PCR-Based Multiparametric Assays in Single Cells

Pathologists have long known that the functional state of a tissue is best understood from an overview of the different cells making up that tissue—cells that may differ radically in their lineage, their phase in the cell cycle, their responses to stimuli, and their clonal history of somatic mutation, e.g., in a tumor. With the radically expanding opportunities for the molecular analysis of nucleic acids, proteins, and combinations thereof, there is currently great interest in collecting information at cellular resolution, rather than recording population means, as has been common practice in molecular biology (1).In this issue of Clinical Chemistry , Stahlberg and coauthors (2) describe an interesting approach for jointly measuring DNA copy numbers and concentrations of mRNAs, microRNAs, and proteins in individual cells. These authors prepared single-cell lysates that were subsequently divided into separate reactions for each of the measured molecular species, and they recorded all of the results of the molecular-detection reactions via real-time quantitative PCR. This report represents an important first step in a new approach to detect multiple biological modalities in single cells with high analytical sensitivity and specificity.Nothing is quite new under the sun, of course, and there are already a number of approaches for molecular analyses at the level of individual cells. Various in situ analyses that provide cellular-level resolution are routinely used for analyzing DNA, RNA, or protein in populations of cells and in tissue sections. …