Periplaneta americana extract promotes osteoblast differentiation of human alveolar bone marrow mesenchymal stem cells.

OBJECTIVES: This study aims to investigate the effects of Traditional Chinese medicine, Periplaneta americana extract (PAE), on osteoblast differentiation of human alveolar bone marrow-derived mesenchymal stem cells (hABMMSCs). MATERIALS AND METHODS: Human alveolar bone marrow-derived mesenchymal stem cells were treated with different concentrations of PAE. Cell Counting Kit-8 (CCK-8) assay and transwell migration assay were conducted to evaluate cell proliferation and migration, respectively. Alkaline phosphatase (ALP) staining, ALP activity assay, and Alizarin red S staining were performed to detect osteogenesis in hABMMSCs. In addition, real-time quantitative polymerase chain reaction (RT-qPCR) and western blot (WB) assay were performed to evaluate expression levels of osteogenic markers. Finally, RNA sequencing analysis and WB were carried out to elucidate the underlying mechanism. RESULTS: A total of 0.1 mg/ml PAE promoted cell proliferation and migration. PAE also increased ALP activity and mineralized nodule formation of hABMMSCs. In addition, PAE upregulated the expression of osteogenesis-related genes (RUNX2, COL1A1, and BGLAP). RNA-sequencing analysis revealed that PAE activated the focal adhesion signaling pathway. Treatment with Defactinib, an inhibitor of FAK, attenuated the effects induced by PAE. CONCLUSIONS: PAE could enhance osteoblast differentiation of hABMMSCs through focal adhesion signaling pathway, suggesting a therapeutic potential for the alveolar bone defect.

Bone regeneration property of tooth-derived bone substitute prepared chairside for periodontal bone defects: an experimental study.

BACKGROUND: Periodontitis often leads to progressive destruction and loss of alveolar bone, the reconstruction of which remains difficult in periodontal therapy. As a novel bone graft material, tooth-derived bone substitute (TDBS) processed from extracted teeth has been previously reported about its osteoconductivity and promising results in bone regeneration. This study was to investigate the biological effects and bone regeneration properties of TDBS in vitro and in vivo using rat periodontal bone defect model. METHODS: Three groups of materials were used in the experiments: TDBS, TDBS treated with ethylene diamine tetraacetic acid (EDTA) (TDBS-E), and allogeneic bone materials. Calcium (Ca) and phosphate (P) ion dissolutions were quantified by spectrophotometer for seven days. The releases of bone morphogenetic protein-2 (BMP-2) and transforming growth factor-ß1 (TGF-ß1) were identified by enzyme-linked immunosorbent assay (ELISA). Human osteoblast proliferation, migration, and differentiation were detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, cell counting, alkaline phosphatase activity (ALP), and alizarin red staining (ARS), respectively. Furthermore, the osteogenic effects of TDBS on periodontal furcation bone defects were evaluated at eight weeks postoperatively using micro-computed tomography (Micro-CT) and histological analysis. RESULTS: The dissolution of both Ca and P ions in TDBS increased over time. The BMP-2 released from TDBS was significantly higher than that from TDBS-E and allografts, while the TGF-ß1 release from TDBS and TDBS-E groups was higher than that in the allografts. The TDBS-E group could induce the highest level of osteoblast proliferation compared to other groups. Cell migration with allografts co-culture was significantly induced compared to the blank control. However, all groups demonstrated similar positive effects on osteoblast differentiation. Furthermore, in the periodontal model, all materials could effectively enhance bone regeneration in the furcation defect. CONCLUSIONS: The TDBS prepared chairside as an autogenous bone graft, demonstrating osteoinductivity, which enhances the osteogenic biological characteristics. Therefore, TDBS is suggested as an economical and biocompatible material for periodontal bone regeneration.

Salivary microbiome in patients undergoing hemodialysis and its associations with the duration of the dialysis.

BACKGROUND: Chronic kidney disease (CKD) patients, especially those with end stage renal disease (ESRD) undergoing hemodialysis (HD), exhibit high prevalence of periodontitis. This cross-sectional study aimed to investigate the periodontal status of HD patients and its relationship with salivary microbiome. METHODS: One hundred eight HD patients and one hundred healthy control individuals were recruited. They were subjected to periodontal examination followed by saliva samples collection for 16S rRNA gene sequencing. RESULTS: The HD patients were with worse periodontal health status, and exhibited higher salivary microbial diversity and lower richness. The periodontal pathogens were significantly enriched in the HD patients. The inferred functional analyze showed microbes enriched in the HD patients were mainly related to metabolism. Despite the periodontal status and overall structure of the microbiome were not significantly altered as the HD duration prolonged, the abundance of Lachnospiraceae [G-2] sp. |HMT_096| is positively correlated with the duration of HD and the community periodontal index (CPI). Five OTUs (operational taxonomic units) belonging to the phyla Firmicutes were enriched as the duration prolonged, and four OTUs originated from the phyla Proteobacteria were negatively related with the CPI index. ESRD patients undergoing HD exhibited microbiota structural, compositional and functional differences compared with the healthy controls. And the species changed as the duration of hemodialysis prolonged. CONCLUSIONS: End stage renal disease changes salivary microbiome and is a risk factor for oral dysbiosis.

Prolactin receptor and osteogenic induction of prolactin in human periodontal ligament fibroblasts.

Prolactin is an important hormone involved in the interaction between maternal, extraembryonic, and fetal tissues that remains in high levels during the entire duration of pregnancy. Although many systemic alterations occur during pregnancy, such as hormonal changes, that are known to be associated with periodontitis and tooth loss, PRL function in human periodontal ligament fibroblasts (HPDLF) had never been studied. Herein, we investigated the role of PRL in the regulation of HPDLF proliferation and differentiation. HPDLF were cultured in differentiating medium with various concentrations of PRL. The present study demonstrated that HPDLF and primary human PDL cells that were extracted for orthodontic purpose expressed both short and long isoforms of PRLR mRNA and its proteins. An incubation with of high concentration of PRL (600 and 1,000 ng/mL) modestly decreased the HPDLF number. In contrast, PRL at a non-reproductive level (10 ng/mL) and pregnant level (100 ng/mL) significantly upregulated the markers of osteogenesis, such as RUNX2, BMP2, and POSTN, but not SOX9. Mineral nodule formation was induced, whereas proteoglycan accumulation was reduced by PRL suggesting that HPDLF were undergoing differentiation into preosteoblastic cells. In conclusion, the presence of hPRLR in human PDL together with PRL-induced upregulation of osteogenic markers strongly suggested a direct regulatory role of PRL in PDL and periodontal tissue development.

Effect of Resorbable Collagen Plug on Bone Regeneration in Rat Critical-Size Defect Model.

OBJECTIVE: The purpose of this investigation was to examine the effect of resorbable collagen plug (RCP) on bone regeneration in rat calvarial critical-size defects. METHODS: About 5-mm-diameter calvarial defects were created in forty 12-week-old male Sprague-Dawley rats and implanted with or without RCP. Animals were killed at 1, 2, 4, and 8 weeks postoperatively. After being killed, specimens were collected and subjected to micro-computed tomography (µCT) and histological analysis. RESULTS: The µCT showed a significant increase of newly formed bone volume/tissue volume in RCP-implanted defect compared with controls at all designated time points. After 8 weeks, the defects implanted with RCP displayed almost complete closure. Hematoxylin and eosin staining of the decalcified sections confirmed these observations and evidenced active bone regeneration in the RCP group. In addition, Masson's trichrome staining demonstrated that RCP implantation accelerated the process of collagen maturation. CONCLUSIONS: The RCP enhances bone regeneration in rat critical-size cranial defects, which suggest it might be a desired material for bone defect repair.

Inhibition of METTL3 Alleviates NLRP3 Inflammasome Activation via Increasing Ubiquitination of NEK7.

N6-methyladenosine (m6A) modification, installed by METTL3-METTL14 complex, is abundant and critical in eukaryotic mRNA. However, its role in oral mucosal immunity remains ambiguous. Periodontitis is a special but prevalent infectious disease characterized as hyperinflammation of oral mucosa and bone resorption. Here, it is reported that genetic deletion of Mettl3 alleviates periodontal destruction via suppressing NLRP3 inflammasome activation. Mechanistically, the stability of TNFAIP3 (also known as A20) transcript is significantly attenuated upon m6A modification. When silencing METTL3, accumulated TNFAIP3 functioning as a ubiquitin-editing enzyme facilitates the ubiquitination of NEK7 [NIMA (never in mitosis gene a)-related kinase 7], and subsequently impairs NLRP3 inflammasome assembly. Furtherly, Coptisine chloride, a natural small-molecule, is discovered as a novel METTL3 inhibitor and performs therapeutic effect on periodontitis. The study unveils a previously unknown pathogenic mechanism of METTL3-mediated m6A modifications in periodontitis and indicates METTL3 as a potential therapeutic target.

The healing capacity and osteogenesis pattern of demineralized dentin matrix (DDM)-fibrin glue (FG) compound.

Demineralized dentin matrix (DDM) is an osteoconductive and osteoinductive material that has been successfully used in sinus floor augmentation and alveolar ridge augmentation in clinical applications. It releases bone morphogenetic proteins (BMPs) and other growth factors, making DDM a suitable grafting material. However, the granular particle of DDM makes it difficult to anchor into the bone defect area. The aim of this study was to investigate the biological effects and osteoinductivity of the combination of DDM and Fibrin Glue (FG) at an optimal ratio on bone healing from a critical bone defect in an animal model. The mouse osteoblastic cell line (MC3T3-E1) was co-cultured with various ratios of DDM and FG to examine their effects on osteoblast proliferation and differentiation, as indicated by alkaline phosphatase (ALP) activity, osteocalcin (OC) production and mineralized nodules formation. The optimal ratio was then chosen for further study with a rabbit calvarial defective model, in which they were implanted with DDM or DDM-FG1 (1 g: 0.1 ml) and DDM-FG2 (1 g: 0.5 ml) compounds, or left blank for 2, 4, 8 and 12 weeks to investigate soft tissue and new bone regeneration. Micro-CT and histology analysis were used to evaluate the total grafting properties according to the different healing periods. The result from in vitro studies demonstrated that the ratio of 1:0.1 induced more ALP activity and mineralized nodules, while the ratio of 1: 0.5 (DDM-FG combined) induced more osteocalcin (OC) at specific time points. In the animal model, the 3D new bone volume in all DDM-FG treatment groups was significantly greater than that in the blank group at 2, 4, 8 and 12 weeks. Furthermore, the new bone volume was greater in DDM-FG2 when compared to the other groups during the early weeks of the healing period. In histological analysis, clusters of osteoblasts were formed adjacent to the DDM particles, and newly formed bone was observed in all groups, suggesting an osteoinductive property of DDM. Moreover, the greater new collagen synthesis observed at 4 weeks suggested that early bone healing was induced in the DDM-FG2 group. This study demonstrated that at an optimal ratio, the DDM-FG compound enhances osteogenic activities and bone regeneration.

METTL5 regulates cranial suture fusion via Wnt signaling.

METTL5 is a methyltransferase that mediates eukaryotic 18S ribosomal RNA m6A modification, and its mutations lead to intellectual disability, microcephaly, and facial dysmorphism in patients. However, the role of METTL5 in craniofacial development remains poorly understood. This study demonstrates that Mettl5 knockout mice exhibit poor ossification, widened cranial sutures, and a cleidocranial dysplasia-like phenotype. Deletion of Mettl5 leads to increased proliferation and decreased osteogenic differentiation of suture mesenchymal stem cells. Mechanistically, we find that Wnt signaling is significantly downregulated after Mettl5 knockout. Overall, we reveal an essential role of METTL5 in craniofacial development and osteogenic differentiation of suture mesenchymal stem cells, making METTL5 a potential diagnostic and therapeutic target for craniofacial developmental diseases.

Chondroregulatory action of prolactin on proliferation and differentiation of mouse chondrogenic ATDC5 cells in 3-dimensional micromass cultures.

A recent investigation in lactating rats has provided evidence that the lactogenic hormone prolactin (PRL) increases endochondral bone growth and bone elongation, presumably by accelerating apoptosis of hypertrophic chondrocytes in the growth plate and/or subsequent chondrogenic matrix mineralization. Herein, we demonstrated the direct chondroregulatory action of PRL on proliferation, differentiation and apoptosis of chondrocytes in 3-dimensional micromass culture of mouse chondrogenic ATDC5 cell line. The results showed that ATDC5 cells expressed PRL receptor (PRLR) transcripts, and responded typically to PRL by downregulating PRLR expression. Exposure to a low PRL concentration of 10 ng/mL, comparable to the normal levels in male and non-pregnant female rats, increased chondrocyte viability, differentiation, proteoglycan accumulation, and mRNA expression of several chondrogenic differentiation markers, such as Sox9, ALP and Hspg2. In contrast, high PRL concentrations of ≥ 100 ng/mL, comparable to the levels in pregnancy or lactation, decreased chondrocyte viability by inducing apoptosis, with no effect on chondrogenic marker expression. It could be concluded that chondrocytes directly but differentially responded to non-pregnant and pregnant/lactating levels of PRL, thus suggesting the stimulatory effect of PRL on chondrogenesis in young growing individuals, and supporting the hypothesis of hypertrophic chondrocyte apoptosis in the growth plate of lactating rats.

Deletion of Zfp521 rescues the growth plate phenotype in a mouse model of Jansen metaphyseal chondrodysplasia.

Jansen metaphyseal chondrodysplasia (JMC) is caused by a constitutively activating mutation of the parathyroid hormone (PTH)/PTH-related protein (PTHrP) receptor (PTHR1) and is characterized by widening of the metaphyses, reduction of long bone length, and short stature. A transgenic mouse expressing this mutation under the collagen α1(II) promoter has been generated to investigate the mechanisms responsible for this chondrodysplasia. We recently identified zinc finger protein 521 (Zfp521) as a downstream target gene of PTHrP signaling. Interestingly, loss of Zfp521 from chondrocytes leads to reduced cell proliferation and increased differentiation in the growth plate. Thus, we hypothesized that specifically ablating Zfp521 from Jansen chondrocytes could sufficiently rescue the chondrodysplasia phenotype. Our results show that Zfp521 expression is up-regulated in Jansen mouse growth plate chondrocytes and that PTHR1 is required for Zfp521 expression. Its ablation from Jansen chondrocytes restored normal cell differentiation, thus initiating chondrocyte apoptosis at the chondro-osseous junction, leading to partial rescue of endochondral bone formation shown by proper bone length. This study provides the first genetic evidence that Zfp521 is required downstream of PTHR1 signaling to act on chondrocyte proliferation, differentiation, and cell death.

A Novel Alveolar Distractor Incorporating Nickel-Titanium Alloy Springs: A Preliminary In Vitro Study.

A new design of an alveolar distractor using nickel−titanium (NiTi) open-coil springs was developed and investigated to produce distraction forces against the tensile forces of porcine attached gingiva to simulate human gingiva. We subjected 15 mm long NiTi open-coil springs (Highland and ORMCO) with three levels of forces (light, medium and heavy) to mechanical testing in a 37 ± 1 °C water bath. Ten strips of porcine mandibular attached gingiva were subjected to tensile tests to determine the resistance force. The forces from the springs were compared with the tensile forces from the porcine attached gingiva. Data between groups were analyzed with independent-samples T-tests (p-value < 0.05). The tensile strength and the Young modulus were greater in buccal compared to lingual porcine attached gingiva. Compared to other spring dimensions and companies, forces generated from 0.014 × 0.036″ ORMCO springs were the highest and could overcome the tensile resistance from porcine attached gingiva over the longest distraction range of 1.6 mm. This preliminary in vitro study introduced a new design of an alveolar distractor incorporated with NiTi open-coil springs that could generate light and continuous forces to overcome the resistance from porcine attached gingiva.

Physicochemical and osteogenic properties of chairside processed tooth derived bone substitute and bone graft materials.

To analyze physicochemical such as surface structures, the crystallinity, chemical composition, calcium phosphate dissolution and osteogenic properties of tooth derived bone substitute (TDBS) processed chair-side and other grafting materials. The number of anaerobic and facultative anaerobic bacteria in the supernatant of processed TDBS was determined. Human osteoblasts were co-cultured with TDBS or allograft in transwell system to examine cell migration. BMP2 released from TDBS was measured by ELISA. TDBS had high crystallinity similar to BoneCeramic while it had a broad pattern to ramus bone, OraGRAFT, and Bio-Oss. TDBS contained carbon, calcium, oxygen, phosphate, sodium and magnesium elements like others. Calcium/phosphorus dissolution of TDBS show closely related to those of mandibular ramus bone and OraGRAFT. In addition, microbial decontamination of TDBS by the chemical processing revealed a hundred percent efficacy. The osteoconductive and osteoinductive properties demonstrated in the TDBS processed chairside suggested the potential of an alternative for bone grafting material.

Author Correction: Chronic Kidney Disease Impairs Bone Defect Healing in Rats.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Evidence for direct effects of prolactin on human osteoblasts: Inhibition of cell growth and mineralization.

Hyperprolactinemia is one of the risk factor of decrease in bone mass which has been believed to be mediated by hypogonadism. However, the presence of prolactin receptor in human osteosarcoma cell line and primary bone cell culture from mouse calvariae supported the hypothesis of a direct prolactin (PRL) action on bone cells. Therefore, the aim of this study was to investigate the role of PRL and its signal transduction pathway in the regulation of bone metabolism via osteoblast differentiation. Human pre-osteoblasts (SV-HFO) that differentiate in a 3-week period from proliferating pre-osteoblasts (days 2-7) to extracellular matrix producing cells (days 7-14) which is eventually mineralized (days 14-21) were used. Concentration of PRL mimicked a lactating period (100 ng/ml) was used to incubate SV-HFO for 21 days in osteogenic medium. Human prolactin receptor mRNA and protein are expressed in SV-HFO. PRL significantly decreased osteoblast number (DNA content) which was due to a decrease in proliferation. PRL increased osteogenic markers, RUNX2 and ALP in early stage of osteoblast differentiation while decreasing it later suggesting a bi-directional effect. Calcium measurement and Alizarin red staining showed a reduction of mineralization by PRL while having neither an effect on osteoblast activity nor RANKL/OPG mRNA ratio. We also demonstrated that PRL action on mineralization was not via PI-3 kinase pathway. The present study provides evidence of a direct effect of prolactin on osteoblast differentiation and in vitro mineralization.

Effect of stannous fluoride and zinc phosphate dentifrice on dental plaque and gingivitis: A randomized clinical trial with 6-month follow-up.

OBJECTIVE: The objective of this study was to compare a stabilized stannous fluoride (SnF2) dentifrice with zinc phosphate (Colgate TotalSF) with SnF2 with zinc lactate and control fluoride dentifrices for gingivitis and plaque control over a 6-month period. METHODS: A total of 135 adult participants were enrolled in this study. After randomization and blinding of examiners and patients, enrolled participants were provided instructions for use of assigned dentifrice. At 3 visits (0, 3, and 6 months), various gingival and plaque indexes were collected to determine the clinical efficacy of a stabilized SnF2 dentifrice. These results were compared with a SnF2 with zinc lactate dentifrice and with a control fluoride dentifrice. RESULTS: A total of 135 participants completed the study. All groups reported statistically significant reductions in gingival inflammation and improvement in plaque control at 3- and 6-month follow-up. Both SnF2 dentifrices showed statistically significant reductions in all indexes compared with the control dentifrice (P < .001). However, the test dentifrice showed higher but nonsignificant improvements in plaque and gingival indexes compared with the other SnF2 dentifrice. CONCLUSIONS: This study reports similar efficacy of a test dentifrice to a commercial SnF2-containing dentifrice for plaque control and reduction in gingival inflammation and provides supporting evidence that the test dentifrice maintains its clinical efficacy with change of formulation. PRACTICAL IMPLICATIONS: This newly formulated SnF2 stabilized with zinc phosphate dentifrice may be of benefit to patients in controlling plaque biofilm and gingivitis.

Prolactin directly enhances bone turnover by raising osteoblast-expressed receptor activator of nuclear factor kappaB ligand/osteoprotegerin ratio.

Hyperprolactinemia leads to high bone turnover as a result of enhanced bone formation and resorption. Although its osteopenic effect has long been explained as hyperprolactinemia-induced hypogonadism, identified prolactin (PRL) receptors in osteoblasts suggested a possible direct action of PRL on bone. In the present study, we found that hyperprolactinemia induced by anterior pituitary transplantation (AP), with or without ovariectomy (Ovx), had no detectable effect on bone mineral density and content measured by dual-energy X-ray absorptiometry (DXA). However, histomorphometric studies revealed increases in the osteoblast and osteoclast surfaces in the AP rats, but a decrease in the osteoblast surface in the AP+Ovx rats. The resorptive activity was predominant since bone volume and trabecular number were decreased, and the trabecular separation was increased in both groups. Estrogen supplement (E2) fully reversed the effect of estrogen depletion in the Ovx but not in the AP+Ovx rats. In contrast to the typical Ovx rats, bone formation and resorption became uncoupled in the AP+Ovx rats. Therefore, hyperprolactinemia was likely to have some estrogen-independent and/or direct actions on bone turnover. Osteoblast-expressed PRL receptor transcripts and proteins shown in the present study confirmed our hypothesis. Furthermore, we demonstrated that the osteoblast-like cells, MG-63, directly exposed to PRL exhibited lower expression of alkaline phosphatase and osteocalcin mRNA, and a decrease in alkaline phosphatase activity. The ratios of receptor activator of nuclear factor kappaB ligand (RANKL) and osteoprotegerin (OPG) proteins were increased, indicating an increase in the osteoclastic bone resorption. The present data thus demonstrated that hyperprolactinemia could act directly on bone to stimulate bone turnover, with more influence on bone resorption than formation. PRL enhanced bone resorption in part by increasing RANKL and decreasing OPG expressions by osteoblasts.

Correlation between the thickness of the crestal and buccolingual cortical bone at varying depths and implant stability quotients.

BACKGROUND/PURPOSE: Resonance frequency analysis (RFA) is clinically used in dentistry to access the stiffness of dental implants in surrounding bone. However, the clear advantages and disadvantages of this method are still inconclusive. The aim of this study was to investigate and compare implant stability quotient (ISQ) values obtained from RFA with parameters obtained from a cone beam computed tomography (CBCT) scan of the same region. MATERIALS AND METHODS: Nineteen implants (Conelog) were inserted in the posterior maxillary and mandibular partially edentulous regions of 16 patients. At the time of implant placement, the ISQ values were obtained using RFA (Osstell). CBCT was used to measure the thickness of the crestal, cortical, buccolingual cortical, and cancellous bone at 3, 6, and 9 mm below the crestal bone level, as indicated by radiographic markers. The ratio of the thickness of the cortical to cancellous bone at varying depths was also calculated and classified into 4 groups (Group 1-4). RESULTS: There was a strong correlation between the crestal cortical bone thickness and ISQ values (P<0.001). The thickness of the buccolingual cortical bone and ratio of the cortical to cancellous bone thickness at 3 mm were significantly related to the ISQ (P = 0.018 and P = 0.034, respectively). Furthermore, the ISQs in Group 1 were the highest compared with those in Group 2 and Group 3, whereas the CBCT parameters at 6 and 9 mm did not have any specific correlation with the ISQ values. CONCLUSION: This study showed that the ISQ values obtained from RFA highly correlated with the quantity and quality of bone 3 mm below the crestal bone level. The correlation between the ISQ and bone surrounding the implant site was dependent on the depth of measurement. Therefore, RFA can help to predict the marginal bone level, as confirmed in this study.

Dental implant treatment for renal failure patients on dialysis: a clinical guideline.

Chronic kidney disease (CKD) is a worldwide public health problem that is growing in prevalence and is associated with severe complications. During the progression of the disease, a majority of CKD patients suffer oral complications. Dental implants are currently the most reliable and successful treatment for missing teeth. However, due to complications of CKD such as infections, bone lesions, bleeding risks, and altered drug metabolism, dental implant treatment for renal failure patients on dialysis is more challenging. In this review, we have summarized the characteristics of CKD and previous publications regarding dental treatments for renal failure patients. In addition, we discuss our recent research results and clinical experience in order to provide dental implant practitioners with a clinical guideline for dental implant treatment for renal failure patients undergoing hemodialysis.

Estrogen Deficiency Leads to Further Bone Loss in the Mandible of CKD Mice.

BACKGROUND: Chronic kidney disease (CKD) has been regarded as a grave public health problem. Estrogen is a critical factor for both renal protection and bone remodeling. Our previous study demonstrated that CKD impairs the healing of titanium implants. The aim of this study was to investigate the effects of estrogen deficiency on the mandibular bone in CKD mice. METHODS: Forty eleven-week-old female C57BL mice were used in this study. Uremia and estrogen deficiency were induced by 5/6 nephrectomy and ovariectomy (OVX), respectively. After 8 weeks, the mice were sacrificed, and their mandibles were collected for micro-CT analysis and histological examination. RESULTS: All the mice survived the experimental period. Serum measurements confirmed a significant increase in BUN in the CKD group that was further increased by OVX. OVX led to significant decreases in both the BV/TV and cortical thickness of the mandibular bone in CKD mice. CONCLUSION: In summary, our findings indicate that estrogen deficiency leads to further mandibular bone loss in CKD mice.

Chronic Kidney Disease Impairs Bone Defect Healing in Rats.

Chronic kidney disease (CKD) has been regarded as a risk for bone health. The aim of this study was to evaluate the effect of CKD on bone defect repair in rats. Uremia was induced by subtotal renal ablation, and serum levels of BUN and PTH were significantly elevated four weeks after the second renal surgery. Calvarial defects of 5-mm diameter were created and implanted with or without deproteinized bovine bone mineral (DBBM). Micro-CT and histological analyses consistently revealed a decreased newly regenerated bone volume for CKD rats after 4 and 8 weeks. In addition, 1.4-mm-diameter cortical bone defects were established in the distal end of femora and filled with gelatin sponge. CKD rats exhibited significantly lower values of regenerated bone and bone mineral density (BMD) within the cortical gap after 2 and 4 weeks. Moreover, histomorphometric analysis showed an increase in both osteoblast number (N.Ob/B.Pm) and osteoclast number (N.Oc/B.Pm) in CKD groups due to hyperparathyroidism. Notably, collagen maturation was delayed in CKD rats as verified by Masson's Trichrome staining. These data indicate that declined renal function negatively affects bone regeneration in both calvarial and femoral defects.