Hypoxia-inducible factor 1α induces osteo/odontoblast differentiation of human dental pulp stem cells via Wnt/β-catenin transcriptional cofactor BCL9

Accelerated dental pulp mineralization is a common complication in avulsed/luxated teeth, although the mechanisms underlying this remain unclear. We hypothesized that hypoxia due to vascular severance may induce osteo/odontoblast differentiation of dental pulp stem cells (DPSCs). This study examined the role of B-cell CLL/lymphoma 9 (BCL9), which is downstream of hypoxia-inducible factor 1α (HIF1α) and a Wnt/β-catenin transcriptional cofactor, in the osteo/odontoblastic differentiation of human DPSCs (hDPSCs) under hypoxic conditions. hDPSCs were isolated from extracted healthy wisdom teeth. Hypoxic conditions and HIF1α overexpression induced significant upregulation of mRNAs for osteo/odontoblast markers (RUNX2, ALP, OC), BCL9, and Wnt/β-catenin signaling target genes (AXIN2, TCF1) in hDPSCs. Overexpression and suppression of BCL9 in hDPSCs up- and downregulated, respectively, the mRNAs for AXIN2, TCF1, and the osteo/odontoblast markers. Hypoxic-cultured mouse pulp tissue explants showed the promotion of HIF1α, BCL9, and β-catenin expression and BCL9-β-catenin co-localization. In addition, BCL9 formed a complex with β-catenin in hDPSCs in vitro. This study demonstrated that hypoxia/HIF1α-induced osteo/odontoblast differentiation of hDPSCs was partially dependent on Wnt/β-catenin signaling, where BCL9 acted as a key mediator between HIF1α and Wnt/β-catenin signaling. These findings may reveal part of the mechanisms of dental pulp mineralization after traumatic dental injury.

Promotion of the Differentiation of Dental Pulp Stem Cells into Oligodendrocytes by Knockdown of Heat-Shock Protein 27

Stem cell-based therapy has been evaluated in many different clinical trials for various diseases. This capability was applied in various neurodegenerative diseases, such as Alzheimer’s disease, which is characterized by synaptic damage accompanied by neuronal loss. Dental pulp stem cells (DPSCs) are mesenchymal stem cells from the oral cavity and have been studied with potential application for regeneration of different tissues. Heat shock protein 27 (HSP27) is known to regulate neurogenesis in the process of neural differentiation of placenta-multipotent stem cells. Here, we hypothesize that HSP27 expression is also critical in neural differentiation of DPSCs. An evaluation of the possible role of HSP27 in differentiation of DPSCs was per-formed by gene knockdown and neural immunofluorescent staining. We found that HSP27 has a role in the differentiation of DPSCs and that knockdown of HSP27 in DPSCs renders cells to oligodendrocyte progenitors. In other words, shHSP27-DPSCs showed NG2-positive immunoreactivity and gave rise to oligodendrocytes or type-2 astrocytes. This neural differentiation of DPSCs may have clinical significance for treatment of patients with neurodegenerative diseases. In conclusion, our data provide an example of oligodendrocyte differentiation of a DPSCs model that may have potential application in human regenerative medicine.

LncRNA-KCNQ1OT1 Promotes the Odontoblastic Differentiation of Dental Pulp Stem Cells via Regulating miR-153-3p/RUNX2 Axis

Background and Objective: Long non-coding RNAs (LncRNAs) play a key role in the odontoblastic differentiation. This study aimed to explore the role of LncRNA-KCNQ1OT1 in the odontoblastic differentiation of human dental pulp stem cells (DPSCs) and its possible mechanism. Methods: The expression of LncRNA-KCNQ1OT1, miR-153-3p, RUNX2 in the odontoblastic differentiation was detected by qRT-PCR. Interaction between LncRNA-KCNQ1OT1 and miR-153-3p and interaction between miR-153-3p and RUNX2 were detected by dual-luciferase assay. The cell viability of DPSCs was detected by cell counting kit-8 (CCK-8), and the effect of LncRNA-KCNQ1OT1 and miR-153-3p on the odontoblastic differentiation of DPSCs was observed by alizarin red staining, alkaline phosphatase (ALP) activity assay and Western blot for RUNX2, DSPP, DMP-1. Results: During odontoblastic differentiation of DPSCs, the expression of LncRNA-KCNQ1OT1 increased, miR-153-3p expression decreased, and RUNX2 expression increased. Dual-luciferase assay showed that LncRNA-KCNQ1OT1 sponges miR-153-3p and miR-153-3p targets on RUNX2. After LncRNA-KCNQ1OT1 and miR-153-3p expressions of DPSCs were changed, the cell viability was not notably changed, but the odontoblastic differentiation was notably changed which was confirmed with alizarin red staining, ALP activity and Western blot for RUNX2, DSPP, DMP-1. Conclusion: LncRNA-KCNQ1OT1 promotes the odontoblastic differentiation of DPSCs via regulating miR-153-3p/RUNX2 axis, which may provide a therapeutic clue for odontogenesis.