Patterning of cells through patterning of biology

For the first time, cells have been patterned on surfaces through the spatial manipulation of native gene expression. By manipulating the inherent biology of the cell, as opposed to the chemical nature of the surfaces they are attached to, we have created a potentially more flexible way of creating patterns of cells that does not depend on the substrate. This was accomplished by bringing an siRNA that targets the expression of pten under the control of light, by modifying it with photocleavable groups. This pten-targeting siRNA has been previously demonstrated to induce dissociation of cells from surfaces. We modified this siRNA with dimethoxy nitro phenyl ethyl photocleavable groups (DMNPE) to allow the activity of the siRNA, and hence pten knockdown, to be toggled with light. Using this approach we demonstrated light dependent cell dissociation only with a DMNPE modified siRNA that targets pten and not with control siRNAs. In addition we demonstrated the ability to make simple patterns of cells through the application of masks during irradiation.