Abstract

Phenotypically identical cells can dramatically vary with respect to behavior during their lifespan and this variation is reflected in their molecular compo-sition such as the transcriptomic landscape. Single-cell transcriptomics using next-generation transcript sequencing (RNA-seq) is now emerging as a pow-erful tool to profile cell-to-cell variability on a ge-nomic scale. Its application has already greatly im-pacted our conceptual understanding of diverse bi-ological processes with broad implications for both basic and clinical research. Different single-cell RNA-seq protocols have been introduced and are reviewed here––each one with its own strengths and current limitations. We further provide an overview of the bio-logical questions single-cell RNA-seq has been used to address, the major findings obtained from such studies, and current challenges and expected future developments in this booming field.