Quantification of VP22-GFP spread by direct fluorescence in 15 commonly used cell lines

Background The intercellular transport property of VP22 chimeric proteins o ffers the opportunity for the improvement of gene therapy delivery systems. Since enhanced therapeutic effects of transduced genes already have been e xemplified for chimeric proteins VP22-p53 and VP22-tk, we were interested i n examining whether spread of VP22 chimeric proteins is a general biologica l phenomenon not restricted to distinct tissues or species. Methods To study intercellular spread of VP22-GFP fusion proteins, 15 diffe rent mammalian cell lines were transfected with 200-2000 ng of VP22-GFP or GFP expression plasmids. Expression of VP22-GFP or GFP was monitored by flu orescence microscopy of live GFP fluorescence and direct FAGS analysis. For selected cell lines, antibody detection of VP22-GFP spread was analysed by confocal microscopy as a control. Results Spread of VP22-GFP fusion proteins was detected in all 15 cell line s tested, and quantified by FAGS analysis. Experimental conditions were fou nd to be critical in the investigation of VP22-mediated intercellular sprea d. Conclusion Results of our study indicate that spread of VP22 chimeric prote ins is a general biological phenomenon not restricted to distinct tissues o r species. Therefore, further evidence is provided that VP22-enhanced gene therapeutic effects may be obtained irrespective of the target organ/tissue to be addressed. Copyright (C) 1999 John Wiley & Sons, Ltd.