Single-Cell Lipidomics: An Automated and Accessible Microfluidic Workflow Validated by Capillary Sampling

We report the first demonstration of a microfluidics-based
approach
to measure lipids in single living cells using widely available liquid
chromatography mass spectrometry (LC-MS) instrumentation. The method
enables the rapid sorting of live cells into liquid chambers formed
on standard Petri dishes and their subsequent dispensing into vials
for analysis using LC-MS. This approach facilitates automated sampling,
data acquisition, and analysis and carries the additional advantage
of chromatographic separation, aimed at reducing matrix effects present
in shotgun lipidomics approaches. We demonstrate that our method detects
comparable numbers of features at around 200 lipids in populations
of single cells versus established live single-cell capillary sampling
methods and with greater throughput, albeit with the loss of spatial
resolution. We also show the importance of optimization steps in addressing
challenges from lipid contamination, especially in blanks, and demonstrate
a 75% increase in the number of lipids identified. This work opens
up a novel, accessible, and high-throughput way to obtain single-cell
lipid profiles and also serves as an important validation of single-cell
lipidomics through the use of different sampling methods.