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3R-Project 111-08
Establishment of an organ ex-vivo tissue slice model for cardiovascular research in particular for therapeutic atherosclerosis targeting
Xueya Wang, Rahel Bänziger and Patrick Hunziker
Medical Intensive Care Unit, University Hospital Basel, Petersgraben 4, CH-4031 Basel, Switzerland
hunziker@uhbs.ch, rbaenziger@uhbs.ch, dou.wang@unibas.ch
Keywords: human; mice; rodents; transgenic mice; blood: vessel; atherosclerosis; infectious diseases; cell cultures: intact tissue; reduction; replacement; drug screening
Duration: 2 years End of the Project: 2011
Background and Aim
Atherosclerosis is the main cause of death nowadays in the Western world. Heart attacks and strokes kill more people than cancer. An early stage in atherosclerotic disease is the formation of so-called plaques (mostly deposits of fat and cell debris) in the aorta and other blood vessels. The plaques grow in size and are prone to inflammation due to infiltrating cells of the immune system (macrophages).
Once the plaques are infected, the early (or stable) plaques are rendered unstable and tend to rupture releasing their content into the blood vessel and therefore causing the blood to coagulate.
A possible consequence of this event is the formation of a thrombus and, in the worst case, a following heart attack or stroke.
We are working in atherosclerosis research using a transgenic mouse model (ApoE-deficient mice) which shows an early onset of plaque development, especially when fed with a high-fat and high-cholesterol diet. Our aim is the reduction and/or stabilization of the unstable plaques.
With the help of nano-sized particles (nanocontainers built with tri-block polymers that form vesicles with an diameter between 100 and 200 nm), we can encapsulate drugs and other substances and target them specifically to the infected cells (macrophages). As shown in the publications listed below, these nanocontainers provide a system for the safe and specific delivery of drugs.
The aim of this project is to reduce the number of animals used in atherosclerosis research with the ApoE-deficient mouse model. We are therefore planning to establish an ex-vivo aortic tissue slice model in culture to study different experimental settings (the efficacy and concentration of drugs) on small stretches of a single isolated aorta before we proceed to the in-vivo approach.
In parallel, we want to compare the results obtained from the mouse model with human aortic tissue samples obtained from operations and therefore test the relevance of the ApoE-deficient mouse model for human research.
Method and Results
in progress (present status)
Mouse breeding and preparation of the aorta
For the experiments, apolipoprotein E (ApoE)-deficient mice on a C57Bl/6 background were purchased from Charles River and cared for in compliance with Swiss federal legislation. The animals will be fed a high-fat and high-cholesterol diet for at least 4 months to enhance their plaque load.
The animals will be anaesthetized and their vasculature perfused by cardiac puncture with PBS to remove all blood from the vessels. The freshly isolated aortas will then be put into petri-dishes with an appropriate medium and kept in the tissue culture incubator. The establishment of the right culture conditions that allow a prolonged vitality and viability of the aortic tissue slices in-vitro will be the first focus of this project.
Preparation of human aortic material
The arterial tissue from human donors (surgical specimens) will be placed immediately in medium containing all necessary supplements. The establishment of the human tissue culture will be done in parallel with the one of the mouse, applying the knowledge from the mouse ex-vivo model and the help of preliminary data.
Once the ex-vivo tissue models are established, we want to study and compare the effects of our functionalized nanocontainers, which are loaded with different drugs, on the biology and the different cell types of the atherosclerotic plaques in both model systems. We are specifically interested in finding ways to prevent destabilization or to enhance the stability of the plaques.
In parallel, our results and also published results, are examined and compared.
The two model systems can then be compared and the relevance of the ApoE-deficient transgenic mouse model for human atherosclerosis research can be evaluated.
Conclusions and Relevance for 3R
In atherosclerotic research, one of the best animal models is the ApoE-deficient transgenic mouse and that is why a lot of these animals are used worldwide.
The availability of a validated ex-vivo aortic tissue slice model will have a great potential for the reduction of these animal experiments in drug testing, toxicity experiments as well as in basic research.
The comparison of the mouse ex-vivo as well as in-vivo data with human data from surgical specimens, as planned by our research, will add validation to the most widely used animal model used in atherosclerotic research.
References
1. Pavel Broz, Nadav Ben-Haim, Mariusz Grzelakowski, Stephan Marsch, Wolfgang Meier, Patrick Hunziker
Inhibition of Macrophage Phagocytotic Activity by a Receptor-targeted Polymer Vesicle-based Drug Delivery Formulation of Pravastatin.
J Cardiovasc Pharmacol. 2008 Mar ;51 (3):246-252
2. Broz P, Marsch S, Hunziker P.
Targeting of vulnerable plaque macrophages with polymer-based nanostructures
Trends Cardiovasc Med. 2007 Aug;17(6):191-197
3. Broz P, Driamov S, Ziegler J, Ben-Haim N, Marsch S, Meier W, Hunziker P.
Toward Intelligent Nanosize Bioreactors: A pH-Switchable, Channel-Equipped, Functional Polymer Nanocontainer.
Nano Lett. 2006 Oct 11;6(10):2349-2353.
Figures
Figure 1: In this idealized image, engineered nanocarriers find and attack specific diseased cells. The yellow, stick-like objects (ligands) allow the nanocarriers to bind to particular cells.
Figure 2: Oil RedO staining of a ApoE-deficient mouse aorta (red are dots are the fat-rich plaques)
| Last modified 2010/08/29 |  |