Dear Mostafa,

Here below, you can find some links to previous questions in this issue:

https://www.researchgate.net/post/Cholesterol_stock_solution_for_cell_culture

https://www.researchgate.net/post/Can_anyone_suggest_how_to_make_cholesterol_to_soluble_in_water

https://www.researchgate.net/post/How_can_I_prepare_stock_solution_of_cholesterol

Best of luck ~