Fetal Tissue Eases Symptoms of Parkinson’s, Team Finds : Medicine: Swedish researchers report longer life of cells taken from fetuses. U.S. government, however, opposes efforts to use fetal cells therapeutically.
Swedish researchers say they have proved that fetal brain tissues implanted into the brain of a victim of Parkinson’s disease can be kept alive for prolonged periods of time and produce significant improvements in the patient’s condition.
Their results represent the “first verified” demonstration that fetal cell implants can successfully reduce the symptoms of Parkinson’s in humans, said neuroscientist John Sladek of the University of Rochester Medical Center.
Other researchers have previously reported that fetal tissue implants can ameliorate the symptoms of Parkinson’s, which affects more than 1 million Americans, most of them over the age of 50. Those symptoms include tremors and incapacitating rigidity of the limbs, as well as mental impairment.
But those researchers have not been able to show that the implanted cells survive and function, leaving their results open to a variety of interpretations.
New Technique
A team headed by neurologists Olle Lindvall and Anders Bjorklund of the University of Lund reports in today’s Science that fetal brain cells implanted using a newly developed technique carry out their metabolic function for at least eight months after the implant. Brain imaging techniques showed that survival of the cells was responsible for the patient’s improvement.
Because the Swedish team is highly respected, the new report seems likely to spur a rash of attempts to duplicate their findings.
But not in the United States, however, where the government has forbidden all federally supported attempts to use fetal tissues therapeutically. As a consequence, the procedure has been attempted only nine times in the United States--twice by neurologist Curt Freed of the University of Colorado Health Sciences Center in Denver and seven times by neurologist D. Eugene Redmond of the Yale University School of Medicine in New Haven, Conn. Both used private funds to carry out the procedures.
In contrast, the operation has been performed at least 35 times in the last 18 months in other countries, most notably Cuba, Spain and China.
“I think it (today’s paper) raises many new questions about the impact of the federal government’s moratorium” on fetal tissue research, Redmond said. The government’s “political stance is making people shy away from a very promising area of research,” Freed added.
Its symptoms are triggered by the death of brain cells that produce a hormone called dopamine, which helps transmit nerve impulses between the brain cells that control muscle activity.
Research with mice, rats and primates over the past two decades has shown that implantation of dopamine-secreting cells from a variety of sources can alleviate the symptoms of Parkinson’s.
Over the last three years, more than 300 patients around the world have had dopamine-secreting tissues from their own adrenal glands, walnut-sized organs that sit atop the kidney, implanted in their brains. The operation produces dramatic improvements in some patients, but overall the therapeutic benefits are modest and the incidence of illness and mortality has been high, primarily because of side effects from the surgical removal of the adrenal tissues.
The use of fetal tissues is considered much more promising, both because the operation to remove adrenal tissue is eliminated and because animal tests have shown that fetal cells are much more effective than adrenal cells. But to date, few results in humans have been reported, although Freed has a paper indicating that his first patient “shows continuing improvement one year after the operation.”
The Lund group has reported that they saw little benefit to the patient in two previous implant attempts. But they used a slightly different procedure with the new patient, a 49-year-old man who developed Parkinson’s in 1977 and was severely impaired before the surgery.
Most Parkinson’s patients go through several periods during the day in which symptoms are severe, interspersed with periods of lesser severity. These are called “off” and “on” periods, respectively. In the 11 months before his surgery, the Lund patient had an average of four to five “off” periods per day and spent nearly half his time in that condition.
The group used a fine needle to inject microscopic quantities of dopamine-producing brain cells from four aborted fetuses into the patient’s brain where his own nerve cells had died. The principal change in the group’s procedure from earlier cases involved the use of a smaller needle, which caused less trauma to the brain.
“That’s the critical difference,” Lindvall said in a telephone interview.
By three months after the surgery, the group reports today, the patient was having at most one to two brief “off” periods per day, with very mild symptoms. His condition has remained stable for the subsequent five months.
Unlike previous researchers, the Lund group used a technique called positron emission tomography or PET scanning to measure brain metabolism before and after the surgery. PET scanning uses radioactively labeled chemicals that release positrons, which are monitored by a series of detectors surrounding the subject.
When the PET scan was run immediately after the operation, the metabolism of the implanted cells was clearly visible. Eight months later, the increased activity was still apparent, indicating that the transplanted cells had survived and were thriving. In their two earlier patients, in contrast, the increased metabolic activity fell off rapidly after the implant.
The Lund group has subsequently performed the operation on three additional patients, but none has been monitored long enough to determine if the procedure was effective.
Although they plan to perform more procedures, Lindvall noted that “this is not an established therapy. . . . But this makes us more optimistic about developing such a therapy.”
