Project Details
Projekt
Targeting of perfluorocarbon nanoemulsions for imaging of specific cell surface epitopes by non-invasive in-vivo 19F MRI
Subject Area
Nuclear Medicine, Radiotherapy, Radiobiology
Term
from 2010 to 2017
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 170888146
In the current funding period, we successfully demonstrated that 19F MRI (magnetic resonance imaging) in combination with perfluorocarbon nanoemulsions (PFC-NE) is a sensitive diagnostic tool for inflammation imaging in a variety of disease models. Based on this prior work, we now plan to substantially extend the application field of this approach for the specific in-vivo targeting of individual cell surface epitopes. We will use a sterol-based post-insertion technique (SPIT) to modify PFC-NE with specific antibodies, Fab-fragments or single-chain antibodies. In case of SPIT, a ligand is coupled to a sterol-PEG-anchor (PEG = polyethylenglycol), which contains a reactive group at its membrane-distal end. Subsequently, this construct is inserted into the lipid layer of preformed PFC-NE. SPIT enables the coupling of ligands to PFC-NE which would be otherwise destroyed during the high-pressure homogenization process. We already exploited this strategy successfully for the visualization of developing thrombi by coupling alpha-2-antiplasmin peptide to the surface of PEGylated PFC-NE.Using this technique we will experimentally address two important biological questions: 1) Selective visualization of preexisting venous thrombi To visualize existing thrombi, we will modify PFC-NE with IgG and Fab-fragments of JON/A(PE) and with a single-chain-antibody (LB24) which both bind to the activated form of the GPIIb/IIIa receptor on murine platelets. All antibodies are well characterized and will be provided by Professor Nieswandt (Würzburg) and Professor Peter (Melbourne, Australia). After coupling to PFC-NE, the sensitivity and specificity of thrombus detection will be verified in-vivo with 19F MRI using an established thrombosis model. 2) Tracking of epicardial mesenchymal progenitor cells (EPDCs) and monocytes We have recently discovered that EPDCs, which develop after myocardial infarction and are able to differentiate into smooth muscle cells and cardiomyocytes, are capable to endocytose PFC-NE in-vivo. Therefore, EPDCs as well as monocytes can be visualized by 19F MRI after intravenous injection. To selectively label and track EPDCs or monocytes, we will develop target-specific PFC-NE. To this end, cell surface proteins which are exclusively expressed by EPDCs or monocytes will be identified by mass spectrometry (Cooperation Professor Stühler, Düsseldorf). Subsequently, monoclonal antibodies are raised against these epitopes (Cooperation Professor Nieswandt) and coupled to PFC-NE by the SPIT-technique for selective non-invasive 19F MRI of EPDCs/monocytes after myocardial infarction.The overall goal of this project is to develop a versatile platform for the in-vivo visualization of specific target-structures by 19F MRI which can be applied to biologically relevant questions.
DFG Programme
Research Grants
International Connection
Australia
