[Orthotopic implantation of human colon cancers into nude mice. Methodology and physiopathological value].

Objective: The xenograft of human cancers into athymic nude mice makes it possible to obtain abundant tumour material and deepen biological characterization. Usually, the tumours are grafted into the subcutaneous tissue whose environment is indeed different from that of original colon cancer.

Methods: In order to transplant tumours into an orthotopic environment, intra-caecal implantation of colon cancers was performed. A tumour fragment (30 mm3) was deposited at the surface of serous membrane of the caecum, previously scrapped, fixed with a thread and recovered with biologic glue. Six different types of colon tumour, previously adapted to transplantation in nude mice, were similarly grafted.

Results: Twenty to forty days after transplantation, tumour takes were observed with a similar rate by the subcutaneous or intra-caecal graft (93% of 115 and 96.8% of 154 transplantations, respectively). Tumour growth varied between the tumours implanted into the two sites. Moreover, only the tumours intracaecally transplanted developed nodal and liver metastases. Histological examination revealed the invasion of the muscle layer, submucosal tissue and mucosal membrane by tumour cells and the mixture of normal glands and neoplastic glands.

Conclusions: This technique of orthotopic implantation of colon cancer samples will contribute to obtain an experimental model for colon cancer research.