Figure 7.

In vitro transfection of HEK 293 cells or primary cultures of ventral midbrain cells using pGDNF. (a) HEK 293 cells were cultured and transfected with 1.0 µg/well pGDNF using Lipofectamine. Some of the transfected cells were treated with lysis buffer in order to release intracellular GDNF into the culture media; control cells were not transfected but received Lipofectamine. Media was collected at DIV 7 and GDNF content was measured in the culture media using enzyme-linked immunosorbent assay (ELISA). ^*P < 0.05, pGDNF or pGDNF + lysis buffer versus control; ^P < 0.05, pGDNF or pGDNF + lysis buffer versus control + lysis buffer; ^#P < 0.05, pGDNF + lysis buffer versus pGDNF. (b) Transfection of rat ventral midbrain cells and dopaminergic differentiation mediated by compacted pGDNF. Cells were plated at a density of 3.75 × 10⁵ cells per well. One microgram of compacted pZeoGFP5.1 or compacted pGDNF plus Lipofectamine were added per well; control did not receive any plasmid treatment. Media was collected at DIV 7 and GDNF content was measured in the culture media using ELISA. Each bar represents the average number of TH⁺ cells (+SEM) counted per cell well (n = 8 for each treatment). Statistical analysis revealed significantly higher number of TH⁺ cells in cultures treated with compacted pGDNF when compared to control cultures or cultures treated with pGeoGFP5.1 [F (2,20) = 99.74, P < 0.001]. ^*P < 0.001, compacted pGDNF versus pZeoGFP5.1; ^P < 0.001, compacted pGDNF versus control. GDNF, glial cell line–derived neurotrophic factor.