I have previously done with adding 8ug/ml polybrene, but was unsuccessful. Next, will try spinoculation but need some expert advice as these cells are sensitive to any sort of stressor. Anyone please suggest me optimum 'G'-force/rpm for the spinoculation? For passaging we need to spin it at 200 g for 10 mins. I afraid that more the G -force or time on centrifugation will cause them to die.