Though cells within a tissue may seem identical, the gene expression in each cell differs, and this heterogeneity impacts the function of the tissue as a whole. A report, published online this week in Nature Methods, describes an approach to unravel these molecular expression patterns in cells.
Cell-to-cell variation in gene and protein expression often drives the development and function of a tissue, but one cannot observe these single cell differences in population-wide analyses. Analyzing individual cells would be an option, but this is difficult because most single cells do not yield enough material for molecular analysis. Moreover, it can be difficult to know whether fluctuations in expression are due to real biological heterogeneity or experimental noise.
With a strategy called stochastic profiling, Joan Brugge and her team provide a solution for single-cell profiling. Instead of isolating just one cell, they randomly dissect pools of ten cells, which gives them enough material to analyze gene expression. Heterogeneously expressed genes will have a wider expression distribution in the pool than genes that are expressed at the same level in every cell, thus allowing the identification of genes with varying expression patterns between cells. The researchers demonstrate the power of stochastic profiling by investigating a three-dimensional culture of breast epithelial cells and identify several molecular pathways, such as oxidative stress response, that differ from cell to cell. Once such pathways are identified, the fluctuations that influence the development of healthy and diseased tissue can be investigated.