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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
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
Mapping transgene expression in
gene therapy: adding a spy
Cancer cells overexpressing luciferase
CMV promotor
Luciferase gene
+ luciferin
Lowik et al
Leiden, The Netherlands
Photon emission
Optical Imaging
CCD Camera
intensifier screen
Image
analysis
photon
emission
2000
Photon
counting
1500
1000
500
i.p.
luciferin
Metastases of luciferase overexpressing
cancer cells
0
0
5
10
15
days
20
25
30
Experimental bone metastasis 20 days
after intra-cardiac injection (3x106 cells)
A
Vehicle
Day 20
Day 23
Day 27
Day 30
Day 34
B
Paclitaxel
15 mg/kg, iv, q.d.
Days 20-24
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: MRI
Amplification 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 superparamagnetic particles
Parametric DT2* map
(color overlay
proportional to
DT2*)
Control (no transferrin receptor)
Tumor expressing transferrin receptor
Weissleder et al., Nature Med. 6, 2000
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
Specific contrast agent design for MRI
 Target specific part
 MAB (fragments)
 Peptides
 Aptamers (short DNA/RNA
strings)
 Linkage
 Contrast agent (multiple)
 Gd
 Iron particle
Imaging of the HER-2/neu receptor with MRI
In vitro
In vivo
Non-HER
expressing
Tumor line
HER
expressing
Tumor line
Artemov et al. Cancer Research, 2003
Melanoma Angiogenesis: Detection With avb3
Integrin-Targeted Paramagnetic Nanoparticles
Time course after injection
of 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
lymph nodes using USPIO
(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
Combined MR contrast agents for
imaging/therapy
 Target specific part
 MAB (fragments)
 Peptides
 Aptamers (short DNA/RNA
strings)
 Linkage
D
 Contrast agent (multiple)
 Gd
 Iron particle
Drugs
Rejection of Mouse Melanoma 7d after anb3Targeted Doxorubicin Nanoparticles
Tumor
4x
Tumor
Inflammatory
cells
rejection
anb3-DXR-NP
Control
viable
Wickline, Lanza et al St Louis
MRI guided FUS for spatio-temporal control of gene
expression under control of a heat sensitive promoter
FUS heating with automatic feedback MR temperature control
f
Fully automatic temp
control in focal point:
SD of 0.58 °C
Guilhon et al, J. Gene Med, J. Mol. Imag. 2003
z
x
1 cm
Analysis of GFP gene Expression
using Confocal Microscope
Heated
region
Transmission Image
Fluorescence Image
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
reference
Day 4 after stem cell inj
<1hr after stem cell inj
Day 2 after stem cell inj
Day 7 after stem cell inj
Day 7 after stem cell inj
Ex vivo
Transplantation of 5x106 cells by intravascular
injection (portal vein): Bos et al. Radiology, 2004
reference
Day 4 post stem cell
Day 2 (CCl4)
Day 8 post stem cell
<1hr after stem cell inj
Day 12 post stem cell
Summary (1)
Molecular imaging allows :
 the non-invasive spatio-temporal evaluation of gene
expression
 the non-invasive characterization of disease processes on
the molecular level in vivo
 the use of image biomarkers for therapy assessment
 the further evaluation of animal models for human disease
 the rapid development of new treatment strategies such
as gene and (stem) cell-based therapies
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