title: Accurate expression profiling of very small cell populations.
abstract: BACKGROUND
  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.
  
  
  RESULTS
  We provide evidence that currently available methods for expression profiling of very small cell populations are prone to technical noise and therefore cannot be used efficiently as discovery tools. Furthermore, we present Pico Profiling, a new expression profiling method from as few as ten cells, and we show that this approach is as informative as standard techniques from thousands to millions of cells. The central component of Pico Profiling is Whole Transcriptome Amplification (WTA), which generates expression profiles that are highly comparable to those produced by others, at different times, by standard protocols or by Real-time PCR. We provide a complete workflow from RNA isolation to analysis of expression profiles.
  
  
  CONCLUSIONS
  Pico Profiling, as presented here, allows generating an accurate expression profile from cell populations as small as ten cells.
authors.affiliation: Institute for Research in Biomedicine, Barcelona, Spain.
authors.forename: Eva
authors.initials: E
authors.lastname: Gonzalez-Roca
authors.forename: Xabier
authors.initials: X
authors.lastname: Garcia-Albéniz
authors.forename: Silvia
authors.initials: S
authors.lastname: Rodriguez-Mulero
authors.forename: Roger R
authors.initials: RR
authors.lastname: Gomis
authors.forename: Karl
authors.initials: K
authors.lastname: Kornacker
authors.forename: Herbert
authors.initials: H
authors.lastname: Auer
mesh_terms: D000818:Animals; D005189:False Positive Reactions; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D015723:Gene Library; D006801:Humans; D008280:Magnetics; D051379:Mice; D008954:Models, Biological; D036103:Nanotechnology / Q000379:methods; D009693:Nucleic Acid Hybridization; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: D012333:RNA, Messenger