Calcium ions promote osteogenic differentiation and mineralization of human dental pulp cells: implications for pulp capping materials

Regenerative endodontic procedures using autologous platelet-rich plasma (PRP) can improve the biologic outcome of treatment. However, its mechanism of action on improving pulp regeneration is not fully elucidated. Autophagy was recently shown to be related to tissue repair and osteogenesis. Therefore, the objective of this study was to investigate the effect of PRP in dental pulp regeneration and to elucidate the role of autophagy involved in this process. Human dental pulp cells (hDPCs) were isolated from healthy dental pulp and co-cultured with an increasing concentration of PRP. Cellular migration and proliferation were determined by scratch assay, transwell assay, and cell-counting kit 8 assay. Osteogenic differentiation was clarified by using alkaline phosphatase staining, alizarin red staining, and real-time polymerase chain reaction (RT-PCR) to measure the gene expression levels of alkaline phosphatase, collagen-1, osteocalcin, dentin matrix protein 1, and dentin sialophosphoprotein. Autophagic bodies were observed by transmission electron microscopy and the expression of autophagy marker light chain 3B (LC3B) was determined by immunofluorescence staining. The mRNA and protein expression level of LC3B and Beclin-1 were quantified by qRT-PCR and western blotting. The effect of PRP on cellular migration, proliferation, and osteogenic differentiation was further investigated in the milieu of autophagy activator, rapamycin, and inhibitor, 3-methyladenine. Results showed that PRP promoted cell migration, proliferation, and osteogenic differentiation. Autophagic bodies were strongly activated and the expression level of LC3B and Beclin-1 was significantly promoted by PRP. Autophagy inhibition suppressed PRP-induced hDPCs migration, proliferation, and osteogenic differentiation, whereas autophagy activator substantially augmented PRP-stimulated migration, proliferation, and differentiation. Taken together, these findings suggested that PRP could effectively promote regenerative potentials associated with autophagy.

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Effect of Magnesium on Dentinogenesis of Human Dental Pulp Cells

International Journal of Biomaterials ◽

10.1155/2021/6567455 ◽

2021 ◽

Vol 2021 ◽

pp. 1-12

Author(s):

Rania M. Salem ◽

Chang Zhang ◽

Laisheng Chou

Keyword(s):

Cell Proliferation ◽

Dental Pulp ◽

Cell Attachment ◽

Proliferation Rate ◽

Dental Pulp Cells ◽

Human Dental Pulp Cells ◽

Pulp Capping ◽

Alp Activity ◽

Human Dental Pulp ◽

Pulp Cells

Introducing therapeutic ions into pulp capping materials has been considered a new approach for enhancing regeneration of dental tissues. However, no studies have been reported on its dentinogenic effects on human dental pulp cells (HDPCs). This study was designed to investigate the effects of magnesium (Mg2+) on cell attachment efficiency, proliferation, differentiation, and mineralization of HDPCs. HDPCs were cultured with 0.5 mM, 1 mM, 2 mM, 4 mM, and 8 mM concentrations of supplemental Mg2+ and 0 mM (control). Cell attachment was measured at 4, 8, 12, 16, and 20 hours. Cell proliferation rate was evaluated at 3, 7, 10, 14, and 21 days. Crystal violet staining was used to determine cell attachment and proliferation rate. Alkaline phosphatase (ALP) activity was assessed using the fluorometric assay at 7, 10, and 14 days. Mineralization of cultures was measured by Alizarin red staining. Statistical analysis was done using multiway analysis of variance (multiway ANOVA) with Wilks’ lambda test. Higher cell attachment was shown with 0.5 mM and 1 mM at 16 hours compared to control ( P < 0.0001 ). Cells with 0.5 mM and 1 mM supplemental Mg2+ showed significantly higher proliferation rates than control at 7, 10, 14, and 21 days ( P < 0.0001 ). However, cell proliferation rates decreased significantly with 4 mM and 8 mM supplemental Mg2+ at 14 and 21 days ( P < 0.0001 ). Significantly higher levels of ALP activity and mineralization were observed in 0.5 mM, 1 mM, and 2 mM supplemental Mg2+ at 10 and 14 days ( P < 0.0001 ). However, 8 mM supplemental Mg2+ showed lower ALP activity compared to control at 14 days ( P < 0.0001 ), while 4 mM and 8 mM supplemental Mg2+showed less mineralization compared to control ( P < 0.0001 ). The study indicated that the optimal (0.5–2 mM) supplemental Mg2+ concentrations significantly upregulated HDPCs by enhancing cell attachment, proliferation rate, ALP activity, and mineralization. Magnesium-containing biomaterials could be considered for a future novel dental pulp-capping additive in regenerative endodontics.

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