99mTc-HYNIC-Annexin V detection of apoptosis in the rabbit model of liver cancer.

To investigate the feasibility of detection of apoptosis in vivo by 99mTc-HYNIC-Annexin V, Annexin V was labeled with 99mTc through HYNIC. 18 New Zealand rabbits implanted VX-2 were randomly divided into control (n = 8) and paclitaxel (PAC, n = 10) groups, given 2 mL/kg of normal saline or 2.4 mg/kg of PAC intravenously. The liver tumor imaging was detected by SPECT through intravenous injection of 99mTc-HYNIC-Annexin V before treatment, 24 hours and 48 hours after treatment respectively. Tumor radioactive count proportion to non-tumor sites was calculated. When the last imaging was finished, the rabbits were sacrificed. The tumor was taken out and divided into two pieces, one for TUNEL immunohistochemical analysis and the other for flow cytometry (FCM). We found that the rate of Annexin V labeled with 99mTc through HYNIC was more than 95%, and radiochemical purity was above 95%. The SPECT showed that two groups had no significant tumor imaging before the treatment. There is no significant tumor imaging in control group, while the PAC group 24 h and 48 h after treatment showed significant accumulation. The Tumor/non-Tumor (T/NT) in PAC group at 24 h and 48 h after chemotherapy was significantly different from that in the control group and PAC group prior to treatment. There was no significant difference between 24 h and 48 h in PAC group. The TUNEL-positive cells detected by immunohistochemistry and apoptotic rate detected by FCM in PAC group were significant different from those in control group. The T/NT was significantly correlated to TUNEL-positive cells and apoptotic rate of the tumor. PAC can induce apoptosis of rabbit VX-2 liver cancer cells. 24-48 h after paclitaxel chemotherapy is a window time for apoptosis detection. Apoptotic cells in vivo can be detected by SPECT through 99mTc-HYNIC-Annexin V.