Biology of Humans 6th Edition by Judith Goodenough,Betty McGuire

Exercise 5

We have seen that blood is a transportation vehicle for many substances and cells. In cancer patients, cancer cells may break free from a tumor and travel in the blood to new locations, where they can start new tumors. Sorting cancer cells from healthy cells is difficult because there may be only a single cancer cell per 100,000 normal cells. A research team developed a device that uses sound waves to separate cancer cells from healthy cells in blood.1 Excerpts from a news article by Anne Taffton, "Using sound waves to detect rare cancer cells," are presented below. You can read the entire article posted on the MIT News website April 6, 2015, here: http://newsoffice.mit.edu/2015/sound-waves-detect-rare-cancer-cells-0406 "Most existing cell-sorting technologies require tagging cells with chemicals or exposing them to strong mechanical forces that may damage them. To sort cells using sound waves, which offer a gentler alternative, the researchers built microfluidic devices with two acoustic transducers, which produce sound waves, on either side of a microchannel. When the two waves meet, they combine to form a standing wave (a wave that remains in constant position). This wave produces pressure nodes, or lines of low pressure. "Because the sound waves are tilted so they run across the microchannel at an angle, each cell encounters several pressure nodes as it flows through the channel. As cells encounter each node, they are pushed further to the side of the channel; the distance of cell movement depends on their size and other properties, such as compressibility. "In the previous study, the researchers were able to separate cancer cells from red and white blood cells, but the sample flow rate through the device was only 1 to 2 microliters per minute. At that rate, it would take more than 50 hours to process a typical patient sample of about 6 milliliters. The new version of the device has a working flow rate about 20 times faster, allowing it to process a patient sample in about five hours... "The researchers tested the new acoustic device with samples consisting of a mix of cancer cells and white blood cells grown in the lab. In these studies, they were able to isolate at least 83 percent of the cancer cells from samples that had as few as one cancer cell per 100,000 white blood cells. "The device also performed well in tests of blood samples from three breast cancer patients. From those samples, the researchers isolated one, eight, and 59 tumor cells, respectively; the first sample was from a patient who was responding very well to treatment, and therefore had few tumor cells circulating. "Their results were similar to those from a commercially available device that can sort cancer cells; however, that device damages cells so they are not viable for further studies.... In contrast, the acoustic technique is very mild and does not require the cells to be tagged with magnetic beads, antibodies or any other molecules, so they are ideal for further analyses once isolated."
What was the hypothesis for this experiment