Ultrahigh-throughput Mammalian single-cell reverse-transcriptase polymerase chain reaction in microfluidic drops.

The behaviors of complex biological systems are often dictated by the properties of their heterogeneous and sometimes rare cellular constituents. Correspondingly, the analysis of individual cells from a heterogeneous population can reveal information not obtainable by ensemble measurements. Reverse-transcriptase polymerase chain reaction (RT-PCR) is a widely used method that enables transcriptional profiling and sequencing analysis on bulk populations of cells. Major barriers to successfully implementing this technique for mammalian single-cell studies are the labor, cost, and low-throughput associated with current approaches. In this report, we describe a novel droplet-based microfluidic system for performing ~50000 single-cell RT-PCR reactions in a single experiment while consuming a minimal amount of reagent. Using cell type-specific staining and TaqMan RT-PCR probes, we demonstrate the identification of specific cells from a mixed human cell population. The throughput, robust detection rate and specificity of this method makes it well-suited for characterizing large, heterogeneous populations of cells at the transcriptional level.