Dual Role of Interleukin-20 in Different Stages of Osteoclast Differentiation and Its Osteoimmune Regulation during Alveolar Bone Remodeling.

Osteoimmunology mediators are critical to balance osteoblastogenesis and osteoclastogenesis to maintain bone homeostasis. A lot of the osteoimmunology mediators are regulated by interleukin-20 (IL-20). However, little is known about the role of IL-20 in bone remodeling. Here, we showed that IL-20 expression was correlated with osteoclast (OC) activity in remodeled alveolar bone during orthodontic tooth movement (OTM). Ovariectomize (OVX) in rats promoted OC activity and enhanced IL-20 expression, while blocking OC inhibited IL-20 expression in osteoclasts. In vitro, IL-20 treatment promoted survival, inhibited apoptosis of the preosteoclast at the early stages of osteoclast differentiation, and boosted the formation of osteoclasts and their bone resorption function at the late stages. More importantly, anti-IL-20 antibody treatment blocked IL-20-induced osteoclastogenesis and the subsequent bone resorption function. Mechanistically, we showed that IL-20 synergistically acts with RANKL to activate the NF-κB signaling pathway to promote the expression of c-Fos and NFATc1 to promote osteoclastogenesis. Moreover, we found that local injection of IL-20 or anti-IL-20 antibody enhanced osteoclast activity and accelerated OTM in rats, while blocking IL-20 reversed this phenomenon. This study revealed a previously unknown role of IL-20 in regulating alveolar bone remodeling and implies the application of IL-20 to accelerated OTM.

Hydrostatic Compress Force Enhances the Viability and Decreases the Apoptosis of Condylar Chondrocytes through Integrin-FAK-ERK/PI3K Pathway.

Reduced mechanical stimuli in many pathological cases, such as hemimastication and limited masticatory movements, can significantly affect the metabolic activity of mandibular condylar chondrocytes and the growth of mandibles. However, the molecular mechanisms for these phenomena remain unclear. In this study, we hypothesized that integrin-focal adhesion kinase (FAK)-ERK (extracellular signal-regulated kinase)/PI3K (phosphatidylinositol-3-kinase) signaling pathway mediated the cellular response of condylar chondrocytes to mechanical loading. Primary condylar chondrocytes were exposed to hydrostatic compressive forces (HCFs) of different magnitudes (0, 50, 100, 150, 200, and 250 kPa) for 2 h. We measured the viability, morphology, and apoptosis of the chondrocytes with different treatments as well as the gene, protein expression, and phosphorylation of mechanosensitivity-related molecules, such as integrin α2, integrin α5, integrin ß1, FAK, ERK, and PI3K. HCFs could significantly increase the viability and surface area of condylar chondrocytes and decrease their apoptosis in a dose-dependent manner. HCF of 250 kPa resulted in a 1.51 ± 0.02-fold increase of cell viability and reduced the ratio of apoptotic cells from 18.10% ± 0.56% to 7.30% ± 1.43%. HCFs could significantly enhance the mRNA and protein expression of integrin α2, integrin α5, and integrin ß1 in a dose-dependent manner, but not ERK1, ERK2, or PI3K. Instead, HCF could significantly increase phosphorylation levels of FAK, ERK1/2, and PI3K in a dose-dependent manner. Cilengitide, the potent integrin inhibitor, could dose-dependently block such effects of HCFs. HCFs enhances the viability and decreases the apoptosis of condylar chondrocytes through the integrin-FAK-ERK/PI3K pathway.

Mechanical force-activated CD109 on periodontal ligament stem cells governs osteogenesis and osteoclast to promote alveolar bone remodeling.

Mechanical force-mediated bone remodeling is crucial for various physiological and pathological processes involving multiple factors, including stem cells and the immune response. However, it remains unclear how stem cells respond to mechanical stimuli to modulate the immune microenvironment and subsequent bone remodeling. Here, we found that mechanical force induced increased expression of CD109 on periodontal ligament stem cells (PDLSCs) in vitro and in periodontal tissues from the force-induced tooth movement rat model in vivo, accompanied by activated alveolar bone remodeling. Under mechanical force stimulation, CD109 suppressed the osteogenesis capacity of PDLSCs through the JAK/STAT3 signaling pathway, whereas it promoted PDLSC-induced osteoclast formation and M1 macrophage polarization through paracrine. Moreover, inhibition of CD109 in vivo by lentivirus-shRNA injection increased the osteogenic activity and bone density in periodontal tissues. On the contrary, it led to decreased osteoclast numbers and pro-inflammatory factor secretion in periodontal tissues and reduced tooth movement. Mechanistically, mechanical force-enhanced CD109 expression via the repression of miR-340-5p. Our findings uncover a CD109-mediated mechanical force response machinery on PDLSCs, which contributes to regulating the immune microenvironment and alveolar bone remodeling during tooth movement.

Extracellular Vesicles for Dental Pulp and Periodontal Regeneration.

Extracellular vesicles (EVs) are lipid bound particles derived from their original cells, which play critical roles in intercellular communication through their cargoes, including protein, lipids, and nucleic acids. According to their biogenesis and release pathway, EVs can be divided into three categories: apoptotic vesicles (ApoVs), microvesicles (MVs), and small EVs (sEVs). Recently, the role of EVs in oral disease has received close attention. In this review, the main characteristics of EVs are described, including their classification, biogenesis, biomarkers, and components. Moreover, the therapeutic mechanism of EVs in tissue regeneration is discussed. We further summarize the current status of EVs in pulp/periodontal tissue regeneration and discuss the potential mechanisms. The therapeutic potential of EVs in pulp and periodontal regeneration might involve the promotion of tissue regeneration and immunomodulatory capabilities. Furthermore, we highlight the current challenges in the translational use of EVs. This review would provide valuable insights into the potential therapeutic strategies of EVs in dental pulp and periodontal regeneration.

Inducing the "re-development state" of periodontal ligament cells via tuning macrophage mediated immune microenvironment.

INTRODUCTION: Periodontal regeneration, specifically the restoration of the cementum-periodontal ligament (PDL)-alveolar bone complex, remains a formidable challenge in the field of regenerative dentistry. In light of periodontal development, harnessing the multi-tissue developmental capabilities of periodontal ligament cells (PDLCs) and reinitiating the periodontal developmental process hold great promise as an effective strategy to foster the regeneration of the periodontal complex. OBJECTIVES: This study aims to delve into the potential effects of the macrophage-mediated immune microenvironment on the "developmental engineering" regeneration strategy and its underlying molecular mechanisms. METHODS: In this study, we conducted a comprehensive examination of the periodontium developmental process in the rat mandibular first molar using histological staining. Through the induction of diverse immune microenvironments in macrophages, we evaluated their potential effects on periodontal re-development events using a cytokine array. Additionally, we investigated PDLC-mediated periodontal re-development events under these distinct immune microenvironments through transcriptome sequencing and relevant functional assays. Furthermore, the underlying molecular mechanism was also performed. RESULTS: The activation of development-related functions in PDLCs proved challenging due to their declined activity. However, our findings suggest that modulating the macrophage immune response can effectively regulate PDLCs-mediated periodontium development-related events. The M1 type macrophage immune microenvironment was found to promote PDLC activities associated with epithelial-mesenchymal transition, fiber degradation, osteoclastogenesis, and inflammation through the Wnt, IL-17, and TNF signaling pathways. Conversely, the M2 type macrophage immune microenvironment demonstrated superiority in inducing epithelium induction, fibers formation, and mineralization performance of PDLCs by upregulating the TGFß and PI3K-Akt signaling pathway. CONCLUSION: The results of this study could provide some favorable theoretical bases for applying periodontal development engineering strategy in resolving the difficulties in periodontal multi-tissue regeneration.

Stem Cells from Human Exfoliated Deciduous Teeth Ameliorate Autistic-Like Behaviors of SHANK3 Mutant Beagle Dogs.

Mesenchymal stem cell-based therapy has emerged as a great potential approach to treat individuals with autism spectrum disorders (ASD), a group of developmental disabilities characterized by impairments in social interaction and communication. Stem cells from human exfoliated deciduous teeth (SHED), holding earlier developing characteristics, have immune-modulatory and anti-inflammatory properties. To investigate whether SHED transplantation can rescue autistic-like symptoms in SHANK3 mutant beagle dogs, 12 SHANK3 mutant beagle dogs were randomly assigned into 2 groups according to their behavior evaluated by social interaction tests. Six mutant dogs received 6 intravenous infusions of SHED and were followed up for 3 months by testing social interaction and inflammatory cytokine levels. We found that infusion of SHED significantly improved impaired social novel preference of SHANK3 mutant beagle dogs at 1- and 3-month follow-ups. Social intimacies (following, sniffing, and licking) between mutant beagle dogs and human experimenters were partly improved. Stressed tail posture, indicating social stress, was also significantly alleviated. In addition, we showed that the levels of serum interferon-γ and interleukin-10 were notably increased and decreased, respectively, in SHANK3 mutant beagle dogs. Infusion of SHED was able to rescue altered interferon-γ and interleukin-10 levels. We failed to observe any serious adverse events after infusion of SHED. In summary, SHED transplantation may be a safe and effective therapy for ASD. The correction in the levels of serum interferon-γ and interleukin-10 may serve as an index to predict autistic severity and therapeutic outcomes.

CD146 controls the quality of clinical grade mesenchymal stem cells from human dental pulp.

BACKGROUND: Human mesenchymal stem cells from dental pulp (hMSC-DP), including dental pulp stem cells from permanent teeth and exfoliated deciduous teeth, possess unique MSC characteristics such as expression of specific surface molecules and a high proliferation rate. Since hMSC-DP have been applied in numerous clinical studies, it is necessary to establish criteria to evaluate their potency for cell-based therapies. METHODS: We compared stem cell properties of hMSC-DP at passages 5, 10 and 20 under serum (SE) and serum-free (SF) culture conditions. Cell morphology, proliferation capacity, chromosomal stability, surface phenotypic profiles, differentiation and immunoregulation ability were evaluated. In addition, we assessed surface molecule that regulates hMSC-DP proliferation and immunomodulation. RESULTS: hMSC-DP exhibited a decrease in proliferation rate and differentiation potential, as well as a reduced expression of CD146 when cultured under continuous passage conditions. SF culture conditions failed to alter surface marker expression, chromosome stability or proliferation rate when compared to SE culture. SF-cultured hMSC-DP were able to differentiate into osteogenic, adipogenic and neural cells, and displayed the capacity to regulate immune responses. Notably, the expression level of CD146 showed a positive correlation with proliferation, differentiation, and immunomodulation, suggesting that CD146 can serve as a surface molecule to evaluate the potency of hMSC-DP. Mechanistically, we found that CD146 regulates proliferation and immunomodulation of hMSC-DP through the ERK/p-ERK pathway. CONCLUSION: This study indicates that SF-cultured hMSC-DP are appropriate for producing clinical-grade cells. CD146 is a functional surface molecule to assess the potency of hMSC-DP.

Dephosphorylation of Caveolin-1 Controls C-X-C Motif Chemokine Ligand 10 Secretion in Mesenchymal Stem Cells to Regulate the Process of Wound Healing.

Mesenchymal stem cells (MSCs) secrete cytokines in a paracrine or autocrine manner to regulate immune response and tissue regeneration. Our previous research revealed that MSCs use the complex of Fas/Fas-associated phosphatase-1 (Fap-1)/caveolin-1 (Cav-1) mediated exocytotic process to regulate cytokine and small extracellular vesicles (EVs) secretion, which contributes to accelerated wound healing. However, the detailed underlying mechanism of cytokine secretion controlled by Cav-1 remains to be explored. We show that Gingiva-derived MSCs (GMSCs) could secrete more C-X-C motif chemokine ligand 10 (CXCL10) but showed lower phospho-Cav-1 (p-Cav-1) expression than skin-derived MSCs (SMSCs). Moreover, dephosphorylation of Cav-1 by a Src kinase inhibitor PP2 significantly enhances CXCL10 secretion, while activating phosphorylation of Cav-1 by H2O2 restraints CXCL10 secretion in GMSCs. We also found that Fas and Fap-1 contribute to the dephosphorylation of Cav-1 to elevate CXCL10 secretion. Tumor necrosis factor-α serves as an activator to up-regulate Fas, Fap-1, and down-regulate p-Cav-1 expression to promote CXCL10 release. Furthermore, local applying p-Cav-1 inhibitor PP2 could accelerate wound healing, reduce the expression of α-smooth muscle actin and increase cleaved-caspase 3 expression. These results indicated that dephosphorylation of Cav-1 could inhibit fibrosis during wound healing. The present study establishes a previously unknown role of p-Cav-1 in controlling cytokine release of MSC and may present a potential therapeutic approach for promoting scarless wound healing.

Exosomes from TNF-α-treated human gingiva-derived MSCs enhance M2 macrophage polarization and inhibit periodontal bone loss.

Mesenchymal stem cell (MSC)-derived exosome plays a central role in the cell-free therapeutics involving MSCs and the contents can be customized under disease-associated microenvironments. However, optimal MSC-preconditioning to enhance its therapeutic potential is largely unknown. Here, we show that preconditioning of gingival tissue-derived MSCs (GMSCs) with tumor necrosis factor-alpha (TNF-α) is ideal for the treatment of periodontitis. TNF-α stimulation not only increased the amount of exosome secreted from GMSCs, but also enhanced the exosomal expression of CD73, thereby inducing anti-inflammatory M2 macrophage polarization. The effect of GMSC-derived exosomes on inflammatory bone loss were examined by ligature-induced periodontitis model in mice. Local injection of GMSC-derived exosomes significantly reduced periodontal bone resorption and the number of tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts, and these effects were further enhanced by preconditioning of GMSCs with TNF-α. Thus, GMSC-derived exosomes also exhibited anti-osteoclastogenic activity. Receptor activator of NF-κB ligand (RANKL) expression was regulated by Wnt5a in periodontal ligament cells (PDLCs), and exosomal miR-1260b was found to target Wnt5a-mediated RANKL pathway and inhibit its osteoclastogenic activity. These results indicate that significant ability of the TNF-α-preconditioned GMSC-derived exosomes to regulate inflammation and osteoclastogenesis paves the way for establishment of a therapeutic approach for periodontitis.

Dental Pulp Stem Cells: From Discovery to Clinical Application.

Postnatal stem cells critically maintain tissue homeostasis and possess immense potential for tissue regeneration. These stem cells in the orofacial system were not identified until early 2000s when they were first found in the dental pulp and termed dental pulp stem cells (DPSCs). Isolated from either permanent or deciduous teeth, DPSCs were characterized to be highly clonogenic with multidifferentiation and neurovascular properties. Subsequent studies suggested that the origin of DPSCs may be associated with neural crest-derived cells and localized adjacent to neurovascular bundles as indicated by specific surface markers. DPSCs serve as key contributors to pulp homeostasis and injury repair. Mechanistic studies have revealed a fine-tuning regulatory network composed of both extrinsic and intrinsic factors that orchestrate fates of DPSCs. These findings have shaped our understanding of their biological nature as niche responsive progenitors. As we explore the potential of DPSCs in pulp regeneration, preclinical studies have developed diverse DPSC transplantation-based strategies, among which preconditioned DPSCs and DPSC aggregates have shown particular promise. Confirmed by recent clinical advances, DPSC transplantation after pulpectomy has successfully rebuilt the physiological pulp structure in situ functionalized with neurovascularization, indicating a novel regenerative approach for treating pulp diseases. Here, we summarized the 20-year golden journey on DPSCs from the unprecedented discovery to current clinical breakthroughs, while also suggesting future directions and challenges regarding expansion of regenerative applications and evaluation of in vivo DPSCs in diseases and therapies. The historical perspective of this field will provide a blueprint for the stem cell research and enlighten principles for de novo organ regeneration.

Mechanical load-induced H2S production by periodontal ligament stem cells activates M1 macrophages to promote bone remodeling and tooth movement via STAT1.

BACKGROUND: Tooth movement is a unique bone remodeling process induced by mechanical stimulation. Macrophages are important in mediating inflammatory processes during mechanical load-induced tooth movement. However, how macrophages are regulated under mechanical stimulation remains unclear. Mesenchymal stem cells (MSCs) can modulate macrophage polarization during bone remodeling. Hydrogen sulfide (H2S) can be produced by MSCs and have been linked to bone homeostasis. Therefore, this study aimed to investigate whether H2S contributed to periodontal ligament stem cell (PDLSC)-regulated macrophage polarization and bone remodeling under mechanical stimulation. METHODS: An experimental mechanical load-induced tooth movement animal model was established. Changes in cystathionine-ß-synthase (CBS), markers of M1/M2 macrophages, tooth movement distance, and the number of osteoclasts were examined. The conditioned medium of PDLSCs with or without mechanical loading was utilized to treat THP-1 derived macrophages for 24 h to further investigate the effect of PDLSCs on macrophage polarization. Different treatments with H2S donor, CBS inhibitor, or the inhibitor of STAT1 were used to investigate the related mechanism. Markers of M1/M2 polarization and STAT1 pathway expression were evaluated in macrophages. RESULTS: Mechanical load promoted tooth movement and increased the number of M1-like macrophages, M1-associated pro-inflammatory cytokines, and the expression of CBS on the compression side of the periodontal ligament. The injection of CBS inhibitor or H2S donor could further repress or increase the number of M1-like macrophages, tartrate-resistant acid phosphatase-positive osteoclasts and the distance of tooth movement. Mechanistically, load-induced PDLSCs enhanced H2S production, which increased the expression of M1-associated cytokines in macrophages. These effects could be blocked by the administration of CBS inhibitor. Moreover, load-induced H2S steered M1 macrophage polarization via the STAT1 signaling pathway. CONCLUSIONS: These data suggest a novel mechanism indicating that mechanical load-stimulated PDLSCs produce H2S to polarize macrophages toward the M1 phenotype via the STAT1 signaling pathway, which contributes to bone remodeling and tooth movement process. These results provide new insights into the role of PDLSCs in regulating macrophage polarization and mediating bone remodeling under mechanical stimulation, and indicate that appropriate H2S supplementation may accelerate tooth movement.

The Role of Interleukin 6 in Osteogenic and Neurogenic Differentiation Potentials of Dental Pulp Stem Cells.

INTRODUCTION: Studies have shown that there is a significantly higher concentration of interleukin 6 (IL-6) in inflamed pulp tissues compared with healthy pulp tissues. The aims of this study were to investigate the baseline differences between mesenchymal stem cells (MSCs) isolated from healthy human dental pulp stem cells (H-DPSCs) and inflamed dental pulp stem cells (I-DPSCs) and their correlation to IL-6 and to determine whether IL-6 can affect the differentiation potentials of these cells. METHODS: MSCs isolated from healthy and inflamed pulp tissues were cultured and characterized in vitro. The levels of secreted IL-6 in the culture supernatants from H-DPSCs and I-DPSCs were measured by enzyme-linked immunosorbent assay. IL-6 and neutralizing IL-6 were added to H-DPSCs and I-DPSCs, respectively. Immunofluorescence staining, alizarin red staining, and Western blotting were performed to assess the differentiation potentials of H-DPSCs and I-DPSCs. The independent unpaired 2-tailed Student's t-test was performed after quantification analysis. RESULTS: H-DPSCs and I-DPSCs showed a similar expression of MSC-associated markers including CD44, CD73, CD90, and CD105, whereas H-DPSCs showed a lower level of IL-6, lower osteogenic differentiation potentials, and higher neurogenic differentiation potentials compared with I-DPSCs. The addition of IL-6 to H-DPSCs increased osteogenic potentials and decreased neurogenic potentials, whereas the neutralization of IL-6 for I-DPSCs led to decreased osteogenic potentials and increased neurogenic potentials. CONCLUSIONS: The findings of this study indicated IL-6 has the capacity to enhance osteogenesis while hindering neurogenesis of DPSCs.

The Fas/Fap-1/Cav-1 complex regulates IL-1RA secretion in mesenchymal stem cells to accelerate wound healing.

Mesenchymal stem cells (MSCs) are capable of secreting exosomes, extracellular vesicles, and cytokines to regulate cell and tissue homeostasis. However, it is unknown whether MSCs use a specific exocytotic fusion mechanism to secrete exosomes and cytokines. We show that Fas binds with Fas-associated phosphatase-1 (Fap-1) and caveolin-1 (Cav-1) to activate a common soluble N-ethylmaleimide-sensitive factor (NSF) attachment protein receptor (SNARE)-mediated membrane fusion mechanism to release small extracellular vesicles (sEVs) in MSCs. Moreover, we reveal that MSCs produce and secrete interleukin-1 receptor antagonist (IL-1RA) associated with sEVs to maintain rapid wound healing in the gingiva via the Fas/Fap-1/Cav-1 cascade. Tumor necrosis factor-α (TNF-α) serves as an activator to up-regulate Fas and Fap-1 expression via the nuclear factor κB pathway to promote IL-1RA release. This study identifies a previously unknown Fas/Fap-1/Cav-1 axis that regulates SNARE-mediated sEV and IL-1RA secretion in stem cells, which contributes to accelerated wound healing.

PD-1 is required to maintain stem cell properties in human dental pulp stem cells.

Programmed cell death-1 (PD-1) belongs to an inhibitory signaling pathway capable of maintaining central and peripheral immune tolerance. Blockage of PD-1 has been identified as a promising immunotherapeutic approach for cancer and chronic infectious diseases. However, it is unknown whether PD-1 pathway regulates stem cell function. It is generally believed that mesenchymal stem cells (MSCs) produce PD-1 ligand, but fail to express PD-1. In this study, we show that neural crest-derived MSCs from dental pulp (MSC-DP), but not MSCs from bone marrow, expressed PD-1. Knocking down PD-1 expression in MSC-DP results in a significantly reduced capacity for cell proliferation and accelerated multipotential differentiation. Mechanistically, we show that PD-1 regulates a SHP2/ERK/Notch cascade to maintain proliferation and a SHP2/ERK/ß-catenin cascade to inhibit osteo-/odontogenic differentiation. This study indicates that PD-1 is a key surface molecule controlling cell proliferation and multipotential differentiation of MSC-DP. Through regulating PD-1/SHP2/ERK signaling, we can significantly improve the quality and quantity of culture-expanded MSC-DP for potential clinical therapies.

Deciduous autologous tooth stem cells regenerate dental pulp after implantation into injured teeth.

Pulp necrosis arrests root development in injured immature permanent teeth, which may result in tooth loss. However, dental pulp regeneration and promotion of root development remains challenging. We show that implantation of autologous tooth stem cells from deciduous teeth regenerated dental pulp with an odontoblast layer, blood vessels, and nerves in two animal models. These results prompted us to enroll 40 patients with pulp necrosis after traumatic dental injuries in a randomized, controlled clinical trial. We randomly allocated 30 patients to the human deciduous pulp stem cell (hDPSC) implantation group and 10 patients to the group receiving traditional apexification treatment. Four patients were excluded from the implantation group due to loss at follow-up (three patients) and retrauma of the treated tooth (one patient). We examined 26 patients (26 teeth) after hDPSC implantation and 10 patients (10 teeth) after apexification treatment. hDPSC implantation, but not apexification treatment, led to regeneration of three-dimensional pulp tissue equipped with blood vessels and sensory nerves at 12 months after treatment. hDPSC implantation increased the length of the root (P < 0.0001) and reduced the width of the apical foramen (P < 0.0001) compared to the apexification group. In addition, hDPSC implantation led to regeneration of dental pulp tissue containing sensory nerves. To evaluate the safety of hDPSC implantation, we followed 20 patients implanted with hDPSCs for 24 months and did not observe any adverse events. Our study suggests that hDPSCs are able to regenerate whole dental pulp and may be useful for treating tooth injuries due to trauma.

Effect of intraoral mechanical stress application on the expression of a force-responsive prognostic marker associated with system disease progression.

OBJECTIVES: Malocclusion may be corrected nonsurgically by mechanical tooth movement. The plasma protein profiles of human subjects receiving the first phase of orthodontic treatment were examined to test the hypothesis that application of mechanical stresses to teeth induces systemic proteomic alterations. METHODS: Tandem mass tag-based liquid chromatography-mass spectrometry (LC-MS/MS) was used to examine systemic proteomic alterations in subjects undergoing controlled stress application (N=10) and in volunteers not receiving treatment (N=7) at 3 time intervals within 24h. Proteins differentially expressed by the tooth movement group were functionally analyzed with "Gene Ontology" (GO) and "Search Tool to Retrieve Interacting Genes/proteins" (STRING) softwares. Enzyme-Linked Immunosorbent Assay and Western-blot were used to validate the in vivo protein alterations. An in vitro model consisting of human periodontal ligament cells (hPDLCs) under compression was used to validate the force-responsive characteristics of galectin-3 binding protein (LGALS3BP). RESULTS: Sixteen out of the 294 proteins identified by LC-MS/MS were differentially expressed in the plasma of subjects receiving controlled mechanical stresses for moving teeth. Those proteins were clustered in biological processes related to acute inflammatory response and vesicle-related transportation. Serotransferrin, fibronectin and LGALS3BP were processed for confirmation in vivo; LGALS3BP was significantly increased in the tooth movement group. In vitro secretion of LGALS3BP in PDLCs was force-responsive. CONCLUSIONS: Regional application of mechanical stresses stimulates systemic proteomic changes. Because serum LGALS3BP is over-expressed in different systemic diseases, including cancer, further work is needed to examine how systemic up-regulation of LGALS3BP affects the progression of those diseases.

Influence of Surface Chemistry on Adhesion and Osteo/Odontogenic Differentiation of Dental Pulp Stem Cells.

The complex interaction between extracellular matrix and cells makes the design of materials for dental regeneration challenging. Chemical composition is an important characteristic of biomaterial surfaces, which plays an essential role in modulating the adhesion and function of cells. The effect of different chemical groups on directing the fate of human dental pulp stem cells (hDPSCs) was thus explored in our study. A range of self-assembled monolayers (SAMs) with amino (-NH2), hydroxyl (-OH), carboxyl (-COOH), and methyl (-CH3) modifications were prepared. Proliferation, morphology, adhesion, and differentiation of hDPSCs were then analyzed to demonstrate the effects of surface chemical groups. The results showed that hDPSCs attached to the -NH2 surface displayed a highly branched osteocyte-like morphology with improved cell adhesion and proliferation abilities. Moreover, hDPSCs cultured on the -NH2 surface also tended to obtain an increased osteo/odontogenesis differentiation potential. However, the hDPSCs on the -COOH, -OH, and -CH3 surfaces preferred to maintain the mesenchymal stem cell-like phenotype. In summary, this study indicated the influence of chemical groups on hDPSCs in vitro and demonstrated that -NH2 might be a promising surface modification strategy to achieve improved biocompatibility, osteoconductivity/osteoinductivity, and osseointegration of dental implants, potentially facilitating dental tissue regeneration.

Effect of nanostructure of mineralized collagen scaffolds on their physical properties and osteogenic potential.

Tissue engineering has enabled development of nanostructured collagen scaffolds to meet current challenges in regeneration of lost bone. In this study, extrafibrillarly-mineralized and intrafibrillarly-mineralized collagen scaffolds were fabricated separately by a conventional crystallization method and a biomimetic, bottom-up crystallization method. Atomic force microscopy (AFM) was employed to examine the nanotopography and nanomechanics of the mineralized collagen scaffolds. The in vitro cell responses to the surface of the mineralized collagen scaffolds were analyzed by laser scanning microscope and field emission scanning electron microscopy. AFM imaging showed that these two mineralized collagen scaffolds exhibited different nanostructure, including the size, morphology and location of the apatites in collagen fibrils. The nanomechanical testing demonstrated that the intrafibrillarly-mineralized collagen scaffold, with bone-like hierarchy, featured a significantly increased Young's modulus compared with the extrafibrillarly-mineralized collagen scaffold in both dry and wet conditions. However, these two mineralized collagen scaffolds had a similar thermal behavior. From the cell culture experiments, the intrafibrillarly-mineralized collagen scaffold showed higher cell proliferation and alkaline phosphatase activity than the extrafibrillarly-mineralized collagen scaffold. The utmost significance of this study is that the nanostructure of the mineralized collagen scaffolds can affect the initial cell adhesion, morphology and further osteogenic potential. The present study will help us to fabricate novel biomaterials for bone grafting and tissue engineering applications.