N Hanley BB/D014670/1

Human embryonic germ cells (EGCs) are capable of turning into many different types of cell, including ones with the potential to treat disease. For this reason, it is important that these cells are widely available to the research community. However, the difficulty of acquiring robust pure lines of EGCs has proven a significant barrier. The major problems for this are an extremely small mixed starting sample from which EGCs are made and a difficulty of propagating the delicate EGCs in laboratory culture. To overcome these difficulties, we need to a method to acquire pure EGCs and their precurors. Current methods are unsuitable. Microelectronics has provided us with very small scale devices capable of performing rapid, massive parallel processing of electrical signals. Likewise, optoelectronics has provided us with small scale devices capable of performing massive parallel processing of optical signals. The silicon technology that has been developed to create these tiny microelectronic devices, has in recent years, been applied to the manipulation and control of very small quantities of fluids. The beauty of this technology is the potential for an integrated single microstructured microchip. In Southampton we have recently developed optical chips for the transport of polymer beads around micrometer sized circuits. Light in the circuits carries these beads and can be switched so that they can be transported in one direction or the other. The speed of these beads depends upon their composition and size. We propose to transport cells in much the same way, thus different cells will be selectively 'pushed' by the light along the different tracks. Light is ideal for this purpose, especially since the wavelength to be used is not absorbed by the cell and thus will not damage it. The different cells will be identified by how quickly they are transported along the tracks. So we plan to identify EGCs without the need for any labels of fluorescent molecules - a significant improvement in the ease with which these cells can be purified. Once we have a pure population of cells for our experiments, we can discover which genes are switched on and off as EGCs are made and what factors we need to add to our laboratory cultures to keep EGCs growing. These advances will allow us to deposit our cell lines in the UK Stem Cell Bank so that other researchers can access them and the research community as a whole can make faster progress towards using stem cells to treat human disease.