The research has been published in an early view article in the journal Biotechnology Progress, and compares the response profiles of anticancer drug paclitaxel in HeLa cells cultured in the new microfluidic system, with those cultured in a standard well plate format. The device contains three main components, a cell culture area, a nutrient transport channel and a microfluidic perfusion barrier that separates the two other compartments. The perfusion barrier consists of a network of 5µm by 2µm channels that allow nutrients and drugs to pass through but help keep the cells in the cell culture compartment, much like the endothelium that line blood cells. CellASIC was formed in 2005 by researchers from the University of Berkeley in California, US, to create the tools needed to control and analyse living cells. The new device design expands on the company's existing product line that has been optimised for studying yeast. "We believe that by controlling the environment around cells using microfluidics you can get better mass transport of nutrients to the cells, look at special signalling effects into how cells form and get a better understanding of tissue formation," said Dr Philip Lee, director of research at CellASIC and lead author of the paper. The devices allow cells to be studied with microscopy and fluorescence spectroscopy techniques as well as standard microtitre based techniques such as the LDH assay that is often used as a biomarker that indicates tissue breakdown. The researchers cultured HeLa cells, an immortalised cervical cancer cell line, for 4 days in the device with a continuous flow of culture medium that led to a high density of the cells in the device. This high density mimics the density of cells observed in tumours much closer than cells grown in normal culture methods. "What we've been able to do is keep the cells fixed in a single location and continuously fed with nutrients," said Dr Lee. The anticancer drug paclitaxel was then added to the nutrient flow and the cells exposed to the drug continuously for 5 days. Different concentrations of the drug were added to different nutrient streams so that a dose - response curve could be generated. Characteristic dose-response curves were observed by live/dead fluorescent staining of the cells. The cells cultured in the microfluidic device exhibited 'multicellular resistance' similar to that observed in clinical tumours with the cells showing drug resistance until day 3, unlike cells grown in a standard monolayer culture which showed significant cell death after 24 hours. "When you get solid masses of cancer cells you get somewhat altered behaviour [from cells cultured in a Petri dish] as it is very difficult to get drugs through the masses of cells" said Dr Lee. The company aims to have a mammalian cell culture device on the market later this year and the tumour model device available sometime in 2008.