Noninvasive imaging of angiogenesis with a 99mTc-labeled peptide targeted at alphavbeta3 integrin after murine hindlimb ischemia.
BACKGROUND
Noninvasive imaging strategies play a critical role in assessment of the efficacy of angiogenesis therapies. The alpha(v)beta3 integrin is activated in angiogenic vessels and represents a potential target for noninvasive imaging of angiogenesis.


RESULTS
We evaluated a 99mTc-labeled peptide (NC100692) targeted at alpha(v)beta3 integrin for imaging in an established murine model of angiogenesis induced by hindlimb ischemia. Control mice (n=9) or mice with surgical right femoral artery occlusion (n=29) were injected with NC100692 (1.5+/-0.2 mCi IV) at different times after femoral occlusion (1, 3, 7, and 14 days) for in vivo pinhole planar gamma camera imaging. Tissue from hindlimb proximal and distal to occlusion was excised for gamma well counting and for immunostaining. On in vivo pinhole images, increased focal NC100692 activity was seen distal to the occlusion at days 3 and 7. This increase in relative NC100692 activity was confirmed by gamma well counting. Lectin staining confirmed increased angiogenesis in the ischemic hindlimb at these time points. A fluorescent analogue of NC100692 was used to confirm specificity and localization of the targeted tracer in cultured endothelial cells. In addition, endothelial cell specificity was confirmed on tissue sections with the use of dual immunofluorescent staining of endothelium and the fluorescent analogue targeted at the alpha(v)beta3 integrin.


CONCLUSIONS
A 99mTc-labeled peptide (NC100692) targeted at alpha(v)beta3 integrin selectively localized to endothelial cells in regions of increased angiogenesis and could be used for noninvasive serial "hot spot" imaging of angiogenesis. This targeted radiotracer imaging approach is a major advance in tracking therapeutic myocardial angiogenesis and has an important clinical potential.
Hua
Jing
J
Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, Conn 06520-8017, USA.
Dobrucki
Lawrence W
LW
Sadeghi
Mehran M
MM
Zhang
Jiasheng
J
Bourke
Brian N
BN
Cavaliere
Patti
P
Song
James
J
Chow
Conroy
C
Jahanshad
Neda
N
van Royen
Niels
N
Buschmann
Ivo
I
Madri
Joseph A
JA
Mendizabal
Marivi
M
Sinusas
Albert J
AJ
D000818:Animals; D004730:Endothelium, Vascular / Q000737:chemistry / Q000166:cytology / Q000000981:diagnostic imaging; D005456:Fluorescent Dyes; D006614:Hindlimb / Q000098:blood supply; D039302:Integrin alphaVbeta3 / Q000032:analysis* / Q000378:metabolism; D007511:Ischemia / Q000000981:diagnostic imaging*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018919:Neovascularization, Physiologic; D009842:Oligopeptides / Q000493:pharmacokinetics; D016491:Peripheral Vascular Diseases / Q000000981:diagnostic imaging; D011875:Radionuclide Angiography / Q000379:methods*; D013667:Technetium
D005456:Fluorescent Dyes; D039302:Integrin alphaVbeta3; D009842:Oligopeptides; D013667:Technetium; C047981:arginyl-glycyl-aspartic acid