In vivo detection of stem cells grafted in infarcted rat myocardium.
The evaluation of stem cell-mediated cardiomyoplasty by noninvasive in vivo imaging is critical for its clinical application. We hypothesized that dual-tracer small-animal SPECT would allow simultaneous imaging of (99m)Tc-sestamibi to assess myocardial perfusion and of (111)In-labeled stem cells to delineate stem cell engraftment.


METHODS
Three to 4 million rat embryonic cardiomyoblasts (H9c2 cells) were labeled with 11.1-14.8 MBq (0.3-0.4 mCi) of (111)In-oxyquinoline and then injected into the border zones of infarcted myocardium of rats. (111)In images were acquired with a SPECT scanner 2, 24, 48, 72, and 96 h after the stem cells were injected into the infarcted myocardium. To visualize the perfusion deficit in the infarcted myocardium, we injected 74 MBq (2 mCi) of (99m)Tc-sestamibi (Cardiolite) intravenously 48 h after grafting. Dual-isotope pinhole SPECT was used to image (99m)Tc-sestamibi uptake simultaneously with (111)In to delineate retention of (111)In-labeled stem cells. The presence of labeled stem cells was confirmed by autoradiography and histology.


RESULTS
SPECT of (99m)Tc-sestamibi was used to delineate perfusion deficits and infarcted myocardium. Bull's-eye plots indicated that the (111)In signal from the labeled stem cells overlapped the perfusion deficits identified from the (99m)Tc-sestamibi images. The (111)In signal associated with the radiolabeled stem cells could be detected with SPECT of the heart for 96 h after engraftment.


CONCLUSIONS
This study demonstrated the feasibility of using dual-isotope pinhole SPECT for high-resolution detection of perfusion deficits with (99m)Tc-sestamibi and with (111)In-labeled stem cells grafted into the region of the infarct.
Zhou
Rong
R
Department of Radiology, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA.
Thomas
Daniel H
DH
Qiao
Hui
H
Bal
Harshali S
HS
Choi
Seok-Rye
SR
Alavi
Abass
A
Ferrari
Victor A
VA
Kung
Hank F
HF
Acton
Paul D
PD
D000818:Animals; D007089:Image Enhancement / Q000379:methods; D007205:Indium Radioisotopes; D008297:Male; D009203:Myocardial Infarction / Q000000981:diagnostic imaging* / Q000601:surgery*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D033581:Stem Cell Transplantation / Q000379:methods*; D013234:Stem Cells / Q000000981:diagnostic imaging*; D017256:Technetium Tc 99m Sestamibi; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*
D007205:Indium Radioisotopes; D017256:Technetium Tc 99m Sestamibi