Cell freezing:
Sterility, mycoplasma and endotoxin tests were performed on the cell
supernatant. 1ml of washing solution (PBS / 5% FBS) was added to
1×107 cells. The cells were then placed on ice for 10
min and then they were added to the freezing solution (20% DMSO, 40%
HSA, 40% PBS) and placed in liquid nitrogen.