Characterization of the inflammatory response in a photothrombotic stroke model by MRI: implications for stem cell transplantation.
OBJECTIVE
The aim of this study was to evaluate the specificity of magnetic resonance imaging (MRI) contrast in a photothrombotic (PT) stroke model with and without engraftment of superparamagnetic iron oxide (SPIO)-labeled stem cells.


METHODS
We monitored animals with PT stroke versus animals with PT stroke and stem cell engraftment by T(2)/T(2)*w MRI 4-8 h and 2, 4, 6/7 and 14 days after PT induction. Results were correlated with immunohistochemistry.


RESULTS
T(2)*w MRI images showed hypointense contrast due to the accumulation of inflammatory cells and corresponding iron accumulation and glial scar formation in the border zone of the lesion, similar as what was observed for SPIO-labeled cells. Histological analysis was thus indispensable to distinguish between labeled transplanted cells and immune cells.


CONCLUSIONS
These results raise caution regarding the non-invasive monitoring of SPIO-labeled transplanted stem cells by MRI in models that result in a strong inflammatory response.
Vandeputte
Caroline
C
Division of Nuclear Medicine, Katholieke Universiteit Leuven, Leuven, Belgium.
Thomas
Debby
D
Dresselaers
Tom
T
Crabbe
Annelies
A
Verfaillie
Catherine
C
Baekelandt
Veerle
V
Van Laere
Koen
K
Himmelreich
Uwe
U
D000818:Animals; D001808:Blood Vessels / Q000378:metabolism / Q000473:pathology; D038524:Diffusion Magnetic Resonance Imaging; D004195:Disease Models, Animal; D005455:Fluorescent Antibody Technique; D049452:Green Fluorescent Proteins / Q000378:metabolism; D007249:Inflammation / Q000150:complications* / Q000473:pathology; D007501:Iron / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D017628:Microglia / Q000378:metabolism / Q000473:pathology; D039902:Multipotent Stem Cells / Q000166:cytology; D051381:Rats; D011916:Rats, Inbred F344; D033581:Stem Cell Transplantation; D020521:Stroke / Q000150:complications* / Q000473:pathology / Q000628:therapy*; D013927:Thrombosis / Q000150:complications* / Q000473:pathology / Q000628:therapy*
D049452:Green Fluorescent Proteins; D007501:Iron