Using acoustic microstreaming to improve detection of gene expression in single cells

Abstract

Functional heterogeneity among different cells of an organism (brain cell, heart cell etc.) is brought about by expression of different subsets of genes drawn from the same genetic template (DNA). Therefore, to understand the molecular basis of normal (healthy) and abnormal (diseased) cell behavior, one must measure gene expression. The typical procedure is to homogenize large numbers (>1,000) of cells together, isolate the first product of gene expression (RNA), reverse transcribe the RNA to a cDNA copy, then identify and quantify gene-specific cDNAs. Unfortunately, the gene expression profile obtained represents an average across all combined cells and cell behaviors rather than any particular cell. Ideally one would measure gene expression in a single cell; however the very small amount of labile RNA obtainable from a single cell mostly degrades before it can be measured. We have developed an acoustic microstreaming-based device (“micromixer”) which improves mixing of solutions within microliter volumes. Here we show application of “micromixing” to standard laboratory reverse transcription reactions significantly improves conversion of single-cell amounts of RNA to cDNA. Micromixing is therefore a low-cost and easy-to-use technology that is compatible with and can be added to standard laboratory hardware, software, reagents and expertise to enable better gene expression measurement from single cells.