Scientists have developed a new cancer drug. So far, they have tested it only in laboratory
animals. The drug is designed to enter and kill cancer cells, but not healthy cells.First, the drug
enters the cancer cells and stops their supply of blood. Then it releases poison to destroy the
cancer cells.
     Researchers at the Massachusetts Institute of Technology(MIT) in Cambridge carried
out the study. The results appeared in Nature magazine. A school report called the drug an
"anticancer smart bomb".
     Ram Sasisekharan is a professor at MIT. He says that his team had to solve three problems.
They had to find a way to destroy the blood vessels, then to prevent the growth of new ones.
But they also needed the blood vessels to supply chemicals to _________.
     So, the researchers designed a two-part "nanocell". The cell is measured in nanometers(毫微米),
or one thousand millionth of a meter.
     The scientists say thay that it was small enough to pass through the blood vessels of the cancer,
but it was too big to enter normal blood vessels. The surface of the nanocells also helped them to
avoid natural defenses.
     The scientists designed the cell as a balloon inside a balloon. They filled the outer part with a
drug that caused the blood vessels to die. That cut off the blood supply and put the nanocells inside
the cancer. Then, the nanocells slowly released drugs to kill the cancer cells.
     The team says that the treatment killed the cancer and avoided healthy cells better than other
treatments. Untreated mice with cancer survived for twenty days. The scientists say that mice with
the best current treatments lived for thirty days. In this study, they say that eighty percent of the mice
treated with the nanocells lived more than sixty-five days.
     The scientists say that more studies are needed before the new drug can be tested in humans.

5. Please translate the underlined sentence in the eighth paragraph into Chinese
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