Indigenous microbiota protects development of medication-related osteonecrosis induced by periapical disease in mice / 国际口腔科学杂志·英文版

Bacterial infection is a common finding in patients, who develop medication-related osteonecrosis of the jaw (MRONJ) by the long-term and/or high-dose use of anti-resorptive agents such as bisphosphonate (BPs). However, pathological role of bacteria in MRONJ development at the early stage remains controversial. Here, we demonstrated that commensal microbiota protects against MRONJ development in the pulp-exposed periapical periodontitis mouse model. C57/BL6 female mice were treated with intragastric broad-spectrum antibiotics for 1 week. Zoledronic acid (ZOL) through intravenous injection and antibiotics in drinking water were administered for throughout the experiment. Pulp was exposed on the left maxillary first molar, then the mice were left for 5 weeks after which bilateral maxillary first molar was extracted and mice were left for additional 3 weeks to heal. All mice were harvested, and cecum, maxilla, and femurs were collected. ONJ development was assessed using μCT and histologic analyses. When antibiotic was treated in mice, these mice had no weight changes, but developed significantly enlarged ceca compared to the control group (CTL mice). Periapical bone resorption prior to the tooth extraction was similarly prevented when treated with antibiotics, which was confirmed by decreased osteoclasts and inflammation. ZOL treatment with pulp exposure significantly increased bone necrosis as determined by empty lacunae and necrotic bone amount. Furthermore, antibiotics treatment could further exacerbate bone necrosis, with increased osteoclast number. Our findings suggest that the commensal microbiome may play protective role, rather than pathological role, in the early stages of MRONJ development.

Author Correction: Single CD271 marker isolates mesenchymal stem cells from human dental pulp / 国际口腔科学杂志·英文版

In the original version of this Article, Figure 1c was inadvertently assembled with a duplicate of Figure 1b. The correct image for Figure 1c, shown below, has been added in the HTML and PDF versions of the Article. This does not affect the conclusions of the study. We sincerely apologize for any inconvenience this may have caused our readers.

Clinical utility of ledipasvir/sofosbuvir in the treatment of adolescents and children with hepatitis C.

Chronic infection with hepatitis C virus (HCV) affects an estimated 0.1%-2% of the pediatric population in the United States. While the clinical course in young children is indolent, adolescents who contract HCV have a disease course similar to adults, with a 26-fold increased risk of chronic liver disease-associated mortality, hepatocellular carcinoma, and need for curative liver transplantation. Furthermore, adolescent patients are entering childbearing age and carry a risk of passing HCV to their offspring via vertical transmission. Pegylated-interferon (PEG-IFN) with ribavirin was previously the only treatment option for pediatric patients with chronic hepatitis C (CHC), but the high likelihood of adverse reactions and subcutaneous route of administration limited its use and efficacy. Recently, the direct-acting antivirals (DAAs) ledipasvir (LDV) and sofosbuvir (SOF) were approved for adolescents with CHC. This review discusses the natural history of CHC in pediatric patients, data supporting LDV/SOF in adolescents, and ongoing studies evaluating DAAs in pediatric patients.

Histological Alterations from Condyle Repositioning with Functional Appliances in Rats.

OBJECTIVE: This study was designed to assess the morphological and histological alterations of the condyle of rats undergoing forward mandibular repositioning via functional appliance. MATERIALS AND METHODS: Functional appliances were mounted onto the upper jaws of rats. Morphological analysis was conducted on micro-CT images of sacrificed animals. Histological changes in condyle were examined by immunohistochemistry using proliferating cell nuclear antigen (PCNA), matrix metalloproteases (MMPs), vascular endothelial growth factor (VEGF), tissue inhibitors of matrix metalloproteinases (TIMP-1), interleukin 1b (IL-1ß), Aggrecan and Type II collagen. Osteoclast activity was identified by tartrate-resistant acid phosphatase (TRAP) staining. RESULTS: Morphological analysis confirmed the forward positioning of the condyles of rats by the appliance, but the position gradually returned to normal on days 14 after treatment. An increase in PCNA positive cells was observed in the posterior region of the condyles on days 7, whereas PCNA positive cells decreased in the anterior region. Aggrecan and Type II collagen localization increased in the posterior region throughout the entire period, but decreased in the anterior region on days 14. In both regions, IL-1ß and VEGF localization was significantly increased for 14 days while MMPs localization was evident throughout the entire period. The TRAP positive cells were significantly elevated on days 3 and 7. CONCLUSIONS: These results suggest that the functional appliance therapy induces significant morphological and histological changes in the anterior and posterior regions of the condyle and subsequently causes adaptive cellular functions such as chondrocyte differentiation and cartilage matrix formation.

The Role of Direct-acting Antivirals in the Treatment of Children with Chronic Hepatitis C.

In the United States, chronic infection with the hepatitis C virus (HCV) affects an estimated 0.1-2% of the pediatric population, who are consequently at risk for major complications, including cirrhosis, hepatocellular carcinoma, and death. The current standard of treatment for chronic hepatitis C (CHC) in children is pegylated-interferon-alpha (PEG-IFN) in combination with ribavirin. PEG-IFN/ribavirin therapy is approved for children ages 3 and older; however, it is often held from use until adulthood because of its extensive list of potential side effects and high likelihood of causing adverse symptoms. While CHC is usually indolent in children and adolescents, immediately treating and curbing the spread of HCV before adulthood is important, as there can be transmission to other individuals via sexual activity and infected females can later vertically transmit the infection during pregnancy, the latter representing the most common means of transmission for children in the United States. The recent development of direct-acting antivirals has shown promising results in clinical trials for use in children and has dramatically increased the rates of sustained virological response in adults while improving side effect profiles as compared to interferon-based treatments. Given the usually indolent course of CHC in children, significant side effects of the currently-approved PEG-IFN/ribavirin therapy, and likely availability of all-oral interferon-free regimens for children within a few years, deferring treatment in clinically-stable children with CHC in anticipation of upcoming superior treatment modalities may be justified.

Histone methyltransferases and demethylases: regulators in balancing osteogenic and adipogenic differentiation of mesenchymal stem cells / 国际口腔科学杂志·英文版

Mesenchymal stem cells (MSCs) are characterized by their self-renewing capacity and differentiation potential into multiple tissues. Thus, management of the differentiation capacities of MSCs is important for MSC-based regenerative medicine, such as craniofacial bone regeneration, and in new treatments for metabolic bone diseases, such as osteoporosis. In recent years, histone modification has been a growing topic in the field of MSC lineage specification, in which the Su(var)3-9, enhancer-of-zeste, trithorax (SET) domain-containing family and the Jumonji C (JmjC) domain-containing family represent the major histone lysine methyltransferases (KMTs) and histone lysine demethylases (KDMs), respectively. In this review, we summarize the current understanding of the epigenetic mechanisms by which SET domain-containing KMTs and JmjC domain-containing KDMs balance the osteogenic and adipogenic differentiation of MSCs.

Single CD271 marker isolates mesenchymal stem cells from human dental pulp / 国际口腔科学杂志·英文版

Mesenchymal stem cells (MSCs) are a promising tool in regenerative medicine due to their capacity to differentiate into multiple lineages. In addition to MSCs isolated from bone marrow (BMSCs), adult MSCs are isolated from craniofacial tissues including dental pulp tissues (DPs) using various stem cell surface markers. However, there has been a lack of consensus on a set of surface makers that are reproducibly effective at isolating putative multipotent dental mesenchymal stem cells (DMSCs). In this study, we used different combinations of surface markers (CD51/CD140α, CD271, and STRO-1/CD146) to isolate homogeneous populations of DMSCs from heterogeneous dental pulp cells (DPCs) obtained from DP and compared their capacity to undergo multilineage differentiation. Fluorescence-activated cell sorting revealed that 27.3% of DPCs were CD51(+)/CD140α(+), 10.6% were CD271(+), and 0.3% were STRO-1(+)/CD146(+). Under odontogenic conditions, all three subsets of isolated DMSCs exhibited differentiation capacity into odontogenic lineages. Among these isolated subsets of DMSCs, CD271(+) DMSCs demonstrated the greatest odontogenic potential. While all three combinations of surface markers in this study successfully isolated DMSCs from DPCs, the single CD271 marker presents the most effective stem cell surface marker for identification of DMSCs with high odontogenic potential. Isolated CD271(+) DMSCs could potentially be utilized for future clinical applications in dentistry and regenerative medicine.

Characterization of the osteogenic potential of mesenchymal stem cells from human periodontal ligament based on cell surface markers / 国际口腔科学杂志·英文版

Mesenchymal stem cell (MSC)-mediated therapy has been shown to be clinically effective in regenerating tissue defects. For improved regenerative therapy, it is critical to isolate homogenous populations of MSCs with high capacity to differentiate into appropriate tissues. The utilization of stem cell surface antigens provides a means to identify MSCs from various tissues. However, few surface markers that consistently isolate highly regenerative MSCs have been validated, making it challenging for routine clinical applications and making it all the more imperative to identify reliable surface markers. In this study, we used three surface marker combinations: CD51/CD140α, CD271, and STRO-1/CD146 for the isolation of homogenous populations of dental mesenchymal stem cells (DMSCs) from heterogeneous periodontal ligament cells (PDLCs). Fluorescence-activated cell sorting analysis revealed that 24% of PDLCs were CD51(+)/CD140α(+), 0.8% were CD271(+), and 2.4% were STRO-1(+)/CD146(+). Sorted cell populations were further assessed for their multipotent properties by inducing osteogenic and chondrogenic differentiation. All three subsets of isolated DMSCs exhibited differentiation capacity into osteogenic and chondrogenic lineages but with varying degrees. CD271(+) DMSCs demonstrated the greatest osteogenic potential with strong induction of osteogenic markers such as DLX5, RUNX2, and BGLAP. Our study provides evidence that surface marker combinations used in this study are sufficient markers for the isolation of DMSCs from PDLCs. These results provide important insight into using specific surface markers for identifying homogenous populations of DMSCs for their improved utilization in regenerative medicine.

KDM6B epigenetically regulates odontogenic differentiation of dental mesenchymal stem cells / 国际口腔科学杂志·英文版

Mesenchymal stem cells (MSCs) have been identified and isolated from dental tissues, including stem cells from apical papilla, which demonstrated the ability to differentiate into dentin-forming odontoblasts. The histone demethylase KDM6B (also known as JMJD3) was shown to play a key role in promoting osteogenic commitment by removing epigenetic marks H3K27me3 from the promoters of osteogenic genes. Whether KDM6B is involved in odontogenic differentiation of dental MSCs, however, is not known. Here, we explored the role of KDM6B in dental MSC fate determination into the odontogenic lineage. Using shRNA-expressing lentivirus, we performed KDM6B knockdown in dental MSCs and observed that KDM6B depletion leads to a significant reduction in alkaline phosphate (ALP) activity and in formation of mineralized nodules assessed by Alizarin Red staining. Additionally, mRNA expression of odontogenic marker gene SP7 (osterix, OSX), as well as extracellular matrix genes BGLAP (osteoclacin, OCN) and SPP1 (osteopontin, OPN), was suppressed by KDM6B depletion. When KDM6B was overexpressed in KDM6B-knockdown MSCs, odontogenic differentiation was restored, further confirming the facilitating role of KDM6B in odontogenic commitment. Mechanistically, KDM6B was recruited to bone morphogenic protein 2 (BMP2) promoters and the subsequent removal of silencing H3K27me3 marks led to the activation of this odontogenic master transcription gene. Taken together, our results demonstrated the critical role of a histone demethylase in the epigenetic regulation of odontogenic differentiation of dental MSCs. KDM6B may present as a potential therapeutic target in the regeneration of tooth structures and the repair of craniofacial defects.