Dear Mamatha, I've read a couple of papers with MRC-5 cells and in some of them this cell line is cultured in DMEM and in others in RPMI so I don't think they get affected by the change of medium. I leave you attached a couple of papers where MRC-5 were cultured in RPMI.
Dear Mamatha, I'm culturing MRC-5 using RPMI , 15% FBS and it's doubling time is 56-72 hours . respectively notice that the cell count per cm2 should be sufficient.