Expression profiling, the measurement of all transcripts of a cell or tissue type, is currently the most comprehensive method to describe their physiological states. Given that accurate profiling methods currently available require RNA amounts found in thousands to millions of cells, many fields of biology working with specialized cell types cannot use these techniques because available cell numbers are limited. Currently available alternative methods for expression profiling from nanograms of RNA or from very small cell populations lack a broad validation of results to provide accurate information about the measured transcripts.
Gonzalez-Roca, E., Garcia-Albéniz, X., Rodriguez-Mulero, S., Gomis, R. R., Kornacker, K., & Auer, H. (2010). Accurate expression profiling of very small cell populations. PLoS ONE, 5(12). https://doi.org/10.1371/journal.pone.0014418