Direct lipido-metabolomics of blood cells and exosomes by live single-cell mass spectrometry
Floating cells have not been the target of single cell mass spectrometry due to low adhesion properties. And while many omics branches have been established, little research has been done to combine these specialties. In this study, we have successfully trapped and analyzed a single white blood cell from a single drop of blood. A single lymphocyte (identified by morphology and structure) was monitored live and picked up using a nanospray tip attached to a micromanipulator. The cell was then injected with minimal pre-treatment into the Orbitrap mass analyzer and the lipido-metabolomics profile was established.
On the other hand, organelle analysis has become an essential target for single cell analysis. Exosomes are granules excreted by most, if not all, living cells, although their specific role and function is still poorly understood. Difficulties in isolating exosomes arise from their small size (30-100nm in diameter) and low concentration. We have efficiently isolated and analyzed exosomes of the blood through our nanospray tip methodology, and in doing so, have taken the first step in compiling the first lipido-metabolomics profile of exosomes.