Gene Injection Effective for Parkinson's in Rats

The injection of two corrective genes into a specific brain region generated significant restoration of normal limb movement in rats with a chemically induced form of Parkinson's disease, according to a study published in the March 26, 2002, online version of the Proceedings of the National Academy of Sciences

After more than four years of study involving nearly 200 rats, a team of researchers from the University of Florida (Gainesville, USA; www.ufl.edu) and Lund University (Sweden) found that a single injection of two different genes, each packaged separately, along with a gene promoter and vector helped the rats to regain motor function. Both genes code for enzymes essential to triggering production of L-dopa, while the vector used was the adeno-associated virus (AAV). Based on prior discoveries by Dr. Anders Bjorklund of Lund University, the researchers injected these genes into the striatal region of the forebrain, the destination point of dopamine-producing cells.

"We found that the simultaneous delivery of two selected genes, coupled with a powerful gene-activating agent, works like a pump to prime the production of L-dopa, which is then converted into dopamine by appropriate nerve cells in the brain,” said Dr. Ronald Mandel, one of the researchers from the University of Florida.

Limb impairments were completely reversed in rats that had near-total Parkinsonian lesions on only one side of the brain, meaning that some of their dopamine-producing cells remained intact. These partial lesions mimic the kind of damage (progressive death of L-dopa-producing cells) found in people with the disease. Furthermore, even in rats with complete destruction of dopamine-producing cells, the delivery of gene therapy resulted in a limited amount of restored motor function.

The researchers said the strategy that proved effective in the rodents is not a cure for Parkinson's disease but is expected to lead to a better method for delaying and controlling symptoms. Dr. Mandel noted that there is no reason why gene therapy could not also be given in addition to medication and surgical procedures such as pallidotomy, or deep-brain stimulation.




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