Toxin-producing stem cells (in blue) help kill brain tumour cells in the tumour cavity (in green)
Scientists from Harvard Medical School have discovered a way of turning stem cells into killing machines to fight brain cancer.
In experiments on mice, the stem cells were genetically engineered to produce and secrete toxins which kill brain tumours, without killing normal cells or themselves. Researchers said the next stage was to test the procedure in humans.
A stem cell expert said this was "the future" of cancer treatment.
The study, published in the journal Stem Cells, was the work of scientists from Massachusetts General Hospital and the Harvard Stem Cell Institute.
For many years, they had been researching a stem-cell-based therapy for cancer, which would kill only tumour cells and no others.
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.
They also posed no risk to normal, healthy cells.
In animal tests, the stem cells were surrounded in gel and placed at the site of the brain tumour after it had been removed.
Their cancer cells then died as they had no defence against the toxins.