Modulation of microenvironment for controlling the fate of periodontal ligament cells: the role of Rho/ROCK signaling and cytoskeletal dynamics

Engineered 3D Periodontal Ligament Model with Magnetic Tensile Loading

In vitro models are invaluable tools for deconstructing the biological complexity of the periodontal ligament (PDL). Model systems that closely reproduce the 3-dimensional (3D) configuration of cell-cell and cell-matrix interactions in native tissue can deliver physiologically relevant insights. However, 3D models of the PDL that incorporate mechanical loading are currently lacking. Hence, we developed a model where periodontal tissue constructs (PTCs) are made by casting PDL cells in a collagen gel suspended between a pair of slender, silicone posts for magnetic tensile loading. Specifically, one of the posts was rigid and the other was flexible with a magnet embedded in its tip so that PTCs could be subjected to tensile loading with an external magnet. Additionally, the deflection of the flexible post could be used to measure the contractile force of PDL cells in the PTCs. Prior to tensile loading, second harmonics generation analysis of collagen fibers in PTCs revealed that incorporation of PDL cells resulted in collagen remodeling. Biomechanical testing of PTCs by tensile loading revealed an elastic response at 4 h, permanent deformation by 1 d, and creep elongation by 1 wk. Subsequently, contractile forces of PDL cells were substantially lower for PTCs under tensile loading. Immunofluorescence analysis revealed that tensile loading caused PDL cells to increase in number, express higher levels of F-actin and α-smooth muscle actin, and become aligned to the tensile axis. Second harmonics generation analysis indicated that collagen fibers in PTCs progressively remodeled over time with tensile loading. Gene expression analysis also confirmed tension-mediated upregulation of the F-actin/Rho pathway and osteogenic genes. Our model is novel in demonstrating the mechanobiological behavior that results in cell-mediated remodeling of the PDL tissue in a 3D context. Hence, it can be a valuable tool to develop therapeutics for periodontitis, periodontal regeneration, and orthodontics.

Identification of critical genes associated with oxidative stress pathways in benzene-induced hematotoxicity

Background and aims

Bone marrow failure (BMF) is chronic benzene-induced hematotoxicity, which is associated with differential gene expression abnormality. Benzene-induced BMF is characterized by irreversible bone marrow depression. Despite extensive studies have been conducted, there is a lack of reliable, useful and simple diagnostic method for BMF. Previous studies have shown that the aberrant gene expression changes and reactive oxygen species production in bone marrow cells related to the development of BMF. Early detection of differentially expressed genes (DEGs) as potential biomarkers is important for diagnosis and treatment. However, the validation of effective biomarker through DEGs analysis in benzene-induced BMF still deserve to be clarified. This study aimed to identify target genes as potential biomarkers with benzene-induced BMF based on DEGs analysis.

Methods

First, we developed a benzene-induced BMF mouse model and obtained the DEGs in bone marrow cells of benzene-exposed CD1 mice. Next, after obtaining the DEGs via RNA-Sequencing (RNA-seq) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were also used, key genes associated with benzene-induced BMF were identified. Additionally, the key markers for benzene poisoning was evaluated using qRT-PCR technique.

Results

We identified DEGs for further KEGG functional analysis. Ten statistically significantly (up or down) regulated genes, namely Mapk11, Foxo1, Lefty1, Ren1, Bank1, Fgf3, Cdc42ep2, Rasgrf1, P2rx7, and Shank3 were found mainly associated with mitogen-activated protein kinases (MAPK) oxidative stress pathway . Further analysis using qRT-PCR identified that eight statistically significant DEGs associated with signaling pathways such as MAPK. We found that the level of mRNA expression of Mapk11, Foxo1, Bank1, Lefty1, Ren1, P2rx7, and Fgf3 genes were increased and Cdc42ep2 gene was decreased in BMF mice compared to control mice. Additionally, we validated the eight candidate genes for potential biomarkers in peripheral blood mononuclear cells of benzene poisoning patients by qRT-PCR.

Conclusion

Our results indicated that Mapk11 and Fgf3 were predominantly candidate genes linked to novel biomarkers for benzene hematotoxicity in human beings. Our study will provide new candidate genes as useful biomarkers involved in benzene-induced hematotoxicity.

Effects of mechanical loading on matrix homeostasis and differentiation potential of periodontal ligament cells: A scoping review

Various mechanical loadings, including mechanical stress, orthodontics forces, and masticatory force, affect the functions of periodontal ligament cells. Regulation of periodontal tissue destruction, formation, and differentiation functions are crucial processes for periodontal regeneration therapy. Numerous studies have reported that different types of mechanical loading play a role in maintaining periodontal tissue matrix homeostasis, and osteogenic differentiation of the periodontal ligament cells. This scoping review aims to evaluate the studies regarding the effects of various mechanical loadings on the secretion of extracellular matrix (ECM) components, regulation of the balance between formation and destruction of periodontal tissue matrix, osteogenic differentiation, and multiple differentiation functions of the periodontal ligament. An electronic search for this review has been conducted on two databases; MEDLINE via PubMed and SCOPUS. Study selection criteria included original research written in English that reported the effects of different mechanical loadings on matrix homeostasis and differentiation potential of periodontal ligament cells. The final 204 articles were mainly included in the present scoping review. Mechanical forces of the appropriate magnitude, duration, and pattern have a positive influence on the secretion of ECM components such as collagen, as well as regulate the secretion of matrix metalloproteinases and tissue inhibitors of matrix metalloproteinases. Additionally, these forces regulate a balance between osteoblastic and osteoclast differentiation. Conversely, incorrect mechanical loadings can lead to abnormal formation and destruction of both soft and hard tissue. This review provides additional insight into how mechanical loadings impact ECM homeostasis and multiple differentiation functions of periodontal ligament cells (PDLCs), thus making it valuable for regenerative periodontal treatment. In combination with advancing technologies, the utilization of ECM components, application of different aspects of mechanical force, and differentiation potential of PDLCs could bring potential benefits to future periodontal regeneration therapy.

[Rho kinase inhibitor Y27632 promotes survival of human induced pluripotent stem cells during differentiation into functional midbrain dopaminergic progenitor cells in vitro]

OBJECTIVE

To improve the efficiency of induced differentiation of primitive neural epithelial cells derived from human induced pluripotent stem cells (hiPSCs-NECs) into functional midbrain dopaminergic progenitor cells (DAPs).

METHODS

HiPSCs were cultured in mTeSRTM medium containing DMH1 (10 μmol/L), SB431542 (10 μmol/L), SHH (200 ng/mL), FGF8 (100 ng/mL), purmorphamine (2 μmol/L), CHIR99021 (3 μmol/L), and N2 (1%) for 12 days to induce their differentiation into primitive neuroepithelial cells (NECs). The hiPSCs-NECs were digested with collagenase Ⅳ and then cultured in neurobasal medium supplemented with 1% N2, 2% B27-A, BDNF (10 ng/mL), GDNF (10 ng/mL), AA, TGF-β, cAMP, and 1% GlutaMax in the presence of different concentrations of Rho kinase inhibitor Y27632, and the culture medium was changed the next day to remove Y27632. Continuous induction was performed until day 28 to obtain DAPs.

RESULTS

Human iPSCs expressed the pluripotency markers OCT4, SOX2, Nanog, and SSEA1 and were positive for alkaline phosphatase staining. The hiPSCs-NECs were obtained on day 13 in the form of neural rosettes expressing neuroepithelial markers SOX2, nestin, and PAX6. In digested hiPSCs-NECs, the addition of 5 μmol/L Y27632 significantly promoted survival of the adherent cells, increased cell viability and the proportion of S-phase cells (P < 0.01), and reduced the rate of apoptotic cells (P < 0.05). On day 28 of induction, the obtained cells highly expressed the specific markers of DAPS (TH, FOXA2, NURR1, and Tuj1).

CONCLUSION

Treatment with Y27632 (5 μmol/L) for 24 h significantly promotes the survival of human iPSCs-NECs during their differentiation into DPAs without affecting the cell differentiation, which indirectly enhances the efficiency of cell differentiation.

3D printed pore morphology mediates bone marrow stem cell behaviors via RhoA/ROCK2 signaling pathway for accelerating bone regeneration

Bone bionics and structural engineering have sparked a broad interest in optimizing artificial scaffolds for better bone regeneration. However, the mechanism behind scaffold pore morphology-regulated bone regeneration remains unclear, making the structure design of scaffolds for bone repair challenging. To address this issue, we have carefully assessed diverse cell behaviors of bone mesenchymal stem cells (BMSCs) on the β-tricalcium phosphate (β-TCP) scaffolds with three representative pore morphologies (i.e., cross column, diamond, and gyroid pore unit, respectively). Among the scaffolds, BMSCs on the β-TCP scaffold with diamond pore unit (designated as D-scaffold) demonstrated enhanced cytoskeletal forces, elongated nucleus, faster cell mobility, and better osteogenic differentiation potential (for example, the alkaline phosphatase expression level in D-scaffold were 1.5-2 times higher than other groups). RNA-sequencing analysis and signaling pathway intervention revealed that Ras homolog gene family A (RhoA)/Rho-associated kinase-2 (ROCK2) has in-depth participated in the pore morphology-mediated BMSCs behaviors, indicating an important role of mechanical signaling transduction in scaffold-cell interactions. Finally, femoral condyle defect repair results showed that D-scaffold could effectively promote endogenous bone regeneration, of which the osteogenesis rate was 1.2-1.8 times higher than the other groups. Overall, this work provides insights into pore morphology-mediated bone regeneration mechanisms for developing novel bioadaptive scaffold designs.

Retinol binding protein 4 promotes the phenotypic transformation of vascular smooth muscle cells under high glucose condition via modulating RhoA/ROCK1 pathway

BACKGROUND

Phenotypic switch of vascular smooth muscle cells (VSMCs) contributes to the pathogenesis of atherosclerosis (AS). High level of retinol binding protein 4 (RBP4) is regarded as a risk factor in cardiac-cerebral vascular disease. This study is performed to clarify the biological function of RBP4 in modulating the phenotypic switch of VSMCs induced via RhoA/ROCK1 signaling pathway.

METHODS AND MATERIALS

In vivo experiment, all the rats were dividedinto control group (NC), diabetic group (DM) and diabetic atherosclerosis group(DAS). The expressions of biochemical indicators, RhoA and Rho associated coiled-coil containing protein kinase 1 (ROCK1) were detected. In vitro experiment, VSMCs were cultured under high glucose condition, and ectogenic RBP4, HA-1100, rapamycin or 3-Methyladenine (3-MA) were supplemented to treat the VSMCs, respectively. The proliferation and migration of VSMCs were evaluated. The regulatory relationship between RBP4 and ROCK1was predicted by bioinformatics analysis, and validated by qRT-PCR and Western blot. The regulatory effects of RBP4 on contractile phenotypic markers such as calponin, MYH11, α-SMA and autophagy markers including LC3II, LC3I and Beclin-1 as well as mTOR were also detected. Moreover, VSMCs were cultured exposed to ROCK1 overexpressed plasmid or short hairpin RNA (shRNA), the proliferation and migration of VSMCs were evluated and the regulatory effects of RhoA/ROCK1 signaling pathway on contractile phenotypic markers and autophagy markers were also detected.

RESULTS

In vivo, RhoA, ROCK1 and mTOR were highly expressed in the rats intraperitoneally injected with RBP4. In vitro, the expressions of calponin, MYH11, α-SMA, LC3II, LC3I and Beclin-1 were decreased in VSMCs treated with ROCK1-OA under high glucose condition, conversely, the expressions were increased in VSMCs exposed to ROCK1-shRNA. Ectogenic RBP4 facilitated high glucose-induced proliferation and migration of VSMCs, and it repressed the expression of calponin, MYH11, α-SMA, LC3II/Iand Beclin-1 in VSMCs. As expected, ROCK1 inhibit or counteracted the biological effects of RBP4 on VSMCs. In addition, the expressions of contractile phenotypic markers, LC3II/I and Beclin-1 were promoted and mTOR were decreased after the VSMCs treated with autophagy agonist, whereas no significant difference was observed in the expressions of ROCK1, RhoA.

CONCLUSION

RBP4 is an injurious factor in the pathogenesis of diabetic AS, and it promotes the phenotypic switch of VSMCs via activating RhoA/ROCK1 pathway and inhibiting autophagy.

LIPUS as a potential strategy for periodontitis treatment: A review of the mechanisms

Periodontitis is a chronic inflammatory condition triggered by oral bacteria. A sustained inflammatory state in periodontitis could eventually destroy the alveolar bone. The key objective of periodontal therapy is to terminate the inflammatory process and reconstruct the periodontal tissues. The traditional Guided tissue regeneration (GTR) procedure has unstable results due to multiple factors such as the inflammatory environment, the immune response caused by the implant, and the operator's technique. Low-intensity pulsed ultrasound (LIPUS), as acoustic energy, transmits the mechanical signals to the target tissue to provide non-invasive physical stimulation. LIPUS has positive effects in promoting bone regeneration, soft-tissue regeneration, inflammation inhibition, and neuromodulation. LIPUS can maintain and regenerate alveolar bone during an inflammatory state by suppressing the expression of inflammatory factors. LIPUS also affects the cellular behavior of periodontal ligament cells (PDLCs), thereby protecting the regenerative potential of bone tissue in an inflammatory state. However, the underlying mechanisms of the LIPUS therapy are still yet to be summarized. The goal of this review is to outline the potential cellular and molecular mechanisms of periodontitis-related LIPUS therapy, as well as to explain how LIPUS manages to transmit mechanical stimulation into the signaling pathway to achieve inflammatory control and periodontal bone regeneration.

Neuroprotective effects of nobiletin on cerebral ischemia/reperfusion injury rats by inhibiting Rho/ROCK signaling pathway

Background

Nobiletin (NOB), an active natural flavonoid component of citrus, is used in Traditional Chinese Medicine for its anti-inflammatory activity, but its efficacy in cerebral ischemia/reperfusion (I/R) injury remains unclear.

Methods

In a middle cerebral artery occlusion (MCAO) rat model, MCAO rats were administered (Sham group and MCAO model group treated with an equal volume of solvent, NOB group treated with 10 or 20 mg/kg NOB) once a day for 7 days before cerebral ischemia and again after reperfusion, 2,3,5-triphenyltetrazolium chloride (TTC) staining was applied to assess the infarct area. Neurological function was evaluated by the modified neurological severity score and Morris water maze. The levels of inflammatory factors, interleukin 6 (IL-6), interleukin 1β (IL-1β) and tumor necrosis factor-α (TNF-α), were examined by enzyme-linked immunosorbent assay (ELISA). Histopathological staining evaluated neuron apoptosis in brain tissue. In an oxygen-glucose deprivation PC12 cell (OGD PC12) model, the proliferation, migration and apoptosis of OGD PC12 cells were detected by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) and cell migration assays and flow cytometry. The gene and protein expression levels of Ras homolog gene family, member A (Rho A), ras-related C3 botulinum toxin substrate 1 (Rac 1), Rho-associated kinase 1 (ROCK 1), ROCK 2 in the Rho/ROCK pathway were measured by Real-time PCR (RT-PCR), immunohistochemistry and western blot.

Results

In rats with cerebral I/R injury, NOB significantly decreased the infarcted area, neuron apoptosis in brain tissue and expressions of IL-6, IL-1β, and TNF-α. It also improved neurological deficits in brain tissue and enhanced learning and memory ability. Further, NOB had a protective effect on OGD PC12 cells, increasing proliferation and migration and decreasing apoptosis. The expressions of Rho A, Rac 1, ROCK 1 and ROCK 2 were high in cerebral I/R injury rats, but were downregulated by NOB in I/R injury rats' brain tissue and OGD PC12 cells.

Conclusions

Nobiletin had a neuroprotective effect in rats with cerebral I/R injury, and its potential mechanism is decreasing neuron apoptosis by inhibiting the Rho/ROCK signaling pathway. These results suggest NOB is a promising neuroprotective agent for patients with cerebral ischemia.

Stem cell homing in periodontal tissue regeneration

The destruction of periodontal tissue is a crucial problem faced by oral diseases, such as periodontitis and tooth avulsion. However, regenerating periodontal tissue is a huge clinical challenge because of the structural complexity and the poor self-healing capability of periodontal tissue. Tissue engineering has led to advances in periodontal regeneration, however, the source of exogenous seed cells is still a major obstacle. With the improvement of in situ tissue engineering and the exploration of stem cell niches, the homing of endogenous stem cells may bring promising treatment strategies in the future. In recent years, the applications of endogenous cell homing have been widely reported in clinical tissue repair, periodontal regeneration, and cell therapy prospects. Stimulating strategies have also been widely studied, such as the combination of cytokines and chemokines, and the implantation of tissue-engineered scaffolds. In the future, more research needs to be done to improve the efficiency of endogenous cell homing and expand the range of clinical applications.

Thymoquinone-Mediated Modulation of Toll-like Receptors and Pluripotency Factors in Gingival Mesenchymal Stem/Progenitor Cells

Thymoquinone (TQ), the key active component of Nigella sativa (NS), demonstrates very promising biomedical anti-inflammatory, antioxidant, antimicrobial and anticancer properties. Several investigations have inspected the modulative activities of TQ on different stem/progenitor cell types, but its possible role in the regulation of gingival mesenchymal stem/progenitor cells (G-MSCs) has not yet been characterized. For the first time, this study investigates the effects of TQ on G-MSCs’ stemness and Toll-like receptor expression profiles. G-MSCs (n = 5) were isolated, sorted via anti-STRO-1 antibodies and then disseminated on cell culture dishes to create colony-forming units (CFUs), and their stem/progenitor cell attributes were characterized. TQ stimulation of the G-MSCs was performed, followed by an examination of the expression of pluripotency-related factors using RT-PCR and the expression profiles of TLRs 1−10 using flowcytometry, and they were compared to a non-stimulated control group. The G-MSCs presented all the predefined stem/progenitor cells’ features. The TQ-activated G-MSCs displayed significantly higher expressions of TLR3 and NANOG with a significantly reduced expression of TLR1 (p < 0.05, Wilcoxon signed-rank test). TQ-mediated stimulation preserves G-MSCs’ pluripotency and facilitates a cellular shift into an immunocompetent-differentiating phenotype through increased TLR3 expression. This characteristic modulation might impact the potential therapeutic applications of G-MSCs.

Emerging modulators for osteogenic differentiation: a combination of chemical and topographical cues for bone microenvironment engineering

Bone presents an intrinsic ability for self-regeneration and repair, however critical defects and large fractures require invasive and time-consuming clinical interventions. As an alternative to current therapy, bone tissue engineering (BTE) has primarily aimed to recreate the bone microenvironment by delivering key biomolecules and/or by modification of scaffolds to guide cell fate towards the osteogenic lineage or other phenotypes that may benefit the bone regeneration mechanism. Considering that bone cells communicate, in their native microenvironment, through biochemical and physical signals, most strategies fail when considering only chemical, geometrical or mechanical cues. This is not representative of the physiological conditions, where the cells are simultaneously in contact and stimulated by several cues. Therefore, this review explores the synergistic effect of biochemical/physical cues in regulating cellular events, namely cell adhesion, proliferation, osteogenic differentiation, and mineralization, highlighting the importance of the combined modifications for the development of innovative bone regenerative therapies.

Bioactive Glasses in Periodontal Regeneration: Existing Strategies and Future Prospects-A Literature Review

The present review deals with bioactive glasses (BGs), a class of biomaterials renowned for their osteoinductive and osteoconductive capabilities, and thus widely used in tissue engineering, i.e., for the repair and replacement of damaged or missing bone. In particular, the paper deals with applications in periodontal regeneration, with a special focus on in vitro, in vivo and clinical studies. The study reviewed eligible publications, identified on the basis of inclusion/exclusion criteria, over a ranged time of fifteen years (from 1 January 2006 to 31 March 2021). While there are many papers dealing with in vitro tests, only a few have reported in vivo (in animal) research, or even clinical trials. Regardless, BGs seem to be an adequate choice as grafts in periodontal regeneration.

Single-Cell RNA Sequencing Identifies New Inflammation-Promoting Cell Subsets in Asian Patients With Chronic Periodontitis

Periodontitis is a highly prevalent chronic inflammatory disease leading to periodontal tissue breakdown and subsequent tooth loss, in which excessive host immune response accounts for most of the tissue damage and disease progression. Despite of the imperative need to develop host modulation therapy, the inflammatory responses and cell population dynamics which are finely tuned by the pathological microenvironment in periodontitis remained unclear. To investigate the local microenvironment of the inflammatory response in periodontitis, 10 periodontitis patients and 10 healthy volunteers were involved in this study. Single-cell transcriptomic profilings of gingival tissues from two patients and two healthy donors were performed. Histology, immunohistochemistry, and flow cytometry analysis were performed to further validate the identified cell subtypes and their involvement in periodontitis. Based on our single-cell resolution analysis, we identified HLA-DR-expressing endothelial cells and CXCL13+ fibroblasts which are highly associated with immune regulation. We also revealed the involvement of the proinflammatory NLRP3+ macrophages in periodontitis. We further showed the increased cell-cell communication between macrophage and T/B cells in the inflammatory periodontal tissues. Our data generated an intriguing catalog of cell types and interaction networks in the human gingiva and identified new inflammation-promoting cell subtypes involved in chronic periodontitis, which will be helpful in advancing host modulation therapy.

Advanced mechanotherapy: Biotensegrity for governing metastatic tumor cell fate via modulating the extracellular matrix

Mechano-transduction is the procedure of mechanical stimulus translation via cells, among substrate shear flow, topography, and stiffness into a biochemical answer. TAZ and YAP are transcriptional coactivators which are recognized as relay proteins that promote mechano-transduction within the Hippo pathway. With regard to healthy cells in homeostasis, mechano-transduction regularly restricts proliferation, and TAZ and YAP are totally inactive. During cancer development a YAP/TAZ - stimulating positive response loop is formed between the growing tumor and the stiffening ECM. As tumor developments, local stromal and cancerous cells take advantage of mechanotransduction to enhance proliferation, induce their migratory into remote tissues, and promote chemotherapeutic resistance. As a newly progresses paradigm, nanoparticle-conjunctions (such as magnetic nanoparticles, and graphene derivatives nanoparticles) hold significant promises for remote regulation of cells and their relevant events at molecular scale. Despite outstanding developments in employing nanoparticles for drug targeting studies, the role of nanoparticles on cellular behaviors (proliferation, migration, and differentiation) has still required more evaluations in the field of mechanotherapy. In this paper, the in-depth contribution of mechano-transduction is discussed during tumor progression, and how these consequences can be evaluated in vitro.

From the Matrix to the Nucleus and Back: Mechanobiology in the Light of Health, Pathologies, and Regeneration of Oral Periodontal Tissues

Among oral tissues, the periodontium is permanently subjected to mechanical forces resulting from chewing, mastication, or orthodontic appliances. Molecularly, these movements induce a series of subsequent signaling processes, which are embedded in the biological concept of cellular mechanotransduction (MT). Cell and tissue structures, ranging from the extracellular matrix (ECM) to the plasma membrane, the cytosol and the nucleus, are involved in MT. Dysregulation of the diverse, fine-tuned interaction of molecular players responsible for transmitting biophysical environmental information into the cell's inner milieu can lead to and promote serious diseases, such as periodontitis or oral squamous cell carcinoma (OSCC). Therefore, periodontal integrity and regeneration is highly dependent on the proper integration and regulation of mechanobiological signals in the context of cell behavior. Recent experimental findings have increased the understanding of classical cellular mechanosensing mechanisms by both integrating exogenic factors such as bacterial gingipain proteases and newly discovered cell-inherent functions of mechanoresponsive co-transcriptional regulators such as the Yes-associated protein 1 (YAP1) or the nuclear cytoskeleton. Regarding periodontal MT research, this review offers insights into the current trends and open aspects. Concerning oral regenerative medicine or weakening of periodontal tissue diseases, perspectives on future applications of mechanobiological principles are discussed.

Silencing integrin α6 enhances the pluripotency-differentiation transition in human dental pulp stem cells

OBJECTIVES

Although integrins have been shown to be associated with proliferation and differentiation in some stem cells, the regulatory effect of integrin α6 (ITGα6) on the human dental pulp stem cells (hDPSCs) has not been reported. Here, we detected the roles of ITGα6 in hDPSCs.

MATERIALS AND METHODS

Attached to Cytodex 3 microcarriers, hDPSCs grown under stimulated microgravity (SMG) or conventional culture conditions were measured the proliferation and different gene expression. Further, ITGα6 was silenced in hDPSCs, and its effect on proliferation, differentiation, and cytoskeletal organization was analyzed.

RESULTS

SMG conditions increased the number of Ki67-positive hDPSCs and progression into S phase of cell cycle. WB analysis showed the expression of ITGα6 was upregulated in hDPSCs under SMG conditions. Knockdown of ITGα6 decreased the expression of stemness markers, CD105 and STRO-1 in hDPSCs, but promoted the osteogenic and odontogenic differentiation by increased ALP expression and Alizarin Red nodules. Moreover, RNA-seq demonstrated that RHO/ROCK signaling pathway upregulated silencing ITGα6-hDPSCs. Treatment with Y-27632 inhibited the effect of ITGα6 depletion on hDPSCs stemness, rearranged the cytoskeleton, promoted the pluripotency, proliferation ability, and inhibited the differentiation.

CONCLUSION

ITGα6 promotes hDPSCs stemness via inhibiting RHO/ROCK and restoring cytoskeleton.

Induction of osteogenic differentiation of bone marrow stromal cells on 3D polyester-based scaffolds solely by subphysiological fluidic stimulation in a laminar flow bioreactor

The fatal determination of bone marrow mesenchymal stem/stromal cells (BMSC) is closely associated with mechano-environmental factors in addition to biochemical clues. The aim of this study was to induce osteogenesis in the absence of chemical stimuli using a custom-designed laminar flow bioreactor. BMSC were seeded onto synthetic microporous scaffolds and subjected to the subphysiological level of fluid flow for up to 21 days. During the perfusion, cell proliferation was significantly inhibited. There were also morphological changes, with F-actin polymerisation and upregulation of ROCK1. Notably, in BMSC subjected to flow, mRNA expression of osteogenic markers was significantly upregulated and RUNX2 was localised in the nuclei. Further, under perfusion, there was greater deposition of collagen type 1 and calcium onto the scaffolds. The results confirm that an appropriate level of fluid stimuli preconditions BMSC towards the osteoblastic lineage on 3D scaffolds in the absence of chemical stimulation, which highlights the utility of flow bioreactors in bone tissue engineering.

Core Matrisome Protein Signature During Periodontal Ligament Maturation From Pre-occlusal Eruption to Occlusal Function

The pre-occlusal eruption brings the molars into functional occlusion and initiates tensional strains during mastication. We hypothesized that upon establishment of occlusal contact, the periodontal ligament (PDL) undergoes cell and extracellular matrix maturation to adapt to this mechanical function. The PDL of 12 Wistar male rats were laser microdissected to observe the proteomic changes between stages of pre-occlusal eruption, initial occlusal contact and 1-week after occlusion. The proteome was screened by mass spectrometry and confirmed by immunofluorescence. The PDL underwent maturation upon establishment of occlusion. Downregulation of alpha-fetoprotein stem cell marker and protein synthesis markers indicate cell differentiation. Upregulated proteins were components of the extracellular matrix (ECM) and were characterized with the matrisome project database. In particular, periostin, a major protein of the PDL, was induced following occlusal contact and localized around collagen α-1 (III) bundles. This co-localization coincided with organization of collagen fibers in direction of the occlusal forces. Establishment of occlusion coincides with cellular differentiation and the maturation of the PDL. Co-localization of periostin and collagen with subsequent fiber organization may help counteract tensional forces and reinforce the ECM structure. This may be a key mechanism of the PDL to adapt to occlusal forces and maintain structural integrity.

MicroRNA-92a promotes vascular smooth muscle cell proliferation and migration through the ROCK/MLCK signalling pathway

To identify the interaction between known regulators of atherosclerosis, microRNA-92a (miR-92a), Rho-associated coiled-coil-forming kinase (ROCK) and myosin light chain kinase (MLCK), we examined their expressions during proliferation and migration of platelet-derived growth factor-BB (PDGF-BB)-regulated vascular smooth muscle cells (VSMCs), both in vivo and in vitro. During the formation of atherosclerosis plaque in mice, a parallel increase in expression levels of MLCK and miR-92a was observed while miR-92a expression was reduced in ML-7 (an inhibitor of MLCK) treated mice and in MLCK-deficient VSMCs. In vitro results indicated that both MLCK and miR-92a shared the same signalling pathway. Transfection of miR-92a mimic partially restored the effect of MLCK's deficiency and antagonized the effect of Y27632 (an inhibitor of ROCK) on the down-regulation of VSMCs activities. ML-7 increased the expression of Kruppel-like factor 4 (KLF4, a target of miR-92a), and siRNA-KLF4 increased VSMCs' activity level. Consistently, inhibition of either MLCK or ROCK enhanced the KLF4 expression. Moreover, we observed that ROCK/MLCK up-regulated miR-92a expression in VSMCs through signal transducer and activator of transcription 3 (STAT3) activation. In conclusion, the activation of ROCK/STAT3 and/or MLCK/STAT3 may up-regulate miR-92a expression, which subsequently inhibits KLF4 expression and promotes PDGF-BB-mediated proliferation and migration of VSMCs. This new downstream node in the ROCK/MLCK signalling pathway may offer a potential intervention target for treatment of atherosclerosis.

Induction of migration of periodontal ligament cells by selective regulation of integrin subunits

The recruitment of tissue-resident stem cells is important for wound regeneration. Periodontal ligament cells (PDL cells) are heterogeneous cell populations with stemness features that migrate into wound sites to regenerate periodontal fibres and neighbouring hard tissues. Cell migration is regulated by the local microenvironment, coordinated by growth factors and the extracellular matrix (ECM). Integrin-mediated cell adhesion to the ECM provides essential signals for migration. We hypothesized that PDL cell migration could be enhanced by selective expression of integrins. The migration of primary cultured PDL cells was induced by platelet-derived growth factor-BB (PDGF-BB). The effects of blocking specific integrins on migration and ECM adhesion were investigated based on the integrin expression profiles observed during migration. Up-regulation of integrins α3, α5, and fibronectin was identified at distinct localizations in migrating PDL cells. Treatment with anti-integrin α5 antibodies inhibited PDL cell migration. Treatment with anti-integrin α3, α3-blocking peptide, and α3 siRNA significantly enhanced cell migration, comparable to treatment with PDGF-BB. Furthermore, integrin α3 inhibition preferentially enhanced adhesion to fibronectin via integrin α5. These findings indicate that PDL cell migration is reciprocally regulated by integrin α3-mediated inhibition and α5-mediated promotion. Thus, targeting integrin expression is a possible therapeutic strategy for periodontal regeneration.

New Functions of Classical Compounds against Orofacial Inflammatory Lesions

Anti-inflammatory agents have been widely used to ameliorate severe inflammatory symptoms of a number of diseases, and such therapeutics are particularly useful for diseases with intolerable pain without significant mortality. A typical example of this is a disease known as stomatitis; although stomatitis itself is not a life-threatening disease, it severely impairs the individual’s quality of life, and thus a standard therapeutic strategy for it has already been established. The topical application of a bioactive agent is quite easy, and a strong anti-inflammatory agent can be used without significant adverse effects. In contrast, natural products with relatively mild bioactivity are used for systemic intervention. However, new aspects of classical drugs used in these established therapeutic methods have recently been discovered, which is expanding the utility of these compounds to other oral diseases such as osteoarthritis of temporomandibular joints (TMJ-OA). In this review article, after summarizing the general concept and pathobiology of stomatitis, its established therapeutics are explained. Thereafter, recent advances in the research into related compounds, which is uncovering new biological functions of the agents used therein, are introduced. Indeed, regenerative therapeutics for TMJ-OA may be developed with the classical compounds currently being used.

Sphingosine-1-phosphate induces airway smooth muscle cell proliferation, migration, and contraction by modulating Hippo signaling effector YAP

Sphingosine-1-phosphate (S1P), a bioactive lipid, has been shown to be elevated in the airways of individuals with asthma and modulates the airway smooth muscle cell (ASMC) functions, yet its underlying molecular mechanisms are not completely understood. The aim of the present study is to address this issue. S1P induced yes-associated protein (YAP) dephosphorylation and nuclear localization via the S1PR_2/3/Rho-associated protein kinase (ROCK) pathway, and this in turn increased forkhead box M1 (FOXM1) and cyclin D1 expression leading to ASMC proliferation, migration, and contraction. Pretreatment of cells with S1PR₂ antagonist JTE013, S1PR₃ antagonist CAY10444, or ROCK inhibitor Y27632 blocked S1P-induced alterations of YAP, FOXM1, cyclin D1, and ASMC proliferation, migration, and contraction. In addition, prior silencing of YAP or FOXM1 with siRNA reversed the effect of S1P on ASMC functions. Taken together, our study indicates that S1P stimulates ASMC proliferation, migration, and contraction by binding to S1PR_2/3 and modulating ROCK/YAP/FOXM1 axis and suggests that targeting this pathway might have potential value in the management of asthma.

Vibration paradox in orthodontics: Anabolic and catabolic effects

Vibration in the form of High Frequency Acceleration (HFA) is anabolic on the craniofacial skeleton in the absence of inflammation. Orthodontic forces trigger an inflammation-dependent catabolic cascade that is crucial for tooth movement. It is unknown what effect HFA has on alveolar bone if applied during orthodontic treatment. The objectives of this study are to examine the effect of HFA on the rate of tooth movement and alveolar bone, and determine the mechanism by which HFA affects tooth movement. Adult Sprague Dawley rats were divided to control, orthodontic force alone (OTM), and different experimental groups that received the same orthodontic forces and different HFA regimens. Orthodontic tooth movement was assessed when HFA parameters, frequency, acceleration, duration of exposure, and direct or indirect application were varied. We found that HFA treatment significantly enhanced the inflammation-dependent catabolic cascade during orthodontic tooth movement. HFA treatment increased inflammatory mediators and osteoclastogenesis, and decreased alveolar bone density during orthodontic tooth movement. Each of the HFA variables produced significant changes in the rate of tooth movement and the effect was PDL-dependent. This is the first report that HFA enhances inflammation-dependent catabolic cascades in bone. The clinical implications of our study are highly significant, as HFA can be utilized to enhance the rate of orthodontic tooth movement during the catabolic phase of treatment and subsequently be utilized to enhance retention during the anabolic remodeling phase after orthodontic forces are removed.