Studies On Biodistribution And Radioimmunoimaging Of ～(99)Tc～m Labeled ND1 Recombined ScFvs In Nude Mice Bearing Human Colonic Carcinoma

ObjectiveTo study biodistribution and radioimmunoimaging of Tcm labeled ND1 recombined scFvsin nude mice bearing human colonic carcinoma.Methods1. The preparation and purification of ND1 recombined scFvs ND1 recombined scFvs is identified to be IgG1 and have immune activity by ELISA. Thereby, it is proved to have better affinity. The concentration of antibody is 1.5mg/ml to reserve.2. Establishing human colonic carcinoma xenograft model in nude mice bearing human colonic carcinoma. 18 pure - blood BALB/c female nude mice with 4 - 6 week - age were included in this study, weighted 20 - 30g. The human carcinoma intestinum crassum cell line CCL - 187 was used for all of the animal experiments. Cell suspension in normal saline containing 1 x 10 cells s. c into the back of BALB/c nude mice, bred in animal antnun with grade SPF. Tumor xenografts reached a usable size (0.5 - 1.0cm, geometric mean diameter) after 4-6 weeks.3. Labeled antibody and determination of labeling rate. ND1 scFv was labeled by direct labeling method, paper chromatography determined labelling rate.4. Biodistribution Of 99Tcm labeled ND1 recombined scFvsin nude mice bearing human colonic carcinoma. 18 pure - blood BALB/c female nude mice bearing human colonic carcinoma were divided into two groups. One of the two groups was devided into 3 groups, 3 nude mice in one group, 99Tcm - ND1 recombined scFvs was administed by celiac injection to each nude mice respectively. At time intervals of 1, 3,8hr postinjection, three mice of each group were imaged on a SPECT, were killed by cervical dislocation immediately after RII. Blood samples were obtained by eyeball puncture. Ten tissues, including whole tumor xenografts, lung, kidney, spleen, liver, stomach, intestinum crassum, back thigh skeleton, muscle and hearts, were sampled. The wet weight of all samples wet recorded, and the radioactivity in each sample measured with gamma counter as cpm and calculate radioactivity ratio of tumor to non - tumor (T/NT).The other of the two groups was devided into 3 groups, 3 nude mice in one group. 99Tcm-ND1 recombined scFvs was administed by celiac injection to each nude mouse respectively. Mice were killed by cervical dislocation at time intervals of l,3,8hr postinjection, whole tumor xenografts and intestinum crassum were sampled. The radioactivity in each sample measured with gamma counter as cpm and calculate radioactivity ratio of tumor to non - tumor (T/NT).5. Handling statistics. Data were expressed in form of x +s, t test was applied in inter - group comparisons.Results1. Determination of labeling rate determination of labeling rate of 99Tcm - ND1 recombined scFvs was 72%.2. The value of blood T/NT was 2.62 +1.23 at 1h, 3.90+3.25at3h, 0. 58 +0. 17 at 8h by celiac injection. There were statistic differences in large intestine of celiac injection and tail vein group ( P <0.05,P<0.005).3. Radioimmunoimaging. Favorable images were obtained in 9 tumor tissues, positive rate being 100%. The imaging at 3h was the most favorable.Conclusions99Tcm - ND1 recombined scFvs had high affinity to nude mice bearing human colonic carcinoma xenografts. ND1 scFv can be a promising direct carrier in diagnosing and prognosis of colonic carcinoma , and provide an effective method for specific diagnosing of colonic carcinoma.