Estrogen Modulates Periodontal Ligament Stem Cells Osteogenesis Differentiation via ERs

Objective: The aim of our research is to investigate the estrogen receptors expression on human periodontal ligament steam cells(HPLSC) and the effects of estrogen on the osteogenesis differentiation of HPLSC. Methods: human periodontal ligament cells were collected from the extracted premolars of adolescents for the orthodontic reason. HPLSC were sorted and approved by the immunomagnetic beads conjunct with STRO-1 antibody and were cultured with osteogenesis inducement medium. Estrogen receptors (ERs) were detected by immunohistochemistry, the mRNA and protein products of ERs were also detected by using the reverse transcriptase polymerase chain reaction (RT-PCR) and Western-blot procedure. 17b-estradiol (E2) on different dosages was added into the treated groups to evaluate the effects of estrogen on proliferation and differentiation of HPLSC by MTT and alkaline phosphatase (ALP) assay. Results: HPLSC expressed mRNA and protein of ERs both subunit ER-a and ER-b on the nuclear of the HPLSC. The expression of ER-a was higher than ER-b. Comparing to the group of control, the DNA synthesis of HPLSC depressed in the first three days, and increased apparently in day 8 While treated with 17b-estradiol (10-7 mol). The ALP activity of HPLSC exhibited positive modulation while treated with 17b-estradiol. All positive effects of estrogen on proliferation and differentiation of HPLSC were inhibited by the blocker of ERs-ICI182780. Conclusion: Estrogen has an important role to modulate osteogenesis differentiation of HPLSC via ERs both ER-a and ER-b regulation mechanism.