Friday November 10 11:53 AM ET
LONDON (Reuters) - A local anesthetic, a small drill-hole in the skull and a syringe full of new cells may one day be all it takes to repair brain damage.
That, at least, is the hope of scientists pioneering a new kind of "brain repair kit" using implants of mass-produced cells to patch up damaged gray matter.
The daring approach offers hope to those incapacitated by stroke or degenerative diseases such as Alzheimer's or Parkinson's. However, experts say it will take years before it is proven to be safe and effective.
A growing number of companies are lining up to commercialize the technology, including Britain's ReNeuron -- a spin-off from the Institute of Psychiatry -- which planned to raise $22 million to $29 million with its initial public offering on London's Alternative Investment Market this week.
ReNeuron uses neural stem cells, grown in culture from aborted fetus tissue, to regenerate damaged parts of the brain. Stem cells are immature "master" cells that can be coaxed into forming virtually any type of tissue in the body.
It has proven the principle in rats and plans to start trials on humans in the second half of next year.
ReNeuron is not alone. At least five other companies are operating in the field with the most advanced work to date done in the United States.
The idea of transplanting cells into damaged brains is not altogether new.
For the last 10 years, doctors have been treating a handful of Parkinson's disease patients using cells transplanted from the brains of aborted fetuses. The technique, pioneered by scientists at Sweden's Lund University, has been shown to alleviate the worst symptoms of the disease.
But it takes an average of six fetuses to treat an adult brain, making the process practically -- and ethically -- problematic.
Biotechnology companies believe they have now found ways round this supply problem.
One option, being pursued by ReNeuron and several others, is to use genetic engineering to "immortalize" human cell lines, which can then be produced indefinitely in the laboratory.
Implanted Pig Cells
Another approach is to turn to animal tissue.
U.S. company Diacrin Inc., which is more advanced than its rivals in terms of clinical trials, harvests brain cells from the fetuses of pigs for implant into humans.
Its research suffered a setback earlier this year after two cases of complications in stroke patients. But product development is continuing and Diacrin is also investigating using porcine cells to treat spinal cord injury and to repair damaged heart muscle.
Nevertheless, many medics have reservations about animal-to-human transplants -- with some speculating they might spread as yet unknown viruses -- and other firms in the field are concentrating on human tissue.
They include the privately owned U.S. company Layton BioScience, which reported two months ago that it had successfully treated stroke patients using human cancer cells that had been "retrained" to become nerve cells.
Among others in the field are U.S. companies StemCells Inc. and unlisted NeuralStem Biopharmaceuticals Ltd., together with the private British firm CellFactors.
The two U.S. firms, like ReNeuron, are working with stem cells while CellFactors is studying the mass-production of specific brain cell types.
Doctors have recently been intrigued by growing evidence of the brain's ability to repair itself, as demonstrated, for example, by dramatic recoveries in some infant stroke victims.
Cell implants might eventually make that kind of a recovery routine for adults.
Great Deal To Prove
But Owen Redahan, director of Britain's Stroke Association, says there is still a great deal to prove.
"The principle is interesting but it's going to be extremely complicated to get the cells to take over functions that have been destroyed after a stroke," he said.
"I think it will take up to 10 years before we can say whether or not it is really possible."
Research so far suggests that cells -- whether human or porcine -- can be transplanted successfully to replace damaged ones. But the big question is whether the brain functions that died when the original brain cells died are replicated precisely, Redahan said.
Martin Edwards, chief executive of ReNeuron, admits it will be a long haul.
"I don't think a product like ours will be on the market for about eight
years because the clinical trials required are likely to be long and quite
difficult, although some of our competitors are far more bullish and talk
of something by 2004 or 2005," he said.