Know more

Molecular phenotyping from tissue sections

The search for markers can be applied to tissues by direct in situ analysis by MALDI-TOF mass spectrometry.
This approach can be applied to proteomics as well as lipidomics.
Tissue phenotyping or tissue profiling consists of analysing biomolecules at one or more points in a tissue in order to obtain spectral profiles characteristic of a tissue or region of interest.
After cryosection, the matrix can be manually deposited using a pipette. Several average spectra can then be recorded for each of these spots.
Tissue profiling is applied for relatively homogeneous tissues (same profiles expected at several points) as opposed to molecular imaging which will be applied rather for the analysis of highly differentiated tissues.
The spectral profiles obtained for different spots, from different tissue sections >> from different organs >> from different animals >> from different conditions are then processed for differential analysis in order to characterize biomarkers.
This approach has recently been applied to the proteomic analysis of cardiac muscle, in the ram, to evaluate the damage caused by electric shocks from a defibrillator.

©PIXANIM@INRAE

Bodin A, Labas V, Bisson A, Teixeira-Gomes AP, Blasco H, Tomas D, Combes-Soia L, Marcelo P, Miquelestorena-Standley E, Baron C, Angoulvant D, Babuty D, Clementy N.Acute pathophysiological myocardial changes following intra-cardiac electrical shocks using a proteomic approach in a sheep model. Sci Rep. 2020 Nov 20;10(1):20252.doi: 10.1038/s41598-020-77346-x. PMID: 33219330; PMCID: PMC7679418.

Molecular phenotyping from biological fluids

Biological fluids are also major targets for the search for markers of a peptide, protein or lipid nature.
Their analysis by MALDI-TOF mass spectrometry may require prior treatment, particularly in proteomics. Depending on the fluids, desalting steps by SPE (ex Zip Tip C4 or C18, spin columns) or protein precipitation or ultracentrifugation (ex Amicon, centricon) can be applied to enrich within a certain mass range. However, in lipidomics, fluids are analysed directly by MALDI-TOF, without prior lipid extraction, using the negative and positive mode (polarity applied to the MALDI plate) in order to visualise different families of lipids.
PIXANIM applies molecular phenotyping by high throughput profiling to different biological models such as saliva, seminal plasma, follicular fluid, cervical mucus, oviductal fluid...
Profiling can also be applied specifically to vesicles present in fluids such as exosomes or microvesicles, in both proteomics and lipidomics.
E.g.: MALDI-TOF spectra representative of exosomes and microvesicles from bovine follicular fluid.

©PIXANIM@INRAE