X-Message-Number: 14786
From: "Jan Coetzee" <>
Subject: Gene Therapy 
Date: Thu, 26 Oct 2000 17:37:38 -0400

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Gene Therapy May Help in Parkinson's, Study Finds 

By Maggie Fox, Health and Science Correspondent 


WASHINGTON (Reuters) - A gene therapy treatment using a gutted version of the 
AIDS virus and a protein that nourishes brain cells may help prevent the onset 
of Parkinson's in patients with early symptoms of the disease, researchers said 
on Thursday. 


Tests done in monkeys suggest that it may be possible to save the brain cells 
lost in Parkinson's, the international team of researchers reports in Friday's 
issue of the journal Science. 


``We were able to completely reverse motor deficits in these animals and also 
completely prevent the destruction of the substantia nigra (the part of the 
brain damaged in Parkinson's),'' Jeffrey Kordower, a neurologist at Rush 
Presbyterian-St. Luke's Medical Centre in Chicago who led the study, said in a 
telephone interview. 


Parkinson's, which affects an estimated 500,000 people in the United States 
alone, is a progressive and incurable disease that involves the destruction of 
brain cells that produce dopamine, an important message-carrying chemical linked
with movement. 


Patients start out with tremors or a strange sort of freezing, and can become 
paralyzed and die. There is no cure and treatments can delay the disease for a 
while but eventually stop working. 


Kordower's team. including scientists at the Swiss Federal Institute of 
Technology in Lausanne, Switzerland and in France, wanted to see if there was 
some way to stop this. 


They used two monkey ``models'' of Parkinson's -- old monkeys whose brains have 
started to degenerate, and monkeys with a Parkinson's-like disease caused by 
chemically damaging the brain. 


``Aged monkeys lose dopamine,'' Kordower said. ``That models the earliest 
cellular changes in patients with Parkinson's.'' 


Monkeys with the damaged brains show symptoms of later Parkinson's. They are 
taught to do tasks -- such as getting fruit out of a box -- that can easily be 
measured so scientists can monitor the changes caused by the damage. 


The researchers gutted the HIV virus to make it harmless. HIV attaches to cells 
and pumps its genetic material inside, so it is a good vector, or carrier, of 
gene therapy. 


Inside the hollowed-out virus they put the gene for glial-derived neurotrophic 
factor (GDNF), a protein shown in previous studies to affect the 
dopamine-producing neurons. 


Then they injected this combination, or a virus carrying a dummy gene, into the 
brains of their monkeys. 

Brain Cells Work Better After Injections 


In both cases, the gene therapy made the dopamine-producing cells work better. 
It lasted for months, and the effects could be clearly seen in the tasks done by
the second group of monkeys, Kordower said. 


``We anticipate that we can get long-term benefit from a single treatment,'' 
said Kordower, who presented his findings to a meeting at the National 
Institutes of Health this week. 

It may even work too well and need to be toned down. 


``This is the most potent gene therapy delivery system seen in Parkinson's,'' 
Kordower said. ``In fact, it is so potent our main concern is it could be too 
potent. What we need to do before we can go into humans is to have a gene that 
we could control.'' 


Kordower hopes to do this by using a common method -- engineering the gene so 
that it can be turned on and off with the use of the antibiotic tetracycline. 


``So if we put it into the brain of a patient and things go bad, there is too 
much dopamine, we can shut it off,'' he said. 


Kordower does not think the method will work for patients with advanced 
Parkinson's, because they have already lost too many brain cells. Experimental 
treatments for such patients include injections of brain cells from human and 
pig embryos. 


Foster City, California-based Cell Genesys Inc. owns the patent for the virus 
vector used in the experiment and Amgen Inc. owns the patent for the GDNF, 
Kordower said. 


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