Molecular histology with imaging Mass Spectrometry
The application of molecular imaging using mass spectrometry in molecular histology is one of the breakthrough technologies in modern biomedical research. A selected number of molecular histology applications that are pursued at AMOLF are described below.
Lipid cartography of mouse atherosclerotic plaques by ToF-SIMS imaging mass spectrometry
A collaboration between the macromolecular ion physics group and the Experimental Vascular Pathology group of Erik Biessen at Maastricht University
The nature and distribution of lipids in atherosclerotic lesions from mice carotid arteries is studied with complementary molecular imaging technique. The lipid content of atherosclerotic plaques determines their mechanical stability, and highly thrombogenic lipids such as lysophosphatidic acids (LPA) can be localized by IMS within lesions.
Spatial resolution down to cellular level using Secondary Ion Mass Spectrometry (SIMS) was performed in order to identify, according to their specific composition, cellular layers of different histological type: phosphate and phosphocholine in vascular smooth muscle cells, cholesterol and LPA in necrotic core. This prima example of translational research in molecular medicine illustrates how innovations from physics can be directly beneficial to biomedical research.
New sample preparation protocols for complementary molecular imaging of brain tissue
A collaboration between the macromolecular ion physics group and the Neuro-Oncology group of Theo Luider and pathologist Max Kros at the Erasmus Medical Centre in Rotterdam
Different complementary imaging mass spectrometry methods, i.e. matrix-assisted laser desorption/ionization (MALDI) and secondary ion mass spectrometry (SIMS) imaging for direct tissue analysis, can be applied on exactly the same tissue sample. This allows the identification of small molecules, peptides and proteins present on the same sample surface. Sample preparation is crucial to obtain high quality, reliable and reproducible complementary molecular images. It is essential to optimize the conditions for each step in the sample preparation protocol, ranging from sample collection and storage to surface modification. We have investigated the importance of correct sample treatment in case of MALDI and SIMS imaging experiments and describe the experimental requirements for optimal sample preparation.
Molecules at the interface of biology and polymers
Imaging mass spectrometry (IMS) has made a big impact in life sciences, giving localized chemical information in tissue samples. Although technical developments have mainly focussed on biological systems, they can very well be applied on combined synthetic/biological systems. IMS could be a very valuable tool for the identification of foreign-body reaction and biodegradation at a molecular level in a drug delivery system. Polymer implants were studied in a rat kidney model. Complementary IMS techniques can contribute in the understanding of the properties of polymers in vivo. A more thorough understanding of these properties opens up possibilities for novel applications of polymers for drug delivery or other medical use.
- The image shows an overlay of an optical image with a mass spectrometric image measured using SIMS (secondary ion mass spectrometry). The colours in the overlay indicate the localization of the characteristic peaks belonging to cholesterol (red), polyethyleneglycol (green) and choline (blue). Thus polymer and tissue can be localized using their molecular profiles.
Hypoxia driven signaling pathways in breast cancer
An NIH funded collaboration between the macromolecular ion physics group and Dr. Kristine Glunde at the Radiology department of Johns Hopkins Medical School in Baltimore, USA
In collaboration with the Johns Hopkins Medical school in Baltimor, USA we study hypoxia-driven molecular signaling pathways in breast cancer. Using various molecular imaging techniques, both in vivo and histological, molecular distribution in tumors, that have grown from human breast cancer cell lines , are mapped two and three-dimensionally.
For this research, which will last four years starting January 2009, AMOLF will use and further develop the high resolution mas spectrometry based molecular imaging. Dr. Kristine Glunde and her group will label selected proteins with GFP. At AMOLF signal molecules are mapped with the same special distribution. KnowEx, the platform for transfer of knowledge, designed at AMOLF for the "Virtual laboratory for e-science", facilitates the bringing together of the various molecular and anatomical image modalities (MRI, Computer Tomography, confocal imaging and MS imaging). This way the researchers hope to visualize for the first time the molecular players that regulate hypoxia-driven processes in breast cancer cells. At the same time the molecular distributions revealed will be used to perform a rapid classification of the cell types within the tumor.
Pinpointing pharmaceutical metabolism: "Google Rat"
A key question in pharmaceutical research focuses on the metabolic pathways. Pharmaceutical research employs imaging MS complementary to whole body autoradiography in both research and development phase of new drugs. MS imaging is particularly interesting as it has the potential to image simultaneously the drugs and their metabolites. MS imaging offers the possibility to not only examine and track drug metabolism in whole animal sections, but can also follow polymer substrate degradation and drug release. With a number of pharmaceutical industries we are developing new imaging protocols for drug metabolic imaging. A protocol we call 'Google Rat' allows us to examine molecular distributions in whole body tissue sections and zoom down to the single cell level on the same sample.