Abstract

Fractionation and Analysis of Nuclear versus Cytoplasmic Nucleic Acids from Single Cells

Juan Santiago, Professor of Mechanical Engineering, Stanford University

Single cell analyses (SCA) have become powerful tools in the study heterogeneous cell populations such as tumors and developing embryos.  However, fractionating and analyzing nuclear versus cytoplasmic fractions of nucleic acids remains a challenge as these fractions easily cross-contaminate.  We present a novel microfluidic system that can fractionate and deliver nucleic acid (NA) fractions from the nucleus (nNA) versus the cytoplasm (cNA) from single cells to independent downstream analyses.  Our technique leverages a selective electrical lysis which disrupts the cell’s (outer) cytoplasmic membrane, while leaving the nucleus relatively intact. We selectively extract, purify, and preconcentrate cNA using isotachophoresis (ITP).  The ITP-focused cNA and nNA-containing nucleus are separated by ITP and fractionated at a bifurcation downstream and then extracted for off chip analyses. We will present example applications of this fractionation including qPCR and next generation sequencing (NGS) analyses of cNA vs. nNA.  This will include preliminary NGS analyses of nuclear vs. cytoplasmic RNA fractions to analyze gene expression and splicing.  We hypothesize that the robust and precise nature of our electric field control is amenable to further automation to increase throughput while removing manuals steps.