More MS news articles for Dec 2001

Stem cells form early brain cells in lab setting

By Merritt McKinney

NEW YORK, Nov 30 (Reuters Health) - Two separate research teams have taken an important step toward using embryonic stem cells to form new brain cells.

The researchers successfully coaxed the immature cells to form brain-cell precursors that should be capable of forming specialized cells in the central nervous system.

The hope is that these so-called neural precursors eventually can be used to treat spinal cord injury and neurological diseases such as Parkinson's and Huntington's diseases.

Despite the encouraging results, the results are a long way from clinical use, according to a scientist involved in the research.

Embryonic stem cells are cells in human embryos that can give rise to a variety of specialized cells. Getting stem cells to specialize is tricky, however, and scientists have had a hard time creating the ideal conditions for this transformation.

Now, two teams report in the December issue of the journal Nature Biotechnology that they have been able to coax human embryonic stem cells into forming precursors of brain cells.

"We have shown that specialized cells with therapeutic potential such as neural precursors can be generated and purified from human embryonic stem cells," Dr. Su-Chun Zhang, of the University of Wisconsin-Madison, told Reuters Health. "This is the first and key step toward the medical use of stem cells," according to Zhang, who is the first author of one of the reports.

The neural precursors derived from stem cells developed into various types of neurons and glial cells not only in the laboratory dish but after they were transplanted into the brains of baby mice, Zhang said.

Another good sign, Zhang explained, is that transplanting the stem cells did not seem to cause any tumors in the mice. Since stem cells constantly divide, the formation of tumors has been a concern.

Despite the promising results of the experiments, the Wisconsin scientist pointed out that researchers are "nowhere near" the clinical use of human embryonic stem cells.

Zhang's team is currently studying neural precursors derived from stem cells in animal models of neurological injuries and diseases to see whether the cells have any therapeutic potential.

According to Zhang, it may be possible to coax the neural precursors to form specialized cells, such as dopamine-producing neurons to treat Parkinson's disease or motor neurons to treat amyotrophic lateral sclerosis, also known as Lou Gehrig's disease. It may also be possible to use the cells to grow cells that produce myelin, the nerve-protecting sheath that is destroyed by multiple sclerosis, Zhang noted.

In the second paper in the journal, Dr. Benjamin E. Reubinoff at Hadassah University Hospital in Jerusalem, Israel, and colleagues report that they, too, have succeeded in deriving neural precursors from embryonic stem cells. When the cells were transplanted to the brains of mice, they differentiated into three different types of precursor cells and migrated throughout the brain.

The results "set the stage for future developments that may allow the use of human embryonic stem cells for the treatment of neurological disorders," Reubinoff's team concludes.

Both studies "are crucial first steps toward exploiting human embryonic stem cell technology for brain repair and provide experimental platforms of human brain development," according to Dr. Lorenz Studer at Memorial Sloan-Kettering Cancer Center in New York.

However, he notes in an accompanying editorial that many obstacles remain before stem cells can be used to treat neurological diseases.

Studer points out that neither group was able to derive clinically useful cells, such as those that produce dopamine.

And despite the apparent lack of tumor formation, long-term studies are "essential" to prove that transplanting stem cells will not cause tumors, Studer stressed.

SOURCE: Nature Biotechnology 2001;19:1117-1118, 1129-1140.

Copyright © 2001 Reuters Limited