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

The Potential of Enamel Matrix Derivative in Countering Bisphosphonate-Induced Effects in Osteoblasts

The suppressive effect of bisphosphonates (BPs) on bone metabolism is considered to be a major cause of medication-related osteonecrosis of the jaw (MRONJ). Enamel matrix derivative (EMD) stimulates and activates growth factors, leading to the regeneration of periodontal tissues. In this study, we aimed to explore the potential of EMD in reversing the detrimental effects of BPs on human fetal osteoblasts (hFOBs) and osteosarcoma-derived immature osteoblasts (MG63s) by assessing cell viability, apoptosis, migration, gene expression, and protein synthesis. While the suppressive effect of zoledronate (Zol) on cell viability and migration was observed, the addition of EMD significantly mitigated this effect and enhanced cell viability and migration. Furthermore, an increased apoptosis rate induced by Zol was decreased with the addition of EMD. The decreased gene expression of alkaline phosphatase (ALP), osteocalcin (OC), and the receptor activator of nuclear factors kappa-B ligand (RANKL) caused by BP treatment was reversed by the co-addition of EMD to hFOB cells. This trend was also observed for ALP and bone sialoprotein (BSP) levels in MG63 cells. Furthermore, suppressed protein levels of OC, macrophage colony-stimulating factor (M-CSF), BSP, and type 1 collagen (COL1) were recovered following the addition of EMD. This finding suggests that EMD could mitigate the effects of BPs, resulting in the recovery of cell survival, migration, and gene and protein expression. However, the behavior of the osteoblasts was not fully restored, and further studies are necessary to confirm their effects at the cellular level and to assess their clinical usefulness in vivo for the prevention and treatment of MRONJ.

Amelogenin-Derived Peptides in Bone Regeneration: A Systematic Review

Amelogenins are enamel matrix proteins currently used to treat bone defects in periodontal surgery. Recent studies have highlighted the relevance of amelogenin-derived peptides, named LRAP, TRAP, SP, and C11, in bone tissue engineering. Interestingly, these peptides seem to maintain or even improve the biological activity of the full-length protein, which has received attention in the field of bone regeneration. In this article, the authors combined a systematic and a narrative review. The former is focused on the existing scientific evidence on LRAP, TRAP, SP, and C11's ability to induce the production of mineralized extracellular matrix, while the latter is concentrated on the structure and function of amelogenin and amelogenin-derived peptides. Overall, the collected data suggest that LRAP and SP are able to induce stromal stem cell differentiation towards osteoblastic phenotypes; specifically, SP seems to be more reliable in bone regenerative approaches due to its osteoinduction and the absence of immunogenicity. However, even if some evidence is convincing, the limited number of studies and the scarcity of in vivo studies force us to wait for further investigations before drawing a solid final statement on the real potential of amelogenin-derived peptides in bone tissue engineering.

Effect of EMD on the orthodontically induced root resorption repair process in rats

BACKGROUND

While different levels of root resorption may occur in orthodontic treatment, several preventive approaches have been reported. Nevertheless, little is known about the effect of enamel matrix derivative (EMD) on root repair during orthodontic tooth movement.

OBJECTIVE

To evaluate the effect of EMD on root resorption repair following the application of orthodontic force.

MATERIALS AND METHODS

A force of 100 g was exerted for 14 days on the left maxillary first molars of twenty 10-week-old Sprague-Dawley rats divided into the EMD and control groups (n = 10 per group). In the EMD group, repeatedly injection of Emdogain® was administered after the appliance was removed, while phosphate-buffered saline was administered in the control group. In vivo microcomputed tomography (CT), haematoxylin and eosin (H&E) staining, and immunohistochemistry were then used to evaluate the effect of EMD on the process of root repair.

RESULTS

In the EMD group, the observed decrease in root resorption crater volume and increase in both the bone volume fraction and trabecular thickness were significantly greater than those in the control group. H&E staining showed that the periodontal fibres were relatively regular in arrangement and that the surface of the cementum was smooth in the EMD group. Immunohistochemical analysis showed higher bone morphogenetic protein 2 (BMP-2) and bone sialoprotein (BSP) expression levels in the EMD group than in the control group. In addition, the osteoprotegerin (OPG) and receptor activator of NF-κB ligand (RANKL) expression levels were similar in both groups.

CONCLUSION

EMD enhanced the repair process following orthodontically induced root resorption in rats.

Outcome of enamel matrix derivative treatment in the presence of chronic stress: histometric study in rats

BACKGROUND

Psychologic stress and clinical hypercortisolism have been related to direct effects on bone metabolism. However, there is a lack of information regarding the outcomes of regenerative approaches under the influence of chronic stress (CS). Enamel matrix derivative (EMD) has been used in periodontal regenerative procedures, resulting in improvement of clinical parameters. Thus, the aim of this histomorphometric study is to evaluate the healing of periodontal defects after treatment with EMD under the influence of CS in the rat model.

METHODS

Twenty Wistar rats were randomly assigned to two groups; G1: CS (restraint stress for 12 hours/day) (n = 10), and G2: not exposed to CS (n = 10). Fifteen days after initiation of CS, fenestration defects were created at the buccal aspect of the first mandibular molar of all animals from both groups. After the surgeries, the defects of each animal were randomly assigned to two subgroups: non-treated control and treated with EMD. The animals were euthanized 21 days later.

RESULTS

G1 showed less bone density (BD) compared to G2. EMD provided an increased defect fill (DF) in G1 and higher BD and new cementum formation (NCF) in both groups. The number of tartrate-resistant acid phosphatase-positive osteoclasts was significantly higher in G1 when compared to G2 and in EMD-treated sites of both groups.

CONCLUSIONS

CS may produce a significant detrimental effect on BD. EMD may provide greater DF compared to non-treated control in the presence of CS and increased BD and NCF in the presence or absence of CS.

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.

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 protects human gingival fibroblasts from TNF-induced apoptosis by inhibiting caspase activation

Emdogain, a formulation of enamel matrix derivative (EMD), is used clinically for regeneration of the periodontium (tooth supporting tissues), but the molecular mechanisms of its action have not been elucidated. Several clinical studies suggested that EMD may also improve gingival healing after periodontal surgery and thus affect the fate of gingival fibroblasts (GFs). Since these cells are targets for local inflammatory mediators such as TNF, a pro-apoptotic cytokine, during the course of periodontal disease, we tested whether EMD protects human GFs (hGFs) from TNF-induced cytotoxicity. Quiescent primary hGFs were challenged with TNF (10-100 ng/ml) with or without EMD (100 microg/ml) pretreatment. Cell viability was assessed by neutral red staining, cell death by LDH release and apoptosis by caspase activity. Signaling pathways were evaluated by Western blotting and pharmacological inhibitors. TNF induced classical signs of apoptosis in hGFs, including typical cellular morphology and increased caspase activity. TNF-induced cytotoxicity was entirely caspase-dependent. Pretreatment (4-24 h) with EMD dramatically inhibited the activation of initiator and executioner caspases and enhanced hGF survival. Although TNF induced the activation of p38 MAPK, JNK, ERK and PI-3K signaling, these pathways were not crucial for EMD protection of hGFs. However, EMD increased the levels of c-FLIP(L), an anti-apoptotic protein located upstream of caspase activation. These data demonstrate, for the first time, that EMD protects hGFs from inflammatory cytokines and, together with our recent reports that EMD stimulates rat and human GF proliferation, could help explain the mechanisms whereby in vivo use of EMD promotes gingival healing.

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 the amelogenin fraction of enamel matrix proteins on fibroblast-mediated collagen matrix reorganization

Enamel matrix proteins (EMP), extracted from developing porcine teeth, promote not only periodontal regeneration but also cutaneous wound healing presumably via the amelogenin fraction. Because it is unclear whether the effect of EMP can be ascribed to amelogenins, we compared EMP with recombinant amelogenin in the relaxed dermal equivalent (DE) in vitro model for early wound contraction. EMP and recombinant porcine amelogenin (rP172) at 1 mg/ml were incorporated into DEs composed of human dermal fibroblasts and a type I collagen matrix. The area reduction, as a measure of contraction, as well as fibroblast numbers and TGF-beta1 levels, were quantified over 7 days in culture in the presence of 10% foetal bovine serum. Both EMP and recombinant amelogenin increased contraction (p < 0.005) and fibroblast numbers (p < 0.005) compared with controls (acetic acid vehicle and 1mg/ml porcine serum albumin) and the positive control TGF-beta1 added at 10 ng/ml. Increased contraction with EMP and recombinant amelogenin was most pronounced after the first day of incubation and was associated with elevated (p < 0.005) TGF-beta1 levels in conditioned medium. In conclusion, the amelogenin component of EMP augmented fibroblast-driven collagen matrix remodelling, at least partially, by increasing the endogenous production of TGF-beta1. These effects of EMP/amelogenin may be beneficial for cutaneous wound healing.