In vitro analysis of osteogenic inhibition in non-union spinal fusion caused by nucleus pulposus cells.

Discectomy and spinal fusion is the gold standard for spinal surgery to relieve pain. However, fusion can be hindered for yet unknown reasons that lead to non-fusions with pseudo-arthrosis. Clinical observations indicate that presence of residual intervertebral disc (IVD) tissue might hinder the ossification. We hypothesize that BMP-antagonists are constantly secreted by IVD cells and potentially prevent the ossification process. Furthermore, L51P, the engineered BMP2 variant, stimulates osseo-induction of bone marrow-derived mesenchymal stem cells (MSC) by antagonizing BMP-inhibitors. Human MSCs, primary nucleus pulposus (NPC) and annulus pulposus cells (AFC) were isolated and expanded in monolayer cultures up to passage 3. IVD cells were seeded in 1.2% alginate beads (4Mio/mL) and separated by culture inserts from MSCs. MSCs were kept in 1:control medium, 2:osteogenic medium±alginate beads, 3:osteogenic medium+NPC (±L51P) and 4:osteogenic medium+AFC (±L51P) for 21 days. Relative gene expression of bone-related genes, alkaline phosphatase assay and histological staining were performed. Osteogenesis of MSCs was hindered as shown by reduced alizarin red staining in the presence of NPC. No such inhibition was observed if co-cultured with alginate only or in the presence of AFC. The results were confirmed on the RNA and protein level. Addition of L51Pto the co- cultures, however, induced mineralization of MSCs in presence of NPC. We demonstrated that NPC secrete BMP-antagonists that prevent osteogenesis of MSCs and L51P can antagonize BMP-antagonists and induce bone formation.

Investigation of bone inhibition in non-union spinal fusion caused by intervertebral disc cells in vitro

Introduction: Discectomy and spinal fusion is the gold standard for spinal surgery to relieve pain. However, fusion can be hindered for yet unknown reasons that lead to non-fusions with pseudo-arthrose. It is hence appealing to develop biomaterials that can enhance bone formation. Clinical observations indicate that presence of residual intervertebral disc (IVD) tissue might hinder the ossification. We hypothesize that BMP-antagonists are constantly secreted by IVD cells and potentially prevent the ossification process. Furthermore, L51P, the engineered BMP2 variant, stimulates osteoinduction of bone marrow-derived mesenchymal stem cells (MSC) by antagonizing BMP-inhibitors. Methods: Human MSCs, primary nucleus pulposus (NPC) and annulus pulposus cells (AFC) were isolated and expanded in monolayer cultures up to passage 3. IVD cells were seeded in 1.2% alginate beads (4Mio/mL) and separated by culture inserts from MSCs in a co-culture set-up. MSCs were kept in 1:control medium, 2:osteogenic medium+alginate control, 3:osteogenic medium+NPC (±L51P) and 4:osteogenic medium+AFC (±L51P) for 21 days. Relative gene expression of bone-related genes, Alkaline Phosphatase (ALP) assay and histological staining were performed. Results: Osteogenesis of MSCs was hindered as shown by reduced alizarin red staining in the presence of NPC. No such inhibition was observed if co-cultured with alginate only or in the presence of AFC. The results were confirmed on the RNA and protein level. Addition of L51P to the co-cultures induced mineralization of MSCs, however a reduced ALP was observed. Conclusion: We demonstrated that NPC secrete BMP-antagonists that prevent osteogenesis of MSCs and L51P can antagonize BMP-antagonists and induce bone formation.

Effect of bone graft density on in vitro cell behavior with enamel matrix derivative

OBJECTIVES Bone replacement grafting materials play an important role in regenerative dentistry. Despite a large array of tested bone-grafting materials, little information is available comparing the effects of bone graft density on in vitro cell behavior. Therefore, the aim of the present study is to compare the effects of cells seeded on bone grafts at low and high density in vitro for osteoblast adhesion, proliferation, and differentiation. MATERIALS AND METHODS The response of osteoblasts to the presence of a growth factor (enamel matrix derivative, (EMD)) in combination with low (8 mg per well) or high (100 mg per well) bone grafts (BG; natural bone mineral, Bio-Oss®) density, was studied and compared for osteoblast cell adhesion, proliferation, and differentiation as assessed by real-time PCR. Standard tissue culture plastic was used as a control with and without EMD. RESULTS The present study demonstrates that in vitro testing of bone-grafting materials is largely influenced by bone graft seeding density. Osteoblast adhesion was up to 50 % lower when cells were seeded on high-density BG when compared to low-density BG and control tissue culture plastic. Furthermore, proliferation was affected in a similar manner whereby cell proliferation on high-density BG (100 mg/well) was significantly increased when compared to that on low-density BG (8 mg/well). In contrast, cell differentiation was significantly increased on high-density BG as assessed by real-time PCR for markers collagen 1 (Col 1), alkaline phosphatase (ALP), and osteocalcin (OC) as well as alizarin red staining. The effects of EMD on osteoblast adhesion, proliferation, and differentiation further demonstrated that the bone graft seeding density largely controls in vitro results. EMD significantly increased cell attachment only on high-density BG, whereas EMD was able to further stimulate cell proliferation and differentiation of osteoblasts on control culture plastic and low-density BG when compared to high-density BG. CONCLUSION The results from the present study demonstrate that the in vitro conditions largely influence cell behavior of osteoblasts seeded on bone grafts and in vitro testing. CLINICAL RELEVANCE These results also illustrate the necessity for careful selection of bone graft seeding density to optimize in vitro testing and provide the clinician with a more accurate description of the osteopromotive potential of bone grafts.

Effects of Prolyl Hydroxylase Inhibitor L-mimosine on Dental Pulp in the Presence of Advanced Glycation End Products

INTRODUCTION Proangiogenic prolyl hydroxylase (PHD) inhibitors represent a novel approach to stimulate tissue regeneration. Diabetes mellitus involves the accumulation of advanced glycation end products (AGEs). Here we evaluated the impact of AGEs on the response of human pulp tissue to the PHD inhibitor L-mimosine (L-MIM) in monolayer cultures of dental pulp-derived cells (DPCs) and tooth slice organ cultures. METHODS In monolayer cultures, DPCs were incubated with L-MIM and AGEs. Viability was assessed based on formazan formation, live-dead staining, annexin V/propidium iodide, and trypan blue exclusion assay. Vascular endothelial growth factor (VEGF), interleukin (IL)-6, and IL-8 production was evaluated by quantitative polymerase chain reaction and immunoassays. Furthermore, expression levels of odontoblast markers were assessed, and alizarin red staining was performed. Tooth slice organ cultures were performed, and VEGF, IL-6, and IL8 levels in their supernatants were measured by immunoassays. Pulp tissue vitality and morphology were assessed by MTT assay and histology. RESULTS In monolayer cultures of DPCs, L-MIM at nontoxic concentrations increased the production of VEGF and IL-8 in the presence of AGEs. Stimulation with L-MIM decreased alkaline phosphatase levels and matrix mineralization also in the presence of AGEs, whereas no significant changes in dentin matrix protein 1 and dentin sialophosphoprotein expression were observed. In tooth slice organ cultures, L-MIM increased VEGF but not IL-6 and IL-8 production in the presence of AGEs. The pulp tissue was vital, and no signs of apoptosis or necrosis were observed. CONCLUSIONS Overall, in the presence of AGEs, L-MIM increases the proangiogenic capacity, but decreases alkaline phosphatase expression and matrix mineralization.

Osteogenic differentiation of bone marrow stromal cells is hindered by the presence of intervertebral disc cells.

BACKGROUND Clinical observations indicate that the presence of nucleus pulposus (NP) tissue during spinal fusion hinders the rate of disc ossification. While the underlying mechanism remains unknown, this observation could be due to incomplete removal of NP cells (NPCs) that secrete factors preventing disc calcification, such as bone morphogenetic protein (BMP) antagonists including noggin and members of the DAN (differential screening selected gene aberrative in neuroblastoma) family. METHODS Monolayer human bone marrow-derived mesenchymal stem cells (MSCs) were cocultured withNPCs and annulus fibrosus cells (AFCs) embedded in alginate for 21 days. At the end of coculture, MSCs were stained for mineral deposition by alizarin red, and relative expression of bone-related genes [Runt-related transcription factor 2, (RUNX2), Osteopontin (OPN), and Alkaline phosphatase (ALP)] and ALP activity were analyzed. Relative expression of three BMP antagonists, chordin (CHRD), gremlin (GREM1), and noggin (NOG), was determined in primary human NPCs and AFCs. These cells were also stained for Gremlin and Noggin by immunocytochemistry. RESULTS Alizarin red staining showed that MSC osteogenesis in monolayer cultures was inhibited by coculture with NPCs or AFCs. ALP activity and RT-PCR analyses confirmed these results and demonstrated inhibition of osteogenesis of MSC in the presence of disc cells. NOG was significantly up-regulated in MSCs after coculture. Relative gene expression of intervertebral disc (IVD) cells showed higher expression of GREM1 in NPCs than in AFCs. CONCLUSIONS We show that primary IVD cells inhibit osteogenesis of MSCs. BMP inhibitors NOG, GREM1 and CHRD were expressed in IVD cells. GREM1 appears to be differentially expressed in NPCs and AFCs. Our results have implications for the design and development of treatments for non-union in spinal fusion.

Association Between Posttraumatic Stress Disorder Following Myocardial Infarction and Liver Enzyme Levels: A Prospective Study

Research in rodents demonstrated that psychological stress increases circulating levels of alanine transaminase, aspartate transaminase, and alkaline phosphatase reflecting liver injury. Moreover, chronic posttraumatic stress disorder and transaminases predicted coronary heart disease.

L51P - A BMP2 variant with osteoinductive activity via inhibition of Noggin

Bone morphogenetic proteins (BMP) have to be applied at high concentrations to stimulate bone healing. The limited therapeutic efficacy may be due to the local presence of BMP antagonists such as Noggin. Thus, inhibiting BMP antagonists is an attractive therapeutic option. We hypothesized that the engineered BMP2 variant L51P stimulates osteoinduction by antagonizing Noggin-mediated inhibition of BMP2. Primary murine osteoblasts (OB) were treated with L51P, BMP2, and Noggin. OB proliferation and differentiation were quantified with XTT and alkaline phosphatase (ALP) assays. BMP receptor dependent intracellular signaling in OB was evaluated with Smad and p38 MAPK phosphorylation assays. BMP2, Noggin, BMP receptor Ia/Ib/II, osteocalcin, and ALP mRNA expressions were analyzed with real-time PCR. L51P stimulated OB differentiation by blocking Noggin mediated inhibition of BMP2. L51P did not induce OB differentiation directly and did not activate BMP receptor dependent intracellular signaling via the Smad pathway. Treatment of OB cultures with BMP2 but not with L51P resulted in an increased expression of ALP, BMP2, and Noggin mRNA. By inhibiting the BMP antagonist Noggin, L51P enhances BMP2 activity and stimulates osteoinduction without exhibiting direct osteoinductive function. Indirect osteoinduction with L51P seems to be advantageous to osteoinduction with BMP2 as BMP2 stimulates the expression of Noggin thereby self-limiting its own osteoinductive activity. Treatment with L51P is the first protein-based approach available to augment BMP2 induced bone regeneration through inhibition of BMP antagonists. The described strategy may help to decrease the amounts of exogenous BMPs currently required to stimulate bone healing.

Staphylococcus rostri sp. nov., a haemolytic bacterium isolated from the noses of healthy pigs

Twenty coagulase-negative Staphylococcus strains displaying alpha-haemolysis (delta-haemolysin) on sheep-blood agar were isolated from the noses of different pigs in Switzerland. The strains were Gram-stain-positive, non-motile cocci, catalase-positive and coagulase-negative. Sequence analysis of the 16S rRNA gene, sodA, rpoB, dnaJ and hsp60 and phylogenetic characteristics revealed that the strains showed the closest relatedness to Staphylococcus microti CCM 4903(T) and Staphylococcus muscae DSM 7068(T). The strains can be differentiated from S. microti by the absence of mannose fermentation and arginine arylamidase and from S. muscae by the absence of beta-glucuronidase activity and production of alkaline phosphatase. The chosen type strain ARI 262(T) shared 20.1 and 31.9 % DNA relatedness with S. microti DSM 22147(T) and S. muscae CCM 4903(T), respectively, by DNA-DNA hybridization. iso-C(15 : 0), anteiso-C(15 : 0) and iso-C(17 : 0) were the most common fatty acids. Cell-wall structure analysis revealed the peptidoglycan type A3alpha l-Lys-Gly(2)-l-Ser-Gly (type A11.3). The presence of teichoic acid was determined by sequencing the N-acetyl-beta-d-mannosaminyltransferase gene tarA, which is involved in biosynthesis of ribitol teichoic acid. Menaquinone 7 (MK-7) was the predominant respiratory quinone. The G+C content of ARI 262(T) was 38.8 mol%. The isolated strains represent a novel species of the genus Staphylococcus, for which we propose the name Staphylococcus rostri sp. nov. The type strain is ARI 262(T) (=DSM 21968(T) =CCUG 57266(T)) and strain ARI 602 (=DSM 21969 =CCUG 57267) is a reference strain.

Meprinα transactivates the epidermal growth factor receptor (EGFR) via ligand shedding, thereby enhancing colorectal cancer cell proliferation and migration

Meprinα, an astacin-type metalloprotease is overexpressed in colorectal cancer cells and is secreted in a non-polarized fashion, leading to the accumulation of meprinα in the tumor stroma. The transition from normal colonocytes to colorectal cancer correlates with increased meprinα activity at primary tumor sites. A role for meprinα in invasion and metastatic dissemination is supported by its pro-angiogenic and pro-migratory activity. In the present study, we provide evidence for a meprinα-mediated transactivation of the EGFR signaling pathway and suggest that this mechanism is involved in colorectal cancer progression. Using alkaline phosphatase-tagged EGFR ligands and an ELISA assay, we demonstrate that meprinα is capable of shedding epidermal growth factor (EGF) and transforming growth factor-α (TGFα) from the plasma membrane. Shedding was abrogated using actinonin, an inhibitor for meprinα. The physiological effects of meprinα-mediated shedding of EGF and TGFα were investigated with human colorectal adenocarcinoma cells (Caco-2). Proteolytically active meprinα leads to an increase in EGFR and ERK1/2 phosphorylation and subsequently enhances cell proliferation and migration. In conclusion, the implication of meprinα in the EGFR/MAPK signaling pathway indicates a role of meprinα in colorectal cancer progression.

Characteristics of aleveolar bone associated with physiological movement of molar in mice: a histological and histochemical study

Mouse molars undergo distal movement, during which new bone is formed at the mesial side of the tooth root whereas the preexisting bone is resorbed at the distal side of the root. However, there is little detailed information available regarding which of the bones that surround the tooth root are involved in physiological tooth movement. In the present study, we therefore aimed to investigate the precise morphological differences of the alveolar bone between the bone formation side of the tooth root, using routine histological procedures including silver impregnation, as well as by immunohistochemical analysis of alkaline phosphatase and tartrate-resistant acid phosphatase activity, and immunohistochemical analysis of the expression of the osteocyte markers dentin matrix protein 1, sclerostin, and fibroblast growth factor 23. Histochemical analysis indicated that bone formation by osteoblasts and bone resorption by osteoclasts occurred at the bone formation side and the bone resorption side, respectively. Osteocyte marker immunoreactivity of osteocytes at the surface of the bone close to the periodontal ligament differed at the bone formation and bone resorption sides. We also showed different specific features of osteocytic lacunar canalicular systems at the bone formation and bone resorption sides by using silver staining. This study suggests that the alveolar bone is different in the osteocyte nature between the bone formation side and the bone resorption side due to physiological distal movement of the mouse molar.

Transient Benign Hyperphophatasemia - A Systematic Review of The Literature

BACKGROUND:: Sometimes, a temporary increase in alkaline phosphatase level is found in healthy infants and toddlers without evidence of liver or bone disease. The condition is customarily termed transient benign hyperphosphatasemia of infancy and early childhood. Most textbooks do not refer to the condition. METHODS:: We completed a systematic review of the literature using the principles underlying the UK Economic and Social Research Council guidance on the conduct of narrative synthesis and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. RESULTS:: The 142 reports retained for analysis included 813 cases (male:female ratio = 1.1:1.0): 80 in subjects >18 years and 733 in subjects ≤18 years of age. The alkaline phosphatase ratio, calculated by dividing the measured level by the upper normal limit, was ≥5.0 in ≈70% and the duration of the elevation ≤4 months in 80% of the cases. Transient benign hyperphosphatasemia often followed a benign infection but available data fail to demonstrate a causal link. The prevalence of transient benign hyperphosphatasemia ranged 1.1-3.5% in infants 2 to 24 months of age. CONCLUSIONS:: Transient benign hyperphosphatasemia is likely the most common cause of hyperphosphatasemia among healthy infants and toddlers. Sometimes, it also occurs in older children and adults, indicating that the traditional term transient benign hyperphosphatasemia of infancy and early childhood might not be correct. The elevation in alkaline phosphatase persists for >4 months in ≈20% of the cases. Recognition of this benign condition is crucial to avoid unnecessary investigations.

Effect of monoterpenes on the formation and activation of osteoclasts in vitro

Monoterpenes, present in aromatic plants, are known to inhibit bone resorption in vivo. In this in vitro study, they inhibited the activation of osteoclasts only at high concentrations but inhibited the formation at much lower concentrations. Therefore, monoterpenes may act in vivo directly on osteoclastogenesis. INTRODUCTION: Monoterpenes are the major components of essential oils, which are formed in many plants. Typically, they are found in herbs and certain fruits. When fed to rats, they inhibit bone resorption by an unknown mechanism. In this study, their effect on the activity and formation of osteoclasts in vitro was studied. MATERIALS AND METHODS: The effect of monoterpenes on the development of osteoclasts was studied in co-cultures of bone marrow cells and osteoblasts and in cultures of spleen cells grown with colony stimulating factor (CSF)-1 and RANKL. In cultures of primary osteoblasts, alkaline phosphatase activity and levels of mRNA encoding RANKL and osteoprotegerin (OPG) mRNA (RT-PCR), and in osteoblast and spleen cell cultures, lactate dehydrogenase activity, a measure of toxicity, were determined. The activity of isolated rat osteoclasts was determined by counting the osteoclasts with actin rings using histofluorometry. RESULTS: The monoterpenes inhibited the formation of osteoclasts more strongly in co-cultures (> or = 1 microM) than in cultures of spleen cells (> or = 10 microM). They had a minor effect on osteoblasts. Toxic effects were not observed. The inhibition of the formation of osteoclasts was not reversed by the addition of farnesol and geranylgeraniol, excluding an effect of the monoterpenes through the mevalonate pathway. A high concentration of 1 mM was required to inhibit the activation of osteoclasts. This effect, shown for menthol and borneol, was reversible. CONCLUSIONS: The results suggest that the monoterpenes inhibit bone resorption in vivo through a direct effect on the formation of osteoclasts acting mainly on the hemopoietic cells.

Alendronate with and without cholecalciferol for osteoporosis: results of a 15-week randomized controlled trial

OBJECTIVE: Many osteoporosis patients have low 25-hydroxyvitamin D (25OHD) and do not take recommended vitamin D amounts. A single tablet containing both cholecalciferol (vitamin D3) and alendronate would improve vitamin D status concurrently, with a drug shown to reduce fracture risk. This study assessed the efficacy, safety, and tolerability of a once-weekly tablet containing alendronate 70 mg and cholecalciferol 70 microg (2800 IU) (ALN + D) versus alendronate 70 mg alone (ALN). METHODS: This 15-week, randomized, double-blind, multi-center, active-controlled study was conducted during a season when 25OHD levels are declining, and patients were required to avoid sunlight and vitamin D supplements for the duration of the study. Men (n = 35) and postmenopausal women (n = 682) with osteoporosis and 25OHD >or= 9 ng/mL were randomized to ALN + D (n = 360) or ALN (n = 357). MAIN OUTCOME MEASURES: Serum 25OHD, parathyroid hormone, bone-specific alkaline phosphatase (BSAP), and urinary N-telopeptide collagen cross-links (NTX). RESULTS: Serum 25OHD declined from 22.2 to 18.6 ng/mL with ALN (adjusted mean change = -3.4; 95% confidence interval [CI]: -4.0 to -2.8), and increased from 22.1 to 23.1 ng/mL with ALN + D (adjusted mean change = 1.2; 95% CI: 0.6 to 1.8). At 15 weeks, adjusted mean 25OHD was 26% higher (p < 0.001, ALN + D versus ALN), the adjusted relative risk (RR) of 25OHD < 15 ng/mL (primary endpoint) was reduced by 64% (incidence 11% vs. 32%; RR = 0.36; 95% CI: 0.27 to 0.48 [p < 0.001]), and the RR of 25OHD < 9 ng/mL (a secondary endpoint) was reduced by 91% (1% vs. 13%; RR = 0.09; 95% CI: 0.03 to 0.23 [p < 0.001]). Antiresorptive efficacy was unaltered, as measured by reduction in bone turnover (BSAP and NTX). CONCLUSION: In osteoporosis patients who avoided sunlight and vitamin D supplements, this once-weekly tablet containing alendronate and cholecalciferol provided equivalent antiresorptive efficacy, reduced the risk of low serum 25OHD, improved vitamin D status over 15 weeks, and was not associated with hypercalcemia, hypercalciuria or other adverse findings, versus alendronate alone.

Expression of phosphoproteins and amelotin in teeth

The organic material of our teeth consists of collagens and a number of calcium-binding phosphoproteins. Six of these phosphoproteins have recently been grouped in the family of the SIBLINGs (small integrin-binding ligand, N-linked glycoproteins), namely osteopontin, bone sialoprotein, dentin matrix protein (DMP1), dentin sialophosphoprotein (DSPP), matrix extracellular phosphoglycoprotein (MEPE) and enamelin. We prepared a cDNA library from rat incisors in order to identify the genes involved in tooth formation. The library was screened by subtractive hybridization with two probes; one specific for teeth, the other for bone. We found that the vast majority of the clones from our library were expressed at similar levels in bone and teeth, demonstrating the close relationship of the two tissues. Only 7% of all the clones were expressed in a tooth-specific fashion. These included clones for the enamel proteins; amelotin, amelogenin, ameloblastin and enamelin; for the dentin proteins DSPP and DMP1; and for the intermediate filament protein cytokeratin 13. Several typical bone proteins, including collagen I, osteocalcin, alkaline phosphatase and FATSO, were also expressed at significantly higher levels in teeth than in bone, probably due to the extreme growth rate of rat incisors. The amino acid sequence of rat amelotin showed 62% identity with the sequence from humans. It was expressed considerably later than the other enamel proteins, suggesting that amelotin may serve a function different from those of amelogenin, ameloblastin and enamelin.

Establishment and characterization of a primary canine duodenal epithelial cell culture

Many mechanisms involved in the pathogenesis of chronic enteropathies or host-pathogen interactions in canine intestine have not been elucidated so far. Next to the clinical and in vivo research tools, an in vitro model of canine intestinal cell culture would be very helpful for studies at the cellular level. Therefore, the purpose of this study was to establish and characterize a primary canine duodenal epithelial cell culture. Neonatal duodenum was disrupted with trypsin-ethylenediaminetetraacetic acid (EDTA) and the mucosa scraped off and digested with collagenase and dispase. After centrifugation on a 2% sorbitol gradient, the cells were incubated at 37 degrees C in OptiMEM supplemented with Primocin, epidermal growth factor, insulin, hydrocortisone, and 10% fetal calf serum (FCS). After 24 h, the FCS concentration was reduced to 2.5%, and the temperature decreased to 33 degrees C. With this method, the cultures were growing to confluent monolayers within 5-6 d and remained viable for an average of 2 wk. Their epithelial nature was confirmed by electron microscopy and immunofluorescence staining using antibodies directed against specific cytokeratins, desmosomes, and tight junctions. The intestinal cells proliferated, as evidenced by immunolabeling with a Ki-67 antibody, and cryptal cell subpopulations could be identified. Furthermore, alkaline phosphatase and sucrase activity were detected.