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Objective: Epigenetic mechanisms play regulatory roles in dental pulp stem cell (DPSC) differentiation. The molecules that modulate these mechanisms can be used to enhance DPSC differentiation in experimental studies and clinical applications. We investigated the combined effects of an epigenetic modulator enhancer of zeste homologue 2 inhibitor (EZH2i), trichostatin A (TSA), and 5-azacytidine (5-AZA) on the osteogenic differentiation of DPSCs., Results: To assess osteogenic differentiation, we measured alkaline phosphatase activity, calcium deposition, and expression of osteogenic differentiation marker genes ( RUNX2 , BMP2 , and ALPL ) after 7 or 21 days of combinatorial drug treatment in normal cell culture medium or osteo-inductive medium (OIM). No synergistic effects were observed for any possible combination of EZH2i, TSA, or 5-AZA. However, the effects of these drugs and their combinations depend on the time and culture conditions., Discussion: We confirmed that EZH2i and TSA have positive effects on the osteogenic differentiation of DPSCs. EZH2i activates the expression of key regulatory genes ( RUNX2 , BMP2 , and ALPL ) directly, whereas TSA interacts with signalling pathways induced by supplements in OIM to activate these genes., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

Bone morphogenetic protein-2 (BMP-2), is a potential factor to enhance osseointegration of dental implants. However, the appropriate cellular system to investigate the osteogenic effect of BMP-2 in vitro in a standardized manner still needs to be defined. The aim of this study was to examine the effect of BMP-2 on the cell proliferation and osteogenic differentiation of human osteogenic progenitors of various origins: dental pulp stem cells (DPSC), human osteosarcoma cell line (Saos-2) and human embryonic palatal mesenchymal cell line (HEPM). For induction of osteogenic differentiation, cell culture medium was supplemented with BMP-2 homodimer alone or in combination with conventionally used differentiation inducing agents. Differentiation was monitored for 6-18 days. To assess differentiation, proliferation rate, alkaline phosphatase activity, calcium deposition and the expression level of osteogenic differentiation marker genes (Runx2, BMP-2) were measured. BMP-2 inhibited cell proliferation in a concentration and time-dependent manner. In a concentration which caused maximal cell proliferation, BMP-2 did not induce osteogenic differentiation in any of the tested systems. However, it had a synergistic effect with the osteoinductive medium in both DPSC and Saos-2, but not in HEPM cells. We also found that the differentiation process was faster in Saos-2 than in DPSCs. Osteogenic differentiation could not be induced in the osteoblast progenitor HEPM cells. Our data suggest that in a concentration that inhibits proliferation the differentiation inducing effect of BMP-2 is evident only in the presence of permissive osteoinductive components. β-glycerophosphate, was identified interacting with BMP-2 in a synergistic manner.

Stem cells are present in many tissues, such as dental pulp. Stem cells can be easily isolated from dental pulp because third molars are often removed from patients. Stem cells could be separated from the tissue derived heterogeneous cell population. There are two main methods to separate a cell type from the other ones: the fluorescence activated cell sorting (FACS) and the magnetic activated cell sorting (MACS). The aim of this study was to compare these methods' effect on cell surviving and population growth after sorting on dental pulp cells. The anti-STRO-1 antibody was used as primary antibody to specifically label stem cells. Two secondary antibodies were used: magnetic or fluorescent labelled. We sorted the cells by MACS or by FACS or by combination of both (MACS-FACS). Our results show that the effectivity of MACS and FACS sorting are comparable while of MACS-FACS was significantly higher (MACS 79.53 ± 5.78%, FACS 88.27 ± 3.70%, MACS-FACS 98.43 ± 0.67%). The cell surviving and the post-sorting population growth, on the contrary, are very different. The cell population is growing on first week after MACS but after FACS did not. Moreover, after MACS-FACS, on first week the cell number of population decreased. Taken together, our results suggest to use MACS instead of FACS, at least in case of sorting dental pulp stem cells with anti-STRO-1 antibody.

In dental implantation missing tooth or teeth are replaced by artificial root. To reduce the time required for the integration newest trends are the enhancement of bone formation around the implant by bioactive molecules, growth factors. Such a molecule is bone morphogenetic protein-2 (BMP-2) accepted by US Food and Drug Administration (FDA). In these kind of applications effect of BMP-2 is tested in vitro on appropriate cell lines. One of these cell lines is the osteoblast like human embrionic palatal mesenchymal cell line (HEPM). In our experiments the effect of BMP-2 homodimer treatment was investigated on the differentiation of HEPM cells to osteoblasts reflected by changes in morphology, and proliferation after a short, 3 days BMP-2 treatment. Results showed that after three days BMP-2 treatment facilitates cell attachment on a concentration dependent manner however changes in cell morphology and proliferation could not be observed. Continuing the BMP-2 treatment inhibitory effect was measured in cell proliferation, which may refer to cell differentiation.