bone Regeneration.

Three-dimensional (3D) bioprinting is an emerging method for tissue regeneration. However, promoting the epithelial-mesenchymal interaction (EMI), while maintaining the characteristics of epithelial cells has always been a challenge in tissue engineering. Since EMI acts as a critical factor in bone regeneration, this study aims to promote EMI by recombining epithelial and mesenchymal cells through 3D bioprinting. Hertwig's epithelial root sheath (HERS) is a transient structure appeared in the process of tooth root formation. Its epithelial characteristics are easy to attenuate under appropriate culture environment. We recombined HERS cells and dental papilla cells (DPCs) through 3D bioprinting to simulate the micro-environment of cell-cell interaction in vivo. HERS cells and DPCs were mixed with gelatin methacrylate (GelMA) separately to prepare bio-inks for bioprinting. The cells/GelMA constructs were transplanted into the alveolar socket of Sprague-Dawley rats and then observed for 8 weeks. Hematoxylin and eosin staining, Masson staining, and immunohistochemical analysis showed that dimensional cultural pattern provided ideal environment for HERS cells and DPCs to generate mineralization texture and promote alveolar bone regeneration through their interactions. 3D bioprinting technology provides a new way for the co-culture of HERS cells and DPCs and this study is inspiring for future research on EMI model.

The application of a new clear removable appliance with an occlusal splint in early anterior crossbite.

BACKGROUND: The effectiveness of anterior crossbite treatment in preschool-aged children depends on the treatment design and patient compliance. Common early treatment appliances with steel wires and acrylic resin can bring about numerous problems, such as toothache, sore gums and mucous membrane injury. The aim of this study was to propose a new clear removable appliance to provide preschool-age children with an improved experience of early occlusal interference treatment. METHODS: Appliances were designed with the help of 3-dimensional (3D) digital reconstruction oral models and fabricated using 3D printing technology and the pressed film method. Then, the mechanical properties of the original dental coping sheet and thermoformed aligners were assessed in a simulated intraoral environment. Preschool-age participants who displayed anterior crossbite were recruited in this study. Records (photographs and impressions) were taken before the treatment (T1), during the treatment (T2) and at the end of the treatment (T3). The effects of treatment were evaluated by clinical examination and questionnaires. RESULTS: Normal degrees of overbite and overjet in the primary dentition were achieved using this new appliance. Dental and soft tissue relationships were improved. Questionnaires showed that the safety evaluation, degree of comfort and convenience grades of the appliance were all relatively high. CONCLUSION: This explorative study demonstrates that our new clear removable appliance is able to correct early-stage anterior crossbite in a safe, comfortable, convenient and efficient way. Thus, it is a promising method to correct a certain type of malocclusion, and its clinical use should be promoted in the future.

Treated dentin matrix paste as a novel pulp capping agent for dentin regeneration.

Regenerating dentin and preserving pulp vitality are the two key targets for the treatment of dental pulp exposure. Calcium hydroxide (CH), the widely used capping agent, may induce potential tunnel defect in reparative dentin and cause inflammation or even necrosis in pulp tissues. This study aimed to produce a novel pulp capping agent with better bioactivities. Treated dentin matrix (TDM) paste (TDMP) was fabricated consisting of TDM powder and aqueous TDM extract. The chemical and biological characteristics of TDMP were investigated, and its effect on the odontogenic differentiation of dental pulp stem cells explored at gene and protein level; the therapeutic effect for pulp exposure in miniature swine was further verified. TDMP possessed better biocompatibility with neutral pH value, significantly promoted the proliferation of dental pulp stem cells, and enhanced the gene and protein expressions of alkaline phosphatase, bone sialoprotein, dentin sialoprotein etc., compared with CH. In vivo pulp capping using TDMP presented the formation of continuous reparative dentin bridge thicker and denser than CH group. Moreover, pulp tissues under TDMP capping sites showed relatively slight angiectasis than those induced by CH. TDMP could achieve both dentin regeneration and vital pulp conservation, and might serve as a feasible substitute for CH in dental pulp repair procedure. Copyright © 2017 John Wiley & Sons, Ltd.

Compositional and in Vitro Evaluation of Nonwoven Type I Collagen/Poly-dl-lactic Acid Scaffolds for Bone Regeneration.

Poly-dl-lactic acid (PDLLA) was blended with type I collagen to attempt to overcome the instantaneous gelation of electrospun collagen scaffolds in biological environments. Scaffolds based on blends of type I collagen and PDLLA were investigated for material stability in cell culture conditions (37 °C; 5% CO2) in which post-electrospinning glutaraldehyde crosslinking was also applied. The resulting wet-stable webs were cultured with bone marrow stromal cells (HBMSC) for five weeks. Scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), Fourier transform infra-red spectroscopy (FTIR) and biochemical assays were used to characterise the scaffolds and the consequent cell-scaffold constructs. To investigate any electrospinning-induced denaturation of collagen, identical PDLLA/collagen and PDLLA/gelatine blends were electrospun and their potential to promote osteogenic differentiation investigated. PDLLA/collagen blends with w/w ratios of 40/60, 60/40 and 80/20 resulted in satisfactory wet stabilities in a humid environment, although chemical crosslinking was essential to ensure long term material cell culture. Scaffolds of PDLLA/collagen at a 60:40 weight ratio provided the greatest stability over a five-week culture period. The PDLLA/collagen scaffolds promoted greater cell proliferation and osteogenic differentiation compared to HMBSCs seeded on the corresponding PDLLA/gelatine scaffolds, suggesting that any electrospinning-induced collagen denaturation did not affect material biofunctionality within 5 weeks in vitro.

Biomechanical analysis and comparison of 12 dental implant systems using 3D finite element study.

Finite element analysis plays an important role in dental implant design. The objective of this study was to show the effect of the overall geometry of dental implants on their biomechanics after implantation. In this study, 12 dental implants, with the same length, diameter and screw design, were simulated from different implant systems. Numerical model of right mandibular incisor bone segment was generated from CT data. The von-Mises stress distributions and the total deformation distributions under vertical/lateral load were compared for each implant by scores ranking method. The implants with cylindrical shapes had highest scores. Results indicated that cylindrical shape represented better geometry over taper implant. This study is helpful in choosing the optimal dental implant for clinical application and also contributes to individual implant design. Our study could also provide reference for choice and modification of dental implant in any other insertion sites and bone qualities.

Secretory factors from rat adipose tissue explants promote adipogenesis and angiogenesis.

Adipogenic differentiation of adipose-derived stem cells (ASCs) is known to be affected by many promoting and inhibiting factors, and correlated with surrounding cells and extracellular matrix. However, few studies have evaluated the effect of secreted biological molecules from adipose tissue explants on the growth of ASCs. In this study, ASCs were isolated and the secretory factors from adipose tissue explants (SFAE) were prepared from adipose tissue explants. The multilineage differentiation potential of ASCs was determined using different inductive media. The influence of SFAE on the colony formation and proliferation of ASCs was determined using colony-forming efficiency assay and Cell Counting Kit-8 assay, respectively. Real-time polymerase chain reaction and Western blot were performed to analyze the beneficial effect of SFAE on the adipogenesis and angiogenesis of ASCs. Utilizing gelatin scaffold, the influence of SFAE on ASCs was investigated in vivo. Subsequently, cell/gelatin constructs were cultured in a subcutaneous pocket on a rat dorsum for 2 and 9 weeks, and the resultant samples were histologically evaluated. Results showed that ASCs derived from adipose explants can differentiate along multiple lineages in vitro. Utilizing SFAE, the proliferation and colony-forming efficiency of ASCs were inhibited, while the expression of adipogenesis markers such as C/EBPß, PPARγ2, and LPL, as well as angiogenesis factor VEGF-A were promoted. Moreover, the beneficial effect of SFAE on adipogenesis was revealed in vivo. In conclusion, our results suggested that SFAE has beneficial influence on adipogenesis and angiogenesis both in vitro and in vivo.

[Research on the effect of extract of dentin matrix on the differentiation of dental pulp cells].

OBJECTIVE: To investigate the effects of human treated dentin matrix (hTDM) extracellular matrix molecules on odontogenetic and neural differentiation of human dental pulp cells (hDPCs) with an aim to find an effective method to collect extracellular matrix molecules to contribute to reparation dental-pulp complex with dentin defects. METHODS: hDPCs were obtained and biological characteristics such as source of cells and multi-differentiation potentials were assessed using immunofluorescence and flow cytometry. Fabrication of hTDM extracts and hDPCs was induced with it for 1 week. The odontogenetic differentiation associated genes were tested by qRT-PCR. Results qRT-PCR results showed that cells were higher expression of odontogenetic differentiation associated genes ALP, OPN, OCN, BSP, DMP-1, DSP, beta-III tubulin. CONCLUSION: The method of extracting extracellular matrix molecules from dentin matrix was effective. The extract liquid provides a suitable microenvironment for odontogenetic and neural differentiation of hDPCs and contributes to reparation dental-pulp complex.

Comparison of odontogenic differentiation of human dental follicle cells and human dental papilla cells.

Classical tooth development theory suggests that dental papilla cells (DPCs) are the precursor cells of odontoblasts, which are responsible for dentin development. However, our previous studies have indicated that dental follicle cells (DFCs) can differentiate into odontoblasts. To further our understanding of tooth development, and the differences in dentinogenesis between DFCs and DPCs, the odontogenic differentiation of DFCs and DPCs was characterized in vitro and in vivo. DFCs and DPCs were individually combined with treated dentin matrix (TDM) before they were subcutaneously implanted into the dorsum of mice for 8 weeks. Results showed that 12 proteins were significantly differential, and phosphoserine aminotransferase 1 (PSAT1), Isoform 2 of hypoxia-inducible factor 1-alpha (HIF1A) and Isoform 1 of annexin A2 (ANXA2), were the most significantly differential proteins. These proteins are related to regulation of bone balance, angiogenesis and cell survival in an anoxic environment. Both DFCs and DPCs express odontogenic, neurogenic and peridontogenic markers. Histological examination of the harvested grafts showed that both DFCs and DPCs form pulp-dentin/cementum-periodentium-like tissues in vivo. Hence, DFCs and DPCs have similar odontogenic differentiation potential in the presence of TDM. However, differences in glucose and amino acid metabolism signal transduction and protein synthesis were observed for the two cell types. This study expands our understanding on tooth development, and provides direct evidence for the use of alternative cell sources in tooth regeneration.

Highly enantioselective copper-catalyzed ring opening of oxabicyclic alkenes with Grignard reagents.

A highly efficient copper-catalyzed enantioselective ring opening of oxabicylic alkenes with Grignard reagents has been developed by using chiral spiro phosphine ligands. Excellent trans selectivities, good yields, and high enantioselectivities are obtained for a broad range of Grignard reagents under mild reaction conditions. The catalyst system shows an extraordinary activity and the TON of the reaction reaches 9000.