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Imagerie Moléculaire
Hervé Trillaud, Chrit Moonen
Laboratory for Molecular and Functional Imaging: from Physiology to Therapy
CNRS/ University Victor Segalen Bordeaux Bordeaux, France
Gene expression profile
List of 210 genes with highest differences in expression profile between Prostate Cancer and Benign Prosthetic Hyperplasia
Down regulation
Up regulation
Luo et al, Cancer Res, 2001
Seeing genes in action
Molecular Imaging: Spatio-temporal mapping of gene expression and its physiological consequences
PET/SPECT
MRI
Optics
Ultrasound
Outline
Improved diagnostics for (individualized) therapy Seeing genes in action:(trans)gene expression Seeing drugs in action Biomarkers
Therapy guided by Molecular Imaging Combined diagnostic/therapeutic contrast agents Local drug delivery Spatio-temporal control of transgene expression Stem cell therapy
Conclusion/Challenges ahead
Outline
Improved diagnostics for (individualized) therapy Seeing genes in action:(trans)gene expression Seeing drugs in action Biomarkers
Therapy guided by Molecular Imaging Combined diagnostic/therapeutic contrast agents Local drug delivery Spatio-temporal control of transgene expression Stem cell therapy
Conclusion/Challenges ahead
Luciferase geneCMV promotor
+ luciferin
Mapping transgene expression in gene therapy: adding a spy
Cancer cells overexpressing luciferaseCancer cells overexpressing luciferase
Photon emissionLowik et al
Leiden, The Netherlands
Optical Imaging
Metastases of luciferase overexpressingcancer cells
i.p. luciferin
CCD Camera
intensifier screen
photonemission
Imageanalysis
0
500
1000
1500
2000
0 5 10 15 20 25 30
days
Photoncounting
Experimental bone metastasis 20 days after intra-cardiac injection (3x106 cells)
Day 20 Day 34Day 30Day 27Day 23
Paclitaxel15 mg/kg, iv, q.d.
Days 20-24
Vehicle
B
A
Lassota et al., Novartis
Optical Imaging
Very powerful tool for rapid evaluation of drug efficacy
Limited clinical use because of light penetration/scattering problems
seeing drugs in action using molecular imaging
Mapping gene expression: MRI
As compared to PET and optical methods, MRI requires a higher concentration of contrast agent
Need a spy with amplification of contrast
Imaging gene expression: MRIAmplification required
MR contrast agent is a weak relaxation agent until galactosidase has cleaved the galactose unit: inner sphere of Gd3+ becomes available to water
Fluorescence image
MRI
Xenopus Laevis embryos: Galactosidase + Green Fluorescent Protein mRNA injection on right.
Meade et al. Nature Biotech 2000
Imaging transgene expression: MRI
Co-expression of transferrin receptor, probed with super-paramagnetic particles
Weissleder et al., Nature Med. 6, 2000Tumor expressing transferrin receptor
Control (no transferrin receptor)
Parametric T2* map(color overlay proportional to T2*)
Expression of endogenous genes of special interest in cancer
General for almost all tumors Angiogenesis (VEGF receptor, Integrins) Proteases (Cathepsin, Matrix MetalloProtease) Apoptosis (Annexin V)
Specific HER2/neu (overexpressed in 25% of breast cancers) P53
Need for specific contrast agent
Target specific part MAB (fragments) Peptides Aptamers (short DNA/RNA
strings)
Linkage
Contrast agent (multiple) Gd Iron particle
Specific contrast agent design for MRI
Imaging of the HER-2/neu receptor with MRI
Artemov et al. Cancer Research, 2003
Non-HER expressingTumor line
HER expressingTumor line
In vitro In vivo
Melanoma Angiogenesis: Detection With v3 Integrin-Targeted Paramagnetic
Nanoparticles
Time course after injectionof target specific contrast agent
Wickline, Lanza et al St Louis
Imaging biomarkers for cancer diagnosis and treatment
Identification of unique signatures related to gene expression
Early diagnosis and detection of metastases (PET FDG)
Assessment of drug response
Helpful in therapeutic decision: stratification
Major field of impact for MRI Perfusion changes in validation of angiogenesis drugs Diffusion changes in drug response Choline metabolism Thermal dose assessment in tumor ablation Macrophage activity
Prostate cancer: improved diagnostics using cell labeling:
Detection of metastases in Detection of metastases in lymph nodes using lymph nodes using USPIOUSPIO
(Sinerem, Combidex)(Sinerem, Combidex)
????
Harisinghani, Barentsz et al. NEJM 2003
Outline
Improved diagnostics for (individualized) therapy Seeing genes in action:(trans)gene expression Seeing drugs in action Biomarkers
Therapy guided by Molecular Imaging Combined diagnostic/therapeutic contrast agents Local drug delivery Spatio-temporal control of transgene expression Stem cell therapy
Conclusion/Challenges ahead
Combined diagnostic/therapeutic contrast agents/drugs
Radio-labelled drugs for detection (PET, SPECT) and radio-therapy
Specific contrast agent used subsequently for (pro)drug delivery Modular contrast agents for MRI, US
Target specific part MAB (fragments) Peptides Aptamers (short DNA/RNA
strings)
Linkage
Contrast agent (multiple) Gd Iron particle
Drugs
Combined MR contrast agents for imaging/therapy
D
4x
ControlDXR-NP
Rejection of Mouse Melanoma 7d after -Targeted Doxorubicin Nanoparticles
Tumor Tumor
Inflammatory cells
0
25
50
75
100
0
25
50
75
100
Targeted DXR Control
rejection viable
Wickline, Lanza et al St Louis
MRI guided FUS for spatio-temporal control of gene expression under control of a heat sensitive
promoter
f zx
FUS heating with automatic feedback MR temperature control
Guilhon et al, J. Gene Med, J. Mol. Imag. 2003
Fully automatic tempcontrol in focal point:SD of 0.58 °C
Analysis of GFP gene Expression using Confocal Microscope
1 cm
Transmission Image Fluorescence Image
Heated region
Outline
Improved diagnostics for (individualized) therapy Seeing genes in action:(trans)gene expression Seeing drugs in action Biomarkers
Therapy guided by Molecular Imaging Combined diagnostic/therapeutic contrast agents Local drug delivery Spatio-temporal control of transgene expression Stem cell therapy
Conclusion/Challenges ahead
Issues in imaging research of stem cells
When and how do stem cells migrate to their target tissue?
When and how do stem cells differentiate in vivo?
What is the timeframe of stem cell multiplication and functional recovery at the target site?
Can we influence stem cell behavior/differentiation in vivo for gene therapy purposes?
Transplantation of cells by intravascular injection (renal artery, rat): Bos et al. Radiology, 2004
referenceDay 2 after stem cell inj
Day 4 after stem cell inj Day 7 after stem cell inj Day 7 after stem cell injEx vivo
<1hr after stem cell inj
Transplantation of 5x106 cells by intravascular injection (portal vein): Bos et al. Radiology, 2004
reference Day 2 (CCl4) <1hr after stem cell inj
Day 4 post stem cell Day 8 post stem cell Day 12 post stem cell
Summary (1)Summary (1)
Molecular imaging allows :
the non-invasive spatio-temporal evaluation of gene
expression
the non-invasive characterization of disease processes on
the molecular levelmolecular level in vivo
the use of image biomarkers for therapy assessment
the further evaluation of animal modelsanimal models for human disease
the rapid development of new treatmentnew treatment strategies such
as gene and (stem) cell-based therapies
Summary (2)Summary (2)
Molecular imaging will lead to :
a need for specialists understanding molecular biology,
imaging and chemistry
blurring between diagnostics and treatment
a new look at clinical imaging instruments with combined
technologies: MRI/(focused)ultrasound; PET/CT; MRI/PET
a large role for optical Molecular Imaging of mice
a paradigm shift in health care towards early molecular
diagnostics and image guided molecular therapy
Ackowledgment
Many thanks for contributions and discussions:
Andreas Jacobs Ralph Weissleder Tobias Schäffter
Alan Koretsky Chris Bakker Simon Cherry
Nicolas Grenier Kullervo Hynynen Tom Meade
Bertrand Tavitian Peter Lassota Silvio Aime
Clemens Lowik Ronald Blasberg Sam Wickline
Arend Heerschap Jim Basilion Dimitri Artemov
Zaver Bhujwalla Jelle Barentsz Robert Muller
Mark Bednarski King Li Michal Neeman
Jeff Bulte Joe Frank Hervé Trillaud