F-spondin regulates the differentiation of human cementoblast-like (HCEM) cells via BMP7 expression

Isolation and characterization of apical papilla cells from root end of human third molar and their differentiation into cementoblast cells: an in vitro study

BACKGROUND

Periodontal regeneration, treatment of periodontal-related diseases and improving the function of implants are global therapeutic challenges. The differentiation of human stem cells from apical papilla into cementoblasts may provide a strategy for periodontitis treatment. This study aimed to evaluate the differentiation of primary human stem cells apical papilla (hSCAPs) to cementoblast cells.

MATERIAL AND METHODS

SCAPs cells were isolated from human third molar and then incubated for 21 days in a differentiation microenvironment. Alkaline phosphatase (ALP) and Alizarin red S staining assays were performed to evaluate the calcium deposition and formation of hydroxyapatite in the cultured hSCAPs microenvironment. Real-time polymerase chain reaction (RT-PCR) assay was performed for cementum protein 1 (CEMP1), collagen type I (COL1), F-Spondin (SPON1), osteocalcin (OCN), and osteopontin (OPN) as specific markers of cementoblasts and their progenitors.

RESULTS

ALP phosphatase activity in day 21 of treatment demonstrated a significant increase in ALP compared to the control. Alizarin red S staining assay showed that the differentiated hSCAPs offered a great amount of calcium deposition nodules compared to the control. The increased expression level of CEMP1, OCN, OPN, COL1 and Spon1 was observed in days 7, 14 and 21 compared to the control, while greatest expression level was observed in day 21.

CONCLUSION

In conclusion, the differentiation microenviroment is convenient and useful for promoting the differentiation of hSCAPs into cementoblast.

Physicochemical Properties, Cytocompatibility, and Biocompatibility of a Bioactive Glass Based Retrograde Filling Material

The ideal retrograde filling material that is easy to handle, has good physicochemical properties, and is biocompatible has not yet been developed. The current study reports the development of a novel bioactive glass based powder for use as a retrograde filling material that is capable of altering the consistency and hardening rate of mixtures when mixed with existing bioactive glass based cement. Furthermore, its physicochemical properties, in vitro effects on human cementoblast-like cells, and in vivo effects on inflammatory responses were evaluated. The surface of the hardened cement showed the formation of hydroxyapatite-like precipitates and calcium and silicate ions were eluted from the cement when the pH level was stabilized at 10.5. Additionally, the cement was found to be insoluble and exhibited favorable handling properties. No adverse effects on viability, proliferation, and expression of differentiated markers were observed in the in vitro experiment, and the cement was capable of inducing calcium deposition in the cells. Moreover, the cement demonstrated a lower number of infiltrated inflammatory cells compared to the other materials used in the in vivo mouse subcutaneous implantation experiment. These findings suggest that the retrograde filling material composed of bioactive glass and the novel bioactive glass based powder exhibits favorable physicochemical properties, cytocompatibility, and biocompatibility.

Evaluation of relationship between SPON1 gene and genetic susceptibility of postmenopausal osteoporosis

Purpose: Postmenopausal osteoporosis (PMOP) is one of systemic bone degenerative diseases characterised by decreased bone mineral density (BMD). Previous studies suggest that the SPON1 gene may be associated with BMD and play an important role in the occurrence and development of PMOP. In this study, we aimed to investigate the potential association between PMOP and the SPON1 gene.Methods: A total of 8062 postmenopausal women comprising 2684 primary PMOP patients, and 5378 healthy controls were recruited. Forty tag SNPs were selected for genotyping to evaluate the association of the SPON1 gene with PMOP and BMD. Genetic association and bioinformatics analyses were performed for PMOP.Results: SNP rs2697825 was identified to be significantly associated with the risk of PMOP at both allelic (T-statistics = -3.84, p = .0001) and genotypic levels (χ²=15.86, p = .0004). The G allele of SNP rs2697825 was significantly associated with a decreased risk of PMOP with an OR [95%] of 0.84 [0.77-0.92]. The G allele of SNP rs2697825 was associated with increased BMD at both the lumbar spine and femoral neck.Conclusions: Our results provide further evidence to support the important role for the SPON1 gene in the aetiology of PMOP, adding to the current understanding of the susceptibility to osteoporosis.

Adiponectin Interacts In-Vitro With Cementoblasts Influencing Cell Migration, Proliferation and Cementogenesis Partly Through the MAPK Signaling Pathway

Current clinical evidences suggest that circulating Adipokines such as Adiponectin can influence the ratio of orthodontic tooth movement. We aimed to investigate the effect that Adiponectin has on cementoblasts (OCCM-30) and on the intracellular signaling molecules of Mitogen-activated protein kinase (MAPK). We demonstrated that OCCM-30 cells express AdipoR1 and AdipoR2. Alizarin Red S staining revealed that Adiponectin increases mineralized nodule formation and quantitative AP activity in a dose-dependent manner. Adiponectin up-regulates the mRNA levels of AP, BSP, OCN, OPG, Runx-2 as well as F-Spondin. Adiponectin also increases the migration and proliferation of OCCM-30 cells. Moreover, Adiponectin induces a transient activation of JNK, P38, ERK1/2 and promotes the phosphorylation of STAT1 and STAT3. The activation of Adiponectin-mediated migration and proliferation was attenuated after pharmacological inhibition of P38, ERK1/2 and JNK in different degrees, whereas mineralization was facilitated by MAPK inhibition in varying degrees. Based on our results, Adiponectin favorably affect OCCM-30 cell migration, proliferation as well as cementogenesis. One of the underlying mechanisms is the activation of MAPK signaling pathway.

Recent advances in periodontal regeneration: A biomaterial perspective

Periodontal disease (PD) is one of the most common inflammatory oral diseases, affecting approximately 47% of adults aged 30 years or older in the United States. If not treated properly, PD leads to degradation of periodontal tissues, causing tooth movement, and eventually tooth loss. Conventional clinical therapy for PD aims at eliminating infectious sources, and reducing inflammation to arrest disease progression, which cannot achieve the regeneration of lost periodontal tissues. Over the past two decades, various regenerative periodontal therapies, such as guided tissue regeneration (GTR), enamel matrix derivative, bone grafts, growth factor delivery, and the combination of cells and growth factors with matrix-based scaffolds have been developed to target the restoration of lost tooth-supporting tissues, including periodontal ligament, alveolar bone, and cementum. This review discusses recent progresses of periodontal regeneration using tissue-engineering and regenerative medicine approaches. Specifically, we focus on the advances of biomaterials and controlled drug delivery for periodontal regeneration in recent years. Special attention is given to the development of advanced bio-inspired scaffolding biomaterials and temporospatial control of multi-drug delivery for the regeneration of cementum-periodontal ligament-alveolar bone complex. Challenges and future perspectives are presented to provide inspiration for the design and development of innovative biomaterials and delivery system for new regenerative periodontal therapy.

Genome-wide association study of extreme high bone mass: Contribution of common genetic variation to extreme BMD phenotypes and potential novel BMD-associated genes

BACKGROUND

Generalised high bone mass (HBM), associated with features of a mild skeletal dysplasia, has a prevalence of 0.18% in a UK DXA-scanned adult population. We hypothesized that the genetic component of extreme HBM includes contributions from common variants of small effect and rarer variants of large effect, both enriched in an extreme phenotype cohort.

METHODS

We performed a genome-wide association study (GWAS) of adults with either extreme high or low BMD. Adults included individuals with unexplained extreme HBM (n = 240) from the UK with BMD Z-scores ≥+3.2, high BMD females from the Anglo-Australasian Osteoporosis Genetics Consortium (AOGC) (n = 1055) with Z-scores +1.5 to +4.0 and low BMD females also part of AOGC (n = 900), with Z-scores -1.5 to -4.0. Following imputation, we tested association between 6,379,332 SNPs and total hip and lumbar spine BMD Z-scores. For potential target genes, we assessed expression in human osteoblasts and murine osteocytes.

RESULTS

We observed significant enrichment for associations with established BMD-associated loci, particularly those known to regulate endochondral ossification and Wnt signalling, suggesting that part of the genetic contribution to unexplained HBM is polygenic. Further, we identified associations exceeding genome-wide significance between BMD and four loci: two established BMD-associated loci (5q14.3 containing MEF2C and 1p36.12 containing WNT4) and two novel loci: 5p13.3 containing NPR3 (rs9292469; minor allele frequency [MAF] = 0.33%) associated with lumbar spine BMD and 11p15.2 containing SPON1 (rs2697825; MAF = 0.17%) associated with total hip BMD. Mouse models with mutations in either Npr3 or Spon1 have been reported, both have altered skeletal phenotypes, providing in vivo validation that these genes are physiologically important in bone. NRP3 regulates endochondral ossification and skeletal growth, whilst SPON1 modulates TGF-β regulated BMP-driven osteoblast differentiation. Rs9292469 (downstream of NPR3) also showed some evidence for association with forearm BMD in the independent GEFOS sample (n = 32,965). We found Spon1 was highly expressed in murine osteocytes from the tibiae, femora, humeri and calvaria, whereas Npr3 expression was more variable.

CONCLUSION

We report the most extreme-truncate GWAS of BMD performed to date. Our findings, suggest potentially new anabolic bone regulatory pathways that warrant further study.

Proliferation and osteo/odontogenic differentiation of stem cells from apical papilla regulated by Zinc fingers and homeoboxes 2: An in vitro study

In the process of tooth root development, stem cells from the apical papilla (SCAPs) can differentiate into odontoblasts and form root dentin, however, molecules regulating SCAPs differentiation have not been elucidated. Zinc fingers and homeoboxes 2 (ZHX2) is a novel transcriptional inhibitor. It is reported to modulate the development of nerve cells, liver cells, B cells, red blood cells, and so on. However, the role of ZHX2 in tooth root development remains unclear. In this study, we explored the potential role of ZHX2 in the process of SCAPs differentiation. The results showed that overexpression of ZHX2 upregulated the expression of osteo/odontogenic related genes and ALP activity, inhibited the proliferation of SCAPs. Consistently, ZHX2 knockdown reduced SCAPs mineralization and promoted SCAPs proliferation. These results indicated that ZHX2 plays a critical role in the proliferation and osteo/odontogenic differentiation of SCAPs.

RNA-seq analysis of broiler liver transcriptome reveals novel responses to high ambient temperature

BACKGROUND

In broilers, high ambient temperature can result in reduced feed consumption, digestive inefficiency, impaired metabolism, and even death. The broiler sector of the U.S. poultry industry incurs approximately $52 million in heat-related losses annually. The objective of this study is to characterize the effects of cyclic high ambient temperature on the transcriptome of a metabolically active organ, the liver. This study provides novel insight into the effects of high ambient temperature on metabolism in broilers, because it is the first reported RNA-seq study to characterize the effect of heat on the transcriptome of a metabolic-related tissue. This information provides a platform for future investigations to further elucidate physiologic responses to high ambient temperature and seek methods to ameliorate the negative impacts of heat.

RESULTS

Transcriptome sequencing of the livers of 8 broiler males using Illumina HiSeq 2000 technology resulted in 138 million, 100-base pair single end reads, yielding a total of 13.8 gigabases of sequence. Forty genes were differentially expressed at a significance level of P-value < 0.05 and a fold-change ≥ 2 in response to a week of cyclic high ambient temperature with 27 down-regulated and 13 up-regulated genes. Two gene networks were created from the function-based Ingenuity Pathway Analysis (IPA) of the differentially expressed genes: "Cell Signaling" and "Endocrine System Development and Function". The gene expression differences in the liver transcriptome of the heat-exposed broilers reflected physiological responses to decrease internal temperature, reduce hyperthermia-induced apoptosis, and promote tissue repair. Additionally, the differential gene expression revealed a physiological response to regulate the perturbed cellular calcium levels that can result from high ambient temperature exposure.

CONCLUSIONS

Exposure to cyclic high ambient temperature results in changes at the metabolic, physiologic, and cellular level that can be characterized through RNA-seq analysis of the liver transcriptome of broilers. The findings highlight specific physiologic mechanisms by which broilers reduce the effects of exposure to high ambient temperature. This information provides a foundation for future investigations into the gene networks involved in the broiler stress response and for development of strategies to ameliorate the negative impacts of heat on animal production and welfare.

F-spondin inhibits differentiation of clastic precursors via lipoprotein receptor-related protein 8 (LRP8)

BACKGROUND

F-spondin, known to be a secreted neuronal glycoprotein, is highly expressed on the tooth root surface. The authors previously reported that F-spondin is one of the specific markers of cementoblasts in periodontal tissue. In chronic periodontitis, significant cemental resorption rarely occurs on the root side, although alveolar bone resorption by osteoclasts is one of the major pathologic changes. Thus, it was hypothesized that secretory F-spondin from cementoblasts might be involved in differentiation of clastic cells on the root surface. The authors studied effects of secretory F-spondin from F-spondin-expressing cells and its pathway on receptor activator of nuclear factor-κB ligand (RANKL)-mediated differentiation of clastic cells.

METHODS

Osteoclast precursors were used in this study. With a chamber assay, the authors examined effects of secretory molecules from F-spondin-expressing cells of transgenic mice on RANKL-induced clastic cell differentiation.

RESULTS

Secretory molecules from F-spondin-overexpressing cells significantly inhibited the RANKL-mediated tartrate-resistant acid phosphatase (TRAP)-positive cells from primary progenitor cells with the chamber system. F-spondin suppressed RANKL-mediated nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1); TRAP; cathepsin K; and dendritic cell-specific transmembrane protein (DC-STAMP) expression in the cells. The suppressive effect of F-spondin on RANKL-induced differentiation of clastic cells was partially blocked by knockdown of low-density lipoprotein receptor-related protein 8 (LRP8).

CONCLUSIONS

These findings indicate that secretory factors from F-spondin-expressing cells, including F-spondin, downregulate differentiation of clastic precursors. Moreover, F-spondin inhibits RANKL-mediated differentiation of clastic cells partially via LRP8. It is suggested that secretory F-spondin may act protectively from cemental resorption partially via LRP8 in periodontal tissue.

Functional tooth restoration by next-generation bio-hybrid implant as a bio-hybrid artificial organ replacement therapy

Bio-hybrid artificial organs are an attractive concept to restore organ function through precise biological cooperation with surrounding tissues in vivo. However, in bio-hybrid artificial organs, an artificial organ with fibrous connective tissues, including muscles, tendons and ligaments, has not been developed. Here, we have enveloped with embryonic dental follicle tissue around a HA-coated dental implant, and transplanted into the lower first molar region of a murine tooth-loss model. We successfully developed a novel fibrous connected tooth implant using a HA-coated dental implant and dental follicle stem cells as a bio-hybrid organ. This bio-hybrid implant restored physiological functions, including bone remodelling, regeneration of severe bone-defect and responsiveness to noxious stimuli, through regeneration with periodontal tissues, such as periodontal ligament and cementum. Thus, this study represents the potential for a next-generation bio-hybrid implant for tooth loss as a future bio-hybrid artificial organ replacement therapy.

F-spondin deficient mice have a high bone mass phenotype

F-spondin is a pericellular matrix protein upregulated in developing growth plate cartilage and articular cartilage during osteoarthritis. To address its function in bone and cartilage in vivo, we generated mice that were deficient for the F-spondin gene, Spon1. Spon1^−/− mice were viable and developed normally to adulthood with no major skeletal abnormalities. At 6 months, femurs and tibiae of Spon1^−/− mice exhibited increased bone mass, evidenced by histological staining and micro CT analyses, which persisted up to 12 months. In contrast, no major abnormalities were observed in articular cartilage at any age group. Immunohistochemical staining of femurs and tibiae revealed increased levels of periostin, alkaline phosphate and tartrate resistant acid phosphatase (TRAP) activity in the growth plate region of Spon1^−/− mice, suggesting elevated bone synthesis and turnover. However, there were no differences in serum levels of TRAP, the bone resorption marker, CTX-1, or osteoclast differentiation potential between genotypes. Knockout mice also exhibited reduced levels of TGF-β1 in serum and cultured costal chondrocytes relative to wild type. This was accompanied by increased levels of the BMP-regulatory SMADs, P-SMAD1/5 in tibiae and chondrocytes. Our findings indicate a previously unrecognized role for Spon1 as a negative regulator of bone mass. We speculate that Spon1 deletion leads to a local and systemic reduction of TGF-β levels resulting in increased BMP signaling and increased bone deposition in adult mice.