Mineralization Nodules Research Articles

Comparative study of two silica mesoporous materials (SBA-16 and SBA-15) modified with a hydroxyapatite layer for clindamycin controlled delivery

Mesoporous silica materials are very promising for biomedical applications due to their superficial area and bioactive behavior and have been widely investigated for control drug release. The bioactive behavior of these materials have been attributed to silanol groups and/or to textural properties. In the present work we studied the bioactive behavior of two mesoporous materials with different textural properties, the formation of an apatite coating on the mesoporous walls and their effect on the controlled delivery of clindamycin, at two different pH conditions. It was found that the textural properties are a determinant factor in the bioactive behavior of these materials; SBA-15 showed a higher bioactive response than SBA-16 after 8 d immersion in simulated body fluid. Also, SBA-15 was more effective for clindamycin drug release; however both materials are very promising as drug carriers. The formation of hydroxyapatite crystallites on the mesoporous walls resulted in new textural properties with a new framework configuration that affects the delivery properties of the mesoporous materials. Additionally, the citotoxicity and osteogenesis of SBA-15 and the modified SBA-Ha were evaluated. The mesoporous silica materials were non-toxic for the cells allowing viability for the studied period with an increase proliferation for the cells exposed to SBA-15/Ha. The results showed that SBA-15 and SBA-15/Ha are osteogenic materials, promoting the formation of mineralization nodules, associated to osteogenesis.

Naked cuticle homolog 2 positively regulates the osteogenic differentiation of rat dental follicle cells

Objective: To examine the expression of naked cuticle homolog 2 (Nkd2) in the process of root development and osteogenic differentiation of dental follicle cells of rat (rDFC), in order to explore the molecular mechanisms of Nkd2 on the osteoblast differentiation of rDFCs. Methods: Immunohistochemical analysis was used to detect the expression of Nkd2 in the base dental follicle of the mandibular first molar of rat at 1, 3, 5, 7, 9, 11 and 13 days postnatal. Mineralization nodule formation of rDFCs was detected by alizarin red staining and cetylpyridine. The change of Nkd2 during osteogenic differentiation of rDFCs was evaluated by Western blotting and the associations between Nkd2 and osteogenic cytokines of alkaline phosphatase (ALP), Runt-related transcription factor-2 (RUNX2) and osteocalcin (OCN) were examined. The rDFCs were transfected with small interfering RNA (siRNA) to knock down the expression of Nkd2 and Western blotting and quantitative real-time PCR (qPCR) were adopted to explore the effects of Nkd2 on osteogenic differentiation by detecting variations of Nkd2 and osteogenic factors ALP, RUNX2, OCN among silencing group (Si), negative control RNA group (Nc) and mock control group (Mock), respectively. Results: The expression of Nkd2 in the base dental follicle of the mandibular first molar of rat was time dependent. Mineralization nodules of rDFCs and absorbance of cetylpyridine after osteogenic induction increased gradually (the absorbances of cetylpyridine were 0 week: 0.017±0.005, 1 week: 0.702±0.044, 2 weeks: 1.812±0.531, 3 weeks: 2.767±0.253, respectively). Results of Western blotting showed that Nkd2 (1.60±0.23) of mineralization group was significantly higher than that of control group (1) (P<0.05) at the early stage of osteogenic differentiation along with the expression of other osteogenic factors. The protein and mRNA of Nkd2 and osteogenic factors were significantly decreased in Si group compared with Nc and Mock groups (P<0.05), and no changes between Nc and Mock groups were observed. The changes of protein in Si, Nc and Mock groups were Nkd2: 0.42±0.10, 1.12±0.07, 1, ALP: 0.70±0.15, 1.11±0.14, 1, RUNX2: 0.58±0.08, 0.93±0.08, 1 and OCN: 0.64±0.06, 0.99±0.02, 1, respectively. The mRNA variances in Si, Nc and Mock groups were Nkd2: 0.39±0.05, 0.96±0.10, 1, ALP: 0.15±0.13, 1.01±0.07, 1, RUNX2: 0.39±0.31, 0.97±0.13, 1, OCN: 0.17±0.08, 1.08±0.21, 1, respectively. Conclusions: Nkd2 participates in the root development process in rat and may acts as a positive role in the early stage of osteogenic differentiation of rDFCs in rat.

Effects of melatonin on the proliferation and differentiation of human dental pulp cells

ObjectiveEffects of melatonin on the proliferation and differentiation of human dental pulp cells (hDPCs) remain unclear. The purpose of this study was to investigate the effect of melatonin on the proliferation and differentiation of the hDPCs. DesignPrimary hDPCs were obtained from the third molar of volunteer aged from 18 to 25. CCK8 assay evaluated the effect of melatonin upon cell proliferation at day 1, 2, 3, 4, 5. After 7days’ osteogenic induction with melatonin or vehicle, alkaline phosphatase (ALP) activity was measured with a commercial kit. Then levels of dentin sialophosphoprotein (DSPP) were determined by immunocytochemical staining and western blot analysis, followed by quantitative real-time reverse transcription-Polymerase chain reaction (qRT-PCR) to analyse mRNA levels of ALP and DSPP. Finally hDPCs exposed to osteogenic medium containing melatonin or vehicle for 14days were stained with alizarin red to detect mineralization nodules formation. ResultsMelatonin significantly inhibited the proliferative ability of the hDPCs in a concentration- and time-dependent manner. The hDPCs cultured in osteogenic induction medium with melatonin presented an increase of ALP activity, expression of DSPP, mRNA levels of ALP and DSPP, and mineralization nodules formation. ConclusionsThese findings indicate that melatonin at physiological concentrations can inhibit proliferation and promote the differentiation of hDPCs, which might give some new insights into the mechanism of regulating DPCs to achieve dentine regeneration.

Lysyl oxidase-mediated VEGF-induced differentiation and angiogenesis in human dental pulp cells.

To investigate the effects of recombinant human vascular endothelial growth factor (rhVEGF) on odontoblastic differentiation, invitro angiogenesis, and expression and activity of lysyl oxidase (LOX) in human dental pulp cells (HDPCs), compared with rhFGF-2. To identify the underlying molecular mechanisms, the study focused on whether LOX was responsible for the actions of rhVEGF. Recombinant human vascular endothelial growth factor (rhVEGF) was constructed using the pBAD-HisA plasmid in Escherichia coli. HDPCs were treated with 1-50μgmL-1 rhVEGF for 14days. Alkaline phosphatase (ALP) activity was measured, and the formation of calcified nodules was assessed using alizarin red staining after the induction of odontogenic differentiation of HDPCs. The expression level of the odontogenic differentiation markers was detected by reverse transcription polymerase chain reaction. Signal pathways were assessed by Western blot and immunocytochemistry. The data were analysed by anova with Bonferroni's test (α=0.05). Recombinant human vascular endothelial growth factor significantly increased cell growth (P<0.05), ALP activity (P<0.05) and mineralization nodule formation and upregulated the mRNA expression levels of the osteogenic/odontogenic markers that were lower with rhFGF-2. rhVEGF significantly increased amine oxidase activity (P<0.05) and upregulated LOX and LOXL mRNA expression in HDPCs. Additionally, rhVEGF dose-dependently upregulated angiogenic gene mRNAs and capillary tube formation to a greater degree than rhFGF-2. Inhibition of LOX using β-aminopropionitrile (BAPN) and LOX or LOXL gene silencing by RNA interference attenuated rhVEGF-induced growth, ALP activity, mineralization, the expression of marker mRNAs and invitro angiogenesis. Furthermore, treatment with rhVEGF resulted in phosphorylation of Akt, ERK, JNK and p38, and activation of NF-κB, which was inhibited by LOX or LOXL silencing and BAPN. Recombinant human vascular endothelial growth factor promoted cell growth, odontogenic potential and invitro angiogenesis via modulation of LOX expression. These results support the concept that rhVEGF may offer therapeutic benefits in regenerative endodontics.

ClC-3 chloride channel mediates the role of parathyroid hormone [1-34] on osteogenic differentiation of osteoblasts.

IntroductionDifferent concentrations of parathyroid hormone [1–34] (PTH [1–34]) can have totally opposite effects on osteoblasts. Intermittent stimulation with PTH can significantly increase bone mineral density in vitro, mainly through the protein kinase A (PKA) signaling pathway, which phosphorylates runt-related transcription factor 2 (Runx2). The ClC-3 chloride channel, an important anion channel, can also promote osteogenesis via the Runx2 pathway based on recent studies. The purpose of our study, therefore, is to research whether the ClC-3 chloride channel has an effect on PTH osteodifferentiation in MC3T3-E1 cells.Methods and resultsA cell counting kit (CCK-8) and real-time PCR were used to investigate the impact of different PTH stimulation modes on MC3T3-E1 cell proliferation and osteogenesis-related gene expression, respectively. We found that the minimum inhibitory concentration of PTH was 10−9 M, and the expression of alkaline phosphatase (Alpl) and Runx2 were at the highest levels when treated with 10−9 M PTH. Next, we used real-time PCR and immunofluorescence technique to detect changes in ClC-3 in MC3T3-E1 cells under PTH treatment. The results showed higher expression of the ClC-3 chloride channel at 10−9 M intermittent PTH administration than in the other groups. Finally, we used the ClC-3 siRNA technique to examine the role of the ClC-3 chloride channel in the effect of PTH on the osteogenesis of osteoblasts, and we found an obvious decrease in the expression of bone sialoprotein (Ibsp), osteocalcin (Bglap), osterix (Sp7), Alpl and Runx2, the formation of mineralization nodules as well.ConclusionsFrom the above data, we conclude that the expression of ClC-3 chloride channels in osteoblasts helps them respond to PTH stimulation, which mediates osteogenic differentiation.

Dentine matrix proteins: isolation and effects on human pulp cells.

To establish a simplified and efficient protocol for the isolation and concentration of matrix proteins from human dentine, and to assess the effects of extracted dentine matrix proteins (eDMP) on the behaviour of human pulp cells. Matrix proteins were isolated from human dentine, purified, concentrated and characterized with protein and enzyme-linked immunosorbent assays (ELISA). Culture media were supplemented with eDMP in different concentrations, referred to as eDMP 1-10000, to assess viability and proliferation of human pulp cells by DNA and MTT assays; apoptotic events were quantified by flow cytometry. Chemotactic effects of eDMP were assessed in a modified Boyden chamber assay. Expression levels of odontoblastic marker genes in pulp cells cultured with eDMPs were determined by real-time quantitative PCR, and the ability to induce mineralization was demonstrated by alizarin red staining. Nonparametric statistical analysis was performed to pairwise compare different groups at all time-points (Mann-Whitney U-test, α=0.05). High concentrations of eDMP exhibited significant antiproliferative effects (P≤0.023) after 5 (eDMP 1000) and 7days (eDMP 500) without affecting cell viability. Apoptosis was barely influenced (P≥0.089). eDMP exerted a concentration-dependent chemotactic stimulus on dental pulp cells with statistical significance already at low dosage (P=0.006 at eDMP 10). Changes in gene expression indicated a differentiation into odontoblast-like cells, which was corroborated by findings of mineral nodule formation. A novel, effective and time-saving protocol for isolation and concentration of dentine matrix proteins is presented. As eDMP stimulates chemotaxis, differentiation and mineralization without affecting viability, endogenous dentine matrix proteins might be valuable for approaches to regenerate or engineer dental pulp.

The effect of accelerated mineral trioxide aggregate on odontoblastic differentiation in dental pulp stem cell niches.

To investigate the effect of accelerated-set mineral trioxide aggregate (MTA) on the proliferation and odontoblastic differentiation of human dental pulp cell niches (DPSC). ProRoot White MTA (WMTA; Dentsply Tulsa Dental, Johnson City, TN, USA) was mixed with various additives, which included distilled water, 2.5% disodium hydrogen phosphate (Na2 HPO4 ; Merck, Darmstadt, Germany) and 5% calcium chloride (CaCl2 ; Merck). DPSC niches extracted from third molars were cultured directly on MTA in the culture medium. Cell viability was evaluated by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4- sulphophenyl)-2H-tetrazolium (MTS) assay. Cell growth and expression of odontoblastic differentiation markers (dentine sialophosphoprotein (DSPP) and collagen type 1 (COL1)) were determined using Real-Time Polymerase Chain Reaction analysis. Osteo-/odontogenic differentiation of DPSC niches was evaluated by measurement of alkaline phosphatase activity (ALP). Calcium deposition was assessed using von Kossa staining. The results were analysed statistically using Mann-Whitney tests and Kruskal-Wallis tests. MTA mixed with 5% CaCl2 and 2.5% Na2 HPO4 exhibited optimal cell viability (P<0.05) compared to MTA mixed with distilled water. MTA mixed with 5% CaCl2 and 2.5% Na2 HPO4 significantly increased ALP activity (P<0.05), significantly promoted mineralization nodule formation (P<0.05) and significantly enhanced the mRNA expression level of the osteogenic/odontogenic markers (P<0.05; DSPP and COL1) compared with MTA mixed with distilled water. MTA mixed with 5% CaCl2 and 2.5% Na2 HPO4 was biocompatible with dental pulp stem cell niches. Accelerated-set MTA promoted better differentiation in DPSC niches than conventional MTA. The accelerators could provide an alternative to MTA mixed with distilled water.

Three novel ANO5 missense mutations in Caucasian and Chinese families and sporadic cases with gnathodiaphyseal dysplasia

Gnathodiaphyseal dysplasia (GDD; MIM#166260) is an autosomal dominant syndrome with characteristic cemento-osseous lesions of jawbones, bone fragility, and diaphyseal sclerosis of tubular bones. To date, only five mutations in the proposed calcium-activated chloride channel ANO5/TMEM16E gene have been identified. In this study, we describe two families and two singular patients with three new mutations. One Caucasian family with seven affected members exhibited frequent bone fractures and florid osseous dysplasia (p.Cys356Tyr), while one Chinese family with two affected members suffered from cementoma and purulent osteomyelitis (p.Cys360Tyr). In addition, two different novel mutations (p.Gly518Glu and p.Arg215Gly) were identified in sporadic patients without family history. In vitro studies overexpressing GDD mutations (p.Cys356Tyr and p.Cys360Tyr) showed significantly reduced ANO5 protein. It appears that all GDD mutations known so far locate in an extracellular domain following the first transmembrane domain or in the 4th putative transmembrane domain. Both wild-type and mutant ANO5 protein localize to the endoplasmic reticulum. After Ano5 gene knock-down with shRNA in MC3T3-E1 osteoblast precursors we saw elevated expression of osteoblast-related genes such as Col1a1, osteocalcin, osterix and Runx2 as well as increased mineral nodule formation in differentiating cells. Our data suggest that ANO5 plays a role in osteoblast differentiation.

The Effect of Vancomycin and Gentamicin Antibiotics on Human Osteoblast Proliferation, Metabolic Function, and Bone Mineralization.

The present study investigates the effect of vancomycin and gentamicin antibiotics on primary human osteoblasts. Osteoblasts were incubated with vancomycin, gentamicin, or with povidone-iodine (PVI), at concentrations advocated for wound irrigation. Osteoblast proliferation, metabolic function, and bone mineralization were measured. The aim of the study was to model gentamicin and vancomycin wound irrigation in vitro and to examine the effect on osteoblast viability and cellular function in comparison to 0.35% PVI. Vancomycin, gentamicin, and dilute PVI are employed as wound irrigants in spinal surgery to reduce infection. We have, however, recently demonstrated that 0.35% PVI has a detrimental effect on osteoblast cellular function and bone mineralization. Studies to determine the effects of antibiotic wound irrigation solutions on osteoblasts and bone mineralization are therefore warranted. Primary human osteoblasts were exposed for 20 minutes to phosphate buffered saline (PBS) control, vancomycin (35 or 3.5 mmol/L), gentamicin (34 or 3.4 mmol/L), or 0.35% PVI for 3 minutes. Cellular proliferation was measured during 7 days by MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay. Osteoblast metabolic function was determined using a Seahorse XFe24 Bioanalyzer. Mineralized bone nodules were quantified using Alizarin red. At concentrations advocated for wound irrigation, both gentamicin (3.4 mmol/L) and vancomycin (3.5 mmol/L) induced a transient 15% to 20% reduction in osteoblast proliferation, which returned to control values within 72 hours. This was in marked contrast to the effect of 0.35% PVI, which resulted in a sustained reduction in osteoblast proliferation of between 40% and 50% during 7 days. Neither gentamicin nor vancomycin at concentrations up to 10× clinical dose had any effect on osteoblast oxygen consumption rate, or significantly affected mineralized bone nodule formation. Vancomycin and gentamicin solutions, at concentrations advocated for intrawound application in spinal surgery, have a small but transient effect on osteoblast proliferation, and no effect on either osteoblast metabolic function or bone nodule mineralization. N/A.

In Situ Release of VEGF Enhances Osteogenesis in 3D Porous Scaffolds Engineered with Osterix-Modified Adipose-Derived Stem Cells.

Adipose-derived stem cells (ADSCs) can differentiate into various cell types and thus have great potential for regenerative medicine. Herein, rat ADSCs were isolated; transduced with lentiviruses expressing Osterix (Osx), a transcriptional factor essential for osteogenesis. Osx overexpression upregulated key osteogenesis-related genes, such as special AT-rich binding protein 2, alkaline phosphatase, osteocalcin, and osteopontin, at both mRNA and protein levels. In addition, mineral nodule formation and alkaline phosphatase activity were enhanced in Osx-overexpressing ADSCs. The expression of dickkopf-related protein 1, a potent Wnt signaling pathway inhibitor, was also increased, whereas that of β-catenin, an intracellular signal transducer in the Wnt pathway, was decreased. β-catenin expression was partially recovered by treatment with lithium chloride, a canonical Wnt pathway activator. The Osx-expressing ADSCs were then combined with 3D gelatin-coated porous poly(ɛ-caprolactone) scaffolds with a unique release prolife of entrapped recombinant human vascular endothelial growth factor (VEGF). The controlled release of VEGF promoted osteogenic differentiation capacity in vitro. When the scaffold-ADSC complexes were transplanted into rat calvarial critical-sized defects, more bone formed on the gelatin/VEGF-coated scaffolds than on other scaffold types. Taken together, the results indicate that, Osx-overexpression promotes ADSCs' osteogenesis both in vitro and in vivo, which could be enhanced by release of VEGF.

Du-Huo-Ji-Sheng-Tang and its active component Ligusticum chuanxiong promote osteogenic differentiation and decrease the aging process of human mesenchymal stem cells

Ethnopharmacological relevancePostmenopausal osteoporosis is the most common bone disease worldwide. Information concerning the effects of herbal medicines on mesenchymal cell osteogenesis and senescence remains lacking. Aim of this studyThis study was designed to investigate the effects of Du-Huo-Ji-Sheng-Tang (DHJST), a Chinese herbal medicine and its active component Ligusticum chuanxiong on osteogenic differentiation and the aging process of human mesenchymal cells (hMSCs). Materials & methodshMSCs were used as in vitro model and osteogenesis was induced by administration of either osteogenesis inducing medium (OIM) or dexamethasone-depleted OIM (DDOIM) for 1-week or 2 weeks and the results were evaluated by measuring the formation of mineralization nodules. The effects of the compound recipe DHJST and its active component L. chuanxiong on hMSCs osteogenesis-related gene expression was determined by real-time PCR that targeted bone morphogenetic protein-2 (BMP2), RUNX2, ALP, COL-1, osteopontin (OPN), and osteocalcin (OCN). Antibodies against BMP-related signaling pathway proteins, such as BMP-2, ERK, SMAD 1/5/8, and RUNX2, were also detected at the protein level by Western blotting. Finally, the cumulative growth curve and senescence of the hMSCs were evaluated in order to assess the aging process. ResultsL. chuanxiong increased osteogenic activity in hMSCs and up-regulated BMP-2 and RUNX2 gene expression via the activation of SMAD 1/5/8 and ERK signaling. Furthermore DHJST also showed a trend towards promoting the same effects in the same system. In the absence of dexamethasone, DHJST did activate SMAD 1/5/8 and ERK signaling and hence increased RUNX2 protein expression in hMSCs. In addition, both DHJST and L. chuanxiong delayed the hMSCs aging process by decreasing cell senescence. ConclusionsWe concluded that DHJST and its active component L. chuanxiong are able to promote osteogenic activity and decrease hMSCs senescence as cells age.

In situ mineralization of bioactive glass in gelatin matrix

Bioactive glass has been focused recently in soft tissue engineering, which requires biomaterials suitable for complex designing along with mechanical strength. Considering this, first time an attempt has been made to investigate in situ mineralization of bioactive glass nodules in gelatin matrix with noticeable creep property in comparison to in situ mineralized bioactive glass needles in glutaraldehyde crosslinked gelatin film along with substantially improved toughness and textural properties.

Evaluation of biocompatibility of Ti-6Al-4V scaffolds fabricated by electron beam melting

Objective: To investigate the biocompatibility of Ti-6Al-4V scaffolds fabricated by electron beam melting(EBM). Methods: Bone marrow mesenchymal stem cells(BMSC) co-cultured with Ti-6Al-4V specimens fabricated with EBM was prepared as experimental group and the regular cells culture was employed as control. The biocompatibility was detected using CCK-8 and cytoskeleton staining. The osteogenic differentiation ability was assessed using mineralization nodule formation. A 24 mm defect was created on the right mandibular body in 12 beagles. The mandibular defects were repaired with Ti-6Al-4V scaffolds mesh fabricated by EBM. General observation, CT and histology examination was carried out to evaluated the biocompatibility of Ti-6Al-4V scaffolds in vivo. Results: CCK-8 result showed the A values of the two groups had no significant difference(P >0.05). There was no significant difference between the two groups (P>0.05). Cytoskeletal staining showed that cells were fully stretched out and grew well on T-i6Al-4V specimen. The actin fibers were arranged in parallel and stained uniformly with fluorescent. After osteogenic culture, the quantity of the nodule formation of the experimental group and control group were 5.7±0.7 and 5.1 ± 0.6, respectively(P>0.05). All animals had tolerated the surgery and healed well. CT examination showed that Ti-6Al-4V scaffolds mesh had good retention with surrounding bone and the continuity of mandible was restored. Histological examination showed that no inflammation reaction or toxity was caused in the soft tissue surrounding the scaffolds and in the liver and kidney after implantation. Ti-6Al-4V scaffolds had good retention with surrounding bone. Conclusions: Ti-6Al-4V fabricated with electron beam melting has good biocompatibility.

Low concentrations of TNF-α promote osteogenic differentiation via activation of the ephrinB2-EphB4 signalling pathway.

Low concentrations of tumour necrosis factor-alpha (TNF-α) have been reported to promote osteogenic differentiation. In this study, a series of in vitro experiments was performed to investigate underlying molecular mechanisms involved. MC3T3-E1 murine preosteoblasts were treated with TNF-α at doses of 0, 0.1 or 1ng/mL. The ephrinB2-EphB4 signalling pathway was activated using ephrinB2-fc, or inhibited using lentiviruses encoding siRNAs specifically targeting EphB4. Cell proliferation/survival was evaluated using the Cell Counting Kit-8 (CCK-8) assay, and expression levels of Runx2, BSP, ephrinB2 and EphB4 were determined using RT-PCR and Western blotting. ALP activity in these cells was also determined, and mineral nodule formation was evaluated with alizarin red S staining. Low concentrations of TNF-α had no influence on cell proliferation/survival. However, expression levels of Runx2, BSP, ephrinB2 and EphB4, as well as ALP activity and mineral nodule formation, were significantly enhanced in MC3T3-E1 cells treated with low concentrations of TNF-α. Moreover, activation of the ephrinB2-EphB4 signalling pathway by ephrinB2-fc enhanced TNF-α-induced osteogenic differentiation, while down-regulation of EphB4 level reversed the positive effect of TNF-α. Low concentrations of TNF-α promoted osteogenic differentiation via activation of the ephrinB2-EphB4 signalling pathway.

Vascular action of bisphosphonates: In vitro effect of alendronate on the regulation of cellular events involved in vessel pathogenesis

In this work we investigate whether, despite the procalcific action of alendronate on bone, the drug would be able to regulate in vitro the main cellular events that take part in atherosclerotic lesion generation. Using endothelial cell cultures we showed that Alendronate (1–50μM) acutely enhances nitric oxide production (10–30min). This stimulatory action of the bisphosphonate involves the participation of MAPK signaling transduction pathway. Under inflammatory stress, the drug reduces monocytes and platelets interactions with endothelial cells induced by lipopolysaccharide. Indeed the bisphophonate exhibits a significant inhibition of endothelial dependent platelet aggregation. The molecular mechanism of alendronate (ALN) on leukocyte adhesion depends on the regulation of the expression of cell adhesion related genes (VCAM-1; ICAM-1); meanwhile the antiplatelet activity is associated with the effect of the drug on nitric oxide production. On vascular smooth muscle cells, the drug exhibits ability to decrease osteogenic transdifferentiation and extracellular matrix mineralization. When vascular smooth muscle cells were cultured in osteogenic medium for 21days, they exhibited an upregulation of calcification markers (RUNX2 and TNAP), high alkaline phosphatase activity and a great amount of mineralization nodules. ALN treatment significantly down-regulates mRNA levels of osteoblasts markers; diminishes alkaline phosphatase activity and reduces the extracellular calcium deposition. The effect of ALN on vascular cells differs from its own bone action. On calvarial osteoblasts ALN induces cell proliferation, enhances alkaline phosphatase activity, and increases mineralization, but does not affect nitric oxide synthesis. Our results support the hypothesis that ALN is an active drug at vascular level that regulates key processes involved in vascular pathogenesis through a direct action on vessel cells.

Insulin-like growth factor 1 promotes the proliferation and committed differentiation of human dental pulp stem cells through MAPK pathways

ObjectivesInsulin-like growth factor 1 (IGF-1) is a broad-spectrum growth-promoting factor that plays a key role in natural tooth development. Human dental pulp stem cells (hDPSCs) are multipotent and can influence the reparative regeneration of dental pulp and dentin. This study was designed to evaluate the effects of IGF-1 on the proliferation and differentiation of human dental pulp stem cells. MethodsHDPSCs were isolated and purified from human dental pulps. The proliferation and osteo/odontogenic differentiation of hDPSCs treated with 100ng/ml exogenous IGF-1 were subsequently investigated. ResultsMTT assays revealed that IGF-1 enhanced the proliferation of hDPSCs. ALP activity in IGF-1-treated group was obviously enhanced compared to the control group from days 3 to 9. Alizarin red staining revealed that the IGF-1-treated cells contained a greater number of mineralization nodules and had higher calcium concentrations. Moreover, western blot and qRT-PCR analyses demonstrated that the expression levels of several osteogenic genes (e.g., RUNX2, OSX, and OCN) and an odontoblast-specific marker (DSPP) were significantly up-regulated in IGF-1-treated hDPSCs as compared with untreated cells (P<0.01). Interestingly, the expression of phospho-ERK and phospho-p38 were also up-regulated, indicating that the MAPK signaling pathway is activated during the differentiation of hDPSCs. ConclusionsIGF-1 can promote the proliferation and osteo/odontogenic differentiation of hDPSCs by activating MAPK pathways.

Icariine Restores LPS-Induced Bone Loss by Downregulating miR-34c Level.

Bacteria-induced inflammatory responses cause excessive bone resorption in chronic inflammatory diseases such as septic arthritis, osteomyelitis, and orthopedic implant failure. Icariine has been reported to facilitate the bone healing and reduce the occurrence of osteoporosis in clinical, moreover, laboratory studies which have proved that Icariine promotes the proliferation and differentiation of osteoblasts in vitro. The present study aimed to evaluate the effects of Icariine on lipopolysaccharide (LPS)-induced bone loss via an osteogenic-in vitro model and to elucidate the underlying molecular mechanisms. Here, we showed that Icariine restored LPS-induced bone loss in a dose-dependent manner without any cytotoxicity even at 100μM in an osteogenic-in vitro model. Interestingly, Icariine restored the protein expression of Runx2, a key transcription factor for osteogenesis, but had no effect on its mRNA expression level. MiRNA-34c was dramatically upregulated after LPS stimulation; however, Icariine preincubation reversed miRNA-34c level. Western blot analysis showed that overexpression of miR-34c markedly inhibited the expression of osteogenic gene makers such as alkaline phosphatase (ALP), Runx2, OPN, and BMP2. ALP activity analysis and Alizarin Red S staining exhibited that both Icariine-induced osteogenic differentiation and mineral nodule formation were significantly inverted by overexpression of miR-34c. Western blot results also showed that Icariine notably inhibited LPS-induced phosphorylation of JNKs, p38, IkBα, IKKβ, and p65. Taken together, our studies suggested that Icariine restored LPS-induced bone loss by downregulating miR-34c level and suppressing JNKs, p38, and NF-kB pathways, which highlighted the potential use of Icariine as a therapeutic agent in the treatment of bacteria-induced bone loss diseases.

Tumor Necrosis Factor-α Attenuates the Osteogenic Differentiation Capacity of Periodontal Ligament Stem Cells by Activating PERK Signaling.

Human periodontal ligament stem cells (PDLSCs) display efficient osteogenic differentiation capacity but fail to rescue bone breakdown associated with periodontitis. Endoplasmic reticulum (ER) stress and the unfolded protein response have recently been linked to inflammation and osteogenic differentiation. Therefore, the role of the double-stranded RNA-activated protein kinase (PKR)-like ER kinase (PERK) pathway in the impaired osteogenic differentiation ability of PDLSCs treated with tumor necrosis factor (TNF)-α was investigated. PDLSCs were isolated and stimulated with osteogenic media containing 1, 10, or 20 ng/mL TNF-α. Assessment included: 1) expression of runt-related transcription factor 2 and osteocalcin; 2) mRNA expression and activity of alkaline phosphatase; and 3) formation of mineralization nodules. Furthermore, expression of PERK pathway-related factors: 1) glucose-regulated protein (GRP) 78; 2) PERK; 3) activating transcription factor (ATF) 4; and 4) CCAAT-enhancer-binding proteins (C/EBP) homologous protein were also measured. Osteogenic differentiation and inhibition of the PERK pathway were also examined in cells pretreated with an inhibitor of ER stress, 4-phenylbutyric acid (PBA), followed by TNF-α stimulation. Finally, PERK small interfering RNA was used to examine osteogenic differentiation attenuated by TNF-α. Higher concentrations of TNF-α (10 and 20 ng/mL) impaired osteogenic differentiation of PDLSCs but activated the PERK pathway. Pretreatment of PDLSCs with lower concentrations of 4-PBA prevented the TNF-α-induced upregulation of GRP78, PERK, and ATF4 and recovered differentiation ability. Finally, PERK knockdown also restored osteogenic differentiation. TNF-α attenuates osteogenic differentiation ability of PDLSCs through activation of the PERK pathway.

Fluoride incorporation in high phosphate containing bioactive glasses and in vitro osteogenic, angiogenic and antibacterial effects

ObjectivesTo manufacture and assess bioactivity of low fluoride/high phosphate (low F−/high P2O5) bioglasses (BGs). Then the effects of BG-conditioned medium on osteoblast-like cell behavior and BG particles on bactericidal activity were investigated. MethodsBGs (0–7% F− content, constant 6.33% P2O5 in mol%) were designed and produced. BG particles was immersed in Tris Buffer solution or α-MEM to determine apatite formation and ion (Ca, P, Si and F) release. Osteoblast-like cells MC3T3-E1 were treated with BG-conditioned medium and assessed for cytotoxicity, pre-osteogenic and pro-angiogenic responses. Antibacterial ability was explored by incubating sub-gingival bacteria with BG particulates. ResultsRapid apatite formation was observed in F− containing BGs after only 2–8h immersion in Tris buffer solution. In the F− free group, apatite was not detectable until 72h. Peak Ca, P and F release into Tris buffer was at 2h immersion, and then the levels decreased. In α-MEM, apatite formation in all the BGs was undetectable until 72h immersion. Alkaline phosphatase activity, cell number, collagen formation, bone-like mineral nodules and osteogenic gene expression of MC3T3-E1 cells were significantly promoted in low F− BG (P6.33F1) conditioned medium. MC3T3-E1 VEGF gene expression was increased, and protein production was dose-dependently promoted with F− BG-conditioned medium. After incubation with BG particulates, the growth of sub-gingival bacteria, Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis, was significantly inhibited; the antibacterial activity being dependent on the F− content of the BGs. SignificanceThese results show that low F−/high P2O5 BGs significantly accelerated apatite formation and promoted both pre-osteogenic and pro-angiogenic responses of MC3T3-E1 osteoblast-like cells and inhibited the growth of periodontal pathogens in vitro. These BGs may prove useful as bone graft substitutes.

Manipulation of Human Primary Endothelial Cell and Osteoblast Coculture Ratios to Augment Vasculogenesis and Mineralization.

Tissue-engineering scaffolds are often seeded with a single type of cell, but there has been more focus on cocultures to improve angiogenesis and bone formation for craniofacial applications. Investigation of bone-derived osteoblasts (OBs) is important because of the use of bone grafts and migration of OBs from native bone into constructs in vivo and therefore, their contribution to bone formation in vivo. The limitation of primary OBs has been their inability to mineralize without osteogenic factors in vitro. Through coculture of OBs and endothelial cells (ECs) and manipulation of the coculture ratio, mineralization can be achieved without osteogenic media or additional growth factors, thus enhancing their utility for tissue-engineering applications. An optimal ratio of EC/OB for vasculogenesis and mineralization has not been determined for human primary cells. Human umbilical vein ECs were cultured with normal human primary OBs in different EC/OB ratios, namely, 10:1, 5:1, 1:1, 1:5, and 1:10 with EC and OB monocultures as controls. The number of vasculogenic networks in a collagen matrix was highest in ratios of 5:1 and 1:1. ECs lined up and formed capillary-like networks by day 10, which was not seen in the other groups. On polystyrene, cells were cocultured with ECs and OBs in direct contact (direct coculture) or separated by a transwell membrane (indirect coculture). At day 21, Alizarin Red staining showed mineralization on the 1:5 and 1:10 direct coculture ratios, with 1:5 having more mineralization nodules present than 1:10. No mineralization was seen in other direct coculture ratios or in any of the indirect coculture ratios. Alkaline phosphatase secretion was highest in the 1:5 direct coculture group. Vascular endothelial growth factor secretion from OBs was present in the 1:5 and 1:10 direct coculture ratios at all time points and inhibited after day 1 in other coculture groups. To improve vasculogenesis, cocultures of primary human ECs and OBs in ratios of 5:1 should be used, but to improve bone formation, the 1:5 direct coculture ratio results in most mineralization.