Ratiometric Mass Spectrometry for Cell Identification and Quantitation Using Intracellular “Dual-Biomarkers”

Abstract

This study proposed an easy-to-use method for cell identification and quantitation by ratiometric matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Two pairs of MS peaks in the molecular fingerprint of cells were selected as intracellular dual-biomarkers due to the stability and specificity of their ratio values in different types of hepatocellular cancer (HCC) cell lines. Five types of HCC cells can be thereafter differentiated based on these two pairs of intracellular peptides/proteins. Two types of HCC cells, Huh7 and LM3 were co-cultured as a model to test whether the method is feasible for cell quantitation. The results indicated that the ratiometric peak intensity of the two pair biomarkers exhibits linear relationship with the proportion of Huh7 cells. Furthermore, tumor heterogeneity was simulated by subcutaneously injecting the co-cultured cells into nude mice. The cell type and proportion in the section of grown tumor tissue can be discriminated using the ratiometric MALDI imaging approach. LC-MS/MS detection revealed that one of the biomarker pairs belongs to thymosin family, β4 and β10. The ratiometric MS spectral approach using intracellular dual-biomarkers might become a pervasive strategy for high-throughput cell identification and quantitation, which is vital in tumor heterogeneity study, clinical diagnosis and drug screening.

Profiling embryonic stem cell differentiation by MALDI TOF mass spectrometry: development of a reproducible and robust sample preparation workflow

“…37 It was indicated before that freeze-thawing of cell pellets prior to MALDI TOF MS analysis may have beneficial effects with respect to the number of features identified and overall spectral intensity. 33,46 This is likely due to the freeze/thaw cycle permeating the cell membrane, thus allowing the cytoplasmic contents of the cells to become exposed and more easily ionised. We therefore decided to test whether a freeze/thaw cycle improved MALDI TOF MS analysis of mammalian cell lines and whether freezing before or after a wash with PBS affected sensitivity and spectral quality compared with direct analysis (Fig.…”

“…30 This study enabled the identification of 520 lipid features and classification of neuron-like and astrocyte-like cells, thus allowing lipid profiles to be assigned to particular cellular functions. Characterising the protein signatures of mammalian cells by MALDI-MS is less common when compared with lipid analysis; however it has been used for phenotypic screening of human cancer cell lines, 31,32 identification of cells within a co-culture 33,34 or tissues 35 and detection of transient changes within a specific cell type, such as immune cells. [36][37][38][39] However, many of these studies list dramatically different experimental procedures with several being adapted from existing biotyping protocols.…”

A MALDI-TOF assay identifies nilotinib as an inhibitor of inflammation in acute myeloid leukaemia

“…Spectra-based PCA plots were generated using ClinPro Tools (Bruker Daltonics). A normalized relative peak area was used to measure a pro-inflammatory response between m/z 4632 and 4963 and was calculated with the following equation: This method of intra-spectra quantification (Chen et al , 2017) was robust over ten different passages, where we were able to quantify the inflammatory response by MALDI-TOF MS with Z’>0.5 and P ≤0.001.…”

“…This method of intra-spectra quantification (Chen et al, 2017) was robust over ten different passages, where we were able to quantify the inflammatory response by MALDI-TOF MS with Z'>0.5 and P≤0.001.…”

Advances in MALDI Mass Spectrometry Imaging Single Cell and Tissues

“…Cell suspensions are deposited onto the MALDI target. After drying of the cell suspension liquid, the matrix is dropped onto the analyte and then used for MALDI-MSI (Chen et al, 2017).…”