Midazolam suppresses osteogenic differentiation of human bone marrow-derived mesenchymal stem cells

OBJECTIVE: Previous study showed that peripheral-type benzodiazepine receptors (PBRs) are expressed in human mesenchymal stem cells (hMSCs) and diazepam was found to inhibit hMCSs viability in high concentration. Midazolam, a benzodiazepine derivative, is widely used as an intravenous sedative in hospital. Peripheral-type benzodiazepine receptors (PBRs) affect a broad spectrum of cellular functions. We tested the cell viability and osteogenic differentiation of hMSCs. PATIENTS AND METHODS: Bone marrow was collected from 12 patients during the operation of spine internal fixation. Cultivated with basal medium, the hBMSCs were incubated with or without midazolam (0.1, 1, 5, 10, 15, 20 M, respectively). Cell viability were tested with MTS assay after 2, 4, 6 hours respectively. Cell morphology was observed and recorded at 6 hour. After cultivated with osteogentic medium, the hBMSCs were incubated with or without midazolam (5, 10, 15, 20 M, respectively). Alkaline phosphatase (ALP) activity and alizarin red S staining were measured. Cultivated with osteogentic medium with or without treatment of 15 M midazolam, the mRNA expression of ALP, type 1 collagen (COL1), Runx2 and PPAR gamma was analyzed by real-time RT-PCR. RESULTS: The treatments of midazolam inhibited cell viability to 85%-16% respectively (p < 0.05). Rounded up phenomenon with floating cells, Membrane-blebbed cells and cytoplasmic contraction were observed after 10, 15 or 20 M midazolam treatment. The ALP activity and Calcium deposition of hBMSCs exposed to 15 and 20 M midazolam was significantly inhibited at 7, 14 and 21 days (p < 0.05). And the mRNA expression of ALP, COL1 and PPAR. was significantly suppressed in the hBMSCs cultured with 15 M midazolam (p < 0.05). CONCLUSIONS: Midazolam exert negative effect on cell viability and osteogenic differentiation of cultured hBMSCs. During sedation in critical care, the use of midazolam may suppress activity of hBMSCs.