Effect of epithelial cells derived from periodontal ligament on osteoblast-like cells in a Transwell membrane coculture system

Analysis of the cells isolated from epithelial cell rests of Malassez through single-cell limiting dilution

The epithelial cell rests of Malassez (ERM) are essential in preventing ankylosis between the alveolar bone and the tooth (dentoalveolar ankylosis). Despite extensive research, the mechanism by which ERM cells suppress ankylosis remains uncertain; perhaps its varied population is to reason. Therefore, in this study, eighteen unique clones of ERM (CRUDE) were isolated using the single-cell limiting dilution and designated as ERM 1-18. qRT-PCR, ELISA, and western blot analyses revealed that ERM-2 and -3 had the highest and lowest amelogenin expression, respectively. Mineralization of human periodontal ligament fibroblasts (HPDLF) was reduced in vitro co-culture with CRUDE ERM, ERM-2, and -3 cells, but recovered when an anti-amelogenin antibody was introduced. Transplanted rat molars grown in ERM-2 cell supernatants produced substantially less bone than those cultured in other cell supernatants; inhibition was rescued when an anti-amelogenin antibody was added to the supernatants. Anti-Osterix antibody staining was used to confirm the development of new bones. In addition, next-generation sequencing (NGS) data were analysed to discover genes related to the distinct roles of CRUDE ERM, ERM-2, and ERM-3. According to this study, amelogenin produced by ERM cells helps to prevent dentoalveolar ankylosis and maintain periodontal ligament (PDL) space, depending on their clonal diversity.

Effects of full-length human amelogenin on the differentiation of dental epithelial cells and osteoblastic cells

BACKGROUND AND OBJECTIVE

Amelogenins are major components of extracellular matrix proteins in developing teeth, and regulate the growth of enamel crystals. They also function as signaling molecules in cell differentiation. This study aimed to determine the biological effects of amelogenins on the differentiation of HAT-7 dental epithelial cells and MC3T3-E1 pre-osteoblastic cells using full-length recombinant human amelogenin (rh-AMEL).

DESIGN

rh-AMEL was expressed in a mammalian cell line (Expi293F™) and was purified by DDK agarose beads. Effects of rh-AMEL on differentiation were evaluated by Mineralization and Alkaline phosphatase (ALP) activity using Alizarin Red S staining and colorimetric substrate p-nitrophenol, respectively.

RESULTS

Western blotting and silver staining confirmed the successful purification of rh-AMEL. Mineralization and ALP activity in HAT-7 cells were significantly higher after treatment with 4 μg/mL rh-AMEL, but not after treatment with Emdogain^® (EMD). In MC3T3-E1 cells, on the other hand, rh-AMEL showed biphasic effects on differentiation. Treatment with low concentrations of rh-AMEL (0.001-0.1 μg/mL) and EMD (0.01-1 μg/mL) increased mineralization and ALP activity in MC3T3-E1 cells, whereas treatment with high concentrations of rh-AMEL (4 μg/mL) and EMD (100 μg/mL) had the opposite effect.

CONCLUSION

High concentrations of rh-AMEL and EMD decreased the differentiation of MC3T3-E1 cells. By contrast, a high concentration of rh-AMEL, but not that of EMD, promoted the differentiation of HAT-7 cells. This study demonstrates that the effects of rh-AMEL on cell differentiation differ between HAT-7 and MC3T3-E1 cells, and suggests that different regions on AMEL may induce the differentiation of these cell types.

MicroRNA-101-3p suppresses proliferation and migration in hepatocellular carcinoma by targeting the HGF/c-Met pathway

MicroRNAs are involved in each stage of tumor development. Activation of the hepatocyte growth factor (HGF)/c-Met axis facilitates the proliferation and migration of cancer cells, and the HGF/c-MET pathway provides potential targets for anticancer treatment. However, the interaction between HGF and miRNAs in hepatocellular carcinoma (HCC) remains unknown. Previous studies have shown that miR-101 is downregulated in various types of cancer and acts as a tumor suppressor, but the role of miR-101 in HCC has not yet been well defined. Here, we show that HGF is upregulated while microRNA-101-3p is significantly downregulated in the tumor tissues of HCC. By combining bioinformatics analysis and luciferase reporter assays, we demonstrated that HGF is a direct target of miR-101. In vitro experiments indicated that miR-101 inhibits the migration and proliferation of HCC cells by targeting the HGF/c-MET axis, and in vivo studies showed that overexpressed miR-101 dramatically suppresses tumor growth. Therefore, the present study identifies miR-101 as a negative regulator of HGF/c-MET and suggests that miRNAs can be used as targeted drugs for the clinical treatment of HCC.

A Review of the Epithelial Cell Rests of Malassez on the Bicentennial of Their Description

The epithelial cell rests of Malassez (ERM) were first described in 1817, yet their significance has remained an enigma for more than 200 years. Given their embryological origins and persistence in adult periodontal tissue, recent research has investigated whether the ERM could be useful as stem cells to regenerate tissues lost as a consequence of periodontitis. The objective of this review is to describe results of studies that have vigorously investigated the functional capabilities of ERM, particularly with regard to periodontal ligament homeostasis and prevention of dentoalveolar ankylosis. The significance of the ERM relative to evolution of the dental attachment apparatus will be examined. The current status of use of ERM as stem cells for dental tissue engineering and in other applications will be reviewed.

Osteoblast Progenitors Enhance Osteogenic Differentiation of Periodontal Ligament Stem Cells

BACKGROUND

Osteoblasts and periodontal ligament stem cells (PDLSCs) play an important role in maintaining physiologic function of periodontal tissues and participating in periodontal regeneration. Elucidation of interactions between osteoblasts and PDLSCs will aid understanding of periodontal regeneration mechanisms. This study aims to determine whether preosteoblasts can promote osteoblastic/cementoblastic differentiation of PDLSCs.

METHODS

PDLSCs were cultured alone (control group), or cocultured indirectly with human gingival fibroblasts (HGFs) (HGFs group) or MC3T3-E1 cells (OB groups). Alkaline phosphatase (ALP) activity and gene/protein expressions levels of ALP, runt-related transcription factor-2, and osteopontin (OPN) were assessed. Cementum attachment protein and cementum protein 23 messenger RNA expressions were also evaluated. Bone morphogenetic protein (BMP)-2 secreted by HGFs/MC3T3-E1 cells was assessed by enzyme-linked immunosorbent assay. Extracellular matrix calcification was measured by staining to quantify calcium content.

RESULTS

ALP activity and gene/protein expression levels of osteogenic markers were significantly higher in the OB groups compared with the HGFs and control groups. Optimal enhancement of these parameters occurred at cell ratios of 2:1 to 1:1 (MC3T3-E1:PDLSCs). Mineralized nodule formation and calcium content were significantly increased in the OB groups compared with the HGF and control groups. The greatest improvement took place at the 2:1 (MC3T3-E1:PDLSCs) seeding ratio. BMP-2 from MC3T3-E1-conditioned medium was significantly and time-dependently increased compared with that from HGF-conditioned medium.

CONCLUSION

Preosteoblasts can indirectly enhance the osteoblastic/cementoblastic differentiation and mineralization of PDLSCs with an optimal preosteoblasts:PDLSCs ratio in the range of 2:1 to 1:1.