A noninvasive method for physically isolating the RNA of a single cell within living tissue is described using mouse and human cells, in a paper published online this week in Nature Methods. These findings will allow for a better understanding of the effects of tissue microenvironment on gene expression in healthy and diseased cells.
Tissues are complex structures composed of various cell types. The identity and function of individual cells are closely linked with their gene expression profiles, that is, which genes are transcribed into RNA. To study single-cell gene expression in situ, methods are needed that do not require the dissociation of tissue into its component cells.
James Eberwine and colleagues describe a noninvasive way to isolate the RNA from a single cell of interest while it is within its native tissue context. They used a chemical tag that is transported into cells and remains inert until it is activated with light. Upon activation, the tag hybridizes to the mRNA within the cell and can be used to physically isolate the entire mRNA complement of that cell. Since tag activation is achieved with light, any cell within the living tissue can in principle be targeted. Eberwine and colleagues use this approach to profile gene expression in single neurons in culture and within living mouse and human brain tissue.