Hypoxic preconditioning of human mesenchymal stem cells overcomes hypoxia-induced inhibition of osteogenic differentiation

In this study the osteogenic differentiation potential of hMSCs under hypoxic conditions of 2 % O2 in comparison to standard tissue culture oxygen atmosphere of 21 % was investigated. Further tests were conducted to determine whether hypoxic preconditioning has an effect on the following osteogenic differentiation of hMSCs and if this pretreatment might be beneficial for the differentiation process. It was found that hMSCs proliferate better when cultured at 2 % O2 but constant hypoxia inhibits osteogenic differentiation. Hypoxic preconditioning of hMSCs prior to osteogenic induction restores osteogenic differentiation of the cells under hypoxic conditions. Hypoxia might be directly connected to the osteogenic differentiation of bone precursor cells as the reduced oxygen supply after bone fracture triggers the healing process. The 21 % oxygen atmosphere commonly used in cell culture is rather considered a state of hyperoxia and low oxygen tensions seem to be a more physiological milieu for stem cells. Cells used for tissue engineering seeded on a 3D scaffold often are subjected to hypoxi