Looking through the eyes of a mouse, scientists monitor circulating cells in its b...(Cancer Institute are interested in helpi...)

Testing the effect of new chemotherapy agents in the bloodstream of a mouse has traditionally been difficult because there was no way to monitor the blood continuously. The best scientists could do was to draw blood samples at various time points and count the number of cancer cells in these samples. But looking for rare cancer cells required drawing a lot of blood. Repeated blood sampling from a single mouse was impossible, though, because mice only have a few milliliters of blood in their body.

A few years ago Lin and his colleagues devised a way to monitor cancer cells in rodents directly. They adapted a technique called flow cytometry, which scientists have used for decades to sort cells in the laboratory. Basically it involves streaming a complex mixture of cells in liquid past the focus of a powerful microscope and looking for particular cellsdistinguishable because they have particular markers that are visible under the microscope.

Lin and his colleagues developed a way to use flow cytometry in vivo and monitor a mouses bloodstream directly. Initially they designed a device that could focus on a vessel in the ear of a mouse. While effective, this device was limited because the one tiny vessel in the mouses thin external ear did not have enough flow to adequately sample the bloodstream. It was a bit like trying to sample the traffic in New York by looking at a single side street in the Bronx. A better strategy would be to monitor several avenues at onceor in vascular terms, a cluster of several vessels at the same time.

This is exactly what the researchers are doing by looking into the back of a rodents eye. The r
'/>"/>