| Posted: Oct 05, 2010 |
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Anti-tumor drugs tested by microfluidic device
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(Nanowerk News) A prototype device developed in Hong Kong will allow laboratory researchers to non-invasively test drugs for their ability to kill tumors by subjecting cancerous cells with different concentration gradients. The new device is built upon microfluidics -- a set of technologies that allows the control and manipulation of fluids at the sub-millimeter scale -- and is described in the American Institute of Physics' journal Biomicrofluidics.
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Microfluidic valves within the device, said Hongkai Wu of Hong Kong University of Science and Technology, accurately meter different solutions and mix them to form a stepwise succession of gradients. Then assays measuring cell apoptosis are applied. The device integrates a previously validated analysis method that quantifies the apoptotic process at the level of single cells in real-time.
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For this test, researchers measured the activity of the drug etoposide in HeLa cells. Etoposide is a commercially available anticancer compound commonly used in chemotherapy. HeLa cells, derived from human cervical cancer cells, are a line of cells frequently used in research.
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The device allows researchers to study the cytotoxicity of multiple concentrations of a drug in parallel on one chip, saving both time and labor and reducing errors caused by variations in conditions often found in larger-scale testing. Also, microfluidic chambers within the device allow long-term tracking of individual cells through fluorescent microscopic imaging that offers high optical sensitivity.
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With some other in vitro tests, like DNA analysis, cells need to be killed in order to be studied. In this analysis method, a change in fluorescence occurs when caspase-3, an indicator of cell apoptosis, is activated. In Wu's test, increasing concentrations of etoposide demonstrated correspondingly higher activation of caspase-3. In a control-group chip without etoposide, caspase-3 was not activated.
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Wu also said that, "Unlike conventional methods, the microfluidic device permits quantitative data to be obtained from individual cells; the device requires fewer numbers of cells and allows testing of amounts of reagents reduced by about 4 orders of magnitude. In a conventional 96-well plate study, each well is around 1 centimeter, while in our microchip device, each cell chamber has a dimension of hundreds of microns. Reducing the sample size has significant merit because in most cases, the biomolecules in use are extremely expensive, even in quantities in milligrams or less."
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While this report concerns a test of five ladder channels on a single chip, higher throughputs should be possible, Wu stated. "This prototype system should be useful in the areas of biology and bioengineering, especially for discovering apoptosis-inducing agents," Wu concluded.
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