An innovative mass spectrometry-diagnostic approach developed in the last years is called “MALDI-TOF imaging mass spectrometry” (MALDIIMS) representing one of the most exciting and promising challenge in the field of diagnostic based-mass spectrometry [13]. This very recent technology exploits the methodology of MALDI-TOF MS combined with the direct employment of histological sections, therefore returning a direct molecular analysis from raw samples [14].
MALDI-IMS provides profiles and two dimensional ion density maps of molecules directly from raw tissue sections, showing the relative abundance and spatial distribution of molecules. Consequently, it gives a protein profile expression with high sensitivity of an histological well defined tissue area, avoiding the loss of some important information coming up from the classic analytical separation methodologies (Fig. 3). Subsequently, proteins identification might be pursued using a classic approach as described for biological fluid investigations.
In conclusion, MALDI-TOF-MS pattern-profiling will undoubtedly attain a prominent and lasting position in the future of the diagnostic. However, today the pattern-profiling proteomics methodology may not be quite reproducible, because several line of evidence indicate that there are a number of clinical and analytical chemistry factors that are major sources of variability and bias [15] (blood samples collection, serum preparation, storage and handling, sample extraction, etc.). Furthermore, human plasma and serum proteomics may be particularly susceptible to observational biases because many possible confounding factors such as smoking, diet or ascertainment bias. These could conceivably cause a phenotypic response that may be confused with a specific characteristic of the disease process under investigation. Future perspectives focus in standardizing samples preparation and preservation, reliable methods validation procedure in order to evaluate the significance of mass spectrometry-profiling proteomics in the clinical practices.
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