Expression of thymosin beta-4 in human periodontal ligament cells and mouse periodontal tissue and its role in osteoblastic/cementoblastic differentiation

Potential application of inorganic nano-materials in modulation of macrophage function: Possible application in bone tissue engineering

Nanomaterials indicate unique physicochemical properties for drug delivery in osteogenesis. Benefiting from high surface area grades, high volume ratio, ease of functionalization by biological targeting moieties, and small size empower nanomaterials to pass through biological barriers for efficient targeting. Inorganic nanomaterials for bone regeneration include inorganic synthetic polymers, ceramic nanoparticles, metallic nanoparticles, and magnetic nanoparticles. These nanoparticles can effectively modulate macrophage polarization and function, as one of the leading players in osteogenesis. Bone healing procedures in close cooperation with the immune system. Inflammation is one of the leading triggers of the bone fracture healing barrier. Macrophages commence anti-inflammatory signaling along with revascularization in the damaged site to promote the formation of a soft callus, bone mineralization, and bone remodeling. In this review, we will discuss the role of macrophages in bone hemostasis and regeneration. Furthermore, we will summarize the influence of the various inorganic nanoparticles on macrophage polarization and function in the benefit of osteogenesis.

Platelets and osteoblasts: secretome connections

Megakaryocyte hyperplasia associated with myeloproliferative neoplasms commonly leads to abnormal bone tissue deposition in the bone marrow, known as osteosclerosis. In this study, we aimed to synthesize the known proteomics literature describing factors released by megakaryocytes and platelets and to examine if any of the secreted factors have a known ability to stimulate the bone-forming cells, osteoblasts. Using a systematic search of Medline, we identified 77 articles reporting on factors secreted by platelets and megakaryocytes. After a full-text screening and analysis of the studies, we selected seven papers that reported proteomics data for factors secreted by platelets from healthy individuals. From 60 proteins reported in at least two studies, we focused on 23 that contained a putative signal peptide, which we searched for a potential osteoblast-stimulatory function. From nine proteins with a positive effect on osteoblast formation and function, two extracellular matrix (ECM) proteins, secreted protein acidic and rich in cysteine (SPARC) and tissue inhibitor of metalloproteinase-1 (TIMP1), and three cellular proteins with known extracellular function, the 70-kDa heat shock protein (HSP70), thymosin-β4 (TB4), and super dismutase (SOD), were identified as hypothetical candidate molecules to be examined as potential mediators in mouse models of osteomyelofibrosis. Thus, careful analysis of prior literature can be beneficial in assisting the planning of future experimental studies.

Thymosin β4: A Multi-Faceted Tissue Repair Stimulating Protein in Heart Injury

Thymosin Beta-4 (Tβ4) is known as a major pleiotropic actin-sequestering protein that is involved in tumorigenesis. Tβ4 is a water-soluble protein that has different promising clinical applications in the remodeling and ulcerated tissues repair following myocardial infarction, stroke, plasticity and neurovascular remodeling of the Peripheral Nervous System (PNS) and the Central Nervous System (CNS). On the other hand, similar effects have been observed for Tβ4 in other kinds of tissues, including cardiac muscle tissue. In recent reports, as it activates resident epicardial progenitor cells and modulates inflammatory-caused injuries, Tβ4 has been suggested as a promoter of the survival of cardiomyocytes. Furthermore, Tβ4 may act in skeletal muscle and different organs in association/synergism with numerous other tissue repair stimulating factors, including melatonin and C-fiber-derived peptides. For these reasons, the present review highlights the promising role of Tβ4 in cardiac healing.

Serotonin Transporter (5-HTT) Gene Polymorphisms and Susceptibility to Chronic Periodontitis: A Case-Control Study

Objective: The current study is aimed at exploring the relationship between chronic periodontitis and serotonin transporter (5-HTT) gene polymorphisms (rs6354 and rs12449783) in the Chinese Han population. Methods: This study included a total of 120 patients with chronic periodontitis and 125 healthy control subjects. The 5-HTT gene (rs6354 and rs12449783) was genotyped using oral mucosal tissue with a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Linkage disequilibrium was examined using Haploview. Genotype and allele frequencies were compared between the cases and controls using a χ2 test. Results: Genotype distribution of the 5-HTT gene polymorphisms rs6354 and rs12449783 in the control group conformed to Hardy-Weinberg equilibrium. The frequency of the AC genotype, the AC + CC genotype and C allele of the 5-HTT rs6354 polymorphism was higher in cases (P < 0.05) vs. the healthy control. The adjusted odds ratio (OR) was 1.910 (95%CI = 1.049-3.476) for the AC genotype, 2.026 (95%CI = 1.115-3.680) for the AC+CC genotype, and 1.875 for the C allele (95%CI = 1.089-3.228. Such an association was particularly strong in women for the AC genotype (OR = 2.167, 95%CI = 1.034-4.542). The genotype and allele frequencies of rs12449783 did not differ between the cases and controls. Haplotype C-C (rs6354-rs12449783) was also more frequent in the cases (OR = 2.372, 95%CI = 1.154-4.875, P = 0.016). Conclusion: Chronic periodontitis is associated with the 5-HTT gene rs6354 polymorphism, as well as rs6354/rs12449783 interaction.

CKIP-1 suppresses odontoblastic differentiation of dental pulp stem cells via BMP2 pathway and can interact with NRP1

AIM

Casein kinase 2 interacting protein-1 (CKIP-1) is a recently discovered intracellular regulator of bone formation, muscle cell differentiation, and tumor cell proliferation. Our study aims to identify the inhibition of BMP2-Smad1/5 signaling by CKIP-1 in odontoblastic differentiation of human dental pulp stem cells (DPSCs).

MATERIALS AND METHODS

DPSCs infected CKIP-1 siRNA or transfected CKIP-1 full-length plasmid were cultured in odontoblastic differentiation medium or added noggin (200 ng/mL) for 21 days. We examined the effects of CKIP-1 on odontoblastic differentiation, mineralized nodules formation, and interaction by western blot, real-time polymerase chain reaction (RT-PCR), alkaline phosphatase (ALP) staining, alizarin red S staining, and immunoprecipitation.

RESULTS

Firstly, we have demonstrated that CKIP-1 expression markedly decreased time-dependently along with cell odontoblastic differentiation. Indeed, the silence of CKIP-1 upregulated odontoblastic differentiation via BMP2-Smad1/5 signaling, while CKIP-1 over-expression had a negative effect on odontoblastic differentiation of DPSCs. Furthermore, CKIP-1 could interact with Neuropilin-1 (NRP1).

CONCLUSIONS

This work provides data that advocates a novel perception on odontoblastic differentiation of DPSCs. Therefore, inhibiting the expression of CKIP-1 may be of great significance to the development of dental caries.

Effects of Melatonin and Its Underlying Mechanism on Ethanol-Stimulated Senescence and Osteoclastic Differentiation in Human Periodontal Ligament Cells and Cementoblasts

The present study evaluated the protective effects of melatonin in ethanol (EtOH)-induced senescence and osteoclastic differentiation in human periodontal ligament cells (HPDLCs) and cementoblasts and the underlying mechanism. EtOH increased senescence activity, levels of reactive oxygen species (ROS) and the expression of cell cycle regulators (p53, p21 and p16) and senescence-associated secretory phenotype (SASP) genes (interleukin [IL]-1β, IL-6, IL-8 and tumor necrosis factor-α) in HPDLCs and cementoblasts. Melatonin inhibited EtOH-induced senescence and the production of ROS as well as the increased expression of cell cycle regulators and SASP genes. However, it recovered EtOH-suppressed osteoblastic/cementoblastic differentiation, as evidenced by alkaline phosphatase activity, alizarin staining and mRNA expression levels of Runt-related transcription factor 2 (Runx2) and osteoblastic and cementoblastic markers (glucose transporter 1 and cementum-derived protein-32) in HPDLCs and cementoblasts. Moreover, it inhibited EtOH-induced osteoclastic differentiation in mouse bone marrow⁻derived macrophages (BMMs). Inhibition of protein never in mitosis gene A interacting-1 (PIN1) by juglone or small interfering RNA reversed the effects of melatonin on EtOH-mediated senescence as well as osteoblastic and osteoclastic differentiation. Melatonin blocked EtOH-induced activation of mammalian target of rapamycin (mTOR), AMP-activated protein kinase (AMPK), mitogen-activated protein kinase (MAPK) and Nuclear factor of activated T-cells (NFAT) c-1 pathways, which was reversed by inhibition of PIN1. This is the first study to show the protective effects of melatonin on senescence-like phenotypes and osteoclastic differentiation induced by oxidative stress in HPDLCs and cementoblasts through the PIN1 pathway.

Tectorigenin Promotes Osteoblast Differentiation and in vivo Bone Healing, but Suppresses Osteoclast Differentiation and in vivo Bone Resorption

Although tectorigenin (TG), a major compound in the rhizome of Belamcanda chinensis, is conventionally used for the treatment of inflammatory diseases, its effects on osteogenesis and osteoclastogenesis have not been reported. The objective of this study was to investigate the effects and possible underlying mechanism of TG on in vitro osteoblastic differentiation and in vivo bone formation, as well as in vitro osteoclast differentiation and in vivo bone resorption. TG promoted the osteogenic differentiation of primary osteoblasts and periodontal ligament cells. Moreover, TG upregulated the expression of the BMP2, BMP4, and Smad-4 genes, and enhanced the expression of Runx2 and Osterix. In vivo studies involving mouse calvarial bone defects with μCT and histologic analysis revealed that TG significantly increased new bone formation. Furthermore, TG treatment inhibited osteoclast differentiation and the mRNA levels of osteoclast markers. In vivo studies of mice demonstrated that TG caused the marked attenuation of bone resorption. These results collectively demonstrated that TG stimulated osteogenic differentiation in vitro, increased in vivo bone regeneration, inhibited osteoclast differentiation in vitro, and suppressed inflammatory bone loss in vivo. These novel findings suggest that TG may be useful for bone regeneration and treatment of bone diseases.

Sulfuretin promotes osteoblastic differentiation in primary cultured osteoblasts and in vivo bone healing

Although sulfuretin, the major flavonoid of Rhus verniciflua Stokes, has a variety of biological actions, its in vitro and in vivo effects on osteogenic potential remain poorly understood. The objective of the present study was to investigate the effects of sulfuretin on in vitro osteoblastic differentiation and the underlying signal pathway mechanisms in primary cultured osteoblasts and on in vivo bone formation using critical-sized calvarial defects in mice. Sulfuretin promoted osteogenic differentiation of primary osteoblasts, with increased ALP activity and mineralization, and upregulated differentiation markers, including ALP, osteocalcin, and osteopontin, in a concentration-dependent manner. The expression levels of Runx2, BMP-2, and phospho-Smad1/5/8 were upregulated by sulfuretin. Moreover, sulfuretin increased phosphorylation of Akt, mTOR, ERK, and JNK. Furthermore, sulfuretin treatment increased mRNA expression of Wnt ligands, phosphorylation of GSK3, and nuclear β-catenin protein expression. In vivo studies with calvarial bone defects revealed that sulfuretin significantly enhanced new bone formation by micro-computed tomography and histologic analysis. Collectively, these data suggest that sulfuretin acts through the activation of BMP, mTOR, Wnt/β-catenin, and Runx2 signaling to promote in vitro osteoblast differentiation and facilitate in vivo bone regeneration, and might be have therapeutic benefits in bone disease and regeneration.

Thymosin β4 in rheumatoid arthritis: Friend or foe

Rheumatoid arthritis (RA) has characteristic pannus tissues, which show tumor-like growth of the synovium through chronic joint inflammation. The synovium is highly penetrated by various immune cells, and the synovial lining becomes hyperplastic due to increased numbers of macrophage-like and fibroblast-like synoviocytes. Thus, a resultant hypoxic condition stimulates the expression of inflammation-related genes in various cells, in particular, vascular endothelial growth factor. Thymosin β4 (Tβ4), a 5-kDa protein, is known to play a significant role in various biological activities, such as actin sequestering, cell motility, migration, inflammation, and damage repair. Recent studies have provided evidence that Tβ4 may have a role in RA pathogenesis. The Tβ4 level has been shown to increase significantly in the joint fluid and serum of RA patients. However, whether Tβ4 stimulates or inhibits activation of RA immune responses remains to be determined. In the present study, we discuss the logical and clinical justifications for Tβ4 as a potential target for RA therapeutics.

Baicalein Promotes Angiogenesis and Odontoblastic Differentiation via the BMP and Wnt Pathways in Human Dental Pulp Cells

Baicalein is an active flavonoid extracted from the root of Scutellaria baicalensis that has anticancer and anti-inflammatory properties; its effects on osteoblastic and angiogenic potential are controversial. The aim of this study was to investigate the effects of baicalein on odontoblastic differentiation and angiogenesis and the underlying mechanism in human dental pulp cells (HDPCs). Baicalein (1–10[Formula: see text][Formula: see text]M) had no cytotoxic effects and promoted alkaline phosphatase (ALP) activity, mineralization assayed by Alizarin Red-S staining, and the mRNA expression of marker genes, in a concentration-dependent manner. In addition, baicalein upregulated angiogenic factors and increased in vitro capillary-like tube formation. Moreover, baicalein upregulated bone morphogenetic protein (BMP)-2 mRNA and phosphorylation of Smad 1/5/8 and Wnt ligand mRNA, glycogen synthase kinase-3, and nuclear [Formula: see text]-catenin. The odontogenic and angiogenic effects of baicalein were abolished by the BMP antagonist noggin and the Wnt/[Formula: see text]-catenin receptor antagonist DKK-1. These results demonstrate that baicalein promoted odontoblastic differentiation and angiogenesis of HDPCs by activating the BMP and Wnt/[Formula: see text]-catenin signal pathways. Our findings suggest that baicalein may contribute to dental pulp repair and regenerative endodontics.

Sonic Hedgehog Promotes Cementoblastic Differentiation via Activating the BMP Pathways

Although sonic hedgehog (SHH), an essential molecule in embryogenesis and organogenesis, stimulates proliferation of human periodontal ligament (PDL) stem cells, the effects of recombinant human SHH (rh-SHH) on osteoblastic differentiation are unclear. To reveal the role of SHH in periodontal regeneration, expression of SHH in mouse periodontal tissues and its effects on the osteoblastic/cementoblastic differentiation in human cementoblasts were investigated. SHH is immunolocalized to differentiating cementoblasts, PDL cells, and osteoblasts of the developing mouse periodontium. Addition of rh-SHH increased cell growth, ALP activity, and mineralization nodule formation, and upregulated mRNA expression of osteoblastic and cementoblastic markers. The osteoblastic/cementoblastic differentiation of rh-SHH was abolished by the SHH inhibitor cyclopamine (Cy) and the BMP antagonist noggin. rh-SHH increased the expression of BMP-2 and -4 mRNA, as well as levels of phosphorylated Akt, ERK, p38, and JNK, and of MAPK and NF-κB activation, which were reversed by noggin, Cy, and BMP-2 siRNA. Collectively, this study is the first to demonstrate that SHH can promote cell growth and cell osteoblastic/cementoblastic differentiation via BMP pathway. Thus, SHH plays important roles in the development of periodontal tissue, and might represent a new therapeutic target for periodontitis and periodontal regeneration.

Characterization and cytocompatibility of thermosensitive hydrogel embedded with chitosan nanoparticles for delivery of bone morphogenetic protein-2 plasmid DNA

A novel injectable chitosan thermosensitive hydrogel was designed as a target multi-effect scaffold for endogenous repair of the periodontium. The hydrogel complex was designed by embedding chitosan nanoparticles (CSn) loaded with bone morphogenetic protein-2 plasmid DNA (pDNA-BMP2) into a chitosan (CS)-based hydrogel with α,β-glycerophosphate (α,β-GP), termed CS/CSn(pDNA-BMP2)-GP. Characterization, the in vitro release profile for pDNA-BMP2, and cytocompatibility to human periodontal ligament cells (HPDLCs), were then conducted. The average diameter of the CSn(pDNA-BMP2) was 270.1 nm with a polydispersity index (PDI) of 0.486 and zeta potential of +27.0 mv. A DNase I protection assay showed that CSn could protect the pDNA-BMP2 from nuclease degradation. Encapsulation efficiency and loading capacity of CSn(pDNA-BMP2) were more than 80 and 30 %, respectively. The sol-gel transition time was only 3 min when CSn(pDNA-BMP2) was added into the CS/α,β-GP system. Scanning electron microscopy showed that CSn(pDNA-BMP2) was randomly dispersed in a network with regular holes and a porous structure. Weighting method showed the swelling ratio and degradation was faster in medium of pH 4.0 than pH 6.8. An in vitro pDNA-BMP2 release test showed that the cumulative release rate of pDNA-BMP2 was much slower from CS/CSn-GP than from CSn in identical release media. In release media with different pH, pDNA-BMP2 release was much slower at pH 6.8 than at pH 4.0. Three-dimensional culture with HPDLCs showed good cell proliferation and the Cell-Counting Kit-8 assay indicated improved cell growth with the addition of CSn(pDNA-BMP2) to CS/α,β-GP. In summary, the CS/CSn(pDNA-BMP2)-GP complex system exhibited excellent biological properties and cytocompatibility, indicating great potential as a gene delivery carrier and tissue regeneration scaffold for endogenous repair of the periodontium.