Microarrays of cells

Analysis of gene function in vivo is typically done one gene at a time, by expressing a DNA construct in cells that over- or under-produce the gene, and then analyzing the effects on cellular physiology. Using protein microarrays for this purpose would be attractive, but they are more technically challenging to create and use than nucleic acid arrays because different proteins require different conditions to maintain their properly folded forms. Taking a different tack, researchers at the Whitehead Institute reported in last week's Nature that they have developed microarrays of transfected mammalian cells that express a variety of proteins.

The cell microarrays are prepared by printing a slide with an array of plasmid DNAs, i.e., cDNA in an expression vector. The printed slide is then put into a dish of mammalian cells that stick to the surface, and the plasmids are taken up into the cells with the help of a transfection reagent. The result is a slide with a layer of cells, and above each DNA spot is a cluster of 80-100 cells that are transfected with the DNA from that spot. ...