Abstract 16037: In vivo Imaging of Oxidative Stress in Mesenchymal Stromal Cells Transplanted After Myocardial Ischemia/Reperfusion Injury
Background Cell therapy for myocardial repair is limited by poor engraftment of transplanted cells. During myocardial ischemia/reperfusion (IR) this may be compounded by pro-oxidant conditions which adversely effect cell survival and function. It is therefore critical to understand the biology of transplanted cells in the host myocardium. This study hypothesized that the oxidative status of progenitor cells can be monitored in vivo using reporter gene-based molecular imaging.
Methods and Results Rat mesenchymal stromal cells (MSCs) were transfected with a novel oxidative stress sensor, comprising the Firefly luciferase reporter gene driven by the pro-oxidant enzyme promoter NAD(P)H p67phox and a cell viability reporter gene (CMV-Renilla luciferase). After in vitro validation of the sensor, MSCs (7.5x105) were transplanted into a rat model of IR (30min ischemia) and bioluminescence imaging was used to monitor their oxidative stress in vivo for 48h. This model resulted in a 50% decrease in left ventricular fractional shortening, along with time-dependent increases in myocardial levels of the pro-oxidant enzymes NAD(P)H p67phox and 8-hydroxy-2’-deoxyguanosine, shown by Western blot and immunohistochemistry. By comparison to their signal in sham controls, MSCs yielded higher Firefly luciferase activity in IR rats (4.0-fold at 6h n=6, 2.3-fold at 24h n=3, 2.7-fold at 48h n=3; P<0.05 for each time; Figure). These data were confirmed by ex vivo measurement of cardiac Firefly luciferase activity, as an indicator of oxidative stress, which was 2.8-fold higher in the IR group than in shams at 48h, after correction for cell number (Renilla luciferase) (P<0.05, n=3).
Conclusion Reporter gene-based molecular imaging allows noninvasive assessment of changes in cellular oxidative stress after delivery to ischemic myocardium. This provides a template to monitor key biological interactions between transplanted cells and their environment in living subjects.
- © 2011 by American Heart Association, Inc.