Effect of estrogen deficiency on the proliferation and osteogenic differentiation potential of mandibular bone marrow stromal cells

Abstract

To determine the effects of estrogen deficiency on the proliferation and osteogenic differentiation of mandibular bone marrow stromal cells (mBMSC). Ten 8-week-old female SD rats were randomly divided into two groups, ovariectomized group (OVX, n = 5) and sham-operation group (n = 5). All rats were anesthetized and both ovaries of OVX-rats were gently removed. Sham-operation rats were treated with the same incisions to expose the ovaries but without any hurt to them. One month after the operation, the mandibular bones were gently separated and mBMSC were isolated. Methyl thiazolyl tetrazolium (MTT) assay, alkaline phosphotase (ALP) activity, alizarin red staining, real-time reverse transcription (RT)-PCR and Western blotting were respectively used to examine the proliferative activity and osteogenic potential of mBMSC. MTT results showed that OVX-mBMSC exhibited the decreased proliferative activity as compared with Sham-mBMSC. ALP activity of OVX-mBMSC [(0.710±0.011) Sigma unit/protein] was lower than that of Sham-mBMSC [(1.512±0.021) Sigma unit/protein] (P < 0.01). Alizarin red staining showed that OVX-mBMSC formed less calcified nodules than Sham-mBMSC. Ca(2+) concentration analysis showed Ca(2+) of OVX-mBMSC [(0.433±0.045) µg/g] was less than Sham-mBMSC [(1.453±0.131) µg/g] (P < 0.01). Real-time RT-PCR and Western blotting results showed that the expression of osteogenic markers (Alp, Runx2/RUNX2, Osx/OSX, Ocn/OCN) in OVX-mBMSC was significantly inhibited as compared with Sham-mBMSC (P < 0.05). Estrogen deficiency significantly inhibits the proliferation and osteogenic capacity of mBMSC.