An exciting emerging area revolves around the use of microfluidic tools for single-cell genomic analysis. We have been using microfluidic devices for both gene expression analysis and for genome sequencing from single cells. In the case of gene expression analysis, it has become routine to analyze hundreds of genes per cell on hundreds to thousands of single cells per experiment. This has led to many new insights into the heterogeneity of cell populations in human tissues, especially in the areas of cancer and stem cell biology. These devices make it possible to perform "reverse tissue engineering" by dissecting complex tissues into their component cell populations, and they are also used to analyze rare cells such as circulating tumor cells or minor populations within a tissue.
We have also used single-cell genome sequencing to analyze the genetic properties of microbes that cannot be grown in culture - the largest component of biological diversity on the planet—as well as to study the recombination potential of humans by characterizing the diversity of novel genomes found in the sperm of an individual. We expect that single cell genome sequencing will become a valuable tool in understanding genetic diversity in many different contexts.