To detect the expression level of miR-27a during the osteogenic differentiation of beagle maxillary sinus membrane stem cells (MSMSCs) and explore the role of miR- 27a in the osteogenic differentiation of MSMSCs.

Beagle MSMSCs were cultured in vitro. The expression level of miR-27a was detected via RT-PCR after an osteogenic inductive culture was prepared. The mRNA expression levels of Runx2 and OPN were examined via RT-PCR, and the protein expression levels of Runx2 and OPN were examined via Western blot after the cells were transfected with pre-miR-27a or anti-miR-27a. Finally, osteoprogenitor cells transfected with pre-miR-27a were composited with Bio-Oss particles and subcutaneously implanted into nude mice to form ectopic bone formation models, and then the inhibition of bone formation from miR-27a was observed in vivo.

The expression level of miR- 27a in the beagle MSMSCs decreased after osteogenic inductive culturing. The relative miR-27a levels were significantly decreased at day 1 (t＝3.795, P＝0.023), day 3 (t＝4.493, P＝0.011), day 7 (t＝11.591, P < 0.001), day 14 (t＝ 12.542, P < 0.001), and day 21 (t＝5.621, P＝0.008) compared with day 0. In addition, the expression levels of Runx2 mRNA (t＝4.923, P＝0.007) and protein (t＝4.425, P＝0.008) were reduced after the cells were transfected with premiR-27a. The expression levels OPN mRNA (t＝5.253, P＝0.006) and protein (t＝5.132, P＝0.006) were also reduced. In contrast, the mRNA expression levels of Runx2 (t＝3.925, P＝0.013) and OPN (t＝3.712, P＝0.019) were increased after the cells were transfected with anti-miR-27a, and bone formation was observed after the subcutaneous implantation of beagle MSMSCs composited with Bio-Oss in nude mice. Nevertheless, ectopic bone formation was inhibited by pre-miR-27a-transfected beagle MSMSCs composited with Bio-Oss (t＝7.219, P＝0.0020).

MiR- 27a negatively regulates the osteogenic differentiation of MSMSCs.