A key to the nanoparticles’ effectiveness is the ability of their RNA strands to bind to a cancer cell membrane. The cell then pulls the particles inside. Having the particles inside the cell has two advantages: it gets the drug where it needs to be to kill the cells, and it decreases the concentration of the drug outside the cancer cells, thereby decreasing toxicity to healthy tissue. The fact that the polymer releases the drug gradually also helps — the drug is released over the hours or days it takes for the particles to be pulled into cells, where it continues to be released, killing the cells.
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Eventually, the MIT-Harvard researchers hope to design nanoparticles that can be injected into the bloodstream, from which they could seek out cancer cells anywhere in the body, making it possible to treat late-stage metastasized cancer. “Even though this represents a small percentage of patients that actually have the disease, these are the ones that have no therapeutic option available to them,” Farokhzad says.