Israeli researchers are the first in the world to have documented that the injection of stem cells from aborted human fetuses can trigger tumors. Stem cells, especially those from few-day-old embryos, are considered by many to be a potential cure for a wide variety of chronic disorders - from Parkinson's and Alzheimer's to diabetes and heart disease - because they have the ability to produce new cells of all types for the repair of diseased organs. But the new research, based on the case of a now-16-year-old Israeli youth suffering from a rare genetic degenerative disease who underwent the highly experimental injections in Russia, is the first documented case of a human brain tumor - albeit a benign, slow-growing one - after fetal stem cell therapy, and sounds an alarm that future stem cell use must be preceded by extensive research. The patient, born here to parents of Moroccan origin, developed ataxia telangiectasia (AT) as a young child. Degeneration of a certain brain region gradually robs these children of movement, and a faulty immune system leads to frequent infections and cancers. Most victims die in their teens or early 20s. Although the boy's doctors at Sheba Medical Center, Tel Hashomer, urged the desperate parents against it, they took him to an unnamed clinic in Moscow for injections of fetal stem cells into his brain and spinal cord. He returned to Russia twice - at age 10 and 12 - for more injections. Then, at the age of 13, he developed painful headaches, and an MRI scan showed he had tumors in several parts of the brain and the spinal cord. Two-and-a-half years ago, hematology Prof. Gideon Rechavi, head of Sheba's Cancer Center and Tel Aviv University's Cancer Biology Center, headed a team that investigated the case and found after extensive pathological and genetic research that the tumors were not germane to the patient, but were sourced from at least two fetuses whose foreign tissue had been injected into him. For example, the tumors contained both XX (female) and XY (male) cells, while if they had come from the boy's body they could not have female chromosomes. They also had two normal copies of the ATM gene, which causes AT when mutated. Since the boy has AT, those genes cannot be his. The team noted, however, that the fact that the boy has AT may have facilitated the growth of the tumors because of the weak immune system in such patients. In 2006, the boy underwent brain and spinal cord surgery performed by Prof. Shlomo Constantini, head of the pediatric neurosurgery department at Tel Aviv Sourasky Medical Center's Dana Children's Hospital. Only those tumors that were believed to grow relatively rapidly were removed. Today, the youth's condition is stable, with the tumors growing slowly enough to be considered benign, but he is wheelchair-bound. While the parents reportedly regret taking him to Russia, AT is such a dangerous genetic disorder - killing most victims by the age of 20 - that it threatens his life more than the tumors. The Jerusalem Post learned that the researchers' work, just published in the US Public Library of Science (PLoS) on-line, open-access journal, was initially turned down for publication by the highly prestigious journals Nature and Science. One of the study's authors, Dr. Ninette Amariglio, suggested that the journals were apparently "fearful of the multi-billion-dollar stem cell lobby, as the study could hurt its prospects." In addition, publishers "prefer optimistic science. Our study is not pessimistic, but it warns that researchers have to be aware of possible complications and dangers," said Amariglio, who heads the Diagnostic Molecular Hemato-Oncology Laboratory at Sheba Medical Center. "We by no means suggest that stem cell research should be halted," Amariglio stressed. "Although this report indicates the need for caution in stem cell therapy, we do not imply that the research in stem cell therapeutics should be abandoned. "We do suggest that extensive research into the biology of stem cells and in-depth preclinical studies, especially of safety, should be pursued in order to maximize the potential benefits of regenerative medicine while minimizing the risks." Stem cells are not medications, Amariglio added, but are still unpredictable, so desperate patients should not undergo questionable "therapies" that could endanger them more than their disease.