ABSTRACT
BACKGROUND: Human olfactory mucosa mesenchymal stem cells (hOM-MSCs) not only have the basic characteristics of mesenchymal stem cells, but also originate from the ectoderm and are prone to differentiate into neurons, which are a kind of ideal seed cells for nerve repair and regeneration. Cells are conventionally cultured in about 21% in vitro, while only 3%-9% oxygen is found in the human body and tissue space. There is still no report on the effect of hypoxia on the proliferation and activity of hOM-MSCs.OBJECTIVE: To explore whether hypoxic microenvironment can promote hOM-MSCs proliferation and activity and the related mechanism. METHODS: hOM-MSCs were isolated, cultured and identified by flow cytometry and immunofluorescence. The passage 4 hOM-MSCs were divided into three groups: 21% O2 group, 3% O2 group and 3% O2+20 μmol/L YC-1 (HIF-1α inhibitors) group. Proliferation and apoptosis of hOM-MSCs was detected by flow cytometry after 72 hours of culture. The proliferating cell nuclear antigen protein expression was detected by western blot. The mRNA and protein expression of HIF-1α and TWIST were detected by Q-PCR and western blot. RESULTS AND CONCLUSION: The purity of hOM-MSCs was up to 97%, as defined by flow cytometry. The proliferation index of 3% O2 group was higher than the 21% O2 group (P < 0.05), and cell survival and apoptosis ratio (apoptotic cells included mechanical death + early apoptosis + late apoptosis) between the two groups had no significant difference (P > 0.05). Western blot results showed that the proliferating cell nuclear antigen protein expression in the 3% O2 group was significantly higher than that in the other groups (P < 0.05). The HIF-1α and TWIST expressions at mRNA and protein levels in the 3% O2 group were significantly higher than those in the other groups (P < 0.05). To conclude, hypoxic microenvironment can promote the hOM-MSCs proliferation and has no effect on the apoptosis, and the HIF-TWIST signal pathway plays an important role in this progress.