Detection of tumor cell apoptosis with ~99Tc~m-rh-Annexin V after radiotherapy or chemotherapy

Objective To evaluate the efficacy of ~(99)Tc~m labeled recombinant human Annexin V(~(99)Tc~m- rh-AnnexinV)in evaluating apoptosis after radio-or chemotherapy in Hca-F25(hepatoma cell line)mice mod- els.Methods The tumor models were established in mice at 8th day(tumor size around 1 cm in diameter)after treated with Hca-F25(subcutaneous injection at right axillary).Mice were divided into three groups.Group A (n=13)were chemotherapy,group B(n=10)were radiotherapy and group C(n=12)were for control.For groups A and C,the imaging time interval were 1 h(n=3 for group A and n=3 for group C),4 h(n=4 for group A and n=4 for group C)and 6 h(n=6 for group A and n=5 for group C)after intravenous in- jection(from tail vein)of ~(99)Tc~m-rh-Annexin V.For group B,~(99)Tc~m-rh-Annexin V was given in all at 1 h af- ter radiation therapy(n=4 for 2 Gy,n=3 for 5 Gy and n=3 for 10 Gy).At 6 h after injection,all had scintigraphic images.After completion of data acquisition,all mice were sacrificed to evaluate the biodistri- bution of ~(99)Tc~m-rh-Annexin V in each tissue and were expressed as the percentage activity of injection dose per gram of tissue(% ID/g).The percentage of cell apoptosis was calculated with Annexin V/PI flow cy- tometry(Annexin V +/PI~- was positive).Results Significantly higher cell apoptotic rates were observed in the treated mice than in the control mice[(11.16±3.83)% vs(2.11 ±1.51)% for chemotherapy group,F=56.414,P0.001;(17.40±5.20)% vs(2.11±1.51)% for radiotherapy group,F= 94.748,P0.001].Besides,positive correlations were observed between the percentage of cell apoptosis and the biodistribution of ~(99)Tc~m-rh-Annexin V in tumor in chemotherapy treated(4 and 6 h,F=14.307, 7.074,28.672,all P0.05,respectively)and radiotherapy treated mice and control with r=0.813(P= 0.002)for chemotherapy treated 4 and 6 h mice and r=0.780(P=0.004)for radiotherapy treated mice. Conclusion ~(99)Tc~m-rh-Annexin V is a promising drug in assessing the degree of apoptosis after chemo-or radiotherapy.