Dual transfer of GFP gene and MGd into stem-progenitor cells: toward in vivo MRI of stem cell-mediated gene therapy of atherosclerosis.
OBJECTIVE
The aim of this study was to develop a new technique, the use of magnetic resonance (MR) imaging (MRI) to monitor gene/MR-cotransferred stem-progenitor cells (SPCs) recruited to atherosclerosis.


METHODS
First, a green fluorescent protein (GFP) gene and a T1 MR contrast agent (motexafin gadolinium [MGd]) were cotransferred into neural or bone marrow (BM)-derived SPCs. GFP expression and MGd signal were confirmed by fluorescent microscopy and quantified by flow cytometry. Cell viability and proliferation were then evaluated by trypan blue exclusion and 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium assay, and GFP/MGd-transferred cells were imaged using 1.5-T and 9.4-T MR scanners. For in vivo validation, GFP/MGd-cotransferred beta-galactosidase-BM SPCs were transplanted to apolipoprotein E-knockout mice, and cell migration to atherosclerotic aortas was monitored using 9.4-T micro-MRI with subsequent histologic correlations.


RESULTS
Fluorescent microscopy demonstrated simultaneous GFP expression and MGd signals in cotransferred-cells. Quantitative flow cytometry showed GFP-positive cells at 47 +/- 25% and 56 +/- 12% and MGd-positive cells at 96 +/- 6% and 57 +/- 11% for neural stem cells and BM cells, respectively. Cell viability and metabolic rates of cotransferred cells were 86 +/- 4% and 84 +/- 12%, respectively. In vivo MRI revealed high MR signals of the aortic walls in GFP/MGd-transferred mice, which were confirmed by histologic correlations.


CONCLUSIONS
This study has initially proven the new concept of MRI for plaque-specific, cell-mediated gene expression of atherosclerosis.
Department of Radiology, University of Washington School of Medicine, Seattle, WA 98195, USA.
Bensheng
B
Qiu
Piper
P
Treuting
Xiangcan
X
Zhan
Daohai
D
Xie
Charles W
CW
Frevert
Xiaoming
X
Yang
D000818:Animals; D050197:Atherosclerosis / Q000175:diagnosis* / Q000235:genetics; D002460:Cell Line; D003287:Contrast Media; D049452:Green Fluorescent Proteins / Q000235:genetics; D008279:Magnetic Resonance Imaging / Q000379:methods*; D045164:Mesenchymal Stem Cell Transplantation / Q000379:methods*; D008665:Metalloporphyrins / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D025321:Surgery, Computer-Assisted / Q000379:methods*
D003287:Contrast Media; D008665:Metalloporphyrins; D049452:Green Fluorescent Proteins; C437683:motexafin gadolinium