Mass spectrometry imaging (MSI) is a proven and effective tool for evaluating the in situ distribution of proteins, peptides, lipids, or metabolites within biological specimens.1,2

MSI acquires molecular data that provide insights into the biochemical variations within clinical specimens. These biochemical variations can be correlated with specific histological features and disease states. Hundreds of biomolecules can be monitored simultaneously to obtain a comprehensive molecular profile of clinical specimens. Through the use of bioinformatics tools, these molecular profiles can be statistically assessed to differentiate between healthy and diseased tissue types, to differentiate between diseases with similar clinical presentations, and to identify molecular distinctions linked to treatment response. This ability to differentiate between phenotypes, in contrast to gene-based profiling tests, enables the development of more accurate diagnostic and prognostic tests.

mass spectrometry imaging

HGMS Profiling

Histology guided mass spectrometry (HGMS) profiling is a propriety application of MSI that allows for the classification of clinical tissue specimens in a high throughput and efficient manner. Whereas MSI typically involves whole tissue imaging, HGMS supplements MSI with histopathological targeting to assess the in situ distribution of select biomolecules.3,4 In this way, HGMS profiling focuses on the direct analysis of histopathologically relevant areas.

HGMS profiling can be performed on formalin fixed paraffin embedded (FFPE) tissue. Serial tissue sections are collected, with one tissue section mounted onto a conductive indium-tin oxide (ITO) slide that is compatible with the mass spectrometer and another tissue section mounted onto a standard microscope slide that is subjected to histological staining.

An experienced veterinary pathologist reviews and annotates the stained tissue section, and the resulting annotated image is merged with the corresponding digital image of the unstained tissue section. This composite image enables the targeting of precise tissue locations for subsequent analysis. The unstained tissue section is subjected to a specimen preparation method designed for the targeted biochemical class, and a molecular profile is acquired using a Bruker rapifleX™ MALDI TOF mass spectrometer. This molecular profile, also referred to as an average mass spectrum, is statistically analyzed by a clinically validated algorithm that classifies the tissue specimen based on the overall distribution and relative intensity of detected biomolecules.

Specimen receipt workflow diagram

Biofluid MS Profiling

In addition to tissue, biofluid mass spectrometry (MS) profiling can be performed on a variety of biological specimens, including urine, cerebrospinal fluid, and various cytological specimens. Similar to HGMS, biofluid MS profiling involves the acquisition of a molecular profile via a Bruker rapifleX™ MALDI TOF mass spectrometer, and data are subsequently analyzed with a clinically validated algorithm to classify the specimen according to the relevant phenotype, including disease state or treatment response.