Team:TU-Eindhoven/Project

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Latest revision as of 22:55, 18 October 2013

Abstract

Our project presents an alternative solution to the use of heavy metals MRI contrast agents (since the most commonly used heavy metal Gadolinium may be involved in the induction of diseasesGNSFT Grobner and FC Prischl, Gadolinium and nephrogenic systemic fibrosis. Kidney International 72, 260–264 (2007)Gsrf34Ihsan Ergün, Kenan Keven, et all., The safety of gadolinium in patients with stage 3 and 4 renal failure. Nephrology Dialysis Transplantation 21, 697-700 (2006) and may be toxic when the patient has kidney failuresGintI. Buhaescu and H. Izzedine, Gadolinium-induced nephrotoxicity. The International Journal of Clinical Practice 62, 1113-1118 (2008)) by focusing on CEST MRI. Within CEST imaging, proteins enclosing hydrogen atoms can generate high quality images. Escherichia coli are used to express CEST proteins when the bacteria sense a hypoxic environment due to a promoter designed for this purpose, thus working as both a production and delivery system for the CEST MRI contrast agent. A rapidly evolving research area in the field of oncology is the one focused on bacterial based cancer therapies, in which bacteria like E. Coli and Salmonella are used to induce cell death. Based on this type of cancer therapy, and considering that hypoxic regions are related to tumors, our eventual goal is to use this device to target and image tumors in humans by injecting the bacteria into the bloodstream. A secondary application is the tracking bacteria in bacterial infection studies. For the iGEM competition however, the proteins were only expressed ex-vivo: in both aerobic and anaerobic conditions. An efficient assessment of the CEST properties of the proteins was performed and we confirmed the promoters ability to express proteins in anaerobic environments.

References

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+==Abstract==
+Our project presents an alternative solution to the use of heavy metals MRI {{:Team:TU-Eindhoven/Template:Tooltip | text=contrast agents | tooltip=Substance that can be distinguished from its surroundings on an MRI scan }} (since the most commonly used heavy metal Gadolinium may be involved in the induction of diseases{{:Team:TU-Eindhoven/Template:Ref | id=GNSF | author=T Grobner and FC Prischl | title=Gadolinium and nephrogenic systemic fibrosis| journal=Kidney International | edition=72 | pages=260–264 | year=2007 }}{{:Team:TU-Eindhoven/Template:Ref | id=Gsrf34 | author=Ihsan Ergün, Kenan Keven, et all. | title=The safety of gadolinium in patients with stage 3 and 4 renal failure | journal=Nephrology Dialysis Transplantation | edition=21 | pages=697-700 | year=2006 }} and may be toxic when the patient has kidney failures{{:Team:TU-Eindhoven/Template:Ref | id=Gint | author=I. Buhaescu and H. Izzedine | title=Gadolinium-induced nephrotoxicity | journal=The International Journal of Clinical Practice | edition=62 | pages=1113-1118 | year=2008 }}) by focusing on {{:Team:TU-Eindhoven/Template:Tooltip | text=CEST | tooltip=Chemical Exchange Saturation Transfer }} MRI. Within CEST  imaging, proteins enclosing hydrogen atoms can generate high quality images.  Escherichia coli are used to express CEST proteins when the  bacteria sense a hypoxic environment due to a promoter designed for this purpose, thus working as both a production and delivery system for the CEST MRI contrast agent.  A rapidly evolving research area in the field of oncology is the one focused on bacterial based cancer therapies, in which bacteria like E. Coli and Salmonella are used to induce cell death. Based on this type of cancer therapy, and considering that hypoxic regions are related to tumors, our eventual goal is to use this device to target and image tumors in humans by injecting the bacteria into the bloodstream. A secondary application is the tracking bacteria in bacterial infection studies. For the iGEM competition however, the proteins were only expressed ex-vivo: in  both aerobic and anaerobic conditions. An efficient assessment of the CEST properties of the proteins was performed and we confirmed the promoters ability to express proteins in anaerobic environments.
+{{:Team:TU-Eindhoven/Template:AbstractEnd}}
+==References==
-  '''Abstract'''
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-  Our project presents an alternative solution to the use of heavy metals MRI {{:Team:TU-Eindhoven/Template:Tooltip | text=contrast agents | tooltip=Substance that can be distinguished from its surroundings on a MRI scan }} by focusing on {{:Team:TU-Eindhoven/Template:Tooltip | text=CEST | tooltip=Chemical Exchange Saturation Transfer }} MRI. Within CEST  imaging, proteins enclosing hydrogen atoms generate high quality images.  We use Escherichia coli to create CEST proteins when the  bacteria sense a hypoxic environment due to a promoter designed for this purpose, thus working as a production and delivery system for the CEST MRI contrast agent. Hypoxic regions are related to tumors,therefore our eventual goal is to use this device to target and image tumors in humans by injecting the bacteria into the bloodstream. A second application is tracking bacteria in bacterial  infections studies. For the iGEM competition however, the proteins are only expressed ex-vivo:in aerobic and anaerobic conditions. We aim to achieve an efficient testing of the CEST properties of the proteins and confirm the promoter’s ability to express each   protein.
-==Project Overview==
-{{:Team:TU-Eindhoven/Template:FloatingImage | position=left | size=5 | filename=genDiagramI.png}}
-Our project focuses on a relatively new form of {{:Team:TU-Eindhoven/Template:Tooltip | text=MRI | tooltip=Magnetic Resonance Imaging }}: {{:Team:TU-Eindhoven/Template:Tooltip | text=CEST | tooltip=Chemical Exchange Saturation Transfer }} imaging. CEST imaging proteins contain hydrogen atoms which can be used to create the same image quality as when conventional heavy metals are used. We use Escherichia coli to express CEST proteins that leads to CEST contrast when the bacteria sense a {{:Team:TU-Eindhoven/Template:Tooltip | text=hypoxic | tooltip=Low oxygen saturation }} environment, thus working as a production factory and delivery system for the CEST MRI contrast agent. We use ten proteins, all of which are rich in Lysine and Arginine content. These proteins were selected with the aid of the {{:Team:TU-Eindhoven/Template:Tooltip | text=Protein Data Bank | tooltip=PDB }}, a python program that analizes the obtained amino acid sequences and calculates the ratio of Lysine or Arginine to the total chain length, and molecular dynamics simulations which allowed us to revise the accessibility of the various exchangable hydrogen atoms of the Lysines and Arginines of the selected peptides.
-In order to achieve the production of our bacteria based CEST MRI contrast agent, we must create a series of diverse [[Team:TU-Eindhoven/Modeling | models]] focusing on the different components of the MRI contrast agent production. These models range from the selection of the most adequate proteins for CEST MRI to the behaviour of the FNR promotor and the bacterial killing mechanism.
-In the [[Team:TU-Eindhoven/Wetlab | lab]] we attempt to produce the CEST MRI proteins, both aerobically and anaerobically. To Enable the anaerobic expression specialized promotors are designed to react to the changes in oxygen saturation and ultimately trigger the protein expression. Once the protein expression is successful either aerobically or anaerobically, these proteins are tested for the quality of their contrast in an MRI machine.
-Based on the principle of our project, we propose two [[Team:TU-Eindhoven/Applications | applications]], tumor CEST MR Imaging and tracking of bacteria in bacterial infections studies. It is well known that tumors present a hypoxic environment, therefore our bacteria can be injected into bloodstream to travel into the tumor region. Once in the tumor region, the hypoxic conditions of the area will trigger the production of the CEST proteins by the E. coli. generating the required CEST contrast agent for MRI. This will ensure that MRI contrast is created where tumors are present, and also provides a good means of tumor targeting for drug delivery systems in the future. Once the CEST MRI images have been taken, the bacteria will be killed and eliminated from the body using the Thymidine kinase/Ganciclovir system as a [[Team:TU-Eindhoven/KillingMechanism | killing mechanism]]. In order to be injected into the bloodstream the bacteria should be modified once more to avoid activating an immune response. Similarly, our production and delivery system can be used for tracking bacteria in bacterial infection studies.
-Further steps include the modifications to the chasis of our device in order to avoid an immune system response, moreover it is necessary to include the kill switch in our device as safety lock.
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