Cell transplants offer stroke victims hope

By SIMON COLLINS science reporter

A New Zealand technique developed to transplant pig cells into diabetics is offering unexpected hope to people who suffer strokes and other brain disorders.

The former New Zealand company that developed the technique, Diatranz, says transplanting brain cells into stroke-injured rats reduces their brain damage by up to 40 per cent.

The company's founder, veteran diabetes researcher Bob Elliott, says that if the same technique works for humans, it will be "the biggest step forward in stroke treatment ever".

"We are looking at a product which will challenge and perhaps usurp many of the chronic medical treatments that are around based on pills or injections," he said.

"This is a better way of delivering what the body needs."

The technique involves inserting cells under the skin of a patient in a tiny capsule, made of material taken from algae, with openings that are just big enough to let small molecules in and out of the transplanted cells - but too small to let in the patient's big antibody molecules that would destroy the intruders.

In diabetics, the transplanted cells were insulin-producing cells. A trial in Mexico in 2001-02 allowed one diabetic teenage girl to stop injecting herself with insulin completely for 2 1/2 years.

The latest experiment involved bleeding newborn rats to death, then inserting some of their brain cells in a capsule under the skull of adult rats that had had one of their brain arteries cut for an hour to simulate a stroke.

The transplanted cells were taken from a part of the brain called the choroid plexus, which makes the fluids that bathe the brain and the spinal cord.

The transplanted cells appeared to stimulate the brain of the stroke-injured animal to produce new "stem cells" which helped to replace damaged brain cells.

"We are recharging the brain's own ability to repair itself," Dr Elliott said.

The research, done in Auckland by a team led by Dr Cesario Borlongan of the Medical College of Georgia in the US, found that rats that received the cell transplants did 40 per cent better than other stroke-injured rats on brain tests such as walking on a narrow plank of wood.

After they died it was found the brain area that had been killed by the stroke was 25 per cent less in the rats that received cell transplants than in the other stroke-injured rats.

Meanwhile, the company is testing insulin-producing pig cell transplants on diabetic monkeys in Singapore before seeking approval for further trials in human diabetics in Australia next year.

New Zealand's Health Ministry twice refused to give Diatranz permission to transplant pig cells into human diabetics.

Dunedin stroke expert Dr David Jackson said similar cell regeneration techniques were being used overseas to treat Parkinson's disease but it might take longer to apply it to strokes where the exact area of brain damage was often unknown.

Pros and cons

* Cell transplants may be an alternative to drugs for conditions such as diabetes and brain damage.

* Their main advantage is that they stimulate the body's own defences. For example, brain cell transplants may stimulate replacement of damaged brain cells.

* The Health Ministry refused permission for transplants of insulin-producing pig cells into human diabetics because of the risk that they might spread animal viruses into the human population.

* Transplants may also fail if doctors do not know the exact area where a stroke or other brain injury has happened.