MSCs derived from the bone marrow of C57BL/6 mice were purchased from Cyagen Biosciences, Inc. (Guangzhou, China).30 (link) The MSCs were cultured in 75 cm2 polystyrene tissue culture flasks (Corning, USA) at a density of 5 ×103 cells/cm2 in DMEM/F12 medium (Hyclone, USA) supplemented with 10% fetal bovine serum (FBS) (Gibco, USA). The MSCs were passaged at a ratio of 1:3 using trypsin/EDTA solution (Hyclone, USA). All cultures were incubated in a humidified incubator containing 5% CO2 at 37 °C.