National Academy of Science, are a “very promising start” in developing a

therapeutic application for embryonic stem cells to treat human diseases,

according to stem cell expert Dr. Arlene Chiu from the National Institute

of Neurological Disorders and Strokes (NINDS).

However, Chiu and other researchers say they agree that practical therapeutic

applications for embryonic stem cells are, at best, years down the road.

Chiu says the type of stem cell used in the Harvard Parkinson’s study, “the youngest ones with the greatest potential,” come with a troubling tendency to form tumors. In fact, five out of the 19 rats tested developed tumors, Chiu notes.

The average tumor size in the rats’ brains was comparable to one the size

of a walnut in a human brain, which is 30 to 40 times larger, according to lead researcher Ole Isacson.

These kinds of glitches, which Isacson says he “anticipated,” are not

surprising given that cell transplantation therapy research is still in

its nascent stage.

WebMD, a popular consumer health website, called the study a “giant step toward Parkinson’s cure” in an optimistic article posted last month.

Isacson’s study was also widely publicized in mainstream press, but observers were quick to qualify its successes with shortcomings.

Some scientists point out a larger trend of misinterpreting the