gms | German Medical Science

To evaluate the therapeutic potential of striatal injection of tricistronic lentiviral vector (equine infectious anemia virus, EIAV) encoding for the three major enzymes of the dopamine (DA) biosynthetic pathway [tyrosine hydroxylase (TH), aromatic L-amino acid decarboxylase (AADC) and the GTP cyclohydrolase 1 (CH1) ] as a DA replacement therapy in Parkinson’s disease (PD).

Six macaques (M. fascicularis) received daily injections of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) i.m. until they reached a severe and stable parkinsonian syndrome. Parkinsonian animals were stereotactically injected bilaterally into the sensorimotor part of the putamen with either EIAV encoding β-galactosidase (EIAV-βGal, n=3, control group) or TH-AADC-CH1 (EIAV-TRIC, n=3), using MRI guidance. By the end of the experiment, putaminal samples were processed and analysed for dopamine content by HPLC separation and electrochemical detection.

EIAV-TRIC animals displayed a significant functional recovery as compared to EIAV-TRIC animals (p<0.05), on both clinical rating scales and objective video-movement analysis study (Ethovision^®). Whereas the two groups displayed an equivalent dramatic decrease of the number of nigral dopaminergic neurons, the EIAV-TRIC animals showed significant recovery in a number of dopaminergic indices in the transduced putamen including increases in TH, AADC and DA immunoreactivity. Elevated putaminal DA levels were observed in animals injected with EIAV-TRIC compared with EIAV-TRIC (p<0.05).

Striatal delivery of multicistronic EIAV lentiviral vector encoding for AADC, TH, and CH1, resulted in transduction of striatal neurons, robust expression of transgenes and significant reversal of parkinsonian symptoms in MPTP macaques, thus opening a potential use in gene therapy for PD.