Background: Human dental pulp stem cell (DPSC)-mediated regenerative endodontics is a promising therapy for damaged teeth; however, the hypoxic environment in root canals can affect tissue regeneration. In this study, we investigate the characteristics and possible regulatory mechanisms of DPSC function under hypoxic conditions.
Methods: Human DPSCs were cultured under normoxia (20% O2) and hypoxia (3% O2). DPSC proliferation and osteo/odontogenic differentiation potential were assessed by Cell Counting Kit-8 (CCK8) assay, carboxyfluorescein succinimidyl ester (CFSE) assay, alkaline phosphatase (ALP) activity, Alizarin red staining, real-time RT-PCR assays, and western blot analysis. Microarray and bioinformatic analyses were performed to investigate the differences in the mRNA, lncRNA, and miRNA expression profiles of DPSCs.
Results: DPSCs exhibited a more powerful proliferation ability and lower osteo/odontogenic differentiation potential in hypoxic conditions. A total of 60 mRNAs (25 upregulated and 35 downregulated), 47 lncRNAs (20 upregulated and 27 downregulated), and 14 miRNAs (7 upregulated and 7 downregulated) in DPSCs were differentially expressed in the hypoxia group compared with the normoxia group. Bioinformatic analysis identified that 7 mRNAs (GRPR, ERO1L, ANPEP, EPHX1, PGD, ANGPT1, and NQO1) and 5 lncRNAs (AF085958, AX750575, uc002czn.2, RP3-413H6.2, and six-twelve leukemia (STL)) may be associated with DPSCs during hypoxia according to CNC network analysis, while 28 mRNAs (including GYS1, PRKACB, and NQO1) and 13 miRNAs (including hsa-miR-3916 and hsa-miR-192-5p) may be involved according to miRNA target gene network analysis. The depletion of one candidate lncRNA, STL, inhibited the osteo/odontogenic differentiation potentials of DPSCs.
Conclusions: Our results revealed that hypoxia could enhance the proliferation ability and impair the osteo/odontogenic differentiation potential of DPSCs in vitro. Furthermore, our results identified candidate coding and noncoding RNAs that could be potential targets for improving DPSC function in regenerative endodontics and lead to a better understanding of the mechanisms of hypoxia's effects on DPSCs.
Keywords: Coding RNA; Dental pulp stem cells (DPSCs); Hypoxia; Long noncoding RNA (lncRNA); MicroRNA (miRNA).