Biomimetic Dentin Repair: Amelogenin-Derived Peptide Guides Occlusion and Peritubular Mineralization of Human Teeth.

Exposure of dentin tubules due to loss of protective enamel (crown) and cementum (root) tissues as a result of erosion, mechanical wear, gingival recession, etc. has been the leading causes of dentin hypersensitivity. Despite being a widespread ailment, no permanent solution exists to address this oral condition. Current treatments are designed to alleviate the pain by either using desensitizers or blocking dentin tubules by deposition of minerals or solid precipitates, which often have short-lived effects. Reproducing an integrated mineral layer that occludes exposed dentin with concomitant peritubular mineralization is essential to reestablish the structural and mechanical integrity of the tooth with long-term durability. Here, we describe a biomimetic treatment that promotes dentin repair using a mineralization-directing peptide, sADP5, derived from amelogenin. The occlusion was achieved through a layer-by-layer peptide-guided remineralization process that forms an infiltrating mineral layer on dentin. The structure, composition, and nanomechanical properties of the remineralized dentin were analyzed by cross-sectional scanning electron microscopy imaging, energy dispersive X-ray spectroscopy, and nanomechanical testing. The elemental analysis provided calcium and phosphate compositions that are similar to those in hydroxyapatite. The measured average hardness and reduced elastic modulus values for the mineral layer were significantly higher than those of the demineralized and sound human dentin. The structural integration of the new mineral and underlying dentin was confirmed by thermal aging demonstrating no physical separation. These results suggest that a structurally robust and mechanically durable interface is formed between the interpenetrating mineral layer and underlying dentin that can withstand long-term mechanical and thermal stresses naturally experienced in the oral environment. The peptide-guided remineralization procedure described herein could provide a foundation for the development of highly effective oral care products leading to novel biomimetic treatments for a wide range of demineralization-related ailments and, in particular, offers a potent long-term solution for dentin hypersensitivity.

The power of weak ion-exchange resins assisted by amelogenin for natural remineralization of dental enamel: an in vitro study.

This study aims to develop an innovative dental product to remineralize dental enamel by a proper combination of ion-exchange resins as controlled release of mineral ions that form dental enamel, in the presence of amelogenin to guide the appropriate crystal growth. The novel product proposed consists of a combination of ion-exchange resins (weak acid and weak base) individually loaded with the remineralizing ions: Ca2+, PO43- and F-, also including Zn2+ in a minor amount as antibacterial, together with the protein amelogenin. Such cocktail provides onsite controlled release of the ions necessary for enamel remineralization due to the weak character of the resins and at the same time, a guiding tool for related crystal growth by the indicated protein. Amelogenin protein is involved in the structural development of natural enamel and takes a key role in controlling the crystal growth morphology and alignment at the enamel surface. Bovine teeth were treated by applying the resins and protein together with artificial saliva. Treated teeth were evaluated with nanoindentation, scanning electron microscopy and energy-dispersive X-ray spectroscopy. The innovative material induces the dental remineralization creating a fluorapatite layer with a hardness equivalent to sound enamel, with the appropriate alignment of corresponding nanocrystals, being the fluorapatite more acid resistant than the original mineral. Our results suggest that the new product shows potential for promoting long-term remineralization leading to the inhibition of caries and protection of dental structures.

Sex estimation of teeth at different developmental stages using dimorphic enamel peptide analysis.

OBJECTIVES: This study tests, for the first time, the applicability of a new method of sex estimation utilizing enamel peptides on a sample of deciduous and permanent teeth at different stages of mineralization, from nonadults of unknown sex, including perinates. MATERIALS AND METHODS: A total of 43 teeth from 29 nonadult individuals aged from 40 gestational weeks to 19 years old were analyzed. The sample included pairs of fully mineralized and just developing teeth from the same individual. The individuals were from four archaeological sites in England: Piddington (1st-2nd centuries AD), Coach Lane, Victoria Gate, and Fewston (all 18th-19th centuries). A method that identifies sex chromosome-linked isoforms of the peptide amelogenin from human tooth enamel was applied. The method utilizes a minimally destructive acid etching procedure and subsequent nano liquid chromatography tandem mass spectrometry. RESULTS: It was possible to determine the sex of 28 of the nonadult individuals sampled (males = 20, females = 8, undetermined = 1). Only one sample failed (CL9), due to insufficient mineralization of the sampled tooth enamel. Data are available via ProteomeXchange with identifier PXD021683. DISCUSSION: Sufficient peptide material to determine sex can be recovered even from the crowns of developing perinatal teeth that are not fully mineralized. The minimally destructive and inexpensive (compared to ancient DNA) nature of this procedure has significant implications for bioarchaeological studies of infancy and childhood.

A comparison of proteomic, genomic, and osteological methods of archaeological sex estimation.

Sex estimation of skeletons is fundamental to many archaeological studies. Currently, three approaches are available to estimate sex-osteology, genomics, or proteomics, but little is known about the relative reliability of these methods in applied settings. We present matching osteological, shotgun-genomic, and proteomic data to estimate the sex of 55 individuals, each with an independent radiocarbon date between 2,440 and 100 cal BP, from two ancestral Ohlone sites in Central California. Sex estimation was possible in 100% of this burial sample using proteomics, in 91% using genomics, and in 51% using osteology. Agreement between the methods was high, however conflicts did occur. Genomic sex estimates were 100% consistent with proteomic and osteological estimates when DNA reads were above 100,000 total sequences. However, more than half the samples had DNA read numbers below this threshold, producing high rates of conflict with osteological and proteomic data where nine out of twenty conditional DNA sex estimates conflicted with proteomics. While the DNA signal decreased by an order of magnitude in the older burial samples, there was no decrease in proteomic signal. We conclude that proteomics provides an important complement to osteological and shotgun-genomic sex estimation.

Naked eye Y amelogenin gene fragment detection using DNAzymes on a paper-based device.

Nowadays, great efforts are made in developing new technology for rapid detection of specific DNA sequences, for environmental monitoring, forensic analysis and rapid biomedical diagnosis applications. Microfluidic paper-based analytical devices are suitable platforms for the development of point of care devices, due to their simple fabrication protocols, ease of use and low cost. Herein, a methodology for in situ detection of single strand DNA by using a colorimetric assay based on the formation of a DNAzyme within a paper substrate was developed. A DNAzyme that could only be formed in the presence of a specific sequence of the Y human amelogenin gene was designed. The performance of the DNAzyme was followed colorimetrically first in solution and then in paper substrates. The reaction was found to be specific to the Y fragment selected as analyte. The DNAzyme reaction on paper enabled the unequivocal colorimetric identification of the Y single strand DNA fragment both qualitatively, with the naked eye (143 ng), and quantitatively by image analysis (45.7 ng). As a proof of concept, a microfluidic paper-based device, pre-loaded with all DNAzyme reagents, was characterized and implemented for the simultaneous detection of X and Y single strand DNA fragments.

Male patient 46,XX SRY-negative and unambiguous genitalia: A case report / Paciente masculino con cariotipo 46 XX negativo para el gen SRY y sin ambigüedad genital: reporte de un caso

In most cases, male sexual differentiation occurs with SRY gene mediation. However, exceptional genotypes have been identified, as shown in this paper. This was a male adult patient seen at the Servicio de Paternidades, Instituto de Genética, Universidad Nacional de Colombia. The following procedures were carried out: Amelogenin gene and short tandem repeat analyses using human identification commercial kits, conventional karyotype, SRY fluorescent in situ hybridization, PCR analysis for Y chromosome microdeletions, clinical evaluation, and genetic counseling. We present an adult male with unambiguous genitalia, karyotype 46,XX, and an SRY negative and ZFY positive molecular profile. The diagnosis of nonsyndromic 46,XX testicular disorder of sex development (DSD) -a rare genetic condition- was established. Only 20 % of similarly diagnosed patients are SRY negative and exhibit diverse molecular profiles. Until now, available evidence seems to indicate that, even in the absence of SRY, the ZFY factor is involved in male sexual differentiation.

En la mayoría de los casos, la diferenciación sexual masculina ocurre con la participación del gen SRY. Sin embargo, se pueden presentar otros genotipos excepcionales, como en el caso que se presenta en este reporte. Se trata de un paciente adulto de sexo masculino atendido en el Servicio de Paternidades del Instituto de Genética de la Universidad Nacional de Colombia. Se le hicieron los análisis del gen de la amelogenina y de repeticiones cortas en tándem (Short Tandem Repeat, STR) específicas para el gen SRY con estuches comerciales de identificación humana, así como los de cariotipo convencional e hibridación in situ fluorescente del SRY, y el estudio de microdeleciones del cromosoma Y mediante reacción en cadena de la polimerasa (PCR). Se le hizo la evaluación clínica y se le brindó asesoramiento genético. El paciente no presentaba ambigüedad genital, su cariotipo era 46 XX, y el perfil molecular era negativo para el gen SRY y positivo para el ZFY. Se le diagnosticó un trastorno de diferenciación sexual 46 XX testicular no sindrómico, una rara condición genética. Solo el 20 % de los pacientes con este diagnóstico son negativos para SRY y exhiben perfiles moleculares diversos. La información disponible parece indicar que el ZFY está relacionado con la diferenciación sexual masculina, aún en ausencia del gen SRY.

Immunohistochemical Co-Localization of Amelogenin and Ameloblastin in Developing Enamel Matrix.

Quantitative co-localization analysis, combined with other in vivo and in vitro techniques, can provide valuable information about the interaction and cooperative function of two proteins. Here we describe in detail the technique of quantitative co-localization analysis of two enamel matrix proteins, amelogenin and ameloblastin, in developing mouse enamel.

Multicolor-based discrimination of 21 short tandem repeats and amelogenin using four fluorescent universal primers.

The aim of this study was to develop a cost-effective genotyping method using high-quality DNA for human identification. A total of 21 short tandem repeats (STRs) and amelogenin were selected, and fluorescent fragments at 22 loci were simultaneously amplified in a single-tube reaction using locus-specific primers with 24-base universal tails and four fluorescent universal primers. Several nucleotide substitutions in universal tails and fluorescent universal primers enabled the detection of specific fluorescent fragments from the 22 loci. Multiplex polymerase chain reaction (PCR) produced intense FAM-, VIC-, NED-, and PET-labeled fragments ranging from 90 to 400 bp, and these fragments were discriminated using standard capillary electrophoretic analysis. The selected 22 loci were also analyzed using two commercial kits (the AmpFLSTR Identifiler Kit and the PowerPlex ESX 17 System), and results for two loci (D19S433 and D16S539) were discordant between these kits due to mutations at the primer binding sites. All genotypes from the 100 samples were determined using 2.5 ng of DNA by our method, and the expected alleles were completely recovered. Multiplex 22-locus genotyping using four fluorescent universal primers effectively reduces the costs to less than 20% of genotyping using commercial kits, and our method would be useful to detect silent alleles from commercial kit analysis.

Weaker dental enamel explains dental decay.

Dental caries continues to be the most prevalent bacteria-mediated non-contagious disease of humankind. Dental professionals assert the disease can be explained by poor oral hygiene and a diet rich in sugars but this does not account for caries free individuals exposed to the same risk factors. In order to test the hypothesis that amount of amelogenin during enamel development can influence caries susceptibility, we generated multiple strains of mice with varying levels of available amelogenin during dental development. Mechanical tests showed that dental enamel developed with less amelogenin is "weaker" while the dental enamel of animals over-expressing amelogenin appears to be more resistant to acid dissolution.

Enamel Hypomineralization and Structural Defects in Amelotin-deficient Mice.

Amelotin (AMTN) is a relatively recently discovered enamel protein that is predominantly expressed by ameloblasts during the maturation stage of amelogenesis and is present at lower levels in the junctional epithelium of erupted teeth. Previous studies have suggested a function of this protein in enamel mineralization and cell attachment. Genetic mouse models have been instrumental in defining the role of many enamel-related proteins, but a genetic mouse model lacking the Amtn gene has not been reported. Here, we describe the generation of amelotin-deficient mice and the analysis of their enamel phenotype in comparison with that of wild-type animals. Ablation of AMTN expression resulted in mechanically inferior enamel of mandibular incisors that showed chipping and fractures at the incisal edge. Enamel mineralization was delayed, resulting in hypomineralized inner enamel and structural defects in the outer enamel. Erupted enamel close to the gingival margin showed increased surface roughness. The expression levels of the enamel matrix proteins AMEL, AMBN, ENAM, and ODAM and the enamel proteases MMP-20 and KLK-4 were not significantly altered, although the expression of KLK-4 was delayed. The morphology of ameloblasts showing prominent Tomes' processes during the secretory stage was not altered, and there was no indication of disruption of cell structures or activities, but a residual layer, presumably consisting of organic material, remained at the enamel surface close to the gingival margin. The integrity of the dentogingival attachment at the junctional epithelium appeared unaffected by AMTN deficiency. These observations indicate that AMTN plays a subtle yet critical role in enamel biomineralization, particularly during the establishment of the outer and surface enamel layers. This role appears to be largely independent of other enamel proteins.

Excess NF-κB induces ectopic odontogenesis in embryonic incisor epithelium.

Nuclear factor kappa B (NF-κB) signaling plays critical roles in many physiological and pathological processes, including regulating organogenesis. Down-regulation of NF-κB signaling during development results in hypohidrotic ectodermal dysplasia. The roles of NF-κB signaling in tooth development, however, are not fully understood. We examined mice overexpressing IKKß, an essential component of the NF-κB pathway, under keratin 5 promoter (K5-Ikkß). K5-Ikkß mice showed supernumerary incisors whose formation was accompanied by up-regulation of canonical Wnt signaling. Apoptosis that is normally observed in wild-type incisor epithelium was reduced in K5-Ikkß mice. The supernumerary incisors in K5-Ikkß mice were found to phenocopy extra incisors in mice with mutations of Wnt inhibitor, Wise. Excess NF-κB activity thus induces an ectopic odontogenesis program that is usually suppressed under physiological conditions.

Fluoride affects enamel protein content via TGF-ß1-mediated KLK4 inhibition.

Dental fluorosis is caused by chronic high-level fluoride (F(-)) exposure during enamel development, and fluorosed enamel has a higher than normal protein content. Matrix metalloproteinase 20 cleaves enamel matrix proteins during the secretory stage, and KLK4 further cleaves these proteins during the maturation stage so that the proteins can be reabsorbed from the hardening enamel. We show that transforming growth factor ß1 (TGF-ß1) can induce Klk4 expression, and we examine the effect of F(-) on TGF-ß1 and KLK4 expression. We found that in vivo F(-) inhibits Klk4 but not Mmp20 transcript levels. LacZ-C57BL/6-Klk4 (+/LacZ) mice have LacZ inserted in frame at the Klk4 translation initiation site so that the endogenous Klk4 promoter drives LacZ expression in the same temporal/spatial way as it does for Klk4. KLK4 protein levels in rat enamel and ß-galactosidase staining in LacZ-C57BL/6-Klk4 (+/LacZ) mouse enamel were both significantly reduced by F(-) treatment. Since TGF-ß1 induces KLK4 expression, we tested and found that F(-) significantly reduced Tgf-ß1 transcript levels in rat enamel organ. These data suggest that F(-)-mediated downregulation of TGF-ß1 expression contributes to reduced KLK4 protein levels in fluorosed enamel and provides an explanation for why fluorosed enamel has a higher than normal protein content.

Tracking endogenous amelogenin and ameloblastin in vivo.

Research on enamel matrix proteins (EMPs) is centered on understanding their role in enamel biomineralization and their bioactivity for tissue engineering. While therapeutic application of EMPs has been widely documented, their expression and biological function in non-enamel tissues is unclear. Our first aim was to screen for amelogenin (AMELX) and ameloblastin (AMBN) gene expression in mandibular bones and soft tissues isolated from adult mice (15 weeks old). Using RT-PCR, we showed mRNA expression of AMELX and AMBN in mandibular alveolar and basal bones and, at low levels, in several soft tissues; eyes and ovaries were RNA-positive for AMELX and eyes, tongues and testicles for AMBN. Moreover, in mandibular tissues AMELX and AMBN mRNA levels varied according to two parameters: 1) ontogenic stage (decreasing with age), and 2) tissue-type (e.g. higher level in dental epithelial cells and alveolar bone when compared to basal bone and dental mesenchymal cells in 1 week old mice). In situ hybridization and immunohistodetection were performed in mandibular tissues using AMELX KO mice as controls. We identified AMELX-producing (RNA-positive) cells lining the adjacent alveolar bone and AMBN and AMELX proteins in the microenvironment surrounding EMPs-producing cells. Western blotting of proteins extracted by non-dissociative means revealed that AMELX and AMBN are not exclusive to mineralized matrix; they are present to some degree in a solubilized state in mandibular bone and presumably have some capacity to diffuse. Our data support the notion that AMELX and AMBN may function as growth factor-like molecules solubilized in the aqueous microenvironment. In jaws, they might play some role in bone physiology through autocrine/paracrine pathways, particularly during development and stress-induced remodeling.

Simple and label-free electrochemical impedance Amelogenin gene hybridization biosensing based on reduced graphene oxide.

The increasing desire for sensitive, easy, low-cost, and label free methods for the detection of DNA sequences has become a vital matter in biomedical research. For the first time a novel label-free biosensor for sensitive detection of Amelogenin gene (AMEL) using reduced graphene oxide modified glassy carbon electrode (GCE/RGO) has been developed. In this work, detection of DNA hybridization of the target and probe DNA was investigated by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The optimum conditions were found for the immobilization of probe on RGO surface and its hybridization with the target DNA. CV and EIS carried out in an aqueous solution containing [Fe(CN)6](3-/4-) redox pair have been used for the biosensor characterization. The biosensor has a wide linear range from 1.0×10(-20) to 1.0×10(-14)M with the lower detection limit of 3.2×10(-21)M. Moreover, the present electrochemical detection offers some unique advantages such as ultrahigh sensitivity, simplicity, and feasibility for apparatus miniaturization in analytical tests. The excellent performance of the biosensor is attributed to large surface-to-volume ratio and high conductivity of RGO, which enhances the probe absorption and promotes direct electron transfer between probe and the electrode surface. This electrochemical DNA sensor could be used for the detection of specific ssDNA sequence in real biological samples.

Ameloblasts express type I collagen during amelogenesis.

Enamel and enameloid, the highly mineralized tooth-covering tissues in living vertebrates, are different in their matrix composition. Enamel, a unique product of ameloblasts, principally contains enamel matrix proteins (EMPs), while enameloid possesses collagen fibrils and probably receives contributions from both odontoblasts and ameloblasts. Here we focused on type I collagen (COL1A1) and amelogenin (AMEL) gene expression during enameloid and enamel formation throughout ontogeny in the caudate amphibian, Pleurodeles waltl. In this model, pre-metamorphic teeth possess enameloid and enamel, while post-metamorphic teeth possess enamel only. In first-generation teeth, qPCR and in situ hybridization (ISH) on sections revealed that ameloblasts weakly expressed AMEL during late-stage enameloid formation, while expression strongly increased during enamel deposition. Using ISH, we identified COL1A1 transcripts in ameloblasts and odontoblasts during enameloid formation. COL1A1 expression in ameloblasts gradually decreased and was no longer detected after metamorphosis. The transition from enameloid-rich to enamel-rich teeth could be related to a switch in ameloblast activity from COL1A1 to AMEL synthesis. P. waltl therefore appears to be an appropriate animal model for the study of the processes involved during enameloid-to-enamel transition, especially because similar events probably occurred in various lineages during vertebrate evolution.

Conserved odontogenic potential in embryonic dental tissues.

Classic tissue recombination studies have demonstrated that, in the early developing mouse tooth germ, the odontogenic potential, known as the tooth-inductive capability, resides initially in the dental epithelium and then shifts to the dental mesenchyme. However, it remains unknown if human embryonic dental tissues also acquire such odontogenic potential. Here we present evidence that human embryonic dental tissues indeed possess similar tooth-inductive capability. We found that human dental epithelium from the cap stage but not the bell stage was able to induce tooth formation when confronted with human embryonic lip mesenchyme. In contrast, human dental mesenchyme from the bell stage but not the cap stage could induce mouse embryonic second-arch epithelium as well as human keratinocyte stem cells, to become enamel-secreting ameloblasts. We showed that neither post-natal human dental pulp stem cells (DPSCs) nor stem cells from human exfoliated deciduous teeth (SHED) possess odontogenic potential or are odontogenic-competent. Our results demonstrate a conservation of odontogenic potential in mouse and human dental tissues during early tooth development, and will have an implication in the future generation of stem-cell-based bioengineered human replacement teeth.

Enamel matrix derivative: protein components and osteoinductive properties.

BACKGROUND: Although enamel matrix derivative (EMD) has demonstrated the ability to promote angiogenesis and osteogenesis both in vitro and in vivo, the specific elements within the EMD compound responsible for these effects remain unknown. METHODS: Nine different protein pools from a commercially produced EMD were collected based on molecular weight. Six of these pools, along with the complete EMD unfractionated compound and positive and negative controls, were tested for their ability to induce bone formation in a calvarial induction assay. Immunocytochemistry of phosphorylated SMAD1/5/8 (phospho-SMAD), osterix, and vascular endothelial growth factor A (VEGF-A) was carried out at selected time points. Finally, proteomic analysis was completed to determine the specific protein-peptide content of the various osteoinductive pools. RESULTS: One of the lower-molecular-weight pools tested, pool 7, showed bone induction responses significantly greater than those of the other pools and the complete EMD compound and was concentration dependent. Dynamic bone formation rate analysis demonstrated that pool 7 was optimally active at the 5- to 10-µg concentration. It was demonstrated that EMD and pool 7 induced phospho-SMAD, osterix, and VEGF-A, which is indicative of increased bone morphogenetic protein (BMP) signaling. Proteomic composition analysis demonstrated that pool 7 had the highest concentration of the biologically active amelogenin-leucine-rich amelogenin peptide and ameloblastin 17-kDa peptides. CONCLUSIONS: These studies demonstrate that the low-molecular-weight protein pools (7 to 17 kDa) within EMD have greater osteoinductive potential than the commercially available complete EMD compound and that the mechanism of action, in part, is through increased BMP signaling and increased osterix and VEGF-A. With this information, selected components of EMD can now be formulated for optimal osteo- and angio-genesis.

Sex determination from dentin and pulp in a medicolegal context.

BACKGROUND: The techniques used to determine the sex of skeletons are limited. The authors conducted a study to analyze the accuracy of sex identification from dentin and pulp via DNA isolation. METHODS: The authors extracted DNA from the dentin and pulp of 14 teeth by using a silica-based methodology. They used the amelogenin gene to determine the sex via polymerase chain reaction. ß-actin, a housekeeping gene, was used as a control gene. The authors checked the results in agarose gel and semiquantified them by using gel analysis software. RESULTS: The DNA yield depended on the type of tooth and was lowest in the smallest teeth (that is, incisors). In all cases, the authors were able to identify the sex, as well as the control gene, which suggests the potential to identify other genes, such as short tandem repeats. CONCLUSIONS: It is possible to correctly identify a person's sex from dentin and pulp; in instances in which one dental material is not available, the other material can be used with the same efficiency. Practical Implications. The results of this study are applicable to forensic dentistry, particularly in situations in which there is commingling of remains and fragmentary remains, and there may be only one tooth with which to identify a person's sex.

Expression and function of enamel-related gene products in calvarial development.

Enamel-related gene products (ERPs) are detected in non-enamel tissues such as bone. We hypothesized that, if functional, ERP expression corresponds with distinct events during osteoblast differentiation and affects bone development and mineralization. In mouse calvariae and MC3T3 cells, expression profiles of enamel-related gene products (ERPs) correlated with key events in post-natal calvarial development and MC3T3 cell mineralization. Developing skulls from both Amel- and Ambn-deficient animals were approximately 15% shorter when compared with those of wild-type controls, and their sutures remained patent for a longer period of time. Analysis of Amel- and Ambn-deficient calvariae and calvarial osteoblast cultures revealed a dramatic reduction in mineralized nodules, a significant reduction in Runx2, Sp7, Ibsp, and Msx2 expression, and a reduction in Alx4 in Amel-deficient calvariae vs. an increase in Alx4 in Ambn-deficient calvariae. Analysis of these data indicates that ERP expression follows defined developmental profiles and affects osteoblast differentiation, mineralization, and calvarial bone development. We propose that, in parallel to their role in the developing enamel matrix, ERPs have retained an evolutionary conserved function related to the biomineralization of bones.

The similarity between human embryonic stem cell-derived epithelial cells and ameloblast-lineage cells.

This study aimed to compare epithelial cells derived from human embryonic stem cells (hESCs) to human ameloblast-lineage cells (ALCs), as a way to determine their potential use as a cell source for ameloblast regeneration. Induced by various concentrations of bone morphogenetic protein 4 (BMP4), retinoic acid (RA) and lithium chloride (LiCl) for 7 days, hESCs adopted cobble-stone epithelial phenotype (hESC-derived epithelial cells (ES-ECs)) and expressed cytokeratin 14. Compared with ALCs and oral epithelial cells (OE), ES-ECs expressed amelogenesis-associated genes similar to ALCs. ES-ECs were compared with human fetal skin epithelium, human fetal oral buccal mucosal epithelial cells and human ALCs for their expression pattern of cytokeratins as well. ALCs had relatively high expression levels of cytokeratin 76, which was also found to be upregulated in ES-ECs. Based on the present study, with the similarity of gene expression with ALCs, ES-ECs are a promising potential cell source for regeneration, which are not available in erupted human teeth for regeneration of enamel.