Enamel matrix derivative prolongs primary osteoblast growth

* Extracellular Matrices for Bone Regeneration: A Literature Review

The gold standard material for bone regeneration is still autologous bone, a mesenchymal tissue that consists mainly of extracellular matrix (ECM) (90% v/v) and little cellular content (10% v/v). However, the fact that decellularized allogenic bone grafts often present a clinical performance comparable to autologous bone grafts demonstrates the crucial role of ECM in bone regeneration. For long, the mechanism by which bone allografts function was not clear, but recent research has unveiled many unique characteristics of ECM that seem to play a key role in tissue regeneration. This is further confirmed by the fact that synthetic biomaterials with composition and properties resembling bone ECM present excellent bone regeneration properties. In this context, ECM molecules such as glycosaminoglycans (GAGs) and self-assembly peptides (SAPs) can improve the performance of bone regeneration biomaterials. Moreover, decellularized ECM derived either from native tissues such as bone, cartilage, skin, and tooth germs or from cells such as osteoblasts, chondrocytes, and stem cells has shown promising results in bone regeneration applications. Understanding the role of ECM in bone regeneration is crucial for the development of the next generation of biomaterials for bone tissue engineering. In this sense, this review addresses the state-of-the-art on this subject matter.

Enamel Matrix Derivative Promotes Human Periodontal Ligament Cell Differentiation and Osteoprotegerin Production in vitro

Enamel matrix derivative (EMD) has been used successfully to aid periodontal repair. We sought to elucidate the mechanism of action of EMD and hypothesized that combined exposure to EMD and parathyroid hormone (PTH), which acts anabolicly when administered intermittently, would enhance periodontal ligament cell proliferation, differentiation, and local factor production. Confluent human periodontal ligament cells were exposed to EMD continuously or to PTH(1-34) intermittently, or a combination of both. Cell number, alkaline phosphatase activity, osteocalcin, and osteoprotegerin production were determined. Continuous challenge with EMD resulted in an increase of the differentiation parameters and osteoprotegerin production, while simultaneously inhibiting proliferation. Intermittent PTH(1-34) administration exerted opposite effects. Combined administration of EMD and PTH(1-34) weakened or even nullified the effects seen for the agents alone. These results suggest that EMD promotes periodontal ligament cell differentiation and osteoprotegerin production, potentially resulting in a microenvironment supporting periodontal repair, whereas combining EMD and PTH(1-34) failed to prove beneficial in this respect.

The effects of bone morphogenetic protein-2 and enamel matrix derivative on the bioactivity of mineral trioxide aggregate in MC3T3-E1cells

Objectives

The effects of bone morphogenetic protein-2 (BMP-2) and enamel matrix derivative (EMD) respectively with mineral trioxide aggregate (MTA) on hard tissue regeneration have been investigated in previous studies. This study aimed to compare the osteogenic effects of MTA/BMP-2 and MTA/EMD treatment in MC3T3-E1 cells.

Materials and Methods

MC3T3-E1 cells were treated with MTA (ProRoot, Dentsply), BMP-2 (R&D Systems), EMD (Emdogain, Straumann) separately and MTA/BMP-2 or MTA/EMD combination. Mineralization was evaluated by staining the calcium deposits with alkaline phosphatase (ALP, Sigma-Aldrich) and Alizarin red (Sigma-Aldrich). The effects on the osteoblast differentiation were evaluated by the expressions of osteogenic markers, including ALP, bone sialoprotein (BSP), osteocalcin (OCN), osteopontin (OPN) and osteonectin (OSN), as determined by reverse-transcription polymerase chain reaction analysis (RT-PCR, AccuPower PCR, Bioneer).

Results

Mineralization increased in the BMP-2 and MTA/BMP-2 groups and increased to a lesser extent in the MTA/EMD group but appeared to decrease in the MTA-only group based on Alizarin red staining. ALP expression largely decreased in the EMD and MTA/EMD groups based on ALP staining. In the MTA/BMP-2 group, mRNA expression of OPN on day 3 and BSP and OCN on day 7 significantly increased. In the MTA/EMD group, OSN and OCN gene expression significantly increased on day 7, whereas ALP expression decreased on days 3 and 7 (p < 0.05).

Conclusions

These results suggest the MTA/BMP-2 combination promoted more rapid differentiation in MC3T3-E1 cells than did MTA/EMD during the early mineralization period.

Human osteoblastic cells discriminate between 20-kDa amelogenin isoforms

Enamel matrix derivative (EMD) is used to stimulate healing of alveolar bone after destructive marginal periodontitis; however, the roles of the different EMD constituents are unclear. The aim here was to compare the effect of two EMD fractions (A1 and A2) on primary human osteoblasts cultured in the presence of 50 μg ml(-1) of A1, A2, or EMD. SDS-PAGE showed that A1 and A2 were comprised of amelogenins migrating at around 20 kDa. Fourier transform infrared (FTIR) analysis revealed that A1 and A2 had different secondary structures, and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) identified different peptide mass values. Osteoblasts responded differently to A1 and A2. Whereas A1 enhanced the proliferation [measured by the incorporation of 5-bromo-2'-deoxyuridine (BrdU)] of osteoblasts, the expression of runt-related transcription factor-2 (RUNX2) mRNA, and the secretion of interleukin 6 (IL-6) into the cell culture medium, exposure to A2 resulted in increased alkaline phosphatase (ALP) activity, increased expression of CD44 mRNA, and increased secretion of osteoprotegrin (OPG) and receptor activator of nuclear factor-kappaB ligand (RANKL). The level of osteocalcin in the cell culture medium was increased after all treatments, while A2 stimulated the expression of dentin matrix protein 1 (DMP1) mRNA. The results suggest that both A1 and A2 participate in the observed effect of EMD, but have different effects on the expression of osteoblast mRNA and the secretion of osteoblast protein, and thus might facilitate the differentiation of a different phenotype.

The effect of enamel matrix derivative (Emdogain®) on gene expression profiles of human primary alveolar bone cells

Emdogain® is frequently used in regenerative periodontal treatment. Understanding its effect on gene expression of bone cells would enable new products and pathways promoting bone formation to be established. The aim of the study was to analyse the effect of Emdogain® on expression profiles of human-derived bone cells with the help of the micro-array, and subsequent validation. Bone was harvested from non-smoking patients during dental implant surgery. After outgrowth, cells were cultured until subconfluence, treated for 24 h with either Emdogain® (100 µg/ml) or control medium, and subsequently RNA was isolated and micro-array was performed. The most important genes demonstrated by micro-array data were confirmed by qPCR and ELISA tests. Emdogain tipped the balance between genes expressed for bone formation and bone resorption towards a more anabolic effect, by interaction of the PGE2 pathway and inhibition of IL-7 production. In addition the results of the present study indicate that Emdogain possibly has an effect on gene expression for extracellular matrix formation of human bone cells, in particular on bone matrix formation and on proliferation and differentiation. With the micro-array and the subsequent validation, the genes possibly involved in Emdogain action on bone cells were identified. These results can contribute to establishing new products and pathways promoting bone formation.

Effects of amelogenin on proliferation, differentiation, and mineralization of rat bone marrow mesenchymal stem cells in vitro

The aim of this study was to clarify the function of amelogenin, the major protein of enamel matrix derivative, on the proliferation, differentiation, and mineralization of cultured rat bone marrow stem cells (BMSCs), toward the establishment of future bone regenerative therapies. No differences in the morphology of BMSCs or in cell numbers were found between amelogenin addition and additive-free groups. The promotion of ALPase activity and the formation of mineralized nodules were detected at an early stage in amelogenin addition group. In quantitative real-time RT-PCR, mRNA expression of osteopontin, osteonectin, and type I collagen was promoted for 0.5 hours and 24 hours by addition of amelogenin. The mRNA expression of osteocalcin and DMP-1 was also stimulated for 24 hours and 0.5 hours, respectively, in amelogenin addition group. These findings clearly indicate that amelogenin promoted the differentiation and mineralization of rat BMSCs but did not affect cell proliferation or cell morphology.

Enamel matrix derivative: a review of cellular effects in vitro and a model of molecular arrangement and functioning

BACKGROUND

Enamel matrix derivative (EMD), the active component of Emdogain®, is a viable option in the treatment of periodontal disease owing to its ability to regenerate lost tissue. It is believed to mimic odontogenesis, though the details of its functioning remain the focus of current research.

OBJECTIVE

The aim of this article is to review all relevant literature reporting on the composition/characterization of EMD as well as the effects of EMD, and its components amelogenin and ameloblastin, on the behavior of various cell types in vitro. In this way, insight into the underlying mechanism of regeneration will be garnered and utilized to propose a model for the molecular arrangement and functioning of EMD.

METHODS

A review of in vitro studies of EMD, or components of EMD, was performed using key words "enamel matrix proteins" OR "EMD" OR "Emdogain" OR "amelogenin" OR "ameloblastin" OR "sheath proteins" AND "cells." Results of this analysis, together with current knowledge on the molecular composition of EMD and the structure and regulation of its components, are then used to present a model of EMD functioning.

RESULTS

Characterization of the molecular composition of EMD confirmed that amelogenin proteins, including their enzymatically cleaved and alternatively spliced fragments, dominate the protein complex (>90%). A small presence of ameloblastin has also been reported. Analysis of the effects of EMD indicated that gene expression, protein production, proliferation, and differentiation of various cell types are affected and often enhanced by EMD, particularly for periodontal ligament and osteoblastic cell types. EMD also stimulated angiogenesis. In contrast, EMD had a cytostatic effect on epithelial cells. Full-length amelogenin elicited similar effects to EMD, though to a lesser extent. Both the leucine-rich amelogenin peptide and the ameloblastin peptides demonstrated osteogenic effects. A model for molecular structure and functioning of EMD involving nanosphere formation, aggregation, and dissolution is presented.

CONCLUSIONS

EMD elicits a regenerative response in periodontal tissues that is only partly replicated by amelogenin or ameloblastin components. A synergistic effect among the various proteins and with the cells, as well as a temporal effect, may prove important aspects of the EMD response in vivo.

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.

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.

In vitro biologic response of human bone marrow stromal cells to enamel matrix derivative

BACKGROUND

In vitro investigations suggest that enamel matrix derivative (EMD) may affect the biologic response of periodontal-related cells, including osteoblasts and their precursors, the bone marrow stromal cells (BMSCs), which could play a crucial role in the regenerative process. In this study, we investigated the effects of EMD on human BMSCs.

METHODS

Primary cultures of BMSCs were obtained from bone marrow samples of healthy donors. Cell proliferation and osteogenic marker expression in response to serial dilutions of EMD (12.5, 25, and 50 microg/ml) were assessed. Cell growth was measured by 3H-thymidine incorporation and type I collagen synthesis by immunoblotting. Alkaline phosphatase (AP)-specific activity in the early phase (7 days), in vitro mineralization by von Kossa staining and calcium quantification, and osteocalcin levels at prolonged times (3 weeks) also were evaluated.

RESULTS

EMD stimulated BMSC growth in a dose-dependent manner. When EMD 50 microg/ml was followed over time, the highest proliferative effect was evident at 24 hours (3.4-fold of the control). Type I collagen level was significantly lower than the control after a 7-day incubation with EMD 50 microg/ml. AP activity was reduced in a dose-dependent manner down to 55% of the control. Also, the extracellular matrix mineralization decreased in EMD-treated cells with respect to the control, whereas only a slight, not significant, decrease in osteocalcin levels was found.

CONCLUSIONS

EMD significantly increased BMSC growth and simultaneously decreased their osteogenic differentiation. The clinical efficacy of EMD in regenerating periodontal tissues can be attributed, in part, to the biologic effects exerted on the bone marrow stromal component of resident cells.

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.

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.

The effect of EmdogainR on the growth and differentiation of rat bone marrow cells

BACKGROUND AND OBJECTIVE

The major extracellular matrix (ECM) proteins in developing enamel can induce and maintain the formation and mineralization of other skeletal hard tissue, such as bone. Therefore, dental matrix proteins are ideal therapeutic agents when direct formation of functional bone is required for a successful clinical outcome. Emdogain (EMD) consists of enamel matrix proteins which are known to stimulate bone formation. However, only a few studies in the literature have reported the effect of EMD on osteoblast-like cells in vitro.

MATERIAL AND METHODS

In this study, rat bone marrow cells, obtained from the femora of Wistar rats, were precultured for 7 d in osteogenic medium. Then, the cells were harvested and seeded in 24-well plates at a concentration of 20,000 cells/well. The wells were either precoated with 100 microg/ml EMD, or left uncoated. The seeded cells were cultured in osteogenic medium for 32 d and analysed for cell attachment (by using the Live and Dead assay), cell growth (by determining DNA content) and cell differentiation (by measuring alkaline phosphatase activity and calcium content, and by using scanning electron microscopy and the reverse transcription-polymerase chain reaction).

RESULTS

The results showed that at the 4-h time point of the experiment, more cells were attached to EMD-negative wells, but this effect was no longer apparent at 24 h. DNA analysis revealed that both groups showed a similar linear trend of cell growth. No differences in alkaline phosphatase activity or calcium content were observed, and no differences in gene expression (osteocalcin, alkaline phosphatase and collagen type I) were found between the groups.

CONCLUSION

Based on our results, we conclude that EMD had no significant effect on the cell growth and differentiation of rat bone marrow cells.

Inflammatory external root resorption following surgical treatment for intra-bony defects: a report of two cases involving EmdogainR and a review of the literature

BACKGROUND

Enamel matrix-derived proteins have been shown to regenerate periodontal tissues lost as a result of disease in humans. Emdogain, a commercial preparation of porcine enamel matrix derivative (EMD), has been shown to induce new cementum, periodontal ligament and bone formation in human periodontal defects. Although a number of studies have reported successful outcomes, local adverse effects have so far not been reported in the literature. This case report describes two examples of external inflammatory resorption following surgical root surface debridement and the use of Emdogain.

TREATMENT

The treatment in both cases involved raising a full-thickness flap following completion of non-surgical therapy. The granulation tissue from the defect was removed and the root surfaces debrided. Emdogain was applied following the manufacturers' instructions and involved conditioning the root surfaces with Pref-Gel and applying the Emdogain to the defect. The flaps were sutured and the site reviewed regularly. Radiographs were taken before the treatment was undertaken and also at 6 months to assess the healing of the defect.

RESULTS

External inflammatory root resorption was observed on the treated teeth 6-24 months after therapy.

CONCLUSION

External inflammatory root resorption may be an unusual adverse event following Emdogain treatment.

Enhanced proliferation, attachment and osteopontin expression by porcine periodontal cells exposed to Emdogain®

Emdogain (EMD) is an enamel matrix derivative extracted from developing porcine teeth with demonstrated periodontal regenerative potential. EMD has been shown to influence a number of properties of periodontal ligament cells including proliferation, cell attachment and matrix synthesis. To date, the effect of EMD on the epithelial cell rests of Malassez (ERM) is unknown. In this study, periodontal ligament fibroblasts, ERM, alveolar bone cells and gingival fibroblasts were obtained from porcine periodontal ligament, alveolar bone and gingiva. This study investigated, in vitro, the effect of EMD at three concentrations on proliferation, cell attachment and expression of mRNA for two mineralised tissue-related proteins (osteopontin and bone sialoprotein). As for other periodontal cells, the ERM proliferative response was enhanced by EMD. Attachment assays revealed a highly significant increase for ERM and gingival fibroblasts after EMD treatment at all concentrations. This study has also shown that EMD stimulated expression of osteopontin mRNA by ERM and alveolar bone cells. The results from this study provide evidence that EMD enhanced cellular events related with proliferation, attachment and osteopontin mRNA expression by porcine periodontal cells, in a manner consistent with its role in periodontal regenerative therapy.

Enamel matrix derivative inhibits TNF-α–induced apoptosis in osteoblastic MC3T3-E1 cells

OBJECTIVE

The purpose of this study was to examine the effect of enamel matrix derivative (EMD) on TNF-alpha-induced apoptosis in osteoblastic MC3T3-E1 cells.

STUDY DESIGN

MC3T3-E1 cells were cultured at an initial density of 5000/cm 2 in Dulbecco's modified eagle medium (DMEM) with 10% fetal bovine serum (FBS) and allowed to adhere for 24 hours. Medium was then changed into DMEM with 0.5% FBS. After 16 hours, cells were treated with EMD (100 microg/mL) alone, tumor necrosis factor alpha (TNF-alpha) (20 ng/mL) alone, transforming growth factor beta 1 (TGF-beta1) (10 ng/mL) alone, TNF-alpha plus TGF-beta1, or TNF-alpha plus EMD. Cells cultured with DMEM and 0.5% FBS served as control. Following 24-hour incubation, apoptosis was assessed by terminal deoxynucleotidyl transferase nick-end labeling (TUNEL) assay, and quantified by cell death enzyme-linked immunosorbent assay (ELISA).

RESULTS

Both TUNEL assay and cell death ELISA show that TNF-alpha induces apoptosis in MC3T3-E1 cells. TNF-alpha increases cell death by approximately 2-fold, which is attenuated by both EMD and TGF-beta1.

CONCLUSION

Like TGF-beta1, EMD protects osteoblasts from inflammation-induced apoptosis.

Effects of enamel matrix proteins on tissue formation along the roots of human teeth

OBJECTIVE

Enamel matrix-derived proteins (EMD) are thought to trigger the formation of acellular extrinsic fibre cementum (AEFC), while other reports indicate that EMD may have osteogenic potential. The aim of the present study was to characterize the tissues developing on the root surface following application of EMD.

METHODS

Twelve human periodontitis-affected teeth, scheduled for extraction, were treated with EMD. Two to 6 weeks later, the teeth were extracted, demineralized and processed for embedding in acrylic and epoxy resins. New tissue formation was analysed by light and transmission electron microscopy.

RESULTS

New tissue formation on the root was observed in the notch and on both scaled and unscaled root surfaces distant of the notch area in six defects. The newly formed tissues on the root were thick, collagenous, devoid of extrinsic fibres, and had an irregular surface contour. The presence of electron-dense, organic material in the collagenous matrix indicated at least partial mineralization. Embedded cells were numerous and the cells on the matrix surface were very large in size. Abundant rough endoplasmic reticulum and a prominent Golgi complex were evident. The presence of a split between the treated root surfaces and the newly formed tissue was a common observation, as was the presence of bacteria and host cells in the interfacial gap.

CONCLUSION

Following treatment with EMD, a bone-like tissue resembling cellular intrinsic fibre cementum may develop on the root surfaces, instead of AEFC. Furthermore, EMD may both induce de novo formation of a mineralized connective tissue on scaled root surfaces and stimulate matrix deposition on old native cementum. Interfacial bonding appeared to be weak after 6 weeks of healing.

Potential of biomimetic surfaces to promote in vitro osteoblast-like cell differentiation

Bioactive glasses, osteoproductive materials, have received considerable attention as bone graft substitutes in the treatment of bony defects. More recent strategies for achieving a predictable periodontal regeneration include the use of enamel matrix proteins, due to their role in the formation of bone tissue. The aim of our study is to examine the effects of these materials on the proliferation and differentiation of the mouse preosteoblastic cell line MC3T3-E1. Cells were cultured up to 28 days in contact with three types of granules: Bioglass 45S5 granules (BG), 45S5 granules coated with enamel matrix proteins (Emdogain) (BG/EMD), and a less reactive glass used as a control (60S). Phase contrast microscopic observations have shown that all substrates supported the growth of osteoblastic cells. Zones of differentiation were observed at an earlier stage in cultures of BG and BG/EMD. TEM observations revealed ultrastructural features very close to what is observed in vivo during intramembranous ossification with a direct bone apposition on the bioactive glasses. Total protein production was higher in the cultures with BG and BG/EMD. Northern Blot analysis revealed a stimulation of the transcription factor Cbfa1/Runx2 at day 13 in cultures of BG when compared to the two other cultures. Bone sialoprotein (early marker of differentiation) and osteocalcin (marker of late-stage differentiation) expression was increased in cultures with BG and BG/EMD when compared to 60S. Taken together, our findings indicate that Bioglass alone or combined with Emdogain, have the ability to support the growth of osteoblast-like cells in vitro and to promote osteoblast differentiation by stimulating the expression of major phenotypic markers. In addition, we noticed that the bioactive granules coated with Emdogain revealed significantly higher protein production than the bioactive granules alone at day 20.

The use of enamel matrix derivative in the treatment of periodontal defects: a literature review and meta-analysis

BACKGROUND

Periodontal disease results in the loss of the attachment apparatus. In the last three decades, an increasing effort has been placed on seeking procedures and materials to promote the regeneration of this tissue. The aim of this paper is to evaluate the effect of enamel matrix derivative (EMD) during regenerative procedures. In addition, a meta-analysis is presented regarding the clinical results during regeneration with EMD, to gain evidence as to what can be accomplished following treatment of intrabony defects with EMD in terms of probing depth reduction, clinical attachment level gain, defect fill (using re-entry studies), and radiographic parameters.

METHODS

The review includes in vitro and in vivo studies as well as human case reports, clinical comparative trials, and histologic findings. In addition, a meta-analysis is presented regarding the regenerative clinical results. For this purpose, we used 28 studies-including 955 intrabony defects treated with EMD that presented baseline and final data on probing depth, clinical attachment level (CAL) gain, or bone gain-to calculate weighted mean changes in the different parameters. The selected studies were pooled from the MEDLINE database at the end of May, 2003.

RESULTS

The meta-analysis of intrabony defects treated with EMD resulted in a mean initial probing depth of 7.94 +/- 0.05 mm that was reduced to 3.63 +/- 0.04 mm (p = 0.000). The mean clinical attachment level changed from 9.4 +/- 0.06 mm to 5.82 +/- 0.07 mm (p = 0.000). These results were significantly better than the results obtained for either open-flap debridement (OFD) or guided tissue regeneration (GTR). In contrast, histologically, GTR is more predictable than EMD in terms of bone and cementum formation. No advantage was found for combining EMD and GTR. Xenograft, or EMD and xenograft, yielded inferior results compared with EMD alone, but a limited number of studies evaluated this issue. Promising results were noted for the combination of allograft materials and EMD.

CONCLUSIONS

EMD seems to be safe, was able to regenerate lost periodontal tissues in previously diseased sites based on clinical parameters, and was better than OFD or GTR. Its combination with allograft materials may be of additional benefit but still needs to be further investigated.

In vitro effects of enamel matrix proteins on rat bone marrow cells and gingival fibroblasts

Emdogain (EMD), a formulation of Enamel Matrix Proteins (EMP), is used clinically for periodontal regeneration, where it stimulates cementum formation and promotes gingival healing. In this study, we investigated the in vitro effects of EMD on rat bone marrow stromal cells (BMSC) and gingival fibroblasts (GF). EMD (at 25 micro g/mL) increased the osteogenic capacity of bone marrow, as evidenced by approximately three-fold increase in BMSC cell number and approximately two-fold increase in alkaline phosphatase (ALP) activity and mineralized nodule formation. The presence of EMD in the initial stages (first 48 hrs) of the culture was crucial for this effect. In contrast, EMD did not induce osteoblastic differentiation of GF (evidenced by lack of mineralization or ALP activity) but increased up to two-fold both their number and the amount of matrix produced. These in vitro data on BMSC and GF could explain the promotive effect of EMD on bone formation and connective tissue regeneration, respectively.

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

OBJECTIVE

The aim of this study was to investigate the effects of enamel matrix derivative (EMD) on proliferation, protein synthesis, and mineralization in primary mouse osteoblasts.

STUDY DESIGN

Osteoblasts were obtained from mouse calvaria by enzymatic digestion and grown in monolayer together with EMD (2-100 microg/ml). Metabolic activity and cell proliferation were determined by tetrazolium salt assay (MTT) and by 5-bromo-2'-deoxyuridine (BrdU) incorporation. For differentiation studies, a 3-dimensional organoid culture system was used. Osteoblastic differentiation was estimated by alkaline phosphatase (ALP) activity and calcium content. Collagen synthesis was assessed by [(3)H]-proline incorporation. Morphologic observations were made by electron microscopy.

RESULTS

EMD treatments increased metabolic cell activity and BrdU incorporation. In the organoid cultures, ALP activity and calcium accumulation were enhanced by EMD treatment, but [(3)H]-proline incorporation was not. Morphologically, an increased deposition of mineralized nodules was found.

CONCLUSIONS

EMD treatment enhanced cellular activities of primary osteoblasts and might support the regeneration of periodontal bony defects.

Effect of enamel matrix protein derivative on the attachment, proliferation, and viability of human SaOs(2) osteoblasts on titanium implants

The purpose of the present study was to investigate the effects of an enamel matrix protein derivative (EMD) on attachment, proliferation, and viability of human SaOs(2) osteoblasts on titanium implants. A total of 220 sand-blasted and acid-etched (SLA) titanium discs were placed into 24-well culture plates. Before cell inoculation, McCoy's 5A medium (MCM) containing EMD at 25 micro g/ml, 50 micro g/ml, 100 micro g/ml, and 200 micro g/ml was added, and the culture plates were incubated for 30 min. As control, MCM alone was used. Human osteoblast-like cells (SaOs(2)) (2 x 10(4) cells, fourth passage) were suspended in MCM containing 1% penicillin/streptomycin and 10% fetal bovine serum and then inoculated into the well chambers. The medium was changed after 3 days without the addition of EMD. At days 1, 3, and 6, DNA content of the cells was assessed using the CyQuant cell proliferation assay kit, and mitochondrial activity of the cells was measured using a CellTiter-Glo luminescent cell viability assay. The presence of EMD on the titanium discs at days 1 and 6 was evaluated using immunofluorescence stain (IFS) by means of polyclonal antibodies against amelogenin. Additionally, cell morphology was investigated using scanning electron microscopy. Enamel matrix derivative at 25 micro g/ml, 50 micro g/ml, 100 micro g/ml, and 200 micro g/ml demonstrated similar increases in cell proliferation as the control medium at days 3 and 6 ( P>0.05 between groups, respectively). Proliferation, however, appeared to be ameliorated with increasing EMD concentrations. At 25 micro g/ml and 50 micro g/ml, EMD also demonstrated an increase in cell viability similar to the control medium at days 3 and 6 ( P>0.05 between groups, respectively), while EMD at 100 micro g/ml and 200 micro g/ml resulted in statistically significant higher increase in cell viability than in the control medium at day 6 ( P<0.001 between groups, respectively). In all test groups, IFS at day 6 was markedly lower than at day 1. Scanning electron microscopy revealed comparable cell morphology in all groups. Within the limits of the present study, it was concluded that EMD enhanced cell proliferation and viability of human SaOs(2) osteoblasts on SLA titanium implants in a concentration-dependent manner.

Emdogain promotes osteoblast proliferation and differentiation and stimulates osteoprotegerin expression

PURPOSE

The purpose of this study was to investigate the effects of EMD on the growth and differentiation of osteoblastic cells (MC3T3-E1) and on the expression of osteoprotegerin (OPG), a key cytokine that inhibits osteoclastogenesis and osteoclast function.

STUDY DESIGN

MC3T3-E1 cells were treated with 100 microg/mL EMD in serum-free medium for 1, 2, 3, 5, and 7 days, or in 2% fetal bovine serum (FBS) for 3 weeks. Cells incubated without EMD served as negative control. At the end of each incubation period, cell numbers were counted and total cellular mRNA was extracted. Northern blot analysis and RT-PCR were performed to determine the mRNA levels of core binding factor alpha (Cbfa1), collagen alpha1 (I), bone sialoprotein (BSP), osteocalcin (OC), insulin-like growth factor I (IGF-I), and OPG. Alkaline phosphatase (ALP) activity was also determined and compared between treatment and control groups.

RESULTS

A marked increase in cell numbers was observed in EMD-treated groups from day 2 to day 7 (P < .01). mRNA expression of collagen alpha1 (I), BSP, OC, OPG, and IGF-I were up-regulated in cells treated with EMD. ALP activity was significantly increased by EMD treatment after 3-week culture under differentiating conditions (P < .05). The expression of Cbfa1 was not affected by EMD treatment from day 1 to day 5; the levels were elevated after culturing for 3 weeks in EMD-treated cells.

CONCLUSIONS

EMD promotes both proliferation and differentiation of MC3T3-E1 cells and indirectly inhibits osteoclastogenesis and osteoclast function by stimulating the expression of OPG.

Effect of enamel matrix proteins (Emdogain® ) on healing after re-implantation of “periodontally compromised” roots

OBJECTIVE

The present experiment was performed to assess whether Emdogain applied on the root surface of extracted teeth or teeth previously exposed to root planning can protect the tooth from ankylosis following re-implantation.

MATERIAL AND METHODS

The experiment included two groups of dogs, including five animals each. The root canals of all mandibular third premolars (3 P 3) were reamed and filled with gutta-percha. A crestal incision was placed from the area of the second to the fourth premolar. Buccal and lingual full thickness flaps were elevated. With the use of a fissure bur, the crown and furcation area of 3 P 3 were severed in an apico-coronal cut. The distal and mesial tooth segments were luxated with an elevator and extracted with forceps. Group A: The mesial and distal segments of 3 P 3 were air dried on a glass surface for 60 min. The roots from the right side were conditioned and exposed to Emdogain application. The roots from the left side received the same treatment with the exception of Emdogain application. The mesial and distal tooth segments were re-implanted and the crown portions were severed with a horizontal cut and removed. The buccal and lingual flaps were mobilized and sutured to obtain complete coverage of the submerged roots. Group B: A notch was prepared in each root, 4-5 mm apical of the cemento-enamel junction. The area of the root that was located coronal to the notch was scaled and planned. The roots in the right side of the mandible were treated with Emdogain, while the roots in the left side served as controls. After 6 months of healing, the dogs were killed and blocks containing one root with surrounding tissues were harvested, and prepared for histological examination, which also included morphometric assessments. Thus, the proportions of the roots that exhibited signs of (i) replacement (ii) inflammatory and (iii) surface resorption were calculated.

RESULTS AND CONCLUSION

It was demonstrated that healing of a re-implanted root that had been extracted and deprived of vital cementoblasts was characterized by processes that included root resorption, ankylosis and new attachment formation. It was also demonstrated that Emdogain treatment, i.e. conditioning with EDTA and placement of enamel matrix proteins on the detached root surface, failed to interfere with the healing process.

Effect of enamel matrix derivative on mouse fibroblasts and marrow stromal osteoblasts

There is increasing evidence that the cells of the epithelial root sheath synthesize enamel matrix proteins and that these proteins play a fundamental role in cementogenesis and periodontal tissue formation. Emdogain, enamel matrix derivative (EMD), is a porcine enamel matrix derived product used to enhance regeneration of the peridontium after inflammatory destruction. Today, little is known about EMD's potential regenerative properties on cell function. The purpose of this study was to investigate the effects of EMD on mouse fibroblasts (L 929 cells) and rat marrow stromal osteoblasts. For effects on cell proliferation, the L929 cell lines were plated in 24-well culture plates at an initial density of 10,000 cell/mL and allowed to attach. Following a 24-h incubation within Dulbecco's modified eagle medium (DMEM) enriched with 10% fetal bovine serum, DMEM supplemented with 0 (Control), 50 microg/mL and 100 microg/mL of EMD was added and cultures maintained for 96h. Cell proliferation was measured at 24, 48, 72 and 96 h as the total cell number per well and cell morphology was investigated. Osteoblasts were digested from mouse tibia marrow and were plated in similar manner as with L 929 cells, while the observation periods were 2, 6, 8 and 10 days in this group. Although both cell types were able to maintain their original cell morphology throughout the tests, in both cell groups the number of cells in the EMD groups at each observation period were not significantly different than that in the control group (ANOVA, p > 0.05). Moreover, EMD failed to show any impact on cell growth with higher concentration (ANOVA, p > 0.05). These results suggest that although EMD had no cytotoxic effect on mouse fibroblasts and stromal marrow osteoblasts, the same material failed to enhance the growth of both cell types.

Involvement of FGF-2 in the action of Emdogain on normal human osteoblastic activity

OBJECTIVE

The present study was designed to evaluate the pharmacological characteristics of Emdogain (EMD) on cell growth and cell activity in human osteoblasts.

METHODS

Cell proliferation as well as several gene and protein expressions were examined using reverse transcription-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) procedures in human osteoblastic cells (SaM-1) treated with EMD (30 microg ml(-1)).

RESULTS

Treatment of osteoblasts with EMD significantly stimulated cell proliferation and fibroblast growth factor (FGF)-2 expression but decreased alkaline phosphatase expression. In addition, increases in cyclooxygenase (COX)-2 expression and decreases in matrix metalloproteinases (MMP)-1 expression were observed in osteoblasts treated with EMD. The effects of EMD on FGF-2 and MMP-1 expressions were not observed in osteoblasts treated with NS-398, an inhibitor of COX-2. The decrease in MMP-1 mRNA by EMD was prevented by treatment with antisense oligodeoxynucleotide (AS-ODN) for FGF-2.

CONCLUSION

Emdogain showing both stimulation of cell proliferation and inhibition of cell differentiation has been shown to increase FGF-2 expression in the mediation of prostaglandin E2 and to decrease MMP-1 mRNA expression through the activation of FGF-2. FGF-2 may underlie in the action of EMD on osteoblasts during periodontal regeneration.

Treatment of intrabony periodontal defects with enamel matrix derivative: a literature review

The enamel matrix derivative (EMD) has been recently introduced in the periodontal field to overcome short-comings associated with currently available regenerative techniques. Information accumulated over the past years with application of EMD guided regeneration (EGR) in intrabony periodontal defects allowed a thorough evidence-based retrospective analysis. Clinical data from EMD controlled studies were pooled for meta-analysis and weighted according to the number of treated defects. Clinical attachment gain amounted to 3.2 +/- 0.9 mm (33% of the original attachment level) and probing reduction averaged 4.0 +/- 0.9 mm (50% of the baseline probing depth) for a total of 317 lesions with a mean baseline depth of 5.4 +/- 0.8 mm. Improvements in clinical parameters achieved with EMD were statistically significant in reference to preoperative measurements. However, despite the overall efficacy of EGR therapy, a significant variation in clinical outcomes was observed. Similar therapeutic results were reported in studies where EGR was compared directly to guided tissue regeneration. However, the controlled clinical trials did not have adequate statistical power to firmly support superiority or equivalency between the 2 regenerative therapies. The statistical superiority of EGR over treatment with open flap debridement has been established. Preliminary histologic investigations with surgically created defects and experimental periodontal lesions demonstrated the ability of EGR to induce formation of acellular cementum and promote significant anaplasis of the supporting periodontal tissues. The potential of EMD to encourage periodontal regeneration was also confirmed in human intrabony defects. However, recent human histologic studies have questioned both the consistency of the histologic outcomes and the ability of EGR to predictably stimulate formation of acellular cementum. Identifying clinical modifying parameters and understanding cellular interactions are apparently essential for the development of methodologies to enhance predictability and extent of EGR clinical and histologic results.

Effect of enamel matrix derivative on the differentiation of C2C12 cells

BACKGROUND

Although enamel matrix derivative (EMD) can initiate de novo cementum and bone formation by stimulating and inducing differentiation of mesenchymal cells in the periodontal ligament, the molecular mechanism of this phenomenon is not fully understood. The purpose of this study was to determine the effect of EMD on the differentiation of pluripotential mesenchymal cells.

METHODS

A typical pluripotential mesenchymal cell line, C2C12, was used to clarify the effect of EMD on cell differentiation. The cells were cultured in 5% serum-containing medium to induce cell differentiation, either with or without the addition of EMD. Differentiation to myoblasts was analyzed by immunostaining of desmin and type II myosin heavy chains. Osteoblast differentiation was evaluated by measuring alkaline phosphatase (ALPase) activity. Furthermore, to verify the cell lineage after culture with EMD, mRNA expression of cellular phenotype-specific markers characterizing osteoblasts (ALPase and osteocalcin), chondroblasts (type X collagen), myoblasts (desmin and MyoD), and adipocytes (lipoprotein lipase) was studied using semiquantitative reverse transcription-polymerase chain reaction.

RESULTS

C2C12 cells cultured in differentiation medium without EMD altered their phenotype to myoblasts, exhibiting positive reactions to desmin and myosin heavy chains by immunological analysis. However, the cells cultured in the presence of EMD were strongly inhibited from developing into myoblasts, and showed high ALPase activity that was approximately 2 to 4 times greater than that of the vehicle. The mRNA expression of ALPase, osteocalcin, and type X collagen was increased markedly by the EMD-stimulated medium, whereas the expression of desmin, MyoD, and lipoprotein lipase was drastically decreased.

CONCLUSIONS

Our study provides clear evidence that EMD converts the differentiation pathway of C2C12 cells into the osteoblast and/or chondroblast lineage.

Is there more to enamel matrix proteins than biomineralization?

Enamel proteins are proteins synthesized by ameloblast cells. These proteins are secreted into the enamel extracellular matrix where they nucleate and regulate the growth of hydroxyapatite crystals to form the mineralized enamel covering the crown of the teeth. Although the exact role of these proteins in enamel mineralization is just beginning to be elucidated, new studies suggest that these proteins might have functions outside enamel formation. Furthermore, extracts of enamel proteins are currently being used to regenerate periodontal tissues destroyed by periodontal disease and new studies suggest that they might have chondrogenic and osteogenic properties. These new functions of enamel proteins will be the focus of this review.