Effects of enamel matrix derivative on proliferation and differentiation of primary osteoblasts

Impact of Cross-Linked Hyaluronic Acid on Osteogenic Differentiation of SAOS-2 Cells in an Air-Lift Model

The aim of this study was to investigate the impact of cross-linked hyaluronic acid on osteoblast-like cells seeded on top of two collagen substrates, native porcine pericardium membrane (substrate A) and ribose cross-linked collagen membranes (substrate B), in an air-lift model. Substrates A or B, saturated with three hyaluronic acid concentrations, served as membranes for SAOS-2 cells seeded on top. Cultivation followed for 7 and 14 days in the air-lift model. Controls used the same substrates without hyaluronic pre-treatment. Cells were harvested, and four (Runx2, BGLAP, IBSP, Cx43) different osteogenic differentiation markers were assessed by qPCR. Triplicated experiment outcomes were statistically analyzed (ANOVA, t-test; SPSS). Supplementary histologic analysis confirmed the cells' vitality. After seven days, only few markers were overexpressed on both substrates. After 14 days, targeted genes were highly expressed on substrate A. The same substrate treated with 1:100 diluted xHyA disclosed statistically significant different expression level vs. substrate B (p = 0.032). Time (p = 0.0001), experimental condition as a function of time (p = 0.022), and substrate (p = 0.028) were statistically significant factors. Histological imaging demonstrated vitality and visualized nuclei. We conclude that the impact of hyaluronic acid resulted in a higher expression profile of SAOS-2 cells on substrate A compared to substrate B in an air-lift culture after two weeks.

Development and application of a 3D periodontal in vitro model for the evaluation of fibrillar biomaterials

Background

Periodontitis is a chronic inflammation of the tooth supporting structures that finally can lead to tooth loss. As chronic periodontitis is associated with systemic diseases multiple approaches have been followed to support regeneration of the destructed tissue. But very few materials are actually used in the clinic. A new and promising group of biomaterials with advantageous biomechanical properties that have the ability to support periodontal regeneration are self-assembling peptides (SAP). However, there is still a lack of 3D periodontal models that can evaluate the migration potential of such novel materials.

Methods

All experiments were performed with primary human periodontal ligament fibroblasts (HPLF). Migration capacity was assessed in a three-dimensional model of the human periodontal ligament by measuring the migration distance of viable cells on coated (Enamel Matrix Protein (EMP), P11–4, collagen I) or uncoated human dentin. Cellular metabolic activity on P11–4 hydrogels was assessed by a metabolic activity assay. Deposition of ECM molecules in a P11–4 hydrogel was visualized by immunostaining of collagen I and III and fibrillin I.

Results

The 3D periodontal model was feasible to show the positive effect of EMP for periodontal regeneration. Subsequently, self-assembling peptide P11–4 was used to evaluate its capacity to support regenerative processes in the 3D periodontal model. HPLF coverage of the dentin surface coated with P11–4 increased significantly over time, even though delayed compared to EMP. Cell viability increased and inclusion of ECM proteins into the biomaterial was shown.

Conclusion

The presented results indicate that the 3D periodontal model is feasible to assess periodontal defect coverage and that P11–4 serves as an efficient supporter of regenerative processes in the periodontal ligament.

Clinical relevance

The establishment of building-block synthetic polymers offers new opportunities for clinical application in dentistry. Self-assembling peptides represent a new generation of biomaterials as they are able to respond dynamically to the changing environment of the biological surrounding. Especially in the context of peri-implant disease prevention and treatment they enable the implementation of new concepts.

In vitro models for evaluation of periodontal wound healing/regeneration

Periodontal wound healing and regeneration are highly complex processes, involving cells, matrices, molecules and genes that must be properly choreographed and orchestrated. As we attempt to understand and influence these clinical entities, we need experimental models to mimic the various aspects of human wound healing and regeneration. In vivo animal models that simulate clinical situations of humans can be costly and cumbersome. In vitro models have been devised to dissect wound healing/regeneration processes into discrete, analyzable steps. For soft tissue (e.g. gingival) healing, in vitro models range from simple culture of cells grown in monolayers and exposed to biological modulators or physical effectors and materials, to models in which cells are 'injured' by scraping and subsequently the 'wound' is filled with new or migrating cells, to three-dimensional models of epithelial-mesenchymal recombination or tissue explants. The cells employed are gingival keratinocytes, fibroblasts or endothelial cells, and their proliferation, migration, attachment, differentiation, survival, gene expression, matrix production or capillary formation are measured. Studies of periodontal regeneration also include periodontal ligament fibroblasts or progenitors, osteoblasts or osteoprogenitors, and cementoblasts. Regeneration models measure cellular proliferation, attachment and migration, as well as gene expression, transfer and differentiation into a mineralizing phenotype and biomineralization. Only by integrating data from models on all levels (i.e. a single cell to the whole organism) can various critical aspects of periodontal wound healing/regeneration be fully evaluated.

Effect of Enamel Matrix Derivative Liquid on Osteoblast and Periodontal Ligament Cell Proliferation and Differentiation

BACKGROUND

Enamel matrix derivatives (EMDs) have been used clinically for more than a decade for the regeneration of periodontal tissues. The aim of the present study is to analyze the effect on cell growth of EMDs in a gel carrier in comparison to EMDs in a liquid carrier. EMDs in a liquid carrier have been shown to adsorb better to bone graft materials.

METHODS

Primary human osteoblasts and periodontal ligament (PDL) cells were exposed to EMDs in both gel and liquid carriers and compared for their ability to induce cell proliferation and differentiation. Alizarin red staining and real-time polymerase chain reaction for expression of genes encoding collagen 1, osteocalcin, and runt-related transcription factor 2, as well as bone morphogenetic protein 2 (BMP2), transforming growth factor (TGF)-β1, and interleukin (IL)-1β, were assessed.

RESULTS

EMDs in both carriers significantly increased cell proliferation of both osteoblasts and PDL cells in a similar manner. Both formulations also significantly upregulated the expression of genes encoding BMP2 and TGF-β1 as well as decreased the expression of IL-1β. EMDs in the liquid carrier further retained similar differentiation potential of both osteoblasts and PDL cells by demonstrating increased collagen and osteocalcin gene expression and significantly higher alizarin red staining.

CONCLUSIONS

The results from the present study indicate that the new formulation of EMDs in a liquid carrier is equally as potent as EMDs in a gel carrier in inducing osteoblast and PDL activity. Future study combining EMDs in a liquid carrier with bone grafting materials is required to further evaluate its potential for combination therapies.

The effects of synthetic oligopeptide derived from enamel matrix derivative on cell proliferation and osteoblastic differentiation of human mesenchymal stem cells

Enamel matrix derivative (EMD) is widely used in periodontal tissue regeneration therapy. However, because the bioactivity of EMD varies from batch to batch, and the use of a synthetic peptide could avoid use from an animal source, a completely synthetic peptide (SP) containing the active component of EMD would be useful. In this study an oligopeptide synthesized derived from EMD was evaluated for whether it contributes to periodontal tissue regeneration. We investigated the effects of the SP on cell proliferation and osteoblast differentiation of human mesenchymal stem cells (MSCs), which are involved in tissue regeneration. MSCs were treated with SP (0 to 1000 ng/mL), to determine the optimal concentration. We examined the effects of SP on cell proliferation and osteoblastic differentiation indicators such as alkaline phosphatase activity, the production of procollagen type 1 C-peptide and osteocalcin, and on mineralization. Additionally, we investigated the role of extracellular signal-related kinases (ERK) in cell proliferation and osteoblastic differentiation induced by SP. Our results suggest that SP promotes these processes in human MSCs, and that ERK inhibitors suppress these effects. In conclusion, SP promotes cell proliferation and osteoblastic differentiation of human MSCs, probably through the ERK pathway.

Amelogenin Peptide Extract Increases Differentiation and Angiogenic and Local Factor Production and Inhibits Apoptosis in Human Osteoblasts

Enamel matrix derivative (EMD), a decellularized porcine extracellular matrix (ECM), is used clinically in periodontal tissue regeneration. Amelogenin, EMD’s principal component, spontaneously assembles into nanospheres in vivo, forming an ECM complex that releases proteolytically cleaved peptides. However, the role of amelogenin or amelogenin peptides in mediating osteoblast response to EMD is not clear. Human MG63 osteoblast-like cells or normal human osteoblasts were treated with recombinant human amelogenin or a 5 kDa tyrosine-rich amelogenin peptide (TRAP) isolated from EMD and the effect on osteogenesis, local factor production, and apoptosis assessed. Treated MG63 cells increased alkaline phosphatase specific activity and levels of osteocalcin, osteoprotegerin, prostaglandin E2, and active/latent TGF-β1, an effect sensitive to the effector and concentration. Primary osteoblasts exhibited similar, but less robust, effects. TRAP-rich 5 kDa peptides yielded more mineralization than rhAmelogenin in osteoblasts in vitro. Both amelogenin and 5 kDa peptides protected MG63s from chelerythrine-induced apoptosis. The data suggest that the 5 kDa TRAP-rich sequence is an active amelogenin peptide that regulates osteoblast differentiation and local factor production and prevents osteoblast apoptosis.

Anabolic Actions of the Regenerative Agent Enamel Matrix Derivative (EMD) in Oral Periosteal Fibroblasts and MG 63 Osteoblasts, Modulation by Nicotine and Glutathione in a Redox Environment

Our study seeks to explore anabolic effects of a periodontal regenerative agent enamel matrix derivative (EMD). Its modulation by nicotine and the anti-oxidant glutathione (GSH) are investigated in human periosteal fibroblasts (HPF) and MG63 osteoblasts. Androgen biomarkers of oxidative stress and healing, resulting from radiolabeled androgen substrates are assayed. This in vitro model simulates a redox environment relevant to the periodontal lesion. It aims to confirm the hypothesis that EMD is an effective regenerative agent in a typically redox environment of the periodontal lesion. Monolayer cultures of MG63 osteoblasts and HPF established in culture medium are incubated with androgen substrates, and optimal concentrations of EMD, nicotine and GSH, alone and in combination. EMD significantly enhances yields of 5α-dihydrotestosterone (DHT) an effective bioactive metabolite, alone and in combination with GSH, to overcome oxidative effects of nicotine across cultures. The ‘in vitro’ findings of this study could be extrapolated to “in vivo” applications of EMD as an adjunctive regenerative therapeutic agent in an environment of chronic inflammation and oxidative stress. Increased yields of DHT implicated in matrix synthesis and direct antioxidant capacity, confirm the potential applications for enamel matrix derivative in periodontal regenerative procedures.

Enamel matrix protein derivatives: role in periodontal regeneration

The role of regenerative periodontal therapy is the reconstitution of lost periodontal structures, ie, new formation of root cementum, periodontal ligament, and alveolar bone. The outcome of basic research has pointed to the important role of enamel matrix protein derivative (EMD) in periodontal wound healing. Histologic results from animal and human studies have shown that treatment with EMD promotes periodontal regeneration. Moreover, clinical studies have indicated that treatment with EMD positively influences periodontal wound healing in humans. The goal of this paper is to review the existing literature on EMD.

Premature osteoblast clustering by enamel matrix proteins induces osteoblast differentiation through up-regulation of connexin 43 and N-cadherin

In recent years, enamel matrix derivative (EMD) has garnered much interest in the dental field for its apparent bioactivity that stimulates regeneration of periodontal tissues including periodontal ligament, cementum and alveolar bone. Despite its widespread use, the underlying cellular mechanisms remain unclear and an understanding of its biological interactions could identify new strategies for tissue engineering. Previous in vitro research has demonstrated that EMD promotes premature osteoblast clustering at early time points. The aim of the present study was to evaluate the influence of cell clustering on vital osteoblast cell-cell communication and adhesion molecules, connexin 43 (cx43) and N-cadherin (N-cad) as assessed by immunofluorescence imaging, real-time PCR and Western blot analysis. In addition, differentiation markers of osteoblasts were quantified using alkaline phosphatase, osteocalcin and von Kossa staining. EMD significantly increased the expression of connexin 43 and N-cadherin at early time points ranging from 2 to 5 days. Protein expression was localized to cell membranes when compared to control groups. Alkaline phosphatase activity was also significantly increased on EMD-coated samples at 3, 5 and 7 days post seeding. Interestingly, higher activity was localized to cell cluster regions. There was a 3 fold increase in osteocalcin and bone sialoprotein mRNA levels for osteoblasts cultured on EMD-coated culture dishes. Moreover, EMD significantly increased extracellular mineral deposition in cell clusters as assessed through von Kossa staining at 5, 7, 10 and 14 days post seeding. We conclude that EMD up-regulates the expression of vital osteoblast cell-cell communication and adhesion molecules, which enhances the differentiation and mineralization activity of osteoblasts. These findings provide further support for the clinical evidence that EMD increases the speed and quality of new bone formation in vivo.

The impact of cigarette smoke inhalation on the outcome of enamel matrix derivative treatment in rats: histometric analysis

BACKGROUND

Tobacco use is the most significant risk factor of periodontal disease. Clinical evidence has demonstrated that tobacco may negatively influence the results after surgical and non-surgical periodontal therapy. Enamel matrix derivative (EMD) have been used in periodontal regenerative procedures resulting in improvement of clinical parameters. The effect of EMD in the presence of tobacco compounds is unclear. Thus, the aim of the present study is to evaluate the impact of cigarette smoke inhalation (CSI) on the results of EMD treatment.

METHODS

Twenty-two Wistar rats were assigned to two groups: Group 1, CSI (n = 11); Group 2, non-exposed (n = 11). Thirty days after initiation of CSI, fenestration defects were created at the buccal aspect of the first mandibular molar. The study followed a split-mouth design. After the surgeries the defects were randomly assigned to two subgroups: non-treated control and treated with EMD. The animals were sacrificed 21 days later and the percentage of defect fill, density of newly formed bone, and new cementum formation were histometrically assessed. The number of osteoclasts was determined by tartrate-resistant acid phosphatase.

RESULTS

CSI was associated with less bone density compared to the non-exposed group. EMD provided an increased defect fill and new cementum formation in both groups. The number of tartrate-resistant acid phosphatase-positive osteoclasts was significantly higher in the CSI non-treated control group compared to the non-treated control of the non-exposed animals.

CONCLUSIONS

EMD may provide increased defect fill and cementum formation in the presence or absence of CSI. However, tobacco smoke produced a detrimental effect on bone healing when density of newly formed bone was considered.

Emdogain in carcinogenesis: a systematic review of in vitro studies

Emdogain is a commercial product of unknown composition and is clinically used to induce periodontal regeneration. This study aims to review current knowledge of the in vitro effects of Emdogain on oral tissues and, in particular, factors related to carcinoma. A systematic approach was used to review studies from the Embase and Pubmed databases; a total of 76 studies were included. These comprised in vitro studies of the cytokines in, or regulated by, Emdogain and assays designed to study the effects of EMD on human cells in oral tissues or malignant cells. Several studies have shown that EMD regulates the proliferation, migration, adhesion, gene expression, and cytokine production of (pre-)osteoblasts, periodontal fibroblasts, and gingival fibroblasts. However, the effects of EMD on malignant oral cells are not well understood. EMD seems to have broad regulatory effects on malignant cells and on several carcinoma-related factors. Evidence suggests that patients with premalignant or malignant mucosal lesions should not be treated with EMD.

Cellular responses and expression profiling of human bone marrow stromal cells stimulated with enamel matrix proteins in vitro

OBJECTIVES

The aim of this study was to investigate biological effects and gene expression profiles of enamel matrix proteins (EMPs), on human bone marrow stromal cells (HBMSCs), for preliminary understanding of mechanisms involved in promoting periodontal regeneration by EMPs.

MATERIALS AND METHODS

EMPs were extracted using the acetic acid method, and HBMSCs from human bone marrow aspirates were cultured. Attachment levels, level of cells morphologically attenuated, cell proliferation, alkaline phosphatase (ALP) activity and staining of HBMSCs were measured in the absence and in the presence of EMPs. Microarray analysis was performed to detect gene profiles of HBMSCs by treatment with 200 microg/ml EMPs, for 5 days. Four differential genes were selected for validation of the microarray data using real-time PCR.

RESULTS

EMPs promoted proliferation and ALP activity of HBMSCs in a time- and dose-dependent manner, and at a concentration of 200 microg/ml significantly enhanced proliferation and ALP expression. However, there were no significant changes between EMP-treated groups and the control group in cell attachment and cell process attenuation levels. Twenty-seven genes were differentially expressed by HBMSCs in the presence of EMPs. Expressions of 18 genes were upregulated and expressions of nine genes were found to be downregulated. There was good consistency between data obtained from the validation group and microarray results.

CONCLUSIONS

EMPs promoted cell proliferation and differentiation and gene expression profiles of HBMSCs were affected. This may help elucidation of mechanisms involved in promoting regeneration of periodontal tissues by EMPs.

Stimulation of cytokines in osteoblasts cultured on enamel matrix derivative

OBJECTIVE

The purpose of this study was to evaluate the influence of enamel matrix derivative (EMD) on the release of transforming growth factor beta 1 (TGF-beta1), interleukin-6 (IL-6), insulin-like growth factor I (IGF-I), bone morphogenetic protein 2 (BMP-2), and osteoprotegerin (OPG) in human and mouse osteoblasts.

STUDY DESIGN

Human MG-63 and mouse MC3T3-E1 cells were seeded onto 6-well culture plates at an initial density of 5,000/cm(2) and grown in Dulbecco's eagle medium (DMEM) with 10% fetal bovine serum for 24 h. Then cells were cultured either with 100 microg/mL EMD added to DMEM or with DMEM only. After 2, 5, and 9 days' incubation the culture medium was collected and analyzed by enzyme-linked immunosorbent analysis. Data were analyzed using Student t test.

RESULTS

The EMD treatment significantly increased the production of IL-6 and TGF-beta1 (P < .05) at all time points. The release of OPG was also increased in mouse osteoblasts (P < .05). IGF-I and BMP-2 were not detected in both control and EMD-treated groups.

CONCLUSION

This study suggests that the stimulatory effects of EMD on tissue regeneration are mediated by the up-regulation of local mediators released by osteoblasts.

Enamel matrix derivative induces connective tissue growth factor expression in human osteoblastic cells

BACKGROUND

Enamel matrix derivative (EMD) stimulates the production of transforming growth factor-beta (TGF-beta), which has been suggested to play a role in mediating the effects of EMD in periodontal tissue regeneration. Connective tissue growth factor (CTGF) is a mediator of TGF-beta and promotes cell development. The interaction between EMD and CTGF is unknown. This study explored the effects of EMD on CTGF expression in human osteoblastic cells and whether the interaction is modulated by the TGF-beta signaling pathway. Also, the roles of CTGF in cell proliferation, cell cycle progression, and mineralized nodule formation of EMD-induced osteoblastic cultures were examined.

METHODS

Human osteoblastic cells (Saos-2) were treated with 25 to 100 microg/ml EMD with or without the addition of TGF-beta inhibitor. CTGF mRNA expression was detected by reverse transcription-polymerase chain reaction (RT-PCR), and CTGF protein levels were assayed by Western blot analysis. In addition, cell cycle progression and DNA synthesis were determined by flow cytometry and 5-bromo-2'-deoxyuridine (BrdU) incorporation following EMD treatment with or without CTGF antibody. Mineralization was examined by alizarin red staining and quantified by elution with cetylpyridinium chloride.

RESULTS

Western blot and RT-PCR analysis demonstrated a dose-dependent increase of CTGF expression by EMD. EMD-induced CTGF expression was reduced significantly in the presence of TGF-beta inhibitor. Cell cycle and BrdU analysis revealed an increase in cell proliferation following EMD treatment, which was due to an increase in the percentage of cells in the G2/M phase of the cell cycle. No significant effect was found when anti-CTGF antibody was added. Conversely, mineralization was inhibited significantly in EMD-treated cultures in the presence of anti-CTGF antibody.

CONCLUSIONS

EMD stimulates CTGF expression, and the interaction is modulated via TGF-beta in osteoblastic cells. Also, CTGF affects EMD-induced osteoblastic mineralization but not cell proliferation. To our knowledge, these results provide novel insight into EMD-CTGF interaction, two biomodifiers that have therapeutic relevance to tissue engineering and regeneration.

Enamel matrix derivative stimulates human gingival fibroblast proliferation via ERK

Emdogain, a formulation of Enamel Matrix Proteins, is used clinically for periodontal regeneration to stimulate PDL (periodontal ligament), cementum, and bone formation. Its effects on gingival fibroblasts and tissue have not been thoroughly studied. Therefore, we investigated the mechanisms by which Emdogain affects the cell cycle of human gingival fibroblasts. Without serum, Emdogain (50 microg/mL) induced human gingival fibroblast entry into the S phase and DNA synthesis, but not completion of the cell cycle. With low serum concentrations (0.2-0.5%), Emdogain synergistically induced completion of the cell cycle, resulting in increased cell numbers. The mitogenic response to Emdogain depended on Extracellular Regulated Kinase (ERK) activation, which occurred in two waves, peaking after 15 min and 4 to 6 hrs, since it was abolished by U0126, a specific MAPK inhibitor. Inhibition of the second wave was sufficient to abrogate mitogenesis. This study characterized the mitogenic effect of Emdogain on primary human gingival fibroblasts, its cooperation with serum growth factors, and the key mediatory role of the ERK cascade.

In vitro assessment of motility and proliferation of human osteogenic cells on different isolated extracellular matrix components compared with enamel matrix derivative by continuous single-cell observation

OBJECTIVES

The composition of the extracellular matrix (ECM) plays a substantial role in bone remodelling, fracture healing and osseointegration of dental implants by regulating proliferation, migration and finally differentiation of osteogenic cell populations. Emdogain, a composition of an enamel matrix derivative (EMD), has been introduced as a potential candidate to promote tissue regeneration. We investigated whether EMD could serve as a potential promoter of cell proliferation and motility as a dynamic cell response and compared the results with the ubiquitous single ECM components type I collagen and laminin.

MATERIAL AND METHODS

In the investigation presented, we used a continuous observation method for the analysis of migratory and proliferative patterns of individual cells. We analyzed the response of four osteoblastic cell lines to specific extracellular ligands (type I collagen, laminin and EMD) over a period of 24 h compared with untreated glass surface and bovine serum albumin (BSA) as control groups.

RESULTS

Type I collagen and laminin promoted cell motility significantly compared with the control groups and, in part, compared with EMD as well. The analysis of all 451 investigated cells revealed the following mean values for cell motiliy: untreated glass (n=99): 5.46+/-2.74 microm/h, BSA (n=89): 6.35+/-2.43 microm/h, type I collagen (n=108): 8.77+/-3.42 microm/h, laminin (n=74): 9.89+/-5.10 microm/h and EMD (n=81): 7.92+/-3.35 microm/h. Proliferation rates on the different surfaces were heterogenous for all investigated cell lines and varied from 0% to 50% within 24 h without a correlation to cell motility.

CONCLUSION

In our study, EMD promotes cell motility better than the control groups. The two investigated single ECM components type I collagen and laminin promoted cell motility superior to EMD. This supports the hypothesis that EMD promotes a less mobile but more differentiated osteogenic phenotype.

The application of an enamel matrix protein derivative (Emdogain) in regenerative periodontal therapy: a review

Regenerative periodontal therapy aims at reconstitution of the lost periodontal structures such as new formation of root cementum, periodontal ligament and alveolar bone. Findings from basic research indicate that enamel matrix protein derivative (EMD) has a key role in periodontal wound healing. Histological results from animal and human studies have shown that treatment with EMD promotes periodontal regeneration. Moreover, clinical studies have indicated that treatment with EMD positively influences periodontal wound healing in humans. This review aims to present an overview of evidence-based clinical indications for regenerative therapy with EMD.

Emdogain-gel stimulates proliferation of odontoblasts and osteoblasts

OBJECTIVE

The purpose of this study was to determine whether a premixed form of enamel matrix derivative (EMD), Emdogain-gel, has the same property as the original formula of EMD in stimulating the proliferation of osteoblasts and odontoblasts.

STUDY DESIGN

Osteoblast cell line (MC3T3) and odontoblast cell line (MDPC) were cultured in the 6-well culture plates and treated in 4 different groups: (1) culture medium control, (2) 100 microg/mL Emdogain-gel directly added to the culture medium, (3) culture medium with a culture plate insert, and (4) 100 microg/mL Emdogain-gel added onto a culture plate insert. The culture plate insert prevented direct contact between Emdogain-gel and the cells. After 3-day incubation, cell morphology was examined and the total cell number per well was counted. Data were analyzed using 1-way ANOVA.

RESULTS

Emdogain-gel significantly increased cell number of both osteoblasts and odontoblasts regardless the presence of the culture plate insert.

CONCLUSION

Emdogain-gel stimulates cell proliferation of odontoblasts and osteoblasts. The direct contact between Emdogain-gel and cells is not required. Heat treatment of EMD and premix with propylene glycol alginate did not change its property of releasing bioactive molecules for promoting cell proliferation.

Effects of an enamel matrix derivative on human osteoblasts and PDL cells grown in organoid cultures

OBJECTIVE

The objective of this study was to investigate cellular effects of enamel matrix derivative (EMD) in human derived, primary osteoblasts and periodontal ligament (PDL) cells grown in organoid cultures.

STUDY DESIGN

Cell replication was assessed by BrdU-incorporation. [(3)H]-proline incorporation was measured to determine the synthesis of proline-containing proteins, such as collagen. In addition, calcium accumulation and alkaline-phosphatase-activity were quantified. Electron microscopy for morphological analysis was performed.

RESULTS

Our results showed that EMD enhances BrdU-incorporation in PDL cells and osteoblasts. Also, in osteoblast organoid cultures [3H]-proline incorporation was 3-fold increased (P < .01). Extensive matrix deposition was noted in osteoblast cultures by electron microscopy. In osteoblasts, high levels of calcium accumulation and alkaline-phosphatase-activity were found. However, EMD did not promote mineralization.

CONCLUSION

Our results indicate that under organoid culture conditions EMD is able to promote the synthesis of proline-containing proteins such as collagen but not matrix mineralization of primary human osteoblastic cells.

Amelogenins regulate expression of genes associated with cementoblasts in vitro

Amelogenins are major proteins expressed by ameloblasts during development of the crown (enamel and dentin). These matrix proteins guide crystal habits of the mineral phase of developing enamel and are possible regulators of other genes/proteins during development and maturation of crown and root (dentin and cementum). This study focused on defining the effect that a specific proteolytic cleavage product of amelogenin, tyrosine-rich amelogenin peptide (TRAP), has on cementoblast behavior. Immortalized cementoblasts (OCCM-30) were exposed to TRAP in vitro. Cells treated with TRAP were evaluated for cell proliferation, gene expression for osteocalcin (OCN), osteopontin (OPN), and bone sialoprotein (BSP), and induction of mineral nodule formation. No significant difference in cell proliferation was found between vehicle-treated cells and those treated with TRAP for up to 9 d after treatment. Gene expression of OCN, OPN, and BSP in TRAP-treated cementoblasts showed down-regulation, up-regulation, and no significant change, respectively, relative to vehicle control. A marked decrease in mineral nodule formation was found in cells treated with TRAP compared with the vehicle control, in a dose-dependent manner. These data, along with our previous results demonstrating similar activity with full-length amelogenin and leucine-rich amelogenin peptide (LRAP), suggest that amelogenin-like molecules regulate mesenchymal cell behavior.

In vitro attachment of osteoblasts on contaminated rough titanium surfaces treated by Er:YAG laser

Microbial contamination of implant surfaces inhibits formation of new osseous tissues. Biocompatibility of sandblasted large grid (SLA) surface, after previous in vitro cocultivation with Porphyromonas gingivalis and concomitant Er:YAG laser irradiation of microorganisms, was tested by attachment of newly cultured osteoblasts. A total of 36 customized titanium cubes with SLA surface were placed into human osteoblast culture for 14 days. After removal of 1 control cube, 35 other cubes were contaminated with precultured P. gingivalis (ATCC33277) and incubated in broth medium for 1 week. Ablation was carried out on 32 cubes. Each side was treated for 23.5 s with a pulsed, water-cooled laser beam. After irradiation, cubes were again placed into fresh osteoblast culture for 2 weeks. One randomly selected single side per cube was analyzed by scanning electron microscope in 22 cubes. On other 10 cubes, vitality of attached cells was tested with ethidiumbromide staining by fluorescence microscopy. Three negative controls revealed constantly adherent P. gingivalis, and no osteoblasts were detectable after P. gingivalis contamination on the surfaces. Laser-treated specimens showed newly attached osteoblasts, extending over 50-80% of the surface. Positive control cube (without bacterial contamination) showed over 80% cell coverage of the surface. Vitality of widely stretched osteoblasts was confirmed by FITC staining. Our results indicate that Er:YAG laser was effective in removing P. gingivalis and cell compounds, offering an acceptable surface for new osteoblast attachment.

The effect of EmdogainR on ectopic bone formation in tubes of rat demineralized dentin matrix

BACKGROUND

Emdogain (EMD) is made from enamel matrix proteins (EMPs) from the tooth germ of swine and propylene glycol alginate (PGA) as a matrix. The function of EMD is known to differentiate cells of the dental follicle into cementoblasts. However, little is known about the effect of EMD on mesenchymal cells in other tissue.

OBJECTIVE

The purpose of this study was to investigate whether EMD has the ability to induce hard tissue when applied with or without demineralized dentin matrix.

METHODS

Half of the dentin tubes prepared from rat incisors were demineralized by treatment with 0.6 N hydrochloric acid for 3 h. EMD or PGA was injected into the demineralized or non-demineralized dentin tubes, which were then transplanted into rectus abdominis muscles. Untreated dentin tubes were also transplanted as a control. Animals were killed at 7, 14 and 21 days after the implantation.

RESULTS

Non-demineralized dentin tubes with or without EMD or PGA did not form any hard tissue. In the demineralized group, chondrogenesis in the PGA groups occurred earlier than in the EMD groups. The expression of vascular endothelial growth factor (VEGF) mRNA in the demineralized group with PGA at day 14 was the highest. The expression of osteopontin and osteocalcin mRNAs was higher in all groups at 21 days compared with 7 or 14 days.

CONCLUSION

These results suggest that neither EMD nor PGA has the ability to induce hard tissue and that EMPs contained within EMD might aggregate on the dentin surface and inhibit the effect of the demineralized dentin matrix.