SternisheFan writes with news that medical researchers from Harvard Medical School and Massachusetts General Hospital have successfully cultivated stem cells that will kill brain cancer cells in mice without damaging healthy cells. "They used genetic engineering to make stem cells that spewed out cancer-killing toxins, but, crucially, were also able to resist the effects of the poison they were producing. ... In animal tests, the stem cells were surrounded in gel and placed at the site of the brain tumor after it had been removed. Their cancer cells then died as they had no defense against the toxins (abstract)." The next step in the research is to try the treatment on humans. Chris Mason, a professor of regenerative medicine, said, "This is a clever study, which signals the beginning of the next wave of therapies. It shows you can attack solid tumors by putting mini pharmacies inside the patient which deliver the toxic payload direct to the tumor. Cells can do so much. This is the way the future is going to be."