The Establishment Of VX2 Esophageal Carcinoma Model In Rabbits And The Effect Of Local Targeted Drug On The Esophageal Mucosa

Objective: 1. To establish VX2 esophageal carcinoma model in rabbits by implanting tumor fragments and investigate its biological characteristics in order to offer ideal experimental model for the esophageal cancer research and looking for effective treatment methods. 2. Using specially designed drug delivery system, we observe the esophageal injury caused by perfusing chemotherapeutic drug(DDP) in local esophageal intracavity. At the same time, we discuss the protective effect of local application of amifostine (cell protective agent) on esophageal injury induced by local chemotherapy.It will provide a new method for clinical using of amifostine in order to reduce its toxocity. It can also provide theoretical basis on the study of local targeted therapy for esophageal carcinoma.Methods: 1. The establishment of VX2 esophageal carcinoma model in rabbits: After anesthesia, tumor tissues were dissected from the VX2 tumor–bearing rabbit's thigh and rinsed three times in saline. We sheared the tumor tissues into 1mm3.Then we fixed the rabbits on the operating table supinated, exposed the rabbits'abdominal esophagus and scissored the esophageal muscularis and serosa 3cm away from the cardia. We implanted the VX2 tumor fragments between the esophageal mucosa and muscularis, sutured the esophageal muscularis and closed the abdomen layer by layer. Each rabbit was injected 400,000 IU of penicillin three days. We observed the rabbits dieting condition and weight–change everyday. At the seventh day,fourteenth day and twenty-first day after implanting the tumor fragments in the rabbits'esophagus, CT scaning and barium meal study were performed to identify the imaging features of the tumor model. At the twenty-first day, rabbits were sacrified and tumor specimens were fixed with formalin for pathological examination. 2.The experimental study of local targeted drug delivery: We designed a special kind of drug delivery system that can block up the esophagus with two sacculuses, forming a lacune between the two sacculuses, and then infuse the DDP and (or) amifostine liquid to the lacune. 24 New Zealand white rabbits were randomly divided into control group, DDP group and combined therapy group. The number of rabbits in each group is 8. The control group: We used the physiological saline to effect the esophagus for 50min . The DDP group: We used the 0.25mg/ml DDP liquid to effect the esophagus for 30min and used the physiological saline to effect the esophagus for 20min before chemotherapy. The combined therapy group: We used the 0.25mg/ml DDP liquid to effect the esophagus for 30min and used the 0.8mg/ml amifostine liquid to effect the esophagus for 20min before chemotherapy. The rabbits were sacrified and specimens were fixed with formalin for pathological examination after 6 days.Results: 1. The establishment of VX2 esophageal carcinoma model in rabbits: There were two rabbits died because of surgical accident at the second day. The dieting condition and psychosis of the remaining 10 rabbits were good at the first 7 days. There were no significant changes in body weight. After 14 days, the body weight of the rabbits began to decrease by an average of 2% ~ 3% everyday.At the twenty-first day,the body weight of the rabbits had obviously decreased by an average of 15% ~20%. The barium meal study and CT scanning showed the tumor at the lower esophagus.The successful ratio of established model was 100%. We executed the rabbits and exposed the esophagus. The place of operation developed solid tumor. The tumor encircled the esophagus and entered the thoracic cavity.The volume was 21.04±10.35cm3. Two rabbits appeared obvious pleural effusion. We can see some pieces of swelling lymph node around the tumor in eight rabbits and pulmonary metastasis in three rabbits. After cutting the tumor and the esophagus, we can see the tumor was off-white and fish-like. The tumor pierced the esophageal wall and the the tumor surface was rotten. Four rabbits appeared esophageal fistula.Poorly differentiated squamous carcinoma was diagnosed with pathological section. At the fourteenth day,the barium meal study showed the length of filling defects of the esophagus was 1.51±0.46cm. CT scanning showed the soft tissue shadow at the lower esophagus,with the maximal diameter of 1.04±0.27cm. At twenty-first day,the barium meal study showed the length of filling defects of the esophagus was 3.90±0.55cm. Four rabbits appeared esophageal perforation. CT scanning showed the maximal diameter was 2.28±0.34cm. Five rabbits appeared pleural effusion. 2. The condition of esophageal mucosal injury: Gross appearance: The esophagus of the DDP group significantly expanded and was edematous on perfusion site. The mucosal surface was covered with off-white "pseudomembranous". The mucosa had obvious hyperemia and erosions.The esophagus of the combined therapy group mildly expanded, had no "pseudomembranous". The mucosal surface was smooth or mild hyperemia. Light microscope: The esophageal epithelium of the DDP group was in part or full-thickness shedding. The mucosa was edematous and submucosal blood vessels was congestive. The submucosa had a large number of inflammatory cells infiltrated,which also invaded the muscularis and the neutrophils was main source.The esophageal epithelium of the combined therapy group was in part shedding. The lamina propria and submucosa had medium dose of inflammatory cells infiltrated. The muscularis had no inflammatory cell infiltrated.Conclusion: 1.The establishment of VX2 esophageal carcinoma model in rabbits by implanting tumor fragments had high successful ratio,short cycle and rapid growth.The biological behavior of VX2 is similar to human esophageal carcinoma.2.The method of local drug delivery for the esophageal carcinoma can be come true by using special device. It can increase the local drug concentration,reduce drug dosage and reduce the systemic side effects. In this way, it can provide us with theoretical basis on the study of local targeted therapy for esophageal carcinoma.3.The esophageal mucosa could be damaged obviously by locally applying DDP.Locally applying cell protective agent-amifostine before chemotherapy can obviously decrease chemical esophagitis. It can provide a new method for the clinical application of amifostine.