RESUMO
ObjectiveTo establish nude mouse tumor models bearing human pancreatic adenocarcinoma SW1990 cells in multiple sites at different time-points and investigate the feasibiilty of multiple tumor-bearing in these models; then the findings and detection rate of 3.0T magnetic resonance image (MRI) in subcutaneous transplanted tumors was analyzed. Methods A total of 6 BALB/C nude mice were randomized into 3 groups (2 mice per group ).At the 1st,8th,15th day,the mice were injected subcutaneously with the suspension of SW1990 cells at left axilla and right axilla and right groin in sequence.Three weeks later,all the bearing-tumor mice were performed with MRI non-contrast enhanced scanning plus Gd-DTPA enhanced scan and the subcutaneous masses were subjected to pathological analysis.ResultsAll the 6 nude mice were alive during the study and obvious mass was observed in every injected site.The tumor size was positively associated with the grwing time.There were 9 tumors which could be de.ted by noncontrast enhanced MRI scanning and one more tumor was detected by contrast enhanced scanning.2 tumors were not detected,the 2 tumors were located at subcutaneous of right groin,with the shortest growing time,and the major axis of the 2 un-detected tumors was less than 5mm.Despite the MRI findings of the transplanted masses similar to that of human pancreatic adenocarcinoma with bleeding,necrosis,they presented the characteristics of a clear rim,with pseudocapeule sign.All the 12 masses were similar with human pancreatic adenocarcinoma under light microscope.ConclusionsIt is feasible to transplant human pancreatic adenocarcinoma cell at three different subcutaneous sites (injected at three different points of time) in the nude mouse,with a minimal survival time of three weeks.However,routine 3.0T MRI cannot detect the early tumors (growing time within 1 week,major axis ＜5 mm).