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Transplanting genetically modified cells can reduce symptoms similar
to those of Parkinson’s disease. A group of doctors in California has used
the cells in rats, and says the animals have shown a marked improvement
in their behaviour and movements. The researchers believe that cells genetically
manipulated in this way have great potential for treating diseases of the
central nervous system such as Parkinson’s disease in humans.

In their experiments, Rein Anton at the University of California in
Los Angeles and his colleagues used brain cells of a type called nigral
cells which produce the neurotransmitter dopamine; most people with Parkinson’s
disease are deficient in this substance. The researchers inserted into the
cells a gene which allowed the cells to proliferate indefinitely at a temperature
below body temperature. In this state, the cells are said to be ‘conditionally
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Anton and his colleagues next inserted into the cells a gene for the
enzyme tyrosine hydroxylase, which is necessary for the production of dopamine.
This markedly boosted their dopamine production. Rats in which symptoms
of Parkinson’s disease had been experimentally induced were given transplants
of these brain cells.

The researchers found that the transplanted cells produced a 70 per
cent reduction in the rats’ symptoms. ‘The results we found are encouraging,’
said Anton, speaking at the annual meeting of the American Academy of Neurology
in San Diego.

When the genetically modified cells are implanted, they reach body temperature,
stop growing, and send out sprouts. But they still produce dopamine, says
Anton. The technique does not require the use of human fetal tissue, and
all the cells used are descended from a single brain cell. According to
Anton, the conditionally immortalised cells can be made available in unlimited
quantities, and can be genetically manipulated at below body temperature.
Yet they remain capable of performing their specialised role at body temperature.

Anton believes there is considerable potential to improve his cells
through further genetic engineering. ‘Further studies are necessary so we
can measure the animals’ reaction, record data, and study their brains,’
he says. ‘Perhaps this will lead to therapy in humans with Parkinson’s disease.’