Insect cell sticking to glassware in suspension culture

[imm]

Hi
I have been growing and expressing proteins in insect cells for aprox 4 years. When I grow my cells in shaker cultures, I get a 'sludge' ring of cells that stick to the glass flask, just slightly higher than the media level.
After a few hours of placing cells in a new flask, I can see the start of this cell loss. As these cells are not in contact with the media they die.
From this I have 2 problems
1. Cell viabilty drops
2. A lot of the cells I seed into the flask end up on the glassware, so my cell number is much lower than it should be. (as a result I am getting very low expression of my protein since not enough cells in culture).
This problem seems to have gotten worse and I have afeeling it is related to the way I am growing the cells (no mycoplasma and have this problem with Sf21 and High 5 cells).

Anyone know what might be happening ??
Thanks in advance

[biostudent84]

Did you try manually stirring the solution every 15 minutes or so?

[imm]

Thanks for reply but I leave these cells culturing 24-7 so would be impossible to manually stir at this interval

[biostudent84]

That's the only thing I can think of...perhaps if you and two other people take "shifts" to stir? I'm afraid that the motions of any automated shaker/stirrer would also give you this problem.

LOL, sometimes, in the interests of carrying out a scientific expirement requires a little sleep deprivation...

[DevGrp]

How about siliconizing the glass with something like Sigmacote (Sigma)?

It might help.

Ian

[imm]

Thank you both for your help, will try the Sigmacote