I am currently working with different mast cell lines, two of them do not want to show viability higher than 75-80 %

HMC-1.1 I cultivate with IMDM (without L-glu)+ 10% FBS+ 1% p/s+ 1.2 mM thioglycerol. Never spin them. Everything according to an official protocol.

MCPV-1.1 I cultivate with IMDM (without L-glu)+ 10% FBS+ 1% p/s+ 10% SCF-containing medium. Spinning or not before splitting does not change anything.

Does anybody have an experience with these cell lines and maybe have any recommendations?

Thank you very much in advance