Wednesday, February 18, 2009

Fetal stem-cell therapy fails: Israeli experiment triggered tumors

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A family desperate to save a child from a lethal brain disease sought highly experimental injections of fetal stem cells — injections that triggered tumors in the boy's brain and spinal cord, Israeli scientists reported Tuesday.

Scientists are furiously trying to harness different types of stem cells — the building blocks for other cells in the body — to regrow damaged tissues and thus treat devastating diseases. But for all the promise, researchers have long warned they must learn to control newly injected stem cells so they don't grow where they shouldn't, and small studies in people are only just beginning.

Tuesday's report in the journal PLoS Medicine is the first documented case of a human brain tumor — albeit a benign, slow-growing one — after fetal stem cell therapy and hammers home the need for careful research. The journal is published by the Public Library of Science.

"Patients, please beware," said Dr. John Gearhart, a stem cell scientist at the University of Pennsylvania who wasn't involved in the Israeli boy's care but who sees similarly desperate U.S. patients head abroad to clinics that offer unproven stem-cell injections.

"Cells are not drugs. They can misbehave in so many different ways, it just is going to take a good deal of time" to prove how best to pursue the potential therapy, Gearhart said.

The unidentified Israeli boy has a rare, fatal genetic disease with a tongue-twisting name— ataxia telangiectasia, or A-T. Degeneration of a certain brain region gradually robs these children of movement. Plus, a faulty immune system leads to frequent infections and cancers. Most die in their teens or early 20s.

A Tel Aviv University team extensively tested the tumor tissue and concluded the fetal cells were to blame. Among other evidence, some of the cells were female and had two normal copies of the gene that causes A-T — although that boy's underlying poor immune function could have allowed the growths to take hold.

Using stem cells from multiple fetuses that also were mixed with growth-spurring compounds "may have created a high-risk situation where abnormal growth of more than one cell occurred," wrote lead researcher Dr. Ninette Amariglio of Sheba Medical. She urged better research to "maximize the potential benefits of regenerative medicine while minimizing the risks."

This brain disease wasn't conducive to stem cell therapy in the first place, said stem cell specialist Dr. Marius Wernig of Stanford University, who said it's unclear exactly what was implanted.

"Stem cell transplantations have a humongous potential," Wernig said. But "if people rush out there without really knowing what they're doing ... that really backfires and can bring this whole field to a halt." Pioneer Press

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