Targeted ultrasound imaging of apoptosis with annexin a5 microbubbles in acute Doxorubicin-induced cardiotoxicity.
BACKGROUND
The aim of this study was to assess the feasibility of targeted ultrasound imaging on apoptosis with annexin A5 microbubbles (A5MB) in acute doxorubicin-induced cardiotoxicity.


METHODS
Avidinated and octafluoropropan-filled phospholipid microbubbles were conjugated with biotinylated annexin A5. To confirm the specific binding of A5MB, flow cytometry was performed with hydrogen peroxide induced apoptosis in rat aorta smooth muscle cells incubated with fluorescein-5-isothiocyanate (FITC) labeled annexin A5 and A5MB. Adult male rats were injected intraperitoneally with 5 mg/kg doxorubicin weekly for 3 weeks (n = 5). Control rats were injected with normal saline (n = 5). At 24 hours after the final treatment, triggering imaging was performed 15 min after an intravenous bolus injection of A5MB for washout of freely circulating microbubbles. After echocardiography, the heart was isolated for histological detection of apoptosis by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay.


RESULTS
In the in vitro tests, fluorescence intensity was low for healthy cells and high for apoptotic cells when incubated with FITC-labeled annexin A5 and A5MB. Rats treated with doxorubicin showed significant contrast opacification of the myocardium on contrast echocardiography using A5MB. However, no opacification was observed in control rats. Apoptosis was confirmed by TUNEL assay in doxorubicin treated rats.


CONCLUSIONS
Acute doxorubicin-induced cardiomyopathy based on early apoptosis can be assessed and imaged with targeted ultrasound imaging using A5MB in rats.
Division of Cardiology, Heart Center, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
Pil-Ki
PK
Min
Soyeon
S
Lim
Soo-Jung
SJ
Kang
Sung-Yu
SY
Hong
Ki-Chul
KC
Hwang
Kwang-Hoe
KH
Chung
Chi Young
CY
Shim
Se-Joong
SJ
Rim
Namsik
N
Chung