``This is really a historic turning point in transplantation therapy,'' Trojanowski said. ``This is the first human neuronal cell line that has been transplanted into a human brain.''
``But by no means do I say we are ready to treat every stroke patient,'' he said. ``There is some serious heavy lifting yet to do. It would be disingenuous to imply anything else.''
The transplant was done June 23 at the University of Pittsburgh Medical Center on Alma Cerasini, a former health-care worker, who is paralyzed in her right arm and leg and has lost most of her ability to speak. In a teleconference yesterday, doctors said they planned to do the same procedure on 11 other patients.
The scientific trial seeks only to establish whether the procedure, which involves inserting a probe into patients' brains and injecting the cells, is safe. If that is established, scientists will go on to test the procedure in larger groups of people to determine whether it works, and can make patients better.
Ideally, doctors hope the implanted cells will take over the functioning of brain cells that have been damaged by disease or injury. Research by Paul Sanberg, a University of South Florida neuroscientist, has shown that this happens in rats.
``Perhaps there will be increased metabolism and activity in the area of the stroke,'' said Lawrence Wechsler, director of Pitt's Stroke Institute. His team injected about two million of the artificial brain cells into the area of Cerasini's brain that had been damaged.
``This may take months,'' he said. ``In animal models, it took a couple of months. Over many months, we may hopefully see improvements. Right now, we are going to closely examine whether the patient is safe.''
While scientists have some medicines to treat brain disorders such as stroke, Parkinson's disease and Alzheimer's, they still aren't able to treat the underlying problem of all these diseases, which is the loss or malfunction of brain cells, and the breakdown of vital connections between them.
The loss of brain cells is normally irreversible. So scientists have been studying ways to implant cells into human brains. They have been working on using fetal brain cells - which retain the capacity to survive in adult brains - but the research has been mired by ethical and logistical hurdles.
Antiabortion activists have argued that scientists should not use fetal cells - taken from abortion clinics - for their work. And scientists have been confronted with the problem that tissue from several fetuses are required for each transfusion of cells, a huge problem considering there are millions of potential candidates for these treatments.
The cells for the current procedure were developed at Penn in the 1980s from a patient who had a rare and primitive tumor, said Douglas Kondziolka, professor of neurological surgery at Pitt's School of Medicine. The tumor contained cells that were immature, which meant they had the ability to become cells in different parts of the body. The Penn scientists guided these cells to become neurons.
``Some of them looked and acted and behaved like human neurons,'' Kondziolka said. In animal experiments, ``they hooked up with existing neurons in the brain and formed synapses. A synapse is the way neurons hook up and communicate.''
One of the concerns that scientists had was that the cells would revert to become tumor cells. The Penn researchers worked hard to make sure that this did not happen, and that the cell lines they were growing were not contaminated by bacteria, viruses or other invaders that could be deadly.
The cell line is being marketed by Layton BioScience, Inc., in Atherton, Calif., which bought the cell line from Penn.
``The cells have been placed into many different parts of the brain'' in animal experiments, Kondziolka said. ``They seem to take on the job of the brain location. They can take on the appearance of neurons in those locations and to release proteins that are specific to those areas.''
If the procedure works the same way in humans, it could be especially useful for patients with Parkinson's disease who have lost brain cells that produce the chemical messenger, dopamine.
But for now, the research will focus on strokes, since the physical disabilities or deficits are obvious and the damage to the brain is usually focused in a single area. About 700,000 Americans suffer strokes each year.
``This treatment offers the hope that we may at some point be able to help these patients with fixed deficits months or even years after the stroke has occurred,'' Wechsler said.