NGF gene expression in dividing and non-dividing cells from AAV-derived constructs.

NGF expression in COS cells when driven by pTR.NGF (CMV promoter, AAV TRs) was more effective than either pc.NGF (CMV promoter, no AAV TRs) or dlk.NGF (AAV promoters and TRs). This NGF was able to differentiate PC12 cells. Differentiated PC12 cells transfected with pTR.NGF released NGF into medium. The fraction of pTR.NGF transfected PC12 cells that extended neurite-like processes 7 days post-transfection was similar to the transfection efficiency, suggesting that transfected cells were selectively differentiated by locally released NGF. pTR.NGF-transfected primary cultures of either neurons or glia did not express exogenous NGF. These results indicate that NGF can be released by dividing and non-dividing cells, but not neonatally derived brain cells.