Abstract

Precision Biology: Deep Profiling of Single Cells Using Electrophoretic Cytometry

Amy Herr, Associate Professor, University Of California Berkeley

Underpinning single-cell measurement tools, microfluidic design offers the throughput, multiplexing, and quantitation needed for rich, multi-dimensional data. Genomics and transcriptomics are leading examples. Yet, while proteins are the dynamic, downstream effectors of function, the immunoassay remains the de facto standard (flow cytometry, mass cytometry, immunofluorescence). We posit that to realize the full potential of high-dimensionality cytometry, new approaches to protein measurement are needed. I will describe our ‘electrophoretic cytometry’ tools that increase target selectivity beyond simple immunoassays. Enhanced selectivity is essential for targets that lack high quality immunoreagents – as is the case for the vast majority of protein forms (proteoforms).  I will share our results on highly multiplexed single-cell western blotting and single-cell isoelectric focusing that resolves single charge-unit proteoform differences. In fundamental engineering and design, I will discuss how the physics and chemistry accessible in microsystems allows both the “scale-down” of electrophoresis to single cells and the “scale-up” to concurrent analyses of large numbers of cells. Precise reagent control allows for integration of cytometry with sophisticated sample preparation – the unsung hero of measurement science. Lastly, I will link our bioengineering research to understanding the role of protein signaling and truncated isoforms in development of breast cancer drug resistance and understanding protein signaling in individual circulating tumor cells. Taken together, we view microfluidic design strategies as key to advancing protein measurement performance needed to address unmet gaps in quantitative biology and precision medicine.