Cells have been experiencing osmotic shock lately. Cells that are cultured in low surface area culture plates (60 mm or 6-well) and among them, cells that are present in center area or isolated shows bubbles formation that seem to be attached to the cells initially and later are seen floating in the media. This change occurs right after changing their media (after washing them with PBS). However cells that are present in 90mm with high density do not show any such changes upon media change by using the same media or PBS.

I presume the changes are due to some osmotic shock, however I have tried preparing new media and used commercial saline solution as well, still the same problem persists in low surface area culture plates.

Your help or suggestion are appreciated!