Experimental Neurology (February, 1998)
NEW YORK (Reuters) -- Specially treated human nerve cells derived from a malignant tumor may be an alternative to using fetal tissue as source of nerve cells to treat brain damage, a new study in rats suggests.
When these nerve cells, called NT2N cells, were transplanted into the brains of rats with stroke-like brain damage, the animals showed improvement in tests of neurologic function, according to a new report in the journal Experimental Neurology.
Transplants of human fetal tissue have been used with some success to treat a small number of Parkinson's disease patients, but this tissue is difficult to obtain and its use is controversial. In addition, human fetal tissue can not be stored in a frozen state, so "there is a very narrow 2-day window to collect and transplant fetal cells into the patient because of the diminished viability of these cells over time," noted study authors Dr. Paul Sanberg of the University of South Florida and colleagues at the University of Pennsylvania.
In the new study, the researchers used cells from a human teratocarcinoma, a type of malignant tumor (most commonly found in the testis) that contains embryonic cells. They treated the tumor cells with retinoic acid, a step that causes the cells to differentiate into different types of cells, including nerve-like cells (NT2N). According to the study, testing indicates that these treated cells can survive and function in a host brain for over one year without behaving like cancer cells.
The treated cells were transplanted into rats with brain damage caused by a temporary blockage of blood flow to the brain -- similar to stroke in humans.
Those rats with the NT2N transplants and treated with immune system-suppressing drugs showed improvement in learning and memory tests, as well as tests of their ability to maneuver for up to six months after the procedure, the point that the animals were sacrificed. Rats not given immune-suppressing drugs showed improvement for up to two months, but began to decline as the implants degenerated. Other rats given a placebo treatments did not show improvement.
While one rat given a transplant of fetal rat brain tissue developed a brain tumor, none of the transplants of NT2N cells grew in an out-of-control, cancer-like manner. What's more, the researchers found that both fresh and previously frozen NT2N cells worked equally as well.
"The grafts' resistance to the effects of cryopreservation is rather remarkable," said Sanberg in a statement released by the University of Pennsylvania Medical Center. "Frozen fetal brain cells do not survive long after they are thawed," said Sanberg, a professor and director of neurosurgical research.
The researchers hope that such cells, or similar types of cells, can eventually be used to treat neurological diseases.
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