[Model mechanism] After subcutaneous implantation of human tumors, tumor cells are not easy to invade surrounding tissues, because envelopes are often formed around the graft, and the same tumor cells are not easy to penetrate into the abdominal cavity or other tissues. After being transplanted in situ, most of them are susceptible to invasion by surrounding tissues and even distant organs.
[Modeling method]
1. Digest the adherent growth of human lung adenocarcinoma cells in logarithmic growth phase with 0.25% trypsin and 0.02% EDTA solution, wash with Hank’s solution, resuspend in saline, and remove 1×1,000,000 cells. Cells/0.2ml as living cells. Planting saline under the skin behind the neck of nude mice is considered physiological.
2. In the intraperitoneal transplantation group, solid tumors grown under the skin were used as cell suspensions, and 1×1,000,000 live cells/0.4ml normal saline and 1×10,000,000 live cells/0.4ml normal saline were respectively inoculated into nudes. In the abdominal cavity of the mouse. done.
3. In the muscle transplantation group, a solid tumor of human lung adenocarcinoma growing under the skin was cut into small pieces of 2-3 cubic millimeters, and transplanted into the muscles of the inner hind limbs of nude mice with a 17-gauge ascites needle. The experiment is performed under sterile conditions or under SPF isolator.
[Characteristics of the model] In the subcutaneous transplantation group, the tumor incubation period was 26 to 117 days, the tumor incidence was 63.6%, and a single tumor began to appear under the skin, gradually becoming multiple nodules and skin. I can move without being attached. In the intraperitoneal transplantation group, the abdomen began to swell 17 to 18 days after the inoculation, and the tumor was rapidly damaged. At the time of autopsy, there were many organs in the abdominal cavity, extensive tumor nodules of various sizes, 0.5-1 ml in most animals. Bloody ascites. In the intramuscular implant group, tumors developed at the inoculation site 20 days after inoculation, swollen and grew, thickened legs, and showed incomplete or non-enveloped tumor sections, and tumor cells directly penetrated into the muscle.
[Model Evaluation and Application] The nude mouse transplanted tumor model of human lung adenocarcinoma is an ideal animal model for studying human cancer in vitro. However, the biological characteristics of human lung adenocarcinoma transplanted tumors in nude mice that have been passaged for a long time may change, and the degree of differentiation of cancer cells gradually increases as the number of passages of transplanted tumors increases. I will. The serum CEA content of tumor-bearing nude mice also gradually decreased. The instability of the biological characteristics of these transplanted tumors may be related to the inherent heterogeneity of tumor cells and host factors.