SCIENCE UPDATE
A small labyrinth in a plastic box can separate cancer cells from the rest of the blood cells. This method helps doctors discover rare types of cancer and target the treatment.
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MEDICINE Blood can hide microscopic cancer cells at various stages of development. If doctors can analyse them individually, give vital clues about the disease – the genes in the cells hold information about the type of cancer, and whether it is spreading.
But the cells are very difficult to get to. For every billion blood cells, there is one cancer cell. But now, scientists from University of Michigan, US, have developed a method to extract the microscopic cells. They pass blood samples from patients through a small labyrinth. Its shape has been specially designed and exploits the characteristics of the blood, so that large cancer cells are separated from small blood cells. In an experiment, scientists passed the blood through the labyrinth twice and got one cancer cell for every 600 blood cells – enough to analyse the cancer cells individually, enabling the doctors to identify their type and stage and maybe develop a custom-made treatment.
Curves and sharp corners sort the blood cells
A long path, soft curves and many bends make the blood content separate in layers, enabling scientists to single out cancer cells that hide in the crowd. Long tube places cells in a row 1 At the entrance, the cells are one big mess. But when passed through the 600-mm-long labyrinth, both cancer cells and blood cells form a line in the middle of the tube.
Whirls put cancer cells in layers
2 The blood runs through 11 curves and around 56 corners. Whirls form in the curves, pressing the cells against the walls and pushing them back. The size determines the speed of a cell, and thus where it is placed.
Four lanes separate cell types
3 At the end, the labyrinth branches out into four tubes of differing sizes. They collect the content of the blood and separate large while corpuscles and cancer cells from other smaller blood components. In an experiment, scientists passed the blood through the labyrinth twice to get a concentrated sample of usable cancer cells to analyse.