One hundred milligram Dex powder (Solarbio, Beijing, China) was dissolved in 1 mL dimethyl sulfoxide, and mixed well, and 19.62 μL of Dex solution was aspirated and added to 10% v/v sodium pentobarbital (FBS) low sugar dulbecco's modified eagle's medium (DMEM) culture solution to fix the volume to 50 mL to obtain a concentration of 3.924 6 × 10−4 g/L of dexamethasone sodium phosphate preparation solution. Short‐term refrigerated storage at 4°C, long‐term frozen storage at −20°C.