Method for expanding mesenchymal stem cells in low-density and hypoxic culture

The present invention relates to a novel method for expanding mesenchymal stem cells (MSCs) in low-density and hypoxic condition as compared to normal air conditions traditionally used in cell culture. The present method provides rapid and efficient expansion of human MSCs without losing cellular proliferation and stem cell properties, including increase in proliferation, decrease in senescence, and increase in differentiation potential both in vitro and in vivo. The expanded MSCs by the present method may maintain normal karyotyping, and will not form tumor when transplanted into mammal.