Study of 99mTc-annexin V uptake in apoptotic cell models of Parkinson's disease.
OBJECTIVE
To investigate the feasibility of radiolabelled annexin V imaging for early diagnosis of Parkinson's disease.


METHODS
99mTc-HYNIC-annexin V was prepared and its binding to apoptotic cell models of Parkinson's disease was studied in vitro. Cellular models of Parkinson's disease were produced by administering different concentrations of 1-methyl-4-phenylpyridinium to PC12 and SH-SY5Y cell lines. Cell apoptosis rates were analysed by flow cytometry. Annexin V was labelled with 99mTc by hydrazinonicotinamide (HYNIC). Cell binding studies were carried out using cellular models of Parkinson's disease. Cell uptake studies were also performed after different levels of MPP treatment, and the correlation between the degree of apoptosis and Tc-HYNIC-annexin V uptake was analysed.


RESULTS
The specific activity of 99mTc-HYNIC-annexin V was 3.7-74 x 10 Bq.mg protein. In-vitro binding of 99mTc-HYNIC-annexin V to model cells was specific, saturable and time dependent. Scatchard analysis gave a Kd of 7.16+/-1.78 nmol.l, Bmax values of 179+/-33 fmol per 10(6) cells (PC12) and 220+/-26 fmol per 10(6) cells (SHSY5Y). MPP at different concentrations can induce cell apoptosis in a dose-dependent manner; cellular uptake of 99mTc-HYNIC-annexin V as indicated by membrane-bound radiolabelled annexin V activity was linearly correlated with total fluorescence, as observed by FITC-annexin V flow cytometry (PC12: r=0.924; SH-SY5Y: r=0.937, P<0.01).


CONCLUSIONS
99mTc-HYNIC-annexin V retains its receptor-binding activity and has a high affinity to cellular models of Parkinson's disease. The uptake of radioactivity correlated well with cell apoptosis rates; thus, 99mTc-annexin V is a potential imaging agent with which to detect early neuron damage in Parkinson's disease.
Cao
Wei
W
Department of aNuclear Medicine, Union Hospital of Huazhong University of Science and Technology, Wuhan, China. caoweii@gmail.com
Huang
Jinsha
J
Wu
Jiyuan
J
Cao
Guoxiang
G
He
Yong
Y
Hu
Dan
D
Sun
Shenggang
S
An
Rui
R
Zhang
Yongxue
Y
D000818:Animals; D017304:Annexin A5 / Q000493:pharmacokinetics*; D017209:Apoptosis; D009474:Neurons / Q000000981:diagnostic imaging* / Q000378:metabolism*; D015609:Organotechnetium Compounds / Q000493:pharmacokinetics*; D016716:PC12 Cells; D010300:Parkinson Disease / Q000000981:diagnostic imaging* / Q000378:metabolism* / Q000473:pathology; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D051381:Rats
D017304:Annexin A5; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C117287:technetium Tc 99m HYNIC annexin V