A human prepro GDNF expression plasmid DNA under the influence of the 8 kb rat TH promoter was engineered [1059], and encapsulated in OX26 TfRMAb-THLs and injected into PD rats at 1, 2, and 3 weeks after toxin administration at a dose of 10 μg DNA/rat per injection [1064]. Here, GDNF is linked to Parkinson disease.