Anti-tumor properties of silver.

The use of silver dates to the period when people used it to mint coins or forge jewels. Towards the end of the 1960s, Resenmberg reported a study on the antitumor activity of cisplatin, and after a few years, cisplatin began to be used all over the world against different types of neoplasias mainly involving testes, ovaries, tumors of the district head-neck. Laryngeal carcinoma cell line HEP2 and tongue carcinoma cell lines PE15 and PE46, were cultured. Cell lines were treated with increasing concentration Ag in order to evaluate the optimal concentration levels that did not significantly affect cell viability. Basing on these data, the concentration adopted for the treatment was 0.007%. Gene expression profile was carried out for 10 genes belong to cell cycle pathways. Significantly up-regulated genes showed ≥ 2-fold change in expression while significantly down-regulated genes showed ≤ 0.5 -fold change in expression. Treatment appears to not significantly affect gene expression in the HEP2 cell line. In fact the only significantly down-regulated gene was CCNE1. All other genes have an expression comparable to that of untreated control. In recent years, the complexes containing gold and silver have been thoroughly studied for their electronic and chemical capabilities and their potential as a valid alternative in the development of new technologies. Further studies on the mechanisms of the biological effect discovered can become fundamental for the development of new high efficiency drugs with minimal minimum effects for the treatment of malignant neoplasia in humans and animals.

Liquid biopsy.

During the early formation and growth of primary tumor (e.g., breast, colon, or prostate cancer), cells are shed from the primary tumor and then circulate through the bloodstream. Many of the major recent advances in targeted therapies have relied on the acquisition of tumor tissue via biopsy before initiation of therapy or after the onset of resistance. The advantage of physical properties is that they allow circulating tumor cells separation without labelling. Methods based on physical properties include density gradient centrifugation, filtration through special filters. In addition to using somatic point mutations as markers for the detection of tumor DNA, strategies to detect tumor-derived rearrangements and chromosomal copy number changes in the plasma of patients with cancer have been developed. Several studies have shown that metastatic cells might have unique characteristics that can differ from the bulk of cancer cells in the primary tumor currently used for stratification of patients to systemic therapy. In conclusion, the molecular and functional analysis of circulating tumor cells and circulating nucleic acids can be used as companion diagnostics to improve the stratification of therapies and to obtain insights into therapy-induced selection of cancer cells..

Colonization of Legionella spp. In dental unit waterlines.

Legionella spp. are ubiquitous in aquatic habitats and water distribution systems, including dental unit waterlines. Surveys have shown that the percentage of samples taken at different dental sites that were positive for Legionella spp. were highly variable and ranged from 0% to 100%. Cultivation is the principal approach to evaluating bacterial contamination employed in the past, but applying this approach to testing for Legionella spp. may result in false-negative data or underestimated bacterial counts. PCR and direct fluorescent counts can detect viable non-cultivable bacteria, which are not counted by plating procedures. Legionella spp., commonly form such viable non-culturable cells and it is likely that they contribute to the difference between plate count results and those of PCR and fluorescent-antibody detection. However, studies have shown that Legionella is present in the municipal water source in spite of the current filtration and chlorination procedures. Once Legionella reaches the building water system, it settles down into a biofilm layer of stagnant water. By means of this layer, Legionella can protect itself from antimicrobial agents and then multiply. Dental unit waterlines may be contaminated with opportunistic bacteria. The water quality in the dental units should be controlled to eliminate opportunistic pathogens and to provide water for dental treatment that meets public health standards for potable water.

Focus on periodontal disease and development of endocarditis.

Infective endocarditis is a devastating disease with high morbidity and mortality. The link to oral bacteria has been known for many decades and has caused ongoing concern for dentists, patients and cardiologists. The microbiota of the mouth is extremely diverse and more than 700 bacterial species have been detected. Half of them are uncultivable so far. Oral microbiota is not uniform, specific sites exist in the mouth such as tongue, palate, cheek, teeth and periodontal pockets that have their own microbiota. Factors involved in the development of a bacterial endocarditis are difficult to define but a vulnerable surface (i.e. a damaged endocardium) and a high bacterial load in the blood seems to be decisive. The cause of microorganisms, in 90% of cases, are staphylococcus, streptococcus and enterococcus. Oral streptococci belong to viridans group (streptococcus mutans and streptococcus sanguis). As they are part of dental plaque, they could enter the bloodstream causing bacteraemia through daily habits like chewing or tooth brushing. Effective treatment of periodontal infections is important to reduce local inflammation and bacteraemia. In addition, poor periodontal health appears to increase the risk of cardiovascular disease, pulmonary disease, and preterm and low birth weight. CONCLUSIONS: Long-standing oral disease prevention protocols reduce the risk of developing periodontal disease. Data suggests that methods used to prevent cases of IE that originate from oral bacteria should focus on improving oral hygiene and reducing or eliminating gingivitis, which should reduce the incidence of bacteraemia after tooth-brushing and the need to extract teeth owing to periodontal disease and caries.

Prevention of bacterial leakage at implant-abutment connection level: an in vitro study of the efficacy of three different implant systems.

Peri-implantitis is the main cause of implant failures. Peri-implantitis is provoked by the presence of bacterial infiltration around Implant-Abutment Connection (IAC). Reduction of bacterial leakage may be achieved by improving the accuracy and precision of the two pieces of IAC. The aim of the present in vitro study was to evaluate bacterial microleakage from the inside to the outside of the IAC, testing the efficacy of three new designs of internal conical connection (FN - nano-fix -, NQ - uNiQo - and Elisir implant systems by FMD, Rome, Italy). To identify the efficacy of three new IAC, the passage of genetically modified Escherichia coli across IAC was evaluated. A total of 17 implants were used (5 FN, 6 NQ and 6 Elisir). All implants were immerged in a bacterial culture for 48 h and bacteria amount was then measured inside and outside IAC with Real-time PCR. Bacterial quantification was performed by Real-Time Polymerase Chain Reaction using the absolute quantification with the standard curve method. In all the tested implants, bacteria were found in the inner side, with a median percentage of 1.9% FN, 1.4% NQ and 2.6% Elisir. The analysis revealed that in both cases (internally and externally), bacteria grew in the first 48 hours but subsequently started to die, probably due to nutrient consumption. Of the three, the most efficacious connection was NQ. Within the limitations of this study, it was concluded that the best implant connection reducing bacterial leakage al IAC level was NQ (NQ implant system by FMD, Rome, Italy).

Evaluation of the efficacy of a new oral gel containing carvacrol and thymol for home oral care in the management of chronic periodontitis using PCR analysis: a microbiological pilot study.

The use of chemical devices for domestic oral hygiene in periodontal patients has led to new treatment strategies aiming primarily at a control of infection. Over the last few years, carvacrol and thymol (CT) have been subjected to many scientific and medical studies. The purpose of the present study was to assess the effect of CT on the red complex bacteria using Polymerase Chain Reaction (PCR) for microbiological analysis. Five patients with a diagnosis of chronic periodontitis in the age group >25 years, were selected. None of these patients had received any surgical or non-surgical periodontal therapy and demonstrated radiographic evidence of moderate bone loss. After scaling and root planning, patients received a CT gel to be used at home. Four non-adjacent sites in separate quadrants were selected in each patient for monitoring, based on criteria that the sites localize chronic periodontitis. Microbial analysis (MA) was analyzed at baseline and at day 15. SPSS program was used for statistical purposes and a paired samples correlation was performed at the end of the observation period. Although an absolute reduction was observed among the studied bacteria (i.e. Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, Fusobacterium nucleatum, Campylobacter rectus and Total bacteria loading) none reach a statistical significant value. The present study demonstrated that CT gel has a small impact on oral biofilm. Additional studies are needed to detect the efficacy of CT gel.

INTERLEUKIN-6 GENE POLYMORPHISM MODULATES THE RISK OF PERIODONTAL DISEASES.

Gingivitis and periodontitis are the two main periodontal diseases. Both are characterized by inflammation of the tissues surrounding the teeth but while tissue damages observed in gingivitis are mild and reversible, destruction caused by periodontitis is deeper and irreversible. Periodontal diseases and levels of degeneration of tissues surrounding teeth depend on several interacting endogenous and exogenous factors. Polymorphisms of genes encoding molecules that modulate the immune response and tissue homeostasis are the main causes of individual susceptibility to periodontal diseases. The aim of this study was to investigate IL6, IL10 and VDR gene polymorphisms in a large number of subjects affected by either gingivitis or chronic periodontitis. The sample included 750 Italian patients. We found that the rs1800795 SNP located in the IL6 gene promoter was strongly associated with the occurrence of both gingivitis and periodontitis. Indeed, homozygous individuals with variant allele appeared less-susceptible to both gingivitis OR=0.47 (95% C.I. 0.27-0.82) and periodontitis OR=0.36 (95% C.I. 0.21-0.64). No evidence of association between periodontal diseases and IL10 or VDR polymorphisms was obtained. This data confirmed the role of IL6 in susceptibility to periodontitis among the Italian population. The evidence that IL6 polymorphisms are also involved in gingivitis has implications in periodontal disease pathogenesis and reduces the appeal of IL6 as a periodontitis biomarker.

HYALURONIC ACID IN DERMAL REJUVENATION: AN IN VITRO STUDY.

The purpose of this paper is to evaluate the role of hyaluronic acid in bio-revitalization by testing several extracellular matrix biological parameters in cultured dermal fibroblasts. To this aim, fibroblastic expressed genes after exposition to three hyaluronic acid medical devices were evaluated. Cells were seeded on a layer of three different medical devices containing 6.2, 10 and 20 mg/ml of hyaluronic acid for 24 h. Real Time Polymerase Chain Reaction was performed to investigate gene expressions. Genes encoding hyaluronic acid synthesis and degradation, Metalloproteinases 2 and 3 and Desmoplakin production as well as GDF6, and IGF1 were activated by hyaluronic acid products. The in vitro study showed similar effects on tested genes despite a different concentration of hyaluronic acid contained in the medical devices and the simultaneous presence of other additives. Based on the reported data, gene activations are an aspect of metabolic modulation of signalling pathways rather than the proportional production of a specific connective tissue molecule. Indeed different hyaluronic acid concentration and the presence of other additives did not change the overall effect on the studied genes. We believe that the optimization of extracellular matrix micro-environment, obtained by enhanced structural support with hyaluronic acid, leads to functional and metabolic improvement.

POLYMERASE CHAIN REACTION TO EVALUATE THE EFFICACY OF SILICA DIOXIDE COLLOIDAL SOLUTIONS IN THE TREATMENT OF CHRONIC PERIODONTITIS: A CASE CONTROL STUDY.

The objective of this study was to compare the efficacy of supportive periodontal therapy [i.e. scaling and rooth planing (SRP)] alone versus a chemical silica dioxide (SiO2) colloidal solution (SDCS) device used in association with SRP in the treatment of chronic periodontitis in adult patients. A total of 20 patients with a diagnosis of chronic periodontitis (40 localized chronic periodontitis sites) in the age group of 35 to 55 were selected. None of these patients had previously received any surgical or non-surgical periodontal therapy and had radiographic evidence of moderate bone loss. Two non-adjacent sites in separate quadrants were selected in each patient to monitorize treatment efficacy (split mouth design). Clinical pocket depth (PD) and microbial analysis (MA) were analyzed at baseline and on 15th day. SPSS program and paired simple statistic t-test were used to detect significant differences. Total bacteria loading, Tannerella forsitia and Treponema denticola loading were statistically reduced when SiO2 was locally delivered. SDCS gel is an adjuvant therapy which should be added to SRP in the management of moderate-to-severe chronic periodontitis.

Human papillomavirus-associated cancers: a survey on otorhinolaryngologists' knowledge and attitudes on prevention.

Human papillomavirus (HPV) infection is a recognised causal factor associated with oropharyngeal cancers. The global burden of HPVrelated oropharyngeal cancers is on the increase and is predicted to surpass the burden of cervical cancer in the near future. As evidence is accumulating on the potential effectiveness of an HPV vaccine in controlling the oropharyngeal cancer epidemic; otorhinolaryngologists assume a key role - not only in the diagnosis and treatment of HPV-related cancers - but also in educating and advocating on HPV prevention. We conducted a survey to assess Italian otorhinolaryngologists' knowledge and attitudes regarding HPV infection, HPV-related oropharyngeal diseases and cancers and available prevention measures, including vaccines. This is the first study conducted in Italy and Europe on this topic. A total of 262 Italian otorhinolaryngologists were recruited during the National Conference of the Italian Association of Otorhinolaryngologists. Our results show that Italian otorhinolaryngologists are knowledgeable regarding HPV infection and have a positive attitude towards HPV vaccine. Our findings provide a useful basis to plan, implement and evaluate targeted educational programmes and training. As we show herein, educational programmes and training specifically focusing on HPV are effective in increasing physicians' knowledge and positive attitudes towards prevention; this ultimately contributes to enhance vaccine uptake among patients and the general population. With the overall aim of controlling the burden of HPV-related cancers, resources and efforts should be devoted to promote continuing education among otorhinolaryngologists and the general medical community and to increase awareness on the role of vaccines in prevention of HPV-related cancers. In this context, there is tremendous opportunity for healthcare providers across fields to cooperate and for public health and otorhinolaryngologist communities to join forces and engage in fruitful collaboration.

Pre-clinical evaluation of a new coral-based bone scaffold.

Coral is used worldwide for bone reconstruction. The favorable characteristics that make this material desirable for implantation are (i) osteoinduction, (ii) and osteoconduction. These proprieties have been demonstrated by in vivo studies with animal models and clinical trials over a twenty-year period. Also poly(2-hydroxyethylmethacrylate) [poly(HEMA)] is a widely used biomaterial. By using coral and poly(HEMA), a scaffold for bone reconstruction application has been recently synthesized. Cytological, histological and genetic analyses were performed to characterize this new alloplastic material. Four samples were analyzed: (a) white coral (WC), (b) red coral (RC), (c) WC plus polymer (WCP) and (d) RC plus polymer (RCP). Quantification of mitochondrial dehydrogenase activity by MTT assay was performed as indirect detector of cytotoxicity. In vivo effects were revealed by implanting corals and coral-based polymers in rabbit tibia. Samples were collected after 4 weeks and subjected to histological analysis. To evaluate the genetic response of cells to corals and coral-derived polymers an osteoblastlike cell line (i.e. MG63) was cultured in wells containing (a) medium, (b) medium plus corals and (c) medium plus two types of scaffolds (RCP or WCP). RNAs extracted from cells were retro-transcribed and hybridized on DNA 19.2K microarrays. No cytotoxicity was detected in corals and coral-based biopolymers. No inflammation or adverse effect was revealed by histological examination. By microarray analysis 154 clones were differentially expressed between RC and WC (81 up and 73 down regulated) whereas only 15 clones were repressed by the polymer. Histological evaluation not only confirmed that coral is a biocompatible material, but also that the polymer has no adverse effect. Microarray results were in agreement with cytological and histological analyses and provided further data regarding the genetic effects of RC, WC and the new polymer.

Calcium sulfate stimulates pulp stem cells towards osteoblasts differentiation.

Calcium sulfate (CaS) is a highly biocompatible material and enhances bone formation in vivo. However, how CaS alters osteoblast activity to promote bone formation is poorly understood. To study how CaS can induce osteoblast differentiation in mesenchymal stem cells, the expression levels of bone related genes and mesenchymal stem cells marker were compared in normal osteoblasts and dental pulp stem cells, using real time Reverse Transcription-Polymerase Chain Reaction. Gene differentially expressed between the two cells type were the trascriptional factor RUNX2, osteopontin (SPP1), COL1A1 (collagen type 1α1) and alkaline phosphatase (ALPL). The obtained results demonstrated that CaS strongly influences the behavior of DPSCs in vitro enhancing proliferation, differentiation and deposition of matrix.

Incidence of low risk human papillomavirus in oral cancer: a real time PCR study on 278 patients.

Squamous cell carcinoma is the most frequent malignant tumour of the oral cavity. It is widely known that tobacco and alcohol consumption are the major causes of the development of oral squamous cell carcinoma (OSCC). The human papilloma virus infection has also been postulated as a risk factor for squamous cell carcinoma, although conflicting results have been reported. The aim of this study is to evaluate the presence of high-risk and low-risk type human papillomavirus in a large sample of squamous cell carcinoma limited to the oral cavity by means of quantitative real-time polymerase chain reaction. Data were obtained from 278 squamous cell carcinoma limited to oral cavity proper. Sequencing revealed that 5 samples were positive for HPV type 16, 5 for HPV type 11, and 1 for HPV type 6. Human papillomavirus 11 was detected in 5 tumours out of the 278 examined. The prevalence rate for Human papillomavirus 11 was 1.8% (C.I. 0.7-3.9). The matched case-controls analysis indicated that the prevalence among controls did not significantly differ with respect to cases and that Human papillomavirus 11 alone did not correlate with squamous cell carcinoma.

Polylactide-polyglycolide resorbable plates stimulates adipose tissue-derived stem cells towards osteoblasts differentiation.

Polylactide, polyglycolide materials or devices have been utilized routinely during maxillofacial, craniofacial, and orthopaedic reconstructive surgical procedures.(1) These materials combine the benefits of rigid fixation with the advantages of biodegradation, avoiding the need for implant removal and minimizing the risk of other complications.(2) To study how polylactide, polyglycolide acids plates (PLPG plates) can induce osteoblast differentiation and proliferation in mesenchymal stem cells, the expression levels of bone related genes (RUNX2, SP7, ALPL, SPP1, COL1A1, COL3A1 and FOSL1) and mesenchymal stem cells marker (ENG) were measured in adipose derived stem cells (ADSCs) and normal osteoblast (NO) cultivated on PLPG plates after 15 and 30 days of treatment using real time Reverse Transcription-Polymerase Chain Reaction. Significantly differentially expressed genes among ADSCs and NO were SP7, ENG, FOSL1, RUNX, ALPL and SPP1 in the first 15 days of treatment and SP7, ENG FOSL1, COL3A1 COL1A1, SPP1 and ALPL after 30 days. The present study demonstrated that PLPG plates strongly influences the behavior of ADSCs in vitro by enhancing proliferation, differentiation and deposition of matrix.

Changes in the gene expression profile of gastric cancer cells in response to ibuprofen: a gene pathway analysis.

Nonsteroidal anti-inflammatory drugs possess antiproliferative activities that can affect cancer cells. The aim of this study was to examine the antiproliferative effects of ibuprofen on the MKN-45 cell line. Cells were treated with ibuprofen for 24, 48 or 72 h, and cell proliferation was evaluated by cell counting and [(3)H]-thymidine incorporation. Using microarray technology, we studied changes in the gene expression profiles over time after ibuprofen treatment. Ibuprofen induced a dose- and time-dependent reduction in cell number without altering cell viability. Genes involved in the 'biological oxidation' and 'G(1)/S checkpoint' pathways were the most significantly represented at 24 h, whereas genes involved in the 'cell cycle' and 'DNA replication' pathways were represented at 48 and 72 h. Genes associated with the 'apoptosis' pathway were also significantly represented at 72 h. Modulation of the expression of p53 and p53-induced genes (CDKN1A/p21 and GADD45), which are involved in the G(1)/S transition, suggested an effect of ibuprofen on cell-cycle progression. Using flow cytometry, we observed an early block in the G(1) phase of the cell cycle after ibuprofen treatment. In addition, P450 family transcripts were upregulated and intracellular reactive oxygen species (ROS) was increased following 12 h of ibuprofen treatment. Ibuprofen induced ROS, which resulted in cellular alterations that promoted a p53-dependent G(1) blockade. These findings suggest that ibuprofen exerts its antiproliferative actions through cell-cycle control and the induction of apoptosis. Both of these mechanisms appear to be independent of ibuprofen's anti-inflammatory effects.

MicroRNA expression profiling of oral carcinoma identifies new markers of tumor progression.

Oral squamous cell carcinoma, the most frequently occurring malignant head and neck tumour, generally exhibits poor prognosis and metastases are the main cause of death. The discovery of reliable prognostic indicators of tumour progression could greatly improve clinical practice. MicroRNAs are involved in the regulation of basic cellular processes such as cell proliferation, differentiation, and apoptosis. Since miRNAs have been shown to be abnormally expressed in different tumours their importance as potential cancer prognostic indicators is increasing. To define the role of miRNA in OSCC tumours we investigated the expression profile of 15 OSCC (8 without metastasis and 7 with lymph node metastasis) using microarray analysis. Thirteen miRNA were significantly overexpressed (miR-489, miR-129, miR-23a, miR-214, miR-23b, miR-92, miR-25, miR-210, miR-212, miR-515, miR-146b, miR-21, miR-338) and 6 miRNA were underexpressed (miR-520h, miR-197, miR-378, miR-135b, miR-224, miR-34a) in oral tumours. Underexpression of mir-155, let-7i, mir-146a was found to characterize progression to metastastatic tumours. Further investigations will elucidate whether differentially expressed miRNAs will help to better classify OSCCs, thus improving diagnoses and patient care.

Lack of association between common polymorphisms of epidermal growth factor receptors and nonsyndromic cleft lip with or without cleft palate.

OBJECTIVES: Nonsyndromic cleft lip with or without cleft palate (CL/P) is a frequent craniofacial malformation with a complex aetiology. Since the first report of an association between DNA sequence variants at the transforming growth factor alpha gene (TGFA) and nonsyndromic oral clefts, several studies have been carried out, which have produced conflicting results. Overall, TGFA is considered as a genetic clefting modifier in humans. Murine models indicate that the Tgfa product (tgfalpha), as well as its receptor (Egfr), actively participates in palate development. Notably, Egfr null mice showed an increased incidence in orofacial clefts. In the present study, genes which code for subunits of epidermal growth factor receptors (EGFRs) have been considered as candidate genes for CL/P. METHODS: A family based investigation was performed using a sample of 239 case/parent triads. The aim was to test for an allelic association between common non-synonymous polymorphisms in EGFR genes and CL/P. RESULTS AND CONCLUSION: The results did not suggest any evidence of a link between the investigated polymorphisms and CL/P, however the involvement of different polymorphisms or mutations in such genes cannot be excluded.

The MTHFD1 gene is not involved in cleft lip with or without palate onset among the Italian population.

Nonsyndromic cleft lip with or without cleft palate (CL/P) is the most common orofacial malformation, having a non-Mendelian and multifactorial aetiology. It has been shown that polymorphic variants of genes encoding key proteins of folate and methionine metabolism might be important maternal risk factors for having a child with these craniofacial anomalies. The aim of this study was to evaluate the role of two polymorphisms of the methylenetetrahydrofolate dehydrogenase 1 (MTHFD1) gene, the A1958G and the G401A variants, on the risk of CL/P in the Italian population. A1958G and G401A polymorphism genotyping of MTHFD1 was performed on 216 CL/P triads, (patient and parents), for this study by restriction endonuclease digestion of PCR products. Linkage disequilibrium between markers and disease was tested using both pairwise and haplotype analyses. In our case-parents triad design no significant association between MTHFD1 and the disease is evident. Our data do not support MTHFD1 involvement in CL/P onset among the Italian population.

Extracellular matrix and growth factors in the pathogenesis of some craniofacial malformations.

The normal development of cranial primordia and orofacial structures involves fundamental processes in which growth, morphogenesis, and cell differentiation take place and interactions between extracellular matrix (ECM) components, growth factors and embryonic tissues are involved. Biochemical and molecular aspects of craniofacial development, such as the biological regulation of normal or premature cranial suture fusion, has just begun to be understood, thanks mainly to studies performed in the last decade. Several mutations has been identified in both syndromic and non-syndromic craniosynostosis patients throwing new light onto the etiology, classification and developmental pathology of these diseases. In the more common craniosynostosis syndromes and other skeletal growth disorders, the mutations were identified in the genes encoding fibroblast growth factor receptor types 1-3 (FGFR1, 2 and 3) where they are dominantly acting and affect specific and important protein binding domain. The unregulated FGF signaling during intramembranous ossification is associated to the Apert and Crouzon syndrome. The non syndromic cleft of the lip and/or palate (CLP) has a more complex genetic background if compared to craniosynostosis syndrome because of the number of involved genes and type of inheritance. Moreover, the influence of environmental factor makes difficult to clarify the primary causes of this malformation. ECM represents cell environment and results mainly composed by collagens, fibronectin, proteoglycans (PG) and hyaluronate (HA). Cooperative effects of ECM and growth factors regulate regional matrix production during the morphogenetic events, connective tissue remodelling and pathological states. In the present review we summarize the studies we performed in the last years to better clarify the role of ECM and growth factors in the etiology and pathogenesis of craniosynostosis and CLP diseases.

Effects of Emdogain on osteoblast gene expression.

OBJECTIVE: Emdogain (EMD) is a protein extract purified from porcine enamel and has been introduced in clinical practice to obtain periodontal regeneration. EMD is composed mainly of amelogenins (90%), while the remaining 10% is composed of non-amelogenin enamel matrix proteins such as enamelins, tuftelin, amelin and ameloblastin. Enamel matrix proteins seem to be involved in root formation. EMD has been reported to promote proliferation, migration, adhesion and differentiation of cells associated with healing periodontal tissues in vivo. DESIGN: How this protein acts on osteoblasts is poorly understood. We therefore attempted to address this question by using a microarray technique to identify genes that are differently regulated in osteoblasts exposed to enamel matrix proteins. RESULTS: By using DNA microarrays containing 20,000 genes, we identified several upregulated and downregulated genes in the osteoblast-like cell line (MG-63) cultured with enamel matrix proteins (Emd). The differentially expressed genes cover a broad range of functional activities: (i) signaling transduction, (ii) transcription, (iii) translation, (iv) cell cycle regulation, proliferation and apoptosis, (v) immune system, (vi) vesicular transport and lysosome activity, and (vii) cytoskeleton, cell adhesion and extracellular matrix production. CONCLUSIONS: The data reported are the first genome-wide scan of the effect of enamel matrix proteins on osteoblast-like cells. These results can contribute to our understanding of the molecular mechanisms of bone regeneration and as a model for comparing other materials with similar clinical effects.