Cell death with DMSO treatment, during transfection using polybrene - (Sep/07/2007 )

I'm trying transfection of BHK -21 with a large size plasmid, 13kb uing polybrene. I'M using Sambrook protocol., but after treatment with 30% DMSO, (as mentioned in protocol),serious cell death is observed. Can anyone help me regarding protocol for transfection using polybrene?

Dont waste time using this old and less efficient method.