Single Cell Untargeted Lipidomics Using Liquid Chromatography Ion Mobility-Mass Spectrometry

Advancements
in technology over the years have propelled omics
analysis to the level of single cell resolution. Following the breakthroughs
in single cell transcriptomics and genomics, single cell proteomics
has recently rapidly progressed, aided by highly sensitive mass spectrometry
instrumentation. However, there is currently a paucity of studies
and methodologies for single cell lipidomics, aside from imaging-based
approaches. Profiling lipids at the single cell level holds promise
for providing novel insights into the complex heterogeneity of cells
in various human disorders. Further, by integrating single cell lipidomics
with other single cell omics including proteomics, it becomes possible
to achieve single cell multiomics, enabling the discovery of novel
molecular signatures. We developed untargeted single cell lipidomics
using nanoflow liquid chromatography-ion mobility spectrometry-mass
spectrometry. To enhance lipid coverage at the single cell level,
the method was conducted in both positive and negative ion modes.
We identified an average of 161 lipids spanning phospholipids, sphingolipids,
cholesteryl esters, and glycerides in positive ion mode from single
cells of human cholangiocarcinoma cells based on a rule-based lipid
annotation. Additionally, an average of 20 species of phospholipids
was identified in the negative ion mode. These preliminary data demonstrate
a new methodology to profile lipids at a single or low input of cells.