Adeno-associated virus-mediated gene transfer of human aromatic L-amino acid decarboxylase protects mixed striatal primary cultures from L-DOPA toxicity.
Although L-DOPA is the drug of choice for Parkinson's disease, prolonged L-DOPA therapy results in decreased drug effectiveness and the appearance of motor complications. This may be due in part to the progressive loss of the enzyme, aromatic L-amino acid decarboxylase (AADC). We have developed an adeno-associated virus vector (AAV-hAADC) that contains human AADC cDNA under the control of the cytomegalovirus promoter. Infusion of this vector into the striatum of parkinsonian rats and monkeys improves L-DOPA responsiveness by improving AADC-mediated conversion of L-DOPA to dopamine. This is now the basis of a proposed therapy for advanced Parkinson's disease. A key concern has been that over-production of dopamine in striatal neurons could cause dopamine toxicity. To investigate this possibility in a controlled system, mixed striatal primary rat neuronal cultures were prepared. Exposure of cultures to high concentrations of L-DOPA induced the following changes: cell death in nigral and striatal neurons, aggregation of neurofilaments and focal axonal swellings, abnormal expression of DARPP-32, and activation of astroglia and microglial cells. Transduction of cultures with AAV-hAADC resulted in efficient and sustained neuronal expression of the AADC protein and prevented all the L-DOPA-induced toxicities. The protective effects were due primarily to AADC-dependent conversion of L-DOPA to dopamine and an increase in induction of vesicular monoamine transporter resulting in dopamine storage in cultured cells. These results suggest a neuroprotective role for AADC gene transfer against L-DOPA toxicity.
Doroudchi
Mohammad M
MM
Avigen Inc., Alameda, California 94502, USA. mdoroudchi@avigen.com
Liauw
Jason
J
Heaton
Krista
K
Zhen
Zhu
Z
Forsayeth
John R
JR
D000818:Animals; D001142:Aromatic-L-Amino-Acid Decarboxylases / Q000008:administration & dosage / Q000235:genetics*; D002460:Cell Line; D002478:Cells, Cultured; D003342:Corpus Striatum / Q000187:drug effects / Q000201:enzymology*; D019610:Cytoprotection / Q000187:drug effects / Q000502:physiology; D000229:Dependovirus / Q000235:genetics*; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D006801:Humans; D007980:Levodopa / Q000633:toxicity*; D051381:Rats; D017207:Rats, Sprague-Dawley
D007980:Levodopa; D001142:Aromatic-L-Amino-Acid Decarboxylases