Objective   This study aims to investigate the neural invasion of orthotopic pancreatic cancer in a nude mouse model.

  Methods  Human pancreatic cancer cell lines MIA PaCa-2 and Capan-2 were cultured and hypodermically injected into nude mice to set up an orthotopic animal model for pancreatic cancer. The mice were killed 4, 6, and 8 weeks post-injection, and specimens were studied using macroscopic methods. Staining with H＆E was also performed to observe tumor volume, metastasis, and neural invasion in the orthotopic xenograft animal model of pancreatic cancer.

  Results  The neoplasm formation ratio in the nude mice was 100%. Neural invasion ratios reached 50.00% and 33.33% in three cases of the MiaPaCa-2 cell line and two cases of the Capan-2 cell line 4 weeks after orthotopic transplantation. Neural invasion ratios 6 weeks after transplantation were 83.33% and 66.67% in the two groups, respectively. Neural ratios were 100% in both lines 8 weeks after the procedure. The neural invasion rate was significantly higher in the group with orthotopic xenograft animal model than in the group with metastasis at other sites (P<0.01).

  Conclusion  Neural invasion is an early and independent event in pancreatic cancer. Pancreatic cancer has the unusual tendency of invasion into and around neural tissues, even at early stages of the disease and with or without other metastases.