Abstract

Tools to Study Single Cells and Single Molecules

Ulf Landegren, Principal Investigator, University of Uppsala

Analysis of protein-level heterogeneity among cells in tissues can offer important insights in cell biology and provide valuable disease diagnostics, but the detection of proteins from small sample aliquots or even single cells requires a combination of high specificity and sensitivity. The proximity ligation and proximity extension techniques can enable such high-performance protein analyses as they depend on simultaneous recognition of each targeted protein or protein complex by two (or more) antibodies. Oligonucleotides attached to the antibody pairs give rise to DNA reaction products that can be amplified by PCR for high multiplex protein analyses in solution phase (Proseek®), or using rolling circle amplification (RCA) for localized detection in situ (Duolink®). We develop and use the Proseek and Duolink assays for measuring hundreds of proteins in small sample aliquots, and for characterizing tumor heterogeneity in situ or by isolating individual cells. Examples of applications of the techniques will be described, as well as ongoing work to further extend these analyses to larger numbers still of proteins, and to identify and locate rare variants of nucleic acid sequences in plasma and among cells.