Survival effects of pigment epithelium-derived factor expressed by a lentiviral vector in rat cerebellar granule cells

We have previously shown that pigment epithelium-derived factor (PEDF) acts as a survival factor for cerebellar granule cells (CGCs), by blocking apop totic death, and can also protect these cells against glutamate-induced neu rotoxicity. In preparation for gene therapy studies, pseudotyped HIV-1-base d lentiviral vectors containing the PEN gene, as well as either green fluor escent protein or beta -galactosidase, were prepared. These bicistronic vec tors are unique in that they express two genes efficiently under one promot er. Primary cell cultures of CGCs from postnatal day 8 rats were infected w ith the vectors encoding PEDF. RT-PCR demonstrated expression of mRNA and W estern blot analysis confirmed that infected CGCs secrete PEN protein to th e medium. Assays for cell survival demonstrated that PEDF-infected cells we re significantly more protected compared with mock-infected controls for 6- 8 days in culture, as well as against induced apoptosis. The PEN vectors ex pressing tat (trans-acting transcription factor) provided more protection t han the tat(-) vectors. These results demonstrate that while the lentiviral vectors expressing PEN are as neuroprotective as the protein itself for CG Cs, the vectors have the advantage of providing long-lasting expression of PEDF protein, which will be more effective in in vivo studies. The present results suggest that this system may be useful for gene therapy for neurode generative disorders. Copyright (C) 2001 S. Karger AG, Basel.