Analysis of gene expression at the single-cell level using microdroplet-based microfluidic technology.

In the present work, we have measured the messenger RNA expression of specific genes both from total RNA and cells encapsulated in droplets. The microfluidic chip introduced includes the following functionalities: RNA∕cell encapsulation, lysis, reverse transcription and real-time polymerase chain reaction. We have shown that simplex and duplex gene expression measurements can be carried out over a population of 100 purified RNA samples encapsulated simultaneously in 2 nl droplets in less than 2 h. An analysis of 100 samples containing one to three cells has shown excellent consistency with standard techniques regarding average values. The cell-to-cell distributions of the E-cadherin expression suggest fluctuations on the order of 80% in the number of transcripts, which is highly consistent with the general findings from the literature. A mathematical model has also been introduced to strengthen the interpretation of our results. The present work paves the way for the systematic acquisition of such information in biological and biomedical studies.