Looking through the eyes of a mouse, scientists monitor circulating cells in its b...( WASHINGTON Dec. 3 A team of researc...)

WASHINGTON, Dec. 3 A team of researchers from the Wellman Center for Photomedicine at Massachusetts General Hospital (MGH) and Harvard Medical School (HMS) have developed an optical device that allows them to peer through the eyes of a mouse and monitor the cells passing through its bloodstream.

In the Dec. 1 issue of the journal Optics Letters, published by the Optical Society of America, the team describes how they used the device, called a retinal flow cytometer, to non-invasively sample the blood passing through the vessels in the retinal tissue in the back of the eye. There they were able to detect circulating fluorescently labeled cells as they wound their way through the mouse.

"We could detect and count circulating cells continuously without drawing blood samples," says MGH/HMS investigator Charles Lin.

The ability to count circulating cells is important in diseases like multiple myeloma because the number of cancer cells in the bloodstream at the onset of the disease may represent only a tiny fraction of circulating cells in the bloodstream.

Though few in number, these rare cells nevertheless can be relentless. Multiple myeloma starts when cancerous immune system cells residing in the bone marrow quickly multiply out of control. Rather than forming a solid tumor, though, they spread throughout the body and crowd out other cells in the bloodstream. Multiple myeloma cells can invade bones throughout the body, eroding and weakening them and leading to fractures and sometimes paralysis because of compression of the spinal cord. Eroding the bones can also drastically increase the calcium levels in the blood, sometimes causing kidney failure. Moreover, multiple myeloma cells can crowd out the oxygen-ferrying red blood cells in the bloodstream and cause anemia.

Multiple myeloma is treatable, but the disease has a high rate of recurrence. Scientists like Lin and his collaborator Irene Ghobrial of the Dana-Farber
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