Cells on the target matrix-assisted laser-desorption/ionization time-of-flight mass-spectrometric analysis of mammalian cells grown on the target

Summary

Handling of small volumes and small amounts of analytes is important in biological science. When the sample amount is limited it is beneficial to be able to investigate the biological variation in expression and processing of cellular material by screening a single cell or a few cells. In this study matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry (MALDI TOF MS) was used to analyse single small mammalian cells (rat adrenal pheochromocytoma PC 12 cells) grown directly on the sample target. The cells were screened for peptide and protein content and analysed before and after stimulation with nerve-growth factor (NGF), a neurotrophic factor. Single-cell analysis of on-target-grown cells was also compared with whole cells placed on top of a matrix layer and with cellular extracts analysed using the conventional sample-matrix mixture technique. The analysis of on-target-grown cells resulted in mass spectra of greater intensity, thus providing more information about cellular peptide and protein content. Stimulation with NGF resulted in the detection of over 14 new peptides and proteins, demonstrating the potential of this technique for the investigation of cellular events, direct protein profiling, and cell fingerprinting. This unique and simple strategy provides the possibility of studying intact cells while keeping the cells in contact with other cells and substrates. Furthermore, the often complicated sample handling in single-cell analysis is also eliminated, making the technique more versatile for new users of biotechnology and cell biology.