Aboody found that she could even introduce stem cells to the opposite side of the brain from the tumors and that the cells would maneuver their way quickly to the cancer.
Fascinating discovery, but what do you do with it? The researchers found that they could engineer the stem cells to produce an enzyme once they reached the tumor. Then researchers introduced a benign drug, called 5-FC, that could get past the blood-brain barrier, and injected it into the rodents.
"When it sees the enzyme that the stem cells are making, it converts to a chemotherapeutic agent [5-FU] at that site," Aboody said. The drug attacks the cancerous cells, and there is no sign of damage to adjacent tissue -- a very important finding.
So the researchers had their delivery system, and a drug that could be turned into a cancer killer at just the right moment, but there was a problem. What if, once inside a human brain, the stem cells decided not to cooperate and turned into something totally undesired by the scientists?
"Neural stem cells change over time," Aboody said. "So you don't know that what you had a month ago is the same thing that you have now."
Fortunately, scientists at the University of British Columbia were working on a similar problem and had engineered a line of stem cells that had been robbed of their ability to morph into a different kind of cell.
Aboody started using those cells in her work and found that not only did they remain unchanged, they soon died if they couldn't find cancerous cells.
So she believes she has found her delivery vehicle, which can be produced "by the billions" in a lab at the City of Hope. There are still some enormous questions that have to be answered.
One of the hottest areas of cancer research these days concerns the discovery that some stem cells produce cancer, and it may be possible to block that, thus eliminating some types of cancer.
That's good news for other researchers, but a problem for Aboody. She will have to prove to the Food and Drug Administration that the stem cells she uses are not cancer-causing stem cells.
If she can answer that, as well as dozens of other questions that are expected to be raised, she may get approval in a couple of years to begin clinical trials involving a handful of people who desperately need help that is not now available.
It is literally a life and death issue that Aboody knows firsthand. Five years ago, her sister-in-law died of breast cancer that had spread to her brain, becoming inoperable.