Effects of prostaglandin E2 on clonogenicity, proliferation and expression of pluripotent markers in human periodontal ligament cells

- Prostaglandin (PG) E2 at low doses enhances formation of periodontal ligament (PDL) clones and proliferation of PDL cells.
- However, PGE2 at a high dose significantly decreases proliferation of PDL cells.
- PGE2 at low doses induces expression of pluripotency-related markers, including NANOG and OCT4.
- PGE2 at low doses increases expression of stage-specific embryonic antigen 4.

Background and objectiveBased on our earlier work on the response of periodontal ligament (PDL) cells to mechanical stress by induction of cyclooxygenase expression and production of prostaglandin PGE2 that could regulate mineralization of PDL cells, it was hypothesized that PGE2 had potential effects on PDL stemness. In this study, we aimed to investigate clonogenicity, proliferation and expression of certain pluripotent markers, considered to be characteristics of PDL stemness, in response to treatment with exogenously-added PGE2.Material and methodsHuman PDL cells were cultured and treated with various doses of PGE2, and the aforementioned characteristics of PDL stemness were analyzed.ResultsThe clonogenicity and proliferation were significantly enhanced by PGE2 at low concentrations (0.01, 0.1 and 1 ng/ml; P < 0.05), but only the proliferation was significantly diminished by PGE2 at a high concentration (100 ng/ml; P < 0.05). Expression of NANOG and OCT4 mRNA and protein was increased by PGE2 treatment at 0.1 and 1 ng/ml. Consistently, expression of stage-specific embryonic antigen 4, a putative stem cell marker, was significantly augmented by PGE2 treatment at 1 ng/ml (P < 0.05).ConclusionOur findings suggest that although a high dose of PGE2 (100 ng/ml) inhibits proliferation of PDL cells, PGE2 at low doses appears to play a role in the maintenance of PDL stemness.